ABSTRACT.
Inheritance and identification of ISSR-RGA markers associated with powdery mildew resistance in mungbean for marker-assisted breeding

Piyada Alisha Tantasawat1*, Oythip Poolsawat1, Chitpan Kativat1, Kitiya Arsakit1, Pitchakon Papan1, Witsarut Chueakhunthod1, and Pakhawat Pookhamsak1
 
Mungbean (Vigna radiata (L.) R. Wilczek var. radiata) yield is dramatically constrained by powdery mildew (PM) caused by Sphaerotheca phaseoli (Z.Y. Zhao) U. Braun (1985), which is considerably prevalent in the cool-dry season of production in South, East, and Southeast Asia countries including Thailand. Exploitation of varieties resistant to the disease is crucial to meet sustainable production. A population of 64 F2:9 and F2:10 recombinant inbred lines (RILs) generated by hybridization of the susceptible parent ‘Chai Nat 72’ (CN72) with the resistant parent ‘V4758’ was used to assess genetic resistance and identify inter simple sequence repeat-anchored resistance gene analog (ISSR-RGA) markers linked to the PM resistance gene. The PM response in these RILs was visually scored in the field during the winter seasons, twice in 2015 and 2018, and the segregation pattern was determined by the chi-square test (χ2 ). The resulting segregation ratios of 1:1 indicated a qualitative nature with a dominantly inherited resistance gene conferring PM resistance. When bulk segregant analysis (BSA) was undertaken using 378 ISSR-RGA primer combinations among both parents and DNA bulks of resistant and susceptible F2:9 individuals, 11 of these exhibited polymorphisms, and one marker I41tP379 was closest to the PM resistance gene which revealed a highly significant correlation with PM resistance (R2 (%) = 26; P < 0.001) with a logarithm of odd (LOD) score of 5.85. The closest marker I41tP379 could trace the PM resistance gene in molecular marker assisted breeding for mungbean improvement.
Keywords: ISSR-RGA marker, powdery mildew (PM) resistance, Vigna radiata.
1 Suranaree University of Technology, School of Crop Production Technology, Nakhon Ratchasima 30000, Thailand. * Corresponding author (piyada@sut.ac.th).