This work was carried out with the supports of Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ010953012018), Rural Development Administration, and the National Research Foundation (Korea) grant funded by the Ministry of Science and ICT (No. 2016R1E1A1A02922014), Republic of Korea.

1. Growth of Arabidopsis Plants
<ol>
	<li>Prepare 1 L Gamborg B5 (B5) medium by adding 3.2 g of B5 medium including vitamins, 20 g of sucrose, 0.5 g of 2-(N-morpholino) ethane sulfonic acid (MES) to approximately 800 mL of deionized water, and adjust the pH to 5.7 with potassium hydroxide (KOH). Add more deionized water bring the total volume to 1 L. Add 8 g of phytoagar and autoclave for 15 min at 121 &#176;C.</li>
	<li>Allow the medium to cool down to 55 &#176;C and pour 20 &#8211; 25 mL of the B5 medium into a Petri...

<ol>
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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonphotosynthetic+Metabolism+in+Plastids.">Nonphotosynthetic Metabolism in Plastids.</a> Annual Review of Plant Physiology and Plant Molecular Biology. 51, 111-140 (2000).</li><li>Rolland, N., 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=The+biosynthetic+capacities+of+the+plastids+and+integration+between+cytoplasmic+and+chloroplast+processes.">The biosynthetic capacities of the plastids and integration between cytoplasmic and chloroplast processes.</a> Annual Review of Genetics. 46, 233-264 (2012).</li><li>Jarvis, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+of+nucleus-encoded+proteins+to+chloroplasts+in+plants.">Targeting of nucleus-encoded proteins to chloroplasts in plants.</a> New Phytologist. 179 (2), 257-285 (2008).</li><li>Li, H. M., Chiu, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+Transport+into+Chloroplasts.">Protein Transport into Chloroplasts.</a> Annual Review of Plant Biology. 61, 157-180 (2010).</li><li>Keegstra, K., Cline, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+import+and+routing+systems+of+chloroplasts.">Protein import and routing systems of chloroplasts.</a> Plant Cell. 11 (4), 557-570 (1999).</li><li>Gasser, S. M., Daum, G., Schatz, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Import+of+proteins+into+mitochondria.+Energy-dependent+uptake+of+precursors+by+isolated+mitochondria.">Import of proteins into mitochondria. Energy-dependent uptake of precursors by isolated mitochondria.</a> Journal of Biological Chemistry. 257 (21), 13034-13041 (1982).</li><li>Smeekens, S., Bauerle, C., Hageman, J., Keegstra, K., Weisbeek, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+the+transit+peptide+in+the+routing+of+precursors+toward+different+chloroplast+compartments.">The role of the transit peptide in the routing of precursors toward different chloroplast compartments.</a> Cell. 46 (3), 365-375 (1986).</li><li>Lee, D. W., 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=Arabidopsis+nuclear-encoded+plastid+transit+peptides+contain+multiple+sequence+subgroups+with+distinctive+chloroplast-targeting+sequence+motifs.">Arabidopsis nuclear-encoded plastid transit peptides contain multiple sequence subgroups with distinctive chloroplast-targeting sequence motifs.</a> Plant Cell. 20 (6), 1603-1622 (2008).</li><li>Lee, S., 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=Mitochondrial+targeting+of+the+Arabidopsis+F1-ATPase+gamma-subunit+via+multiple+compensatory+and+synergistic+presequence+motifs.">Mitochondrial targeting of the Arabidopsis F1-ATPase gamma-subunit via multiple compensatory and synergistic presequence motifs.</a> Plant Cell. 24 (12), 5037-5057 (2012).</li><li>Jin, J. B., 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=A+new+dynamin-like+protein,+ADL6,+is+involved+in+trafficking+from+the+trans-Golgi+network+to+the+central+vacuole+in+Arabidopsis.">A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis.</a> Plant Cell. 13 (7), 1511-1526 (2001).</li><li>Lee, K. H., Kim, D. H., Lee, S. W., Kim, Z. H., Hwang, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+import+experiments+in+protoplasts+reveal+the+importance+of+the+overall+context+but+not+specific+amino+acid+residues+of+the+transit+peptide+during+import+into+chloroplasts.">In vivo import experiments in protoplasts reveal the importance of the overall context but not specific amino acid residues of the transit peptide during import into chloroplasts.</a> Molecules and Cells. 14 (3), 388-397 (2002).</li><li>Lee, D. W., Lee, S., Oh, Y. J., Hwang, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+sequence+motifs+in+the+rubisco+small+subunit+transit+peptide+independently+contribute+to+Toc159-dependent+import+of+proteins+into+chloroplasts.">Multiple sequence motifs in the rubisco small subunit transit peptide independently contribute to Toc159-dependent import of proteins into chloroplasts.</a> Plant Physiology. 151 (1), 129-141 (2009).</li><li>Lee, D. W., Woo, S., Geem, K. R., Hwang, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequence+motifs+in+transit+peptides+act+as+independent+functional+units+and+can+be+transferred+to+new+sequence+contexts.">Sequence motifs in transit peptides act as independent functional units and can be transferred to new sequence contexts.</a> Plant Physiology. 169 (1), 471-484 (2015).</li><li>Lee, 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=Both+the+hydrophobicity+and+a+positively+charged+region+flanking+the+C-terminal+region+of+the+transmembrane+domain+of+signal-anchored+proteins+play+critical+roles+in+determining+their+targeting+specificity+to+the+endoplasmic+reticulum+or+endosymbiotic+organelles+in+Arabidopsis+cells.">Both the hydrophobicity and a positively charged region flanking the C-terminal region of the transmembrane domain of signal-anchored proteins play critical roles in determining their targeting specificity to the endoplasmic reticulum or endosymbiotic organelles in Arabidopsis cells.</a> Plant Cell. 23 (4), 1588-1607 (2011).</li><li>Cleary, S. P., 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=Isolated+plant+mitochondria+import+chloroplast+precursor+proteins+in+vitro+with+the+same+efficiency+as+chloroplasts.">Isolated plant mitochondria import chloroplast precursor proteins in vitro with the same efficiency as chloroplasts.</a> Journal of Biological Chemistry. 277 (7), 5562-5569 (2002).</li></ol>

