Identification of DNA markers linked to an induced mutated gene conferring resistance to powdery mildew in pea (Pisum sativum L.)

We have recently induced two powdery mildew (Erysiphe pisi Syd) resistant mutants in Pisum sativum L. via ethylnitrosourea (ENU) mutagenesis. Both mutations (er1mut1 and er1mut2) affected the same locus er1 that determines most of the identified natural sources of powdery mildew resistance (PMR) in this crop. The mutated gene er1mut2 was mapped to a linkage group of 16 DNA markers combining three main strategies: near isogenic lines (NILs) analysis, bulked segregant analysis and genetic mapping of randomly identified polymorphic markers, together with three DNA-markers techniques: ISSR, RAPDs and AFLPs. Markers located closer to the PMR locus, OPO06(1100y) (0.5 cM), OPT06(480) (3.3 cM) and AGG/CAA(125) (5.5 cM), were cloned and converted into SCAR markers. Markers AH1R(850) and AHR(920y) were found to be allelic and converted into the co-dominant marker ScAH1 (16.3 cM). Two previously known DNA markers, ScOPE16(1600) and A5(420y,) were mapped at 9.6 and 23.0 cM from the PMR locus, respectively. The novel markers identified in this study are currently being transferred to a new F2 mapping population derived from a cross between the induced PMR mutant line F(er1mut2) and a more genetically distant susceptible line of Pisum sativum var. arvense