Identification of Indica rice chromosome segments for the improvement of Japonica inbreds and hybrids

Abstract

Exploitation of heterosis has brought significant advance in plant breeding and agricultural production, although its genetic basis is still poorly understood. In this study, a total of 66 chromosome segment substitution (CSS) lines, derived from a cross between japonica rice inbred line Asominori (as the recurrent parent) and indica rice inbred line IR24 (as the donor parent), were used to investigate the genetic basis of heterosis in indica × japonica inter-subspecific rice hybrids. Each CSS line was crossed with the background parent Asominori, and the heterosis of F(1) hybrids was estimated by comparing the F(1) performance with its two parental lines. Field experiments were carried out across six different environments to evaluate yield and yield-related traits in the 66 CSS lines and their 66 corresponding F(1) hybrids. Quantitative trait loci (QTL) analyses were conducted using a likelihood ratio test based on the stepwise regression. Thirty-six QTL were identified with significant effects in CSSL, 21 with significant effects in hybrids and 13 with significant effects in both. On the basis of average dominance degree, of all the 70 QTL affecting yield-related agronomic traits, 28.6% (20) showed an overdominance, 35.7% (25) a partial dominance and 30% (21) an additive effect, indicating that all effects contribute to trait variation in japonica-indica rice hybrids. Effects of these QTL were examined to identify Indica rice chromosome segments of interest for the improvement of japonica inbred lines and hybrids.

Next-generation phenotyping: requirements and strategies for enhancing our understanding of genotype–phenotype relationships and its relevance to crop improvement

“…Additionally, more genetically structured resources such as chromosome segment substitution lines (Ali et al 2010; Lu et al 2011; Wang et al 2012; Fukuoka et al 2010; Xu et al 2010; Zhang et al 2011), multi-parent advanced generation inter-cross (MAGIC) populations (Huang et al 2011, 2012; Rakshit et al 2012), and nested association mapping (NAM) populations (Yu et al 2008) will permit the interrogation of natural variation in elite genetic backgrounds that may be intractable otherwise. These genetically structured populations partition the variation in ways that facilitate the identification of exotic alleles that may have a significant impact on a phenotype of interest, but only when introgressed into the elite background.…”

Exploitation of heterosis loci for yield and yield components in rice using chromosome segment substitution lines

“…For instance, 21 heterosis loci with significant effects on hybrids were identified in rice using 66 CSSLs and their 66 corresponding F 1 plants with the recurrent parent19. Fifteen QTLs contributing to heterosis of plant height were identified by comparing performance among 15 CSSLs, their hybrids, and the recurrent parent20.…”

Construction of chromosomal segment substitution lines and genetic dissection of introgressed segments associated with yield determination in the parents of a super‐hybrid rice

“…Of three QTL ( qGPP2.1 , qGPP2.2 and qGPP3 ) identified, one ( qGPP2.2 ) was located near marker RM5390 had likely been detected by Wang et al. () using 66 CSSLs derived from a cross between ‘Asominori’ and ‘IR24’. A new QTL ( qTGW12 ) for TGW, located near marker RM7102 on chromosome 12, was detected in all six environments and accounted for 20.07% of the phenotypic variation in E2 (Table ).…”

“…, Wang et al. ). In contrast, the correlations between SS and HD, PL and GPP were significantly negative (P < 0.01), suggesting that GPP, PL and SS could be used as indirect selection criteria for enhancing yield.…”

“…, Wang et al. ). Although LYP9 was a pioneer super‐hybrid rice cultivar widely grown in China (Gao et al.…”