The authors have nothing to disclose.

We provided a detailed protocol for the use of protoplasts of Arabidopsis to study protein import into chloroplasts. This method is powerful for investigating the protein import process. This simple, versatile technique is useful for examining the targeting of the intended cargo proteins to chloroplasts. Using this method, protoplasts are prepared from leaf tissues of Arabidopsis11,12 which can be obtained from plants at many different growth st...

The chloroplast is one of the most important organelles in plants. One of the main functions of chloroplasts is to carry out photosynthesis1. Chloroplasts also carry out many other biochemical reactions for the production of fatty acids, amino acids, nucleotides, and numerous secondary metabolites1,2. For all of these reactions, chloroplasts require a large number of different types of proteins. However, the chloroplast genome contains only approximately 100 genes3,4. Therefore, chloroplasts must import the majority of their proteins from the cytosol. In fact, most chloroplast proteins were shown to be imported from the cytosol after translation4,5,6. Plant cells require specific mechanisms to import proteins from the cytosol to chloroplasts. However, although these protein import mechanisms have been investigated for the past several decades, we still do not fully understand them at the molecular level. Here, we provide a detailed method for preparing protoplasts and exogenously expressing genes in protoplasts. This method could be valuable for elucidating the molecular mechanisms underlying protein import into chloroplasts in detail.
Protein import can be studied using many different approaches. One of these methods involves the use of an in vitro protein import system7,8. Using this approach, in vitro-translated protein precursors are incubated with purified chloroplasts in vitro, and protein import is analyzed by SDS-PAGE followed by western blot analysis. The advantage of this approach is that each step of protein import into chloroplasts can be studied in detail. Thus, this method has been widely used to define the components of the protein import molecular machinery and to dissect sequence information for transit peptides. More recently, another approach involving the use of protoplasts from leaf tissues was developed and it has become widely used to study protein import into chloroplasts9,10. The advantage of this approach is that protoplasts provide a cellular environment that is closer to that of intact cells than the in vitro system. Thus, the protoplast system allows us to address many additional aspects of this process, such as the associated cytosolic events and how the specificity of targeting signals is determined. Here, we present a detailed protocol for the use of protoplasts to study protein import into chloroplasts.

