In Vivo Leaf Inoculation: An Alternative Method to Assess the Disease Resistance of Hybrid Clones in Poplar Breeding of Stem Canker Disease

The scope of this research protocol is to examine the methodology of pathogen inoculation and disease-resistant assessment methods using the poplar hybrid breeding. We are proposing the in vivo leaf inoculation method as an alternative to the traditional method with the aim of advancing the breeding of poplar stem canker disease. Using the leaf inoculation method, researchers can screen the disease resistance of large-scale hybrid clones, in the second years of hybrid lesion, realizing earlier on the sliding selections in poplar hybrid grading of stem canker disease.

The most advantageous aspects of the leaf inoculation method are as high efficiency and high throughput. First, the leaf method can sharply shorten the period of disease resistance selection from five to seven years after hybridization to two years after hybridization. Second, the method can assess the disease resistance of large-scale hybrid clones within several weeks.

The leaf inoculation method will advance the hybrid breeding of poplar Botryosphaeria dothidea and Cytospora chrysosperma canker in China, and the poplar hybrid breeding of Septoria canker in North America. Moreover, the method can be used to mine disease resistance genes and improve the development of poplar molecular breeding. In addition to poplar hybrid breeding of stem canker disease, the leaf method can be used to screen the disease resistance of natural or mutant poplar populations, and the susceptibility of poplar stem canker pathogens.

Moreover, the method can provide pathotypes for the mining of disease resistance genes, and the genetic analysis of disease resistance.