Name: determination of self-(in)compatibility and inter-(in)compatibility relationships in citrus using manual pollination, microscopy, and s-genotype analyses
Uploaded: 2023-06-30T14:50:00
Description: Watch this Scientific Journal Video about Determination of Self-Incompatibility and Inter-Incompatibility Relationships in Citrus Using Manual Pollination, Microscopy, and S-Genotype Analyses at JoVE.

This project was financially supported by the National Natural Science Foundation of China (32122075, 32072523).

1. Preparation for aniline blue staining
<ol>
	<li>Prepare the following reagents and tools for the experiment: a pollinator brush, tweezers, a pencil, sulfate paper, a pollination bag, zip lock bags, paper clips, formaldehyde, glacial acetic acid, absolute ethanol, centrifuge tubes, forceps, glue droppers, glass slides, coverslips, scalpels, and polyethylene glycol.</li>
	<li>Prepare in vitro germination medium containing 0.02% MgSO4, 0.01% KNO3, 0.03% Ca(NO3)...

<ol>
	<li>Matsumoto, D., Tao, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+of+S-RNases+by+an+S+locus+F-box+like+protein+and+an+S+haplotype-specific+F-box+like+protein+in+the+Prunus-specific+self-incompatibility+system.">Recognition of S-RNases by an S locus F-box like protein and an S haplotype-specific F-box like protein in the Prunus-specific self-incompatibility system.</a> Plant Molecular Biology. 100 (4-5), 367-378 (2019).</li><li>Goldberg, E. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Species+selection+maintains+self-incompatibility.">Species selection maintains self-incompatibility.</a> Science. 330 (6003), 493-495 (2010).</li><li>Zhang, L., Wang, R., Zhao, G., Wang, A., Lin, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+study+on+fruit+quality+of+Guangfeng+Ma+jia+pummelo+and+Pinghe+red+pummelo.">Comparative study on fruit quality of Guangfeng Ma jia pummelo and Pinghe red pummelo.</a> China Agricultural Science Bulletin. 37 (22), 126-130 (2021).</li><li>Min, H. E., Chao, G. U., Juyou, W. U., Shaoling, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+on+self-incompatibility+mechanism+in+fruit+trees.">Recent advances on self-incompatibility mechanism in fruit trees.</a> Acta Horticulturae Sinica. 48 (4), 759-777 (2021).</li><li>Fujii, S., Kubo, K., Takayama, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-self-+and+self-recognition+models+in+plant+self-incompatibility.">Non-self- and self-recognition models in plant self-incompatibility.</a> Nature Plants. 2 (9), 2-9 (2016).</li><li>Meng, X., Sun, P., Kao, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=S-RNase-based+self-incompatibility+in+Petunia+inflata.">S-RNase-based self-incompatibility in Petunia inflata.</a> Annals of Botany. 108 (4), 637-646 (2011).</li><li>Liang, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+self-compatibility+by+a+mutant+Sm-RNase+in+citrus.">Evolution of self-compatibility by a mutant Sm-RNase in citrus.</a> Nature Plants. 6 (2), 131-142 (2020).</li><li>Thomas, S. G., Franklin-Tong, V. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-incompatibility+triggers+programmed+cell+death+in+Papaver+pollen.">Self-incompatibility triggers programmed cell death in Papaver pollen.</a> Nature. 429, 305-309 (2004).</li><li>Hu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Downregulated+expression+of+S2-RNase+attenuates+self-incompatibility+in+&amp;#34;Guiyou+No.+1&amp;#34;+pummelo.">Downregulated expression of S2-RNase attenuates self-incompatibility in &amp;#34;Guiyou No. 1&amp;#34; pummelo.</a> Horticulture Research. 8 (1), 199 (2021).</li><li>Guo, H., Halitschke, R., Wielsch, N., Gase, K., Baldwin, I. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mate+selection+in+self-compatible+wild+tobacco+results+from+coordinated+variation+in+homologous+self-Incompatibility+genes.">Mate selection in self-compatible wild tobacco results from coordinated variation in homologous self-Incompatibility genes.</a> Current Biology. 29 (12), 2020-2030 (2019).</li><li>Sun, P., Li, S., Lu, D., Williams, J. S., Kao, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pollen+S-locus+F-box+proteins+of+petunia+involved+in+S-RNase-based+self-incompatibility+are+themselves+subject+to+ubiquitin-mediated+degradation.">Pollen S-locus F-box proteins of petunia involved in S-RNase-based self-incompatibility are themselves subject to ubiquitin-mediated degradation.</a> The Plant Journal. 83 (2), 213-223 (2015).