Marker-assisted selection to introgress rice QTLs controlling root traits into an Indian upland rice variety

Steele, K.A. and Price, A.H. and Shashidhar, H.E. and Witcombe, J.R. (2006) Marker-assisted selection to introgress rice QTLs controlling root traits into an Indian upland rice variety. TAG Theoretical and Applied Genetics, 112 (2). pp. 208-221.

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A marker-assisted back-crossing (MABC) breeding programme was conducted to improve the root morphological traits, and thereby drought tolerance, of the Indian upland rice variety, Kalinga III. This variety, the recurrent parent in the MABC, had not previously been used for quantitative trait locus (QTL) mapping. The donor parent was Azucena, an upland japonica variety from Philippines. Five segments on different chromosomes were targeted for introgression; four segments carried QTLs for improved root morphological traits (root length and thickness) and the fifth carried a recessive QTL for aroma. Some selection was made at non-target regions for recurrent parent alleles. We describe the selection made in three backcross (BC) generations and two further crosses between BC3 lines to pyramid (stack) all five target segments. Pyramids with four root QTLs were obtained in eight generations, completed in 6 years using 3,000 marker assays in a total of 323 lines. Twenty-two near-isogenic lines (NILs) were evaluated for root traits in five field experiments in (RM242-RM201) significantly increased root length under both irrigated and drought stress treatments, confirming that this root length QTL from Azucena functions in a novel genetic background. No significant effects on root length were found at the other four targets. Azucena alleles at the locus RM248 (below the target root QTL on chromosome 7) delayed flowering. Selection for the recurrent parent allele at this locus produced early-flowering NILs that were suited for upland environments in eastern India.

Item Type: Article
Author Affiliation: CAZS Natural Resources, University of Wales, Bangor, LL57 2UW, Gwynedd UK
Subjects: Crop Improvement > Genetics/Genomics
Divisions: Other Crops
Depositing User: Sandhya Gir
Date Deposited: 09 Feb 2011 18:06
Last Modified: 09 Feb 2011 18:07
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