The present study was conducted to identify quantitative trait loci (QTLs) for leaf size traits in IR64 introgression lines (INLs). For this purpose, selected F(2) populations derived from crosses between recurrent parent IR64 and its derived INLs, unique for leaf length and leaf width, were used to confirm QTLs. A total of eight QTLs, mapped on three chromosomes, were identified for the four leaf size traits in six F(2) populations. A QTL for leaf length, qLLnpt-1, in HKL69 was identified around simple sequence repeat (SSR) marker RM3709 on chromosome 1. Two QTLs for flag leaf length, qFLLnpt-2 and qFLLnpt-4, in HFG39 were indentified on chromosomes 2 and 4, respectively. For flag leaf width, a QTL, qFLWnpt-4, in HFG39 was identified around RM17483 on chromosome 4. While another QTL for flag leaf width, qFLWnpt-1, in HFG27 was identified around RM3252 on chromosome 1. A QTL for leaf width, qLWnpt-2, in HKL75 was identified around RM7451 on chromosome 2. For leaf width, two QTLs, qLWnpt-4a, qLWnpt-4b, in HKL48 and HKL99 were identified around RM7208 and RM6909, respectively on chromosome 4. Results from this study suggest the possibilities to use marker-assisted selection and pyramiding these QTLs to improve rice water productivity.
A total of 334 introgression lines (INLs: BC3-derived lines) derived from crosses between Indica cultivar IR64 as a recurrent parent and 10 donor parents including new plant type lines (IR65600-87-2-2-3, IR65598-112-2, IR65564-2-2-3, IR66750-6-2-1, IR69093-41-2-3-2, IR69125-25-3-1-1, Hoshiaoba, IR66215-44-2-3, IR68522-10-2-2, and IR71195-AC1) have been developed by recurrent backcross breeding, to introduce unique traits into IR64 genetic background and to use for breeding materials. The agronomic traits of the 334 INLs were evaluated in International Rice Research Institute from 2005 to 2007 and the genotypes of the 334 INLs were detected using SSR markers. Particularly, 117 out of the 334 INLs which showed unique agronomic traits were selected as the "core set" for detailed evaluation. Variation in agronomic traits: days to heading (DTH), leaf length and width, culm and panicle length, number of panicles, total spikelet number per panicle (TSN), and 100-grain weight (GW), in the 117 INLs were characterized. As a result of comparison between the several INLs and IR64, significant differences were observed in DTH, TSN and GW in at least one season. The developed INLs with the IR64 genetic background are useful for both breeding and genetic dissection of agronomic traits across various environments.Discipline: Plant breeding Additional key words: days to heading, grain weight, new plant type, Oryza sativa L
Days to heading (DTH) is considered as one of the most important traits for rice cultivation. A total of 334 introgression lines (ILs) of rice (Oryza sativa L.), with variation in agronomic traits in the genetic background of an Indica-type variety, ÔIR64Õ, were developed and used in this study. Two ILs derived from ÔIR65600-87-2-2-3Õ and ÔHos-hiaobaÕ showed earlier heading than ÔIR64Õ, whereas two ILs from ÔIR65598-112-2Õ and ÔIR69125-25-3-1-1Õ showed later heading. To ascertain the genetic basis of four ILs, quantitative trait loci (QTL) analysis for DTH was conducted using F 2 populations. Three QTLs for short DTH were detected on chromosome 8 in ÔIR65600-87-2-2-3Õ and on chromosomes 6 and 11 in ÔHoshiaobaÕ. Two QTLs for long DTH were detected on chromosome 6 in ÔIR65598-112-2Õ and on chromosome 11 in ÔIR69125-25-3-1-1Õ. Three near-isogenic lines (NILs) having a QTL from ÔIR65600-87-2-2-3Õ and ÔHoshiaobaÕ were developed through marker-assisted selection and they showed earlier heading than ÔIR64Õ, while two NILs from ÔIR65598-112-2Õ and ÔIR69125-25-3-1-1Õ showed later heading. These NILs for DTH are useful as research and breeding materials.
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