</li><li>Hua, Z., Kao, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+characterization+of+components+of+a+putative+petunia+S-locus+F-box-containing+E3+ligase+complex+involved+in+S-RNase-based+self-incompatibility.">Identification and characterization of components of a putative petunia S-locus F-box-containing E3 ligase complex involved in S-RNase-based self-incompatibility.</a> Plant Cell. 18 (10), 2531-2553 (2006).</li><li>Entani, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ubiquitin-proteasome-mediated+degradation+of+S-RNase+in+a+solanaceous+cross-compatibility+reaction.">Ubiquitin-proteasome-mediated degradation of S-RNase in a solanaceous cross-compatibility reaction.</a> The Plant Journal. 78 (6), 1014-1021 (2014).</li><li>Abdallah, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+self-incompatibility+and+genetic+diversity+in+diploid+and+hexaploid+plum+genotypes.">Analysis of self-incompatibility and genetic diversity in diploid and hexaploid plum genotypes.</a> Frontiers in Plant Science. 10, 896 (2019).</li><li>Herrera, S., Lora, J., Hormaza, J. I., Herrero, M., Rodrigo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimizing+production+in+the+new+generation+of+apricot+cultivars:+self-incompatibility,+S-RNase+allele+identification,+and+incompatibility+group+assignment.+.">Optimizing production in the new generation of apricot cultivars: self-incompatibility, S-RNase allele identification, and incompatibility group assignment. .</a> Frontiers in Plant Science. 9, 527 (2018).</li><li>Yuan, S. C., Chin, S. W., Lee, C. Y., Chen, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phalaenopsis+pollinia+storage+at+sub-zero+temperature+and+its+pollen+viability+assessment.">Phalaenopsis pollinia storage at sub-zero temperature and its pollen viability assessment.</a> Botanical Studies. 59 (1), 1 (2018).</li><li>Liang, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+evolution+of+genes+related+to+self-incompatibility+in+citrus.">Identification and evolution of genes related to self-incompatibility in citrus.</a> , (2019).</li><li>Cheng, Y. J., Guo, W. W., Yi, H. L., Pang, X. M., Deng, X. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+efficient+protocol+for+genomic+DNA+extraction+from+Citrus+species.">An efficient protocol for genomic DNA extraction from Citrus species.</a> Plant Molecular Biology Reporter. 21 (2), 177-178 (2003).</li><li>Wei, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+S-genotypes+of+63+pummelo+germplasm+resources.">Identification of S-genotypes of 63 pummelo germplasm resources.</a> Acta Horticulturae Sinica. 49 (5), 1111-1120 (2021).</li><li>de Nettancourt, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incompatibility+in+angiosperms.">Incompatibility in angiosperms.</a> Sexual Plant Reproduction. 10, 185-199 (1997).</li><li>Igic, B., Lande, R., Kohn, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loss+of+self-incompatibility+and+its+evolutionary+consequences.">Loss of self-incompatibility and its evolutionary consequences.</a> International Journal of Plant Sciences. 169 (1), 93-104 (2008).</li><li>Guerrero, B. I., Guerra, M. E., Rodrigo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishing+pollination+requirements+in+Japanese+plum+by+phenological+monitoring,+hand+pollinations,+fluorescence+microscopy+and+molecular+genotyping.">Establishing pollination requirements in Japanese plum by phenological monitoring, hand pollinations, fluorescence microscopy and molecular genotyping.</a> Journal of Visualized Experiments. (165), e61897 (2020).</li><li>Herrera, S., Lora, J., Hormaza, J. I., Rodrigo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+self-+and+inter-(in)compatibility+relationships+in+apricot+combining+hand-pollination,+microscopy+and+genetic+analyses.">Determination of self- and inter-(in)compatibility relationships in apricot combining hand-pollination, microscopy and genetic analyses.</a> Journal of Visualized Experiments. (160), e60241 (2020).</li></ol>

In fruit crops, both parthenocarpy and SI are important traits because they pave the way for seedless fruits - a trait that is highly appreciated by consumers. Self-incompatibility promotes the rejection of self-pollen and, thus, prevents inbreeding20. Among citrus, pummelo is a self-incompatible variety7. Almost 40% of all angiosperm species exhibit SI21. This trait prevents fruit setting, lowers the yield, and brings huge economic losses to growers...

