Yield performances of japonica introgression lines selected for drought tolerance in a BC breeding programme

Abstract

Developing drought tolerant cultivars is a preferred strategy to solve water-shortage facing rice farmers. A backcross (BC) breeding was initiated to improve drought tolerance (DT) of japonica hybrids in North China using an elite japonica restorer, C418, as recipient and five indica cultivars as donors. A two-round-selection for yield under severe drought together with a two-round-selection for yield under irrigation resulted in 113 BC 2 F 8 introgression lines (ILs). Progeny testing allowed the identification of 46 (40.7%) superior-C418-ILs that had significantly improved yield potential under water stress and/or normal irrigation, demonstrating the power of BC breeding in exploiting favourable variation hidden in the indica gene pool for improving complex traits of japonica rice. Increased height and acceleratedheading were major phenotypic changes correlated with improvedyield under stress in these ILs, suggesting the possible involvement of gibberellin (GA) pathway and drought escaping. Considerable variations in yield components among these ILs indicate the presence of different underlying mechanisms. The C418-ILs developed in this study provide useful materials for dissecting DT and yield, and for further target-trait-improvement by pyramiding.

Joint Mapping and Allele Mining of the Rolled Leaf Trait in Rice (Oryza sativa L.)

“…Therefore, transgressive segregation of the rolled leaf trait in the RIL population can be partially explained by the reverse patterns of the allelic effects at the seven loci. Our results further support the observation that even though the germplasms themselves do not show prominent traits, they do harbor some excellent alleles, as previously observed for grain yield [75], salt tolerance [76], cold tolerance [13], and drought tolerance [12]. …”

“…Unlike the extremely rolled leaf phenotype, moderately rolled leaves or leaves with various degrees of rolling, especially inside-rolled (adaxial rolled) leaves, would be a useful trait to target in breeding. Uncovering hidden diversity in the progenies of parents with minor phenotypic differences in target traits is also important for dissecting complex traits including resistance to various biotic and abiotic stresses [12, 13]. Whether the mechanisms underlying hidden diversity also function for relatively simple traits such as rolled leaves remains unclear.…”

Rice GROWTH UNDER DROUGHT KINASE Is Required for Drought Tolerance and Grain Yield under Normal and Drought Stress Conditions

“…Overall drought tolerance of plants cannot be inferred from performance of plants under vegetative drought alone because drought stress during the reproductive stage can lead to a significant reduction in rice yield (Venuprasad et al, 2007;Centritto et al, 2009;He et al, 2010). Therefore, sustained growth and yield under drought will be the major criterion for developing drought-tolerant rice plants.…”

Drought-tolerance QTLs commonly detected in two sets of reciprocal introgression lines in rice

“…Recent studies on molecular quantitative genetics of complex traits demonstrated the fact that even though the germplasms or modern varieties do not show stress tolerance, they do harbor some excellent genes such as drought tolerance Lafitte et al 2006;He et al 2010), salt tolerance (Cheng et al 2012;Wang et al 2012), and cold tolerance (Andaya and Tai 2006;Jiang et al 2008). Such favourable genes were found to be 'hidden' in germplasms, and advance backcross populations appears to be an effective way to mine them by introgressing and further pyramiding favourable genes of parents and different donors with molecular marker technologies Guan et al 2010).…”