<table>
	<tbody>
		<tr>
			<td>GAMBORG B5 MEDIUM INCLUDING VITAMINS</td>
			<td>Duchefa Biochemie</td>
			<td>G0210.0050</td>
			<td></td>
		</tr>
		<tr>
			<td>SUCROSE</td>
			<td>Duchefa Biochemie</td>
			<td>S0809.5000</td>
			<td></td>
		</tr>
		<tr>
			<td>MES MONOHYDRATE</td>
			<td>Duchefa Biochemie</td>
			<td>M1503.0250</td>
			<td></td>
		</tr>
		<tr>
			<td>Agar, powder</td>
			<td>JUNSEI</td>
			<td>24440S1201</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropore Surgical tape</td>
			<td>3M</td>
			<td>1530-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical blade stainless No.10</td>
			<td>FEATHER</td>
			<td>Unavailable</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical Tube, 50ml</td>
			<td>SPL LIFE SCIENCES</td>
			<td>50050</td>
			<td></td>
		</tr>
		<tr>
			<td>Macerozyme R-10</td>
			<td>YAKULT PHARMACEUTICAL IND.</td>
			<td>Unavailable</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellulase ONOZUKA R-10</td>
			<td>YAKULT PHARMACEUTICAL IND.</td>
			<td>Unavailable</td>
			<td></td>
		</tr>
		<tr>
			<td>ALBUMIN, BOVINE (BSA)</td>
			<td>VWR</td>
			<td>0332-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Mannitol</td>
			<td>SIGMA</td>
			<td>M1902-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>CALCIUM CHLORIDE, DIHYDRATE</td>
			<td>MP BIOMEDICALS</td>
			<td>0219463505-5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Twister</td>
			<td>VISION SCIENTIFIC</td>
			<td>VS-96TW</td>
			<td></td>
		</tr>
		<tr>
			<td>Screen cup for CD-1</td>
			<td>SIGMA</td>
			<td>S1145</td>
			<td></td>
		</tr>
		<tr>
			<td>Screens for CD-1</td>
			<td>SIGMA</td>
			<td>S3895</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri Dish</td>
			<td>SPL LIFE SCIENCES</td>
			<td>10090</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette</td>
			<td>HILGENBERG</td>
			<td>3150102</td>
			<td></td>
		</tr>
		<tr>
			<td>LABORATORY CENTRIFUGE / BENCH-TOP</td>
			<td>VISION SCIENTIFIC</td>
			<td>VS-5500N</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>JUNSEI</td>
			<td>19015S0350</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>SIGMA</td>
			<td>P3911-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>D-GLUCOSE, ANHYDROUS</td>
			<td>BIO BASIC</td>
			<td>GB0219</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Hydroxide</td>
			<td>DUKSAN</td>
			<td>40</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium nitrate tetrahydrate</td>
			<td>SIGMA</td>
			<td>C2786-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol)</td>
			<td>SIGMA</td>
			<td>P2139-2KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride hexahydrate</td>
			<td>SIGMA</td>
			<td>M2393-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Tube 13ml, 100x16mm, PP</td>
			<td>SARSTEDT</td>
			<td>55.515</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides</td>
			<td>MARIENFELD</td>
			<td>1000412</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Cover Glasses</td>
			<td>MARIENFELD</td>
			<td>101030</td>
			<td></td>
		</tr>
		<tr>
			<td>Counting Chamber</td>
			<td>MARIENFELD</td>
			<td>650030</td>
			<td></td>
		</tr>
		<tr>
			<td>Axioplan 2 Imaging Microscope</td>
			<td>Carl Zeiss</td>
			<td>Unavailable</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro tube 1.5ml</td>
			<td>SARSTEDT</td>
			<td>72.690.001</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>SIGMA</td>
			<td>M3148-250ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Dodecyl Sulfate (SDS), Proteomics Grade</td>
			<td>VWR</td>
			<td>M107-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIS, Ultra Pure Grade</td>
			<td>VWR</td>
			<td>0497-5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>DTT (DL-Dithiothreitol), Biotechnology Grade</td>
			<td>VWR</td>
			<td>0281-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol blue sodium salt ACS</td>
			<td>VWR</td>
			<td>0312-50G</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>JUNSEI</td>
			<td>27210S0350</td>
			<td></td>
		</tr>
		<tr>
			<td>Living Colors A.v. Monoclonal Antibody (JL-8)</td>
			<td>TAKARA</td>
			<td>632381</td>
			<td></td>
		</tr>
	</tbody>
</table>