Self-incompatibility (SI) is a genetically controlled mechanism present in approximately 40% of angiosperm species. In this process, the pistil rejects pollen from a plant with the same SI genotype and, thus, prevents self-fertilization1,2. Ma jia pummelo is a local variety in Jinagsu province, China, with the excellent qualities of large, pink fruit, a rich juice content, a sweet and sour taste, and a thick peel3. Although SI promotes outcrossing, it negatively impacts the yield and quality of fruits4 and necessitates suitable pollinizer trees with distinct SI genotypes for reliable fruit-setting rates and high yields. At present, there are two main types of SI, sporophytic self-incompatibility (SSI), represented by Brassicaceae, and gametophytic self-incompatibility (GSI), represented by Rosaceae, Papaveraceae, Rutaceae, and Solanaceae5,6,7,8.
Citrus is one of the most important fruit crops in the world. The S-RNase-based GSI system is found in many citrus accessions and negatively influences the fruit-setting rate9. In this system, SI is controlled by the S locus, a single polymorphic locus with two complex alleles that carry pistil S determinants and pollen S determinants7. The female determinant is the S ribonuclease (S-RNase), and the male determinant is the S locus F-box (SLF)7. The cells of the pistil secrete S-RNase proteins. The non-self S-RNases are recognized by the SLF proteins, which leads to the ubiquitination and degradation of the non-self S-RNases by the 26S proteasome pathway. In contrast, the self S-RNases are able to accumulate and inhibit pollen tube (PT) growth because they evade the SLF proteins and, therefore, are prevented from ubiquitinzation10,11,12,13.
Here, we report an in vivo technique that is useful for identifying S-genotypes and degrees of pollen compatibility and incompatibility. The protocol involves extracting total DNA from leaves and predicting the S genotype using S-specific primers. Moreover, aniline blue staining and fluorescence microscopy followed by hand pollination provide evidence for the degree of compatibility and incompatibility. The semi in vivo pollination procedure, which involves the manual pollination of flowers in the laboratory14,15,&#160;has also been adapted to assess the degrees of self-compatibility and incompatibility. However, we have also used field pollination followed by the bagging of flowers to avoid contamination from undesired pollen to allow the pollen tubes to develop in natural conditions. This protocol is simple and straightforward and provides the information necessary for the successful selection of suitable pollinizer trees.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>absolute ethanol</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10009218</td>
			<td></td>
		</tr>
		<tr>
			<td>Aniline blue</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Boric acid, H3BO3</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10004818</td>
			<td></td>
		</tr>
		<tr>
			<td>Brown bottle</td>
			<td>Labgic Technology Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium nitrate tetrahydrate, Ca(NO3 )2</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>80029062</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifugal tube</td>
			<td>Labgic Technology Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge tubes</td>
			<td>Labgic Technology Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CTAB</td>
			<td>GEN-VIEW SCIENTIFIC INC</td>
			<td>57-09-0(CAS)</td>
			<td></td>
		</tr>
		<tr>
			<td>Dropping</td>
			<td>Jiangsu Songchang Medical Equipment Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid, EDTA</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10009617</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>LUXIANZI Biotechnology Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>formaldehyde</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10010018</td>
			<td></td>
		</tr>
		<tr>
			<td>Fully automatic sample fast grinder</td>
			<td>Shanghai Jingxin Industrial Development Co., Ltd</td>
			<td>Tissuelyser-96</td>
			<td></td>
		</tr>
		<tr>
			<td>glacial acetic acid</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10000218</td>
			<td></td>
		</tr>
		<tr>
			<td>Grinding Tube</td>
			<td>Shanghai Jingxin Industrial Development Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Isoamyl alcohol</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10003218</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl alcohol</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>80109218</td>
			<td></td>
		</tr>
		<tr>
			<td>label</td>
			<td>M&#38;G Chenguang Stationery Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Leica DMi8</td>
			<td>Shanghai Leica Co.,Ltd</td>
			<td>21903797</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium sulfate heptahydrate, MgSO4</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10013018</td>
			<td></td>
		</tr>
		<tr>
			<td>MICROSCOPE Cover glass</td>
			<td>Zhejiang Shitai Industrial Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10019318</td>
			<td></td>
		</tr>
		<tr>
			<td>paper clips</td>
			<td>M&#38;G Chenguang Stationery Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pencil</td>
			<td>M&#38;G Chenguang Stationery Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pollinator brush</td>
			<td>Shanghai Yimei Plastics Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene glycol, PEG 6000</td>
			<td>Beijing Dingguo Changsheng Biotechnology Co., Ltd</td>
			<td>DH229-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene glycol, PEG-4000</td>
			<td>Guangzhou saiguo biotech Co., Ltd</td>
			<td>1521GR500</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium hydroxide, KOH</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10017008</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium nitrate, KNO3</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10017218</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel</td>
			<td>Jiangsu Songchang Medical Equipment Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Slide</td>
			<td>Zhejiang Shitai Industrial Co., Ltd</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide, NAOH</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10019718</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10021418</td>
			<td></td>
		</tr>
		<tr>
			<td>sulfate paper</td>
			<td>Taizhou Jinnong Mesh Factory</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thermostat water bath</td>
			<td>Shanghai Jinghong Experimental Equipment Co., Ltd</td>
			<td>L-909193</td>
			<td></td>
		</tr>
		<tr>
			<td>Trichloromethane</td>
			<td>Sinopharm Chemical Reagent Co.,Ltd</td>
			<td>10006818</td>
			<td></td>
		</tr>
		<tr>
			<td>Tripotassium phosphate tribasic trihydrate, K3PO4</td>
			<td>Shanghai Lingfeng Chemical Reagent Co.,Ltd</td>
			<td>20032318</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-HCl</td>
			<td>GEN-VIEW SCIENTIFIC INC</td>
			<td>1185-53-1</td>
			<td></td>
		</tr>
		<tr>
			<td>zip lock bags</td>
			<td>M&#38;G Chenguang Stationery Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#946;-Mercaptoethanol</td>
			<td>GEN-VIEW SCIENTIFIC INC</td>
			<td>60-24-2(CAS)</td>
			<td></td>
		</tr>
	</tbody>
</table>

