Genetic Dissection for Chlorophyll Content of the Top Three Leaves During Grain Filling in Rice (Oryza sativa L.)

Leaf senescence and the consequent decline in chlorophyll (Chl) content is a normal event in the life cycle of plants. Although many studies on Chl content or leaf senescence in rice have been conducted, the understanding of this process is limited. By using a double haploid population derived from a cross between japonica Chunjiang06 (CJ06) and indica Taichong native (TN1), quantitative trait locus (