RNA-Sequencing of Bulk Segregant F1 Populations Segregating for Powdery Mildew Resistance in Cannabis

Breeding genetic resistance to plant pathogens is a effective and sustainable approach to disease management within economically important crops. As legal restrictions around Cannabis sativa relax, a need for breeding genetically resistant cultivars to common cannabis pathogens are needed as the industry expands. Powdery mildew (PM), caused by Golovinomyces ambrosiae, is one of the most wide spread cannabis pathogens affecting indoor, greenhouse and field grown cannabis crops. Identifying naturally occurring forms of genetic resistance in cannabis is therefore a critical step to breeding resistant cultivars.Bulk segregant analysis using RNA-seq data was performed to map PM resistance in two F1 mapping populations derived from crossing PM resistance plants (N88 and W03) to susceptible cultivar (AC). For each F1 population (N88 x AC and W03 x AC), plants were grown from seed under greenhouse conditions. At 3 weeks of age, plants were artificially infected with PM. At 7 weeks of age, plants were evaluated for resistance and tissue collected for RNA sequencing. Resistant and susceptible bulks consisted of 25 plants each. Equal amounts of leaf tissue were collected and flash frozen.