determination of self-(in)compatibility and inter-(in)compatibility relationships in citrus using manual pollination, microscopy, and s-genotype analyses

Citrus uses S-RNase-based self-incompatibility to reject self-pollen and, therefore, requires nearby pollinizer trees for successful pollination and fertilization. However, identifying suitable varieties to serve as pollinizers is a time-consuming process. To solve this problem, we have developed a rapid method for identifying pollination-compatible citrus cultivars that utilizes agarose gel electrophoresis and aniline blue staining. Pollen compatibility is determined based on the identification of S genotypes by extracting total DNA and performing PCR-based genotyping assays with specific primers. Additionally, styles are collected 3-4 days after manual pollination, and aniline blue staining is performed. Finally, the growth status of the pollen tubes is observed with a fluorescence microscope. Pollen compatibility and incompatibility can be established by observing whether the pollen tube growth is normal or suppressed, respectively. Due to its simplicity and cost-effectiveness, this method is an effective tool for determining the pollen compatibility and incompatibility of different citrus varieties to establish incompatibility groups and incompatibility relationships between different cultivars. This method provides information essential for the successful selection of suitable pollinizer trees and, thus, facilitates the establishment of new orchards and the selection of appropriate parents for breeding programs.

For the experiments done here, mature flowers were selected, the anthers&#160;were collected, dried in an oven, and the pollen was germinated at 28&#176;C for 12 h. The pollen viability and germination rates were quantified as shown in Figure 1.
Citrus was manually pollinated, and the pollen compatibility and incompatibility were assessed using aniline blue staining and fluorescence microscopy. The compatible pollen could germinate on the surface of the stigma and...

Watch this Scientific Journal Video about Determination of Self-Incompatibility and Inter-Incompatibility Relationships in Citrus Using Manual Pollination, Microscopy, and S-Genotype Analyses at JoVE.

Determination of Self-Incompatibility and Inter-Incompatibility Relationships in Citrus Using Manual Pollination, Microscopy, and S-Genotype Analyses

This protocol provides a rapid method for determining pollen compatibility and incompatibility in citrus cultivars.

Determination of Self-(In)compatibility and Inter-(In)compatibility Relationships in Citrus Using Manual Pollination, Microscopy, and S-Genotype Analyses

Citrus uses S-RNase-based self-incompatibility to reject self-pollen and, therefore, requires nearby pollinizer trees for successful pollination and ...

