Development of a coupling-phase SCAR marker linked to the powdery mildew resistance gene 'er1' in pea (Pisum sativum L.)

Pea powdery mildew is one of the major constraints in pea production worldwide, causing severe seed yield and quality loss. The resistance is governed by a single recessive gene er1 in majority of resistant cultivars, but er2 and Er3 have also been reported. The objective of the study was to find out tightly linked sequence characterized amplified regions (SCAR) markers to er1 gene using NILs. A total of 620 random amplified polymorphic DNA (RAPD) markers were screened for length polymorphism between seven sets of NILs. The 880 bp polymorphic band of the tightly linked RAPD marker OPX 04(880) was cloned, sequenced and a SCAR marker ScOPX 04(880) was developed. In a population of completely classified 208 F-2 plants (supported by phenotypic data from 208 F-2:3 and 4,390 F-3:4 families) ScOPX 04(880) was linked at 0.6 cM in coupling phase with er1 gene in the order ScOPX 04(880)-er1-ScOPD 10(650). ScOPX 04(880) will correctly differentiate homozygous resistant plants from the susceptible accessions with more than 99 % accuracy. In combination with repulsion phase marker ScOPD 10(650), ScOPX 04(880) can help in an error free marker-assisted selection.