Reference Report for IND21986777
| Title: | QTL mapping for nodule number and common bacterial blight in Phaseolus vulgaris L. |
| Authors: | Tsai, S.M., Nodari, R.O., Moon, D.H., Camargo, L.E.A., Vencovsky, R., Gepts, P. |
| Source: | Plant Soil, 1998, 204(10):135-145 |
| Abstract: | A recently developed bean RFLP linkage map was used to identify genetic elements affecting quantitative trait loci (QTLs) in two contrasting common bean genotypes. BAT-93 and Jalo EEP558, under two levels of mineral nitrogen: low -0.25 mM NH4NO3 and a high -6 mM NH4NO3. QTLs affecting nodule number (NN) and response to Xanthomonas campestris bv. phaseoli [X. axonopodis pv. phaseoli], which causes common bacterial blight (CBB) were identified and mapped. Analyses of 70 F2-derived F3 families, using the F1, the two parents, and a nodulation-defective mutant (Nod-) inoculated with R. tropici UM1899 under both levels of N showed significant differences (P < 0.0001) among the F3 families for NN. Under low N, 3 genomic regions influenced both traits, with 7 linked markers. In 3 of the 6 regions influencing NN, higher NN was associated with the Jalo EEP-558 allele, whereas in only 2 regions was the BAT-93 allele associated with higher NN. One-way analysis of variance, with each marker as the independent variable and NN as the dependent variable, and interval mapping analysis identified 4 QTLs, which accounted for 45% of the total variation, and 2 additional QTLs near to yet unassigned loci. In linkage group D7, one QTL mapped to the same region as a QTL for CBB. Under high N, 3 additional regions were linked to NN, one where the BAT-93 allele was closely associated with CH18 (chitinase), and the others where the Jalo EEP-558 allele was associated with CHS (chalcone synthetase) and PAL-1 (phenylalanine ammonia lyase). Four regions for CBB were mapped adjacent to or in the same region as a QTL for NN. Thus, N showed dual and opposite effects on the expression of NN and CBB. Analysis of these RFLP markers revealed these 'hidden' favourable alleles and can serve as an indirect selection tool to increase NN and resistance to CBB. |
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