RESUMO
The stigma exertion rate is a polygenic inherited trait that is important for increased seed yield in hybrid rice breeding. To identify quantitative trait loci (QTL) associated with high stigma exertion rate, we conducted QTL mapping using 134 recombinant inbred lines derived from XieqingzaoB and Zhonghui9308, which have high and low stigma exertion rates, respectively. A total of eight QTLs (qSES6, qSSE11, qDSE1a, qDSE1b, qDSE10, qDSE11, qTSE1, and qTSE11) for single stigma exertion, double stigma exertion, and total stigma exertion were detected. The locations of qSSE11 and qTSE11 have not been previously reported, and the qDSE11 allele from parent XQZB exhibited a positive additive effect. In addition, three QTLs (qSNP1, qSNP3a, and qSNP3b), for spikelet number per panicle were identified. Of note, one QTL (qSNP1) was detected in two different environments (Hainan and Zhejiang). To evaluate the advantage of exerted stigma for cross-pollination, single, dual, and total stigma exertion should be considered separately for future genetic improvement in the production of rice hybrid seeds. In addition, this study provides information for fine mapping, gene cloning, and marker assisted selection, with emphasis on the latter.
Assuntos
Mapeamento Cromossômico/métodos , Oryza/anatomia & histologia , Oryza/genética , Locos de Características Quantitativas/genética , Análise de Variância , Cromossomos de Plantas/genética , Meio Ambiente , Genética Populacional , Endogamia , Modelos Genéticos , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Recombinação Genética/genética , TemperaturaRESUMO
Genetic improvement is the fundamental basis for improving nitrogen-use efficiency. A better understanding of genetic factors controlling nitrogen uptake and utilization is required for crop genetic improvement. In this study, we identified the quantitative trait loci (QTLs) associated with traits of nitrogen uptake and utilization by using the single-sequence repeat marker method and a recombinant inbred line (RIL) population derived from a super hybrid Xieyou9308. All the traits investigated were inherited quantitatively by continuous variation and showed normal distribution in phenotype with transgressive segregation in the RIL population. Most of the traits were significantly correlated with each other except for nitrogen absorption ability (NAA) with nitrogen harvest index (NHI) and NHI with agricultural nitrogen-absorption efficiency (ANAE). At logarithmic odds value of 2.3, total 13 candidate QTLs, including 4 for NAA, 2 for NHI, 2 for physiological nitrogen-use efficiency, 1 for agricultural nitrogen-use efficiency (ANUE), and 4 for ANAE, were detected and mapped on chromosomes 2, 3, 4, 5, 8, 9, 10, and 12. Significant pleiotropic effect or neighboring expression of QTLs was observed among traits. At position 64.8 cM on chromosome 4 near the marker RM5757, there was a QTL cluster of NAA, ANUE, and ANAE, and at chromosome 5 near the marker RM5968, there was a QTL cluster of NAA and ANUE. The QTL clusters might provide partial explanation and genetic mechanism for the observed correlations between nitrogen uptake and utilization efficiency traits and might form a basis for future breeding programs.