studying protein import into chloroplasts using protoplasts

The chloroplast is an essential organelle that is responsible for various cellular processes in plants, such as photosynthesis and the production of many secondary metabolites and lipids. Chloroplasts require a large number of proteins for these various physiological processes. Over 95% of chloroplast proteins are nucleus-encoded and imported into chloroplasts from the cytosol after translation on cytosolic ribosomes. Thus, the proper import or targeting of these nucleus-encoded chloroplast proteins to chloroplasts is essential for the proper functioning of chloroplasts as well as the plant cell. Nucleus-encoded chloroplast proteins contain signal sequences for specific targeting to chloroplasts. Molecular machinery localized to the chloroplast or cytosol recognize these signals and carry out the import process. To investigate the mechanisms of protein import or targeting to chloroplasts in vivo, we developed a rapid, efficient protoplast-based method to analyze protein import into chloroplasts of Arabidopsis. In this method, we use protoplasts isolated from leaf tissues of Arabidopsis. Here, we provide a detailed protocol for using protoplasts to investigate the mechanism by which proteins are imported into chloroplasts.

The import of proteins into chloroplasts can be examined using two approaches: fluorescence microscopy and immunoblot analysis after SDS-PAGE-mediated separation. Here, we used RbcS-nt:GFP, a fusion construct encoding the 79 N-terminal amino acid residues of RbcS containing the transit peptide fused to GFP. When proteins are imported into chloroplasts, green fluorescence signals from the target protein RbcS-nt:GFP should merge with the red fluorescent signals from chlorophyll auto-fluores...

Watch this Scientific Journal Video about Studying Protein Import into Chloroplasts Using Protoplasts at JoVE.com

Studying Protein Import into Chloroplasts Using Protoplasts

Here we describe a protocol to express proteins into protoplasts by using PEG-mediated transformation method. The method provides easy expression of proteins of interest, and efficient investigation of protein localization and the import process for various experimental conditions in vivo.

The chloroplast is an essential organelle that is responsible for various cellular processes in plants, such as photosynthesis and the production of many ...

