Assessing garden pea germplasm for powdery mildew resistance through disease phenotyping and genotyping using molecular markers

Abstract

Erysiphe pisi is the causal agent of powdery mildew disease in garden pea. So far, the resistance genes comprising two recessive (er1 and er2) and one dominant (Er3) have been reported to confer resistance to powdery mildew in garden pea. A set of 46 pea genotypes were screened against the E. pisi isolate, Ep01 in greenhouse conditions to identify resistant genotypes. Disease phenotyping and genotyping were carried to test for resistance/susceptibility through gene-specific sequence characterized amplified region (SCAR) markers. The presence of the resistant genes in the control pea genotypes; JI2302 for er1 gene, JI2480 for er2 gene and P660-4 for Er3 were confirmed through their respective gene-specific markers. The pea genotype, Arkel served as a negative control. Screening of the pea germplasm revealed three genotypes as highly resistant, six genotypes as resistant while ten genotypes were moderately resistant, thirteen genotypes were moderately susceptible, nine genotypes were susceptible and five were highly susceptible. The molecular markers for er1 resistance gene Sc-OPE-161600 was found to be segregating in most of the pea genotypes except in the susceptible control, Arkel. The marker ScX17_1400 for er2 gene was found to be in homozygous condition in the resistant pea genotypes while the marker associated with Er3 resistance, SCW4637 was found to be in heterozygous condition in majority of the pea lines except in the resistant control genotype, P660-4.