This technique can efficiently identify the S genotype and accurately identify citrus self-incompatibility, providing necessary information for selecting suitable pollenizer trees. This is a time-efficient, simple, and reliable technique to select the appropriate parents trees in breeding programs. This technique is simple and easy to do and doing experiment for the first time needs patience and care.The S genotype identification and S-specific primer designing needs more attention and care. Demonstrating the procedure will be Yu Hu, a master graduate student from my laboratory. Begin pollen collection by taking the Majia pomelo, Citrus maxima, flowers to the laboratory.Collect the anthers using tweezers and place them in a Petri dish containing filter paper. Dry the pollen grains by placing the Petri dish containing the anthers in a 28-degree-Celsius oven for 24 hours. After drying, save the pollen in a Micro Centron airtight zip lock bag containing color-changing silica gel.Close the bag and label the bag with the name of the pollen variety and the date of storage. Pour 300 microliters of the liquid medium into the cap of a two-milliliter centrifuge tube and sprinkle the pollen evenly with the help of a pollination brush. Place the pollen in a humidified black box and incubate at 28 degrees Celsius for 12 hours.After incubation, cut the top one-millimeter tip off a 1, 000 microliter pipette tip and aspirate the pollen with a small amount of culture solution. Place the pollen at the center of the microscope slide and cover it with a cover slip. Once done, observe the specimen with an inverted microscope using a 10X objective.Perform three independent replicates using approximately the same pollen density for each replicate. For pollination, use a pollination brush to spread a sufficient amount of viable pollen onto the surface of the stigma, ensuring not to damage the pistil. Cover the pollinated flowers with a sulfate paper bag and prevent pollination by genotypically-distinct pollens by sealing the bag using a paperclip.Write the name of the species and the number and time of pollination on the label. Hang the label on the branches near the pollinated flowers. Remove the pollination bags approximately three to four days after pollination and collect the pollinated flowers in zip lock bags.Immediately remove the petals, receptacles, and ovaries from the flowers and immerse the stigma fused to style in a centrifuge tube containing a freshly-prepared fixative solution. Incubate the stigma and style in the fixative solution overnight at four degrees Celsius. The next day, discard the fixative solution before washing the stigma and style two to three times in 95%ethanol.Then, add 70%ethanol solution to the style, ensuring the sample is completely immersed in the solution. The styles at this stage can be stored at four degrees Celsius for one to two months. For aniline blue staining, wash the style samples stored in 70%ethanol with distilled water three to four times.Immerse it in a four molar sodium hydroxide solution and seal it before incubating it in a 65-degree-Celsius water bath for 60 minutes. During this step, the color of the style changes from yellow-white to orange-red. Next, soak the styles in distilled water.After 30 minutes, discard the distilled water and wash the styles with distilled water three to four times or until the color of the style becomes yellow. Then, add the aniline blue until the sample is submerged and incubate for 12 hours in the dark. Observe the pollen tube growth under the fluorescence microscope.Place the slide on a flat table. Divide the style into two halves along the longitudinal axis using a scalpel. Place one half of the style on a glass slide and add two to three drops of polyethylene glycol to the surface of the slide.Then, cover it with a cover slip. Once done, place the slide on the microscope stage above the aperture and visualize using a 10X objective. Use the DAPI filter and observe the pollen tube growth.Observe five styles for each type of pollination. The pollen viability of Citrus maxima and germination rates were quantified using fluorescent microscopy. The compatible pollen successfully germinated on the surface of the stigma and produced a normal pollen tube, which grew and ultimately led to fertilization in the ovary.In contrast, incompatible pollen tubes grew through approximately 2/3 of the style and then stopped growing. Agarose gel electrophoresis detected the DNA product amplified using the S locus-specific primers. It showed the amplification of the DNA product between 500 to 1, 000 base pairs.The corresponding S genotype was identified. 21 S haplotypes in different citrus species were identified using this method. The pollination step is critical.Only the successful pollination can ensure the subsequent observation of pollen tubes. The technique was used to analyze the self-incompatibility traits and to explore and identify the female determinants of the self-incompatibility. This method is important for self-incompatibility research and breeding programs.It can also facilitate the farming community for selecting pollenizer trees for their orchards.

determination-self-incompatibility-inter-incompatibility

Research

JoVE Journal

Biology

Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the lipidic cubic phase or in meso method. The method has been shown to be quite versatile in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and alpha-helical and beta-barrel proteins. Recent successes using in meso crystallization are the human engineered beta2-adrenergic and adenosine A2a G protein-coupled receptors. Protocols are presented for reconstituting the membrane protein into the monoolein-based mesophase, and for setting up crystallizations in the manual mode. Additional steps in the overall process, such as crystal harvesting, are to be addressed in future video articles. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour.

