Validation of QTLs associated with spikelets per panicle and grain weight in rice

Abstract

In this study, a near-isogenic line (BC 4 F 10 ) CR572 developed by introgressing a chromosomal segment from Oryza rufipogon (accession no. 105491) into the Oryza sativa subsp. japonica cv. Hwaseong was found to exhibit a significant increase in the number of spikelets per panicle (SPP) and grain weight compared with the recurrent parent Hwaseong. Quantitative trait locus (QTL) analysis in F 2 generation derived from the cross between CR572 and Hwaseong revealed that two QTLs, qSPP1 and qTGW1, were linked to a simple sequence repeat marker, RM283, on chromosome 1. The additive effect of the O. rufipogon allele at qSPP1 was 13 SPP, and 21.6% of the phenotypic variance was explained by the segregation of RM283. The qTGW1 QTL explained 19.1% of the phenotypic variance for grain weight. Substitution mapping was carried out with five F 3 lines derived from F 2 plants having informative recombination breakpoints within the target region. Substitution mapping indicated the linkage of qSPP1 and qTGW1. The grain yield of CR572 was 18.2 and 15.8% higher than that of Hwaseong at two locations, respectively, mainly due to the increase in 1000-grain weight and SPP. These results are very useful for QTL cluster transfer by molecular marker-assisted selection in rice breeding programmes and for QTL gene cloning by map-based cloning.

Brassinosteroid biosynthesis gene OsD2 is associated with low-temperature germinability in rice

“…In addition, two introgression lines TR5 and TR20 harboring the O. rufipogon qLTG1 allele showed improved agronomic traits, such as increased grain size, spikelets per panicle, 1,000-grain weight, and grain yield whereas their tall statue are unfavorable because of lodging (Yun et al, 2016, Supplementary Figures 7, 8). Although it is unclear whether these changes in agronomic traits are due to the pleiotropic effect of OsD2 or other tightly linked genes, these results support the fact that wild rice is a valuable resource for improving yield stability and widening genetic diversity in rice breeding programs (Xiao et al, 1996;Yeo et al, 2014;Yun et al, 2016;Shim et al, 2019).…”