Breeding french bean (Phaseolus vulgaris L.) for resistance to mung bean yellow mosaic virus

Abstract

The genetic information on resistance to mung bean yellow mosaic virus (MYMV) was generated in french bean (Phaseolus vulgaris L.) by employing diallel analysis involving one resistant line IIHR-55 (IC 525260) and four susceptible commercial cultivars viz., Arka Komal, Arka Anoop, Arka Suvidha and IIHR-78 and their F1 and F2 progenies. Environmental conditions at experimental site were quite favorable for the disease development. Further, screening of F1 and F2 populations was also done under laboratory conditions for confirmation of resistance. The frequency distribution of resistant and susceptible grouped in the ratio of 1: 15. The X2 analysis results were found highly significant at P < 0.05 and acceptance of null hypothesis gave a good fit to duplicate gene interaction ratio 1: 15 resistant to susceptible, respectively. It was found that two recessive genes governed the resistance in donor parent. Based on the F2 mean per se performances, it was concluded that plants of the crosses IIHR 55 x AK and IIHR 55 x AA were promising with high yield and resistance. The combining ability studies indicated high proportions of gca variances than sca variances for all the characters studied indicating the predominance of additive gene action. Negative association of quantitative characters with % disease incidence and coefficient of infection were significant for all the characters except days to 50 per cent flowering and days to pod maturity. The magnitude of negative correlation of PDI and CI was high for pod yield per plant and pod number per plant. It was found that none of the parental lines was superior general combiner for all the traits. Similarly none of the cross combination had SCA effects for all the characters. Among the parents, and F1s studied, the parental line IIHR- 55 (IC525260) was the best general combiner with high gca effect, the crosses IIHR 78 X AK and IIHR 78 X AA were best specific combiners with high sca values and the cross IIHR 78 X AA was best reciprocal combiner for most of the quantitative characters studied, viz., plant spread in both directions, pod yield per plant, pod number per plant, ten pod weight. The identified RAPD marker OP7730 which is linked to MYMV resistance in french bean can be successfully used for rapid screening and identification of genotypes resistant to MYMV.