Herein is described the procedure implemented in the Caffrey Membrane Structural and Functional Biology Group to set up manually crystallization trials of membrane proteins in lipidic mesophases.

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the ...

Manual Restraint and Common Compound Administration Routes in Mice and Rats

Being able to safely and effectively restrain mice and rats is an important part of conducting research. Working confidently and humanely with mice and rats requires a basic competency in handling and restraint methods. This article will present the basic principles required to safely handle animals. One-handed, two-handed, and restraint with specially designed restraint objects will be illustrated. Often, another part of the research or testing use of animals is the effective administration of compounds to mice and rats. Although there are a large number of possible administration routes (limited only by the size and organs of the animal), most are not used regularly in research. This video will illustrate several of the more common routes, including intravenous, intramuscular, subcutaneous, and oral gavage. The goal of this article is to expose a viewer unfamiliar with these techniques to basic restraint and substance administration routes. This video does not replace required hands-on training at your facility, but is meant to augment and supplement that training.

Working safely and humanely with research rodents requires a core competency in handling and restraint methods. This article will present the basic principles required to safely handle and effectively administer compounds to mice and rats.

Being able to safely and effectively restrain mice and rats is an important part of conducting research.  Working confidently and humanely with mice and ...

Evisceration of Mouse Vitreous and Retina for Proteomic Analyses

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is a highly aqueous extracellular matrix overlying the retina where intraocular as well as extraocular proteins accumulate during disease.1-3 Abnormal interactions between vitreous and retina underlie several diseases such as retinal detachment, proliferative diabetic retinopathy, uveitis, and proliferative vitreoretinopathy.1,4 The relative mouse vitreous volume is significantly smaller than the human vitreous (Figure 1), since the mouse lens occupies nearly 75% of its eye.5 This has made biochemical studies of mouse vitreous challenging. In this video article, we present a technique to dissect and isolate the mouse vitreous from the retina, which will allow use of transgenic mouse models to more clearly define the role of this extracellular matrix in the development of vitreoretinal diseases.

The dissection technique illustrates evisceration of the vitreous, retina, and lens from the mouse eye, separation by centrifugation, and characterization with protein assays.

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is ...

Nano-fEM: Protein Localization Using Photo-activated Localization Microscopy and Electron Microscopy

Mapping the distribution of proteins is essential for understanding the function of proteins in a cell. Fluorescence microscopy is extensively used for protein localization, but subcellular context is often absent in fluorescence images. Immuno-electron microscopy, on the other hand, can localize proteins, but the technique is limited by a lack of compatible antibodies, poor preservation of morphology and because most antigens are not exposed to the specimen surface. Correlative approaches can acquire the fluorescence image from a whole cell first, either from immuno-fluorescence or genetically tagged proteins. The sample is then fixed and embedded for electron microscopy, and the images are correlated 1-3. However, the low-resolution fluorescence image and the lack of fiducial markers preclude the precise localization of proteins. 
Alternatively, fluorescence imaging can be done after preserving the specimen in plastic. In this approach, the block is sectioned, and fluorescence images and electron micrographs of the same section are correlated 4-7. However, the diffraction limit of light in the correlated image obscures the locations of individual molecules, and the fluorescence often extends beyond the boundary of the cell. 
Nano-resolution fluorescence electron microscopy (nano-fEM) is designed to localize proteins at nano-scale by imaging the same sections using photo-activated localization microscopy (PALM) and electron microscopy. PALM overcomes the diffraction limit by imaging individual fluorescent proteins and subsequently mapping the centroid of each fluorescent spot 8-10. 
We outline the nano-fEM technique in five steps. First, the sample is fixed and embedded using conditions that preserve the fluorescence of tagged proteins. Second, the resin blocks are sectioned into ultrathin segments (70-80 nm) that are mounted on a cover glass. Third, fluorescence is imaged in these sections using the Zeiss PALM microscope. Fourth, electron dense structures are imaged in these same sections using a scanning electron microscope. Fifth, the fluorescence and electron micrographs are aligned using gold particles as fiducial markers. In summary, the subcellular localization of fluorescently tagged proteins can be determined at nanometer resolution in approximately one week.

