Genetic Dissection of Agronomic Traits in Introgression Lines and Improvement of an Elite <i>Indica</i> Rice Variety

Abstract

To enhance the yield potential of rice by improving plant type, we have developed introgression lines (ILs: BC 3 -derived lines) with the genetic background of the elite indica variety IR64. A total of 334 ILs derived from crosses between IR64 as the recurrent parent and 10 donor parents (nine new-planttype lines , and one Japanese high-yielding cultivar, 'Hoshiaoba') have been developed by recurrent backcross breeding. The agronomic traits of the 334 ILs were evaluated in the experimental field of the International Rice Research Institute from 2005 to 2007, and their genotypes were determined using SSR markers. Several agronomic traits (days to heading, leaf length and width, culm and panicle length, number of panicles, total spikelet number per panicle, and 100-grain weight) were dissected genetically by QTL analysis using hybrid populations derived from crosses between IR64 and ILs with unique traits. More than 30 QTLs were detected and their effects were confirmed by developing and evaluating near-isogenic lines (NILs). These ILs and NILs are useful for both breeding and further genetic dissection of agronomic traits across various environments. Discipline: Plant breedingAdditional key words: grain yield, near-isogenic line, new plant type, Oryza sativa, quantitative trait locus This paper reports the results of a collaborative research project conducted between IRRI and JIRCAS, and supported by Japan's Ministry of Agriculture, Forestry and Fisheries (MAFF) and Ministry of Foreign Affairs (MOFA).

The Selection of Gamma-Ray Irradiated Higher Yield Rice Mutants by Directed Evolution Method

“…Higher yield gene explorations using high and low yield cross-combinations have not been successful since it is difficult to overcome the high-yielding parents by using such combinations. Fujita et al found NAL1 / SPIKE from the new plant type cultivar YP9 (Daringan, IR68522-10-2-2), which showed 24% to 28% higher yield than its original high-yielding cultivar, IR64 [ 20 , 21 ]. In these reports, higher yield traits of YP9 were introduced into IR64.…”

“…The introduction of Takanari’s GPS into Koshihikari increased the photosynthesis rate of Koshihikari but not the yield. Fujita et al also found NAL1 from the new plant type cultivar YP9 that was backcrossed with IR64 as a recurrent parent [ 20 , 21 ]. They developed IRRI146- SPIKE , which showed 24% to 28% higher yield than its original high-yielding cultivar IR64.…”