Characterization of powdery mildew resistance gene at the er1 locus in resistant/ tolerant genotypes of pea (Pisum sativum L.)

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Date
2018-08
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu
Abstract
Pea (Pisum sativum L.) is one of the most widely grown legume food crops and represents a versatile and inexpensive protein source for animal feeding. Diseases such as powdery mildew, caused by the obligate biotrophic fungus Erysiphe pisi DC belonging to the ascomycete order of Erysiphales, is a serious destructive disease of the crop causing heavy yield losses. For powdery mildew resistance three genes (two recessive ‘er1’, ‘er2’ and one dominant ‘Er3’) have been reported till date. PsMLO1 is Er1 and that the loss of PsMLO1 function conditions durable broad-spectrum powdery mildew resistance in pea. To date, seven er1 alleles (er1-1 to er1-7) have been identified conferring the er1-resistant phenotype. In the present study, an initiative was taken to profile 37 different Pisum genotypes, comprising of resistant/tolerant and susceptible notified genotypes, using molecular markers linked to powdery mildew resistance genes. A set of 37 Pisum genotypes was sown in pots during rabi 2017-18 at the Research Farm of School of Biotechnology, SKUAST-J, Chatha. For molecular profiling a total of ten markers were used (Sc-OPO-181200, Sc-OPE-161600, Sc-OPO-10650, AD-60, AA-374e A-5 and OPL-6: er1 linked; ScX-171400 and AA-278: er2 linked; ScAB1874 Er3 linked). For all the markers the data was highly polymorphic among the resistant and susceptible genotypes and thus might serve as a ready reference for breeders aiming introgression of powdery mildew resistance genes in pea. For the characterization of PsMLO locus, out of the 12 genotypes used, only five genotypes (Improved JI-1559, Bonneville, Pb-89, IC- 219002 and DPPMR-09-1) were able to amplify with PsMLO specific markers. The sequencing of these amplified products was carried out and good contigs of length 1764 and 1778bp were obtained for IC- 219002 and DPPMR-09-1, respectively only. Based on sequence alignment analysis the sequence of IC- 219002 and DPPMR-09-1 showed that the PsMLO1 c-DNA had a 10-bp deletion (TCATGTTATT) corresponding to position 111–120 of the wild-type PsMLO1 c-DNA thus confirming the presence of er1 allele, designated as er1-7. Therefore, these accessions might be used in pea breeding studies as the functional markers flanking this 10 bp deletion have been developed and can effectively be used in the MAS.
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