Mapping oligogenic resistance to powdery mildew in mungbean with RFLPs

Abstract

We have used restriction fragment length polymorphisms (RFLPs) to map genes in mungbean (Vigna radiata) that confer partial resistance to the powdery mildew fungus, Erysiphe polygoni. DNA genotypes for 145 RFLP loci spanning 1570 centimorgans of the mungbean genome were assayed in a population of 58 F2 plants. This population was derived from a cross between a moderately powdery mildew resistant ("VC3980A") and a susceptible ("TC1966") mungbean parent. F3 lines derived from the F2 plants were assayed in the field for powdery mildew response and the results were compared to the RFLP genotype data, thereby identifying loci associated with powdery mildew response. A total of three genomic regions were found to have an effect on powdery mildew response, together explaining 58% of the total variation. At 65 days after planting, two genomic regions were significantly associated with powdery mildew resistance. For both loci, the allele from "VC3890A" was associated with increased resistance. At 85 days, a third genomic region was also associated with powdery mildew response. For this locus, the allele from the susceptible parent ("TC1966") was the one associated with higher levels of powdery mildew resistance. These results indicate that putative partial resistance loci for powdery mildew in mungbean can be identified with DNA markers, even in a population of modest size analyzed at a single location in a single year.

QTL identification for early blight resistance (Alternaria solani) in a Solanum lycopersicum × S. arcanum cross

“…Two of these (the QTL on chromosomes 2 and 7) inherited the resistant allele from the susceptible parent. This is not uncommon and has been reported in many plant species (e.g., Young et al 1993;Lefebvre and Palloix 1996;Pilet et al 1998). For EB resistance in tomato, Zhang et al (2003) also detected a QTL on chromosome 3 for which the resistance allele was inherited from the susceptible parent.…”

“…), PSmL percentage of small lesions, PEBI percentage of early blight index, RAUDPC relative area under the disease progress curve, RAULEC relative area under the lesion expansion curve, PstLI percentage of stem lesion index a Based on 2-LOD support interval obtained from restricted MQM mapping; distance between flanking markers b The LOD thresholds obtained from 1,000· permutation tests for a genome wide significance (P < 0.05) were 3.70, 3.54, 3.51, 3.67, 3.67, and 3.69 for LS, PSmL, RAULEC, PEBI, RAUDPC, and PStLI, respectively c The QTL effects of PSmL are opposite to those for all other traits, as a high value for PSmL indicates resistance while a high value of the other traits indicates susceptibility *P < 0.05, according to t-test **P < 0.01, according to t-test ***P < 0.001, according to t-test Plant conditions, including developmental stage and physiological state may affect the expression of QTL for resistance. Young et al (1993) observed two QTL for resistance to powdery mildew in mungbean, which were significant at 65 days after planting and detected a different QTL at 85 days after planting. In our study, the QTL on chromosome 7 showed an effect in glasshouse tests with young plants (56-63 days after planting), whereas the QTL on chromosomes 1 and 6 were only effective in the field at later plant stage (90-110 days after sowing).…”

Perspectives and Challenges for Sustainable Management of Fungal Diseases of Mungbean [Vigna radiata (L.) R. Wilczek var. radiata]: A Review

“…Several earlier studies reported monogenic inheritance of powdery mildew resistance controlled by single dominant genes and studies were conducted using mungbean varieties ML3 and ML5 (AVRDC, 1979), and breeding lines VC 1560A (AVRDC, 1981), ATF 3640 (Humphry et al, 2003) and RUM (Reddy et al, 1994a). Using restriction fragment length polymorphism (RFLP) markers, Chaitieng et al (2002) (Young et al, 1993;Sorajjapinun et al, 2005). Sorajjapinun et al (2005) reported that additive gene action was found to play a major role in controlling powdery mildew (E. polygoni) resistance in the population of crosses developed between moderately resistant KPS 2 and resistant VC 6468-11-1A (sourced from the World Vegetable Center).…”

“…Sorajjapinun et al (2005) reported that additive gene action was found to play a major role in controlling powdery mildew (E. polygoni) resistance in the population of crosses developed between moderately resistant KPS 2 and resistant VC 6468-11-1A (sourced from the World Vegetable Center). Using mapping population developed from advanced mungbean breeding line VC3890 (from World Vegetable Center) as a resistance parent, Young et al (1993) identified three QTL associated with powdery mildew (E. polygoni) resistance. These QTL explained 17 to 28 and 58% of phenotypic variation (R 2 ) individually and together, respectively.…”

Study of Powdery Mildew Resistance in seven Lines of Snow Pea, Pisumsativum

“…th nodes and a whole plant at 45, 55, 65 and 75 days, respectively. Disease severity scoring was based on the amount of disease on each leaf and calculated for the percentage of infected area ranging from 0 to 100% (Ondrej et al, 2005;Young et al, 1993) and the scores were analyzed by Statistix version 8.0.…”