Quantitative trait loci for early maturity and their potential in breeding for earliness in Brassica juncea |
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Authors: | Tariq Mahmood Muhammad H. Rahman Gary R. Stringam Francis Yeh Allen G. Good |
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Affiliation: | (1) Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5;(2) Present address: Alberta Research Council, PO Bag 4000, Vegreville, AB, Canada, T9C 1T4;(3) Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada, T6G 2H1;(4) Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E1 |
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Abstract: | A doubled haploid population of Brassica juncea, developed from a cross between two parental lines differing for days to maturity, was used to study the efficiency of indirect selection for a primary trait through selection of secondary trait(s) over direct selection for the primary trait when quantitative trait loci information is available for both primary and secondary traits, and applied. Days to maturity was considered as primary trait, while days to first flowering, days to end of flowering, flowering period and plant height were considered as secondary traits. An RFLP linkage map was employed for QTL analysis of maturity and maturity-determinant traits, and a stable QTL B6 simultaneously affecting these two types of traits was identified. This linked QTL explained 11.7% phenotypic variation for days to maturity, 20.7% variation for days to first flowering, 24.3% variation for days to end of flowering and 14.4% variation for plant height. Phenotypic evaluation of maturity and/or maturity-determinant traits, viz. days to first flowering, days to end of flowering and plant height revealed that limited genetic advance for early maturity can be achieved through phenotypic selection of the primary and/or the secondary trait(s). However, the estimates of genetic advance for early maturity based on combined phenotypic evaluation and linked QTL data was found to be, at least, three times higher compared to genetic advance based on phenotypic evaluation only, demonstrating the potential of marker-assisted selection in breeding for early maturity in B. juncea. |
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Keywords: | Brassica juncea Maturity Flowering time Flowering period Plant height Quantitative trait loci Marker-assisted selection Indirect selection |
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