|Title||Effector-mediated discovery of a novel resistance gene against Bremia Lactucae in a nonhost lettuce species|
|Author(s)||Giesbers, A.K.J.; Pelgrom, Alexandra; Visser, R.G.F.; Niks, R.E.; Ackerveken, Guido Van Den; Jeuken, M.J.W.|
|Source||New Phytologist 216 (2017)3. - ISSN 0028-646X - p. 915 - 926.|
Laboratory of Plant Breeding
PBR Non host en Insectenresistentie
|Publication type||Refereed Article in a scientific journal|
|Abstract||Candidate effectors from lettuce downy mildew (Bremia lactucae) enable high-throughput germplasm screening for the presence of resistance (R) genes. The nonhost species Lactuca saligna comprises a source of B. lactucae R genes that has hardly been exploited in lettuce breeding. Its cross-compatibility with the host species L. sativa enables the study of inheritance of nonhost resistance (NHR).
We performed transient expression of candidate RXLR effector genes from B. lactucae in a diverse Lactuca germplasm set. Responses to two candidate effectors (BLR31 and BLN08) were genetically mapped and tested for co-segregation with disease resistance.
BLN08 induced a hypersensitive response (HR) in 55% of the L. saligna accessions, but responsiveness did not co-segregate with resistance to Bl:24. BLR31 triggered an HR in 5% of the L. saligna accessions, and revealed a novel R gene providing complete B. lactucae race Bl:24 resistance. Resistant hybrid plants that were BLR31 nonresponsive indicated other unlinked R genes and/or nonhost QTLs.
We have identified a candidate avirulence effector of B. lactucae (BLR31) and its cognate R gene in L. saligna. Concurrently, our results suggest that R genes are not required for NHR of L. saligna.