This mystery can help answer a few questions in the field of cell biology such as protein input into chloroplasts. The main advantage of this technology is that protein input into chloroplasts can be studied under en vivo conditions. Demonstrating the procedure will be Junho Lee and Hyangju Kang, two post outs from my laboratory.To begin, harvest intact leaf tissues from two-week-old plants from one to two B5 plates. Use a surgical knife to harvest the leaves and place them into a 50 milliliter conical tube containing 25 milliliters of enzyme solution. Place the tube horizontally on a rotary shaker and incubate with gentle agitation at 22 degrees Celsius in the dark for eight to 12 hours until only petioles and stems remain in the solution.After completing incubation, filter the enzyme solution containing released protoplasts through a 140 micrometer pore size mesh into a fresh Petri dish. Then carefully layer the solution on top of 15 milliliters of 21%sucrose solution in a 50 milliliter conical tube. Centrifuge the tube in a swinging bucket rotor at 98 gs for 10 minutes with the lowest acceleration and deceleration settings.After that, use patura pipette to carefully removed the protoplasts from the uppermost layer containing enzyme solution and from the interface between the enzymes solution and sucrose solution. Transfer this solution to a 50 milliliter conical tube containing 30 milliliters of W5 solution and invert the tube to mix. Centrifuge the tube at 51 gs for six minutes.Use a pipette to discard this supernatant carefully without disturbing the protoplasts in the pellet. Add 25 milliliters of W5 solution and gently re-suspend the protoplasts. For stabilization, incubate in a four Celsius refrigerator for a minimum of one hour.After four degree Celsius incubation, pellet the protoplasts completely by centrifuging them at 46 gs for two minutes. Carefully remove the supernatent completely and add MANG solution to the protoplast pellet to achieve five times ten to the six per milliliter. Use a pipette to add 10 micrograms of the plasma DNA and 300 microliters of protoplast solution to a fresh 13 milliliter round bottomed tube.Mix by gently rotating the tubes by hand and then immediately add 300 microliters of freshly prepared 40%PEG solution. Mix completely by tilting the tube almost horizontally and rotating it gentle several times by hand. Incubate at room temperature for 30 minutes.Then add one milliliter of W5 solution and mix completely by gently rotating the tube by hand as previously. Incubate the sample for 10 minutes at room temperature. Repeat two more times with adding first 1.5 milliliter and then two milliliters of W5 and after the final addition and mixing, incubate for 30 minutes.Centrifuge the tube at 46 gs for four minutes and then discard the supernatant. Add two milliliters of W5 solution to the pellet and mix gently, but completely, in the same manner as previously. Incubate at 22 degrees Celsius in a dark chamber for 18 hours.To analyze the protein import using florescence microscopy, use a pipette with a trimmed tip to place 10 microliters of the protoplast solution on a glass slide. Use a cover slip to carefully cover the solution to avoid damaging the protoplasts. Place the slide on the stage of a fluorescence microscope with an excitation admission filter that is set for observing green fluorescent protein and chlorophyll autofluorescence.Use a cooled charge couple device camera to capture images and process them using an imagine editing software to produce pseudo-color images. For total protein extraction and immunoblotting, remove one milliliter from the protoplast solution and mix the remaining one milliliter. Transfer this protoplast solution into a centrifuge tube and centrifuge at 46 gs for four minutes.Remove the supernatant after completing centrifugation and add 80 microliters of denaturation buffer. Vortex vigoriously for five seconds. Add five XDS sample buffer, mix well and boil for 10 minutes to denature.Proceed with standard STS page and immunoblotting with anti-GFP antibody. RbcS and TGFT, a fusion construct encoding the 79 end terminal amino acid residues of RBCS containing the transit peptide fused to GFP, was used to study the import of proteins into chloroplasts by florescence microscopy and immunoblotting. When examined by florescence microscopy, green fluorescent signals from the target protein merged with the red fluorescent signals from chlorophyll autoflorescence indicating protein import into chloroplasts.After isolating total protein, two protein bands are observed in the immunoblot, showing that a protein was properly imported into chloroplasts. The upper band corresponds to the full length precursor and the lower band to the processed form after import into chloroplasts. The amount of the processed form of the protein increased in a time-dependent manner, suggesting that the protein is imported into chloroplasts.At this development, this technique paved the way for researchers in the field of cell biology to explore protein tiring or membrane thread picking in Arabidopsis.

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Research

JoVE Journal

Biochemistry

9.5K visualizações.  Pohang University of Science and Technology. Esse mistério pode ajudar a responder algumas perguntas no campo da biologia celular, como a entrada de proteínas em cloroplastos. A principal vantagem dessa tecnologia é que a entrada de proteínas em cloroplastos pode ser estudada em condições en vivo. Demonstrando o procedimento serão Junho Lee e Hyangju Kang, dois post outs do meu laboratório.Para começar, colhiu tecidos de folhas intactas de plantas de duas semanas de idade de uma a duas placas B5. Use uma faca cirúrgica ...