Genetic inheritance and identification of a resistance gene analogue polymorphic (RGAP) marker linked to Chilli veinal mottle virus resistance in chilli (Capsicum annuum L.)

摘要

Chilli veinal mottle virus (ChiVMV) is a most destructive virus, which causes severe yield losses in pepper. Host plant resistance is the only option to tackle this problem. Eleven ChiVMVresistant lines were selected from an initial screening of chilli pepper germplasm and their resistance was reconfirmed by artificial inoculation. To understand the genetic basis of inheritance and to identify a resistance gene analogue polymorphic (RGAP) marker associated with resistance, the ChiVMV-resistant chilli pepper line 'IHR 2451' (Parent 1) was crossed with the ChiVMV-susceptible line ` IHR 3476' (Parent 2) to develop six generations. Individual plants from all six generations (35 P1, 50 P 1, 30 F1, 200 F2, 44 B 1, and 41 B2) were artificially inoculated with ChiVMV (Bengaluru isolate) and the pattern of segregation of susceptibility or resistance was investigated using the chi-square (x(2)) test. All F1 progeny plants were susceptible to ChiVMV. The pattern of segregation of resistant and susceptible plants in the F2 and two back-cross generations (B-1 and B-2) revealed that resistance in 'IHR 2451' was monogenic recessive. A total of 108 RGAP primer combinations were used to search for parental (P-1 and P-2) polymorphisms, and three polymorphic RGAP markers, K5-HD6, K7-HD6, and K8-HD6, were found by bulk segregant analysis. Use of the K5-HD6 marker was extended to screen individual plants in the F-2 and B-1 generations and was found to co-segregate with ChiVMV resistance. Furthermore, K5-HD6 was validated in different ChiVMV-resistant lines, where it could clearly differentiate between resistant and susceptible lines. The RGAP marker K5-HD6 could differentiate homozygous resistant plants from susceptible plants, and therefore may be used effectively during marker-assisted selection and breeding of chilli pepper for resistance to ChiVMV.