NWO TTW LettuceKnow 2.1 - Stress resilience_Immunity_genetics

Downy mildew is a notorious disease for the crop lettuce, Lactuca sativa. The crop-wild relative, Lactuca saligna, is completely resistant to downy mildew and considered a nonhost species. L. saligna and L. sativa have a fascinating evolutionary relationship, as they diverged about 3 Million years ago, but can still be crossed. Previous interspecific mapping attempts (cross L. saligna x L. sativa) for complete resistance were hindered partly by reproductive barriers and showed a complex inheritance of the resistance. A different opportunity to explore immunity in the species L. saligna presents itself in the exceptional existence of the rare susceptible variant "accession 275-5". Exploring this rare variant is expected to answer the following questions: What gene and mechanism causes this susceptibility? How can we use this information to identify or design a gene variant(s) resulting in resistance in the crop lettuce? Intraspecific mapping populations of L. saligna (cross of rare susceptible variant x resistant variant), genotype-phenotype analysis, genetic mapping techniques and potentially allele mining and molecular techniques for functional analysis, will be used. In consultation with the team members of the LettuceKnow subtheme resilience-immunity, other related leads from an analysis of genome-wide association mapping panel of ~500 lettuce lines, may also be explored.