We describe a method to localize fluorescently tagged proteins in electron micrographs. Fluorescence is first localized using photo-activated localization microscopy on ultrathin sections. These images are then aligned to electron micrographs of the same section.

Mapping the distribution of proteins is essential for understanding the function of proteins in a cell. Fluorescence microscopy is extensively used for ...

Using High Resolution Computed Tomography to Visualize the Three Dimensional Structure and Function of Plant Vasculature

High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D) (e.g. Brodersen et al. 2010; 2011; 2012a,b). HRCT imaging is based on the same principles as medical CT systems, but a high intensity synchrotron x-ray source results in higher spatial resolution and decreased image acquisition time. Here, we demonstrate in detail how synchrotron-based HRCT (performed at the Advanced Light Source-LBNL Berkeley, CA, USA) in combination with Avizo software (VSG Inc., Burlington, MA, USA) is being used to explore plant xylem in excised tissue and living plants. This new imaging tool allows users to move beyond traditional static, 2D light or electron micrographs and study samples using virtual serial sections in any plane. An infinite number of slices in any orientation can be made on the same sample, a feature that is physically impossible using traditional microscopy methods.
Results demonstrate that HRCT can be applied to both herbaceous and woody plant species, and a range of plant organs (i.e. leaves, petioles, stems, trunks, roots). Figures presented here help demonstrate both a range of representative plant vascular anatomy and the type of detail extracted from HRCT datasets, including scans for coast redwood (Sequoia sempervirens), walnut (Juglans spp.), oak (Quercus spp.), and maple (Acer spp.) tree saplings to sunflowers (Helianthus annuus), grapevines (Vitis spp.), and ferns (Pteridium aquilinum and Woodwardia fimbriata). Excised and dried samples from woody species are easiest to scan and typically yield the best images. However, recent improvements (i.e. more rapid scans and sample stabilization) have made it possible to use this visualization technique on green tissues (e.g. petioles) and in living plants. On occasion some shrinkage of hydrated green plant tissues will cause images to blur and methods to avoid these issues are described. These recent advances with HRCT provide promising new insights into plant vascular function.

High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique that can be used to study the structure and function of plant vasculature in 3D. We demonstrate how HRCT facilitates exploration of xylem networks across a wide range of plant tissues and species.

High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being ...

In vivo Clonal Tracking of Hematopoietic Stem and Progenitor Cells Marked by Five Fluorescent Proteins using Confocal and Multiphoton Microscopy

We developed and validated a fluorescent marking methodology for clonal tracking of hematopoietic stem and progenitor cells (HSPCs) with high spatial and temporal resolution to study in vivo hematopoiesis using the murine bone marrow transplant experimental model. Genetic combinatorial marking using lentiviral vectors encoding fluorescent proteins (FPs) enabled cell fate mapping through advanced microscopy imaging. Vectors encoding five different FPs: Cerulean, EGFP, Venus, tdTomato, and mCherry were used to concurrently transduce HSPCs, creating a diverse palette of color marked cells. Imaging using confocal/two-photon hybrid microscopy enables simultaneous high resolution assessment of uniquely marked cells and their progeny in conjunction with structural components of the tissues. Volumetric analyses over large areas reveal that spectrally coded HSPC-derived cells can be detected non-invasively in various intact tissues, including the bone marrow (BM), for extensive periods of time following transplantation. Live studies combining video-rate multiphoton and confocal time-lapse imaging in 4D demonstrate the possibility of dynamic cellular and clonal tracking in a quantitative manner.

In vivo Clonal Tracking of Hematopoietic Stem and Progenitor Cells Marked by Five Fluorescent Proteins using Confocal and Multiphoton Microscopy

Combinatorial 5 fluorescent proteins marking of hematopoietic stem and progenitor cells allows in vivo clonal tracking via confocal and two-photon microscopy, providing insights into bone marrow hematopoietic architecture during regeneration. This method allows non-invasive fate mapping of spectrally-coded HSPCs-derived cells in intact tissues for extensive periods of time following transplantation.

We developed and validated a fluorescent marking methodology for clonal tracking of hematopoietic stem and progenitor cells (HSPCs) with high spatial and ...

Determination of Fatty Acid Oxidation and Lipogenesis in Mouse Primary Hepatocytes

Lipid metabolism in liver is complex. In addition to importing and exporting lipid via lipoproteins, hepatocytes can oxidize lipid via fatty acid oxidation, or alternatively, synthesize new lipid via de novo lipogenesis. The net sum of these pathways is dictated by a number of factors, which in certain disease states leads to fatty liver disease. Excess hepatic lipid accumulation is associated with whole body insulin resistance and coronary heart disease. Tools to study lipid metabolism in hepatocytes are useful to understand the role of hepatic lipid metabolism in certain metabolic disorders.
In the liver, hepatocytes regulate the breakdown and synthesis of fatty acids via &#946;-fatty oxidation and de novo lipogenesis, respectively. Quantifying metabolism in these pathways provides insight into hepatic lipid handling. Unlike in vitro quantification, using primary hepatocytes, making measurements in vivo is technically challenging and resource intensive. Hence, quantifying &#946;-fatty acid oxidation and de novo lipogenesis in cultured mouse hepatocytes provides a straight forward method to assess hepatocyte lipid handling. 
Here we describe a method for the isolation of primary mouse hepatocytes, and we demonstrate quantification of &#946;-fatty acid oxidation and de novo lipogenesis, using radiolabeled substrates.

De novo lipogenesis and &#946;-fatty acid oxidation constitute key metabolic pathways in hepatocyte, pathways that are perturbed in several metabolic disorders, including fatty liver disease. Here we demonstrate isolation of mouse primary hepatocytes and describe quantification of &#946;-fatty acid oxidation and lipogenesis.

Lipid metabolism in liver is complex. In addition to importing and exporting lipid via lipoproteins, hepatocytes can oxidize lipid via fatty acid ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

Field-Deployable Candidatus Liberibacter asiaticus Detection Using Recombinase Polymerase Amplification Combined with CRISPR-Cas12a

The early detection of Candidatus Liberibacter asiaticus (CLas) by citrus growers facilitates early intervention and prevents the spread of disease. A simple method for rapid and portable Huanglongbing (HLB) diagnosis is presented here that combines recombinase polymerase amplification and a fluorescent reporter utilizing the nuclease activity of the clustered regularly interspaced short palindromic repeats/CRISPR-associated 12a (CRISPR-Cas12a) system. The sensitivity of this technique is much higher than PCR. Furthermore, this method showed similar results to qPCR when leaf samples were used. Compared with conventional CLas detection methods, the detection method presented here can be completed in 90 min and works in an isothermal condition that does not require the use of PCR machines. In addition, the results can be visualized through a handheld fluorescent detection device in the field.

Field-Deployable Candidatus Liberibacter asiaticus Detection Using Recombinase Polymerase Amplification Combined with CRISPR-Cas12a

In this work, a rapid, sensitive, and portable detection method for Candidatus Liberibacter asiaticus based on recombinase polymerase amplification combined with CRISPR-Cas12a was developed.

The early detection of Candidatus Liberibacter asiaticus (CLas) by citrus growers facilitates early intervention and prevents the spread of disease. A ...

Quantitative Determination of De Novo Fatty Acid Synthesis in Brown Adipose Tissue Using Deuterium Oxide

Fatty acid synthesis is a complex and highly energy demanding metabolic pathway with important functional roles in the control of whole-body metabolic homeostasis and other physiological and pathological processes. Contrary to other key metabolic pathways, such as glucose disposal, fatty acid synthesis is not routinely functionally assessed, leading to incomplete interpretations of metabolic status. In addition, there is a lack of publicly available detailed protocols suitable for newcomers in the field. Here, we describe an inexpensive quantitative method utilizing deuterium oxide and gas chromatography mass spectrometry (GCMS) for the analysis of total fatty acid de novo synthesis in brown adipose tissue in vivo. This method measures the synthesis of the products of fatty acid synthase independently of a carbon source, and it is potentially useful for virtually any tissue, in any mouse model, and under any external perturbation. Details on the sample preparation for GCMS and downstream calculations are provided. We focus on the analysis of brown fat due to its high levels of de novo fatty acid synthesis and critical roles in maintaining metabolic homeostasis.

Quantitative Determination of De Novo Fatty Acid Synthesis in Brown Adipose Tissue Using Deuterium Oxide

Here, we present an inexpensive quantitative method utilizing deuterium oxide and gas chromatography mass spectrometry (GCMS) for the analysis of total fatty acid de novo lipogenesis in brown adipose tissue in vivo.

Fatty acid synthesis is a complex and highly energy demanding metabolic pathway with important functional roles in the control of whole-body metabolic ...