Mapping and Validation of Quantitative Trait Loci Associated with Tiller Production in Rice

An increase in early tiller production is desired in rice (Oryza sativa L.) to increase yield potential and enhance ability to shade and suppress weeds. Unfortunately, tiller production and survival are sensitive to many environmental cues, making tillering pattern a difficult trait to reliably evaluate in field plots. The present objective was to use pot-grown plants where seeding depth and the environment could be controlled to identify quantitative trait loci (QTLs) associated with rate of seedling development (seedling leaf number, SLN) and tiller production (tiller number, TN) as well as the node from which the first tiller originated (N1T). The QTLs were identified in two related mapping populations, the first being a set of 280 'Lemont'. 'TeQing' recombinant inbred lines (RILs) observed over four trials, in which nine QTLs associated with TN, three for SLN, and two for N1T were detected. Eight of the TN QTLs were verified in a second population consisting of 123 TeQing-into-Lemont backcross introgression lines (TILs). Each SLN and N1T QTL was colocated with a TN QTL, and all nine detected TN QTLs were located in genomic regions previously reported to contain TN major genes or QTLs, demonstrating their robustness under diverse genetic backgrounds and growth conditions. Early tillering was associated with rapid seedling development as detected by an increased number of leaves and nodes on 8-wk-old seedlings. The present data indicated that breeders could effectively select for enhanced early tiller production among segregating genotypes based on tiller counts conducted at a single time point approximately 8 to 9 wk after germination under greenhouse conditions. Marker-trait linkages reported here can support marker-assisted selection of these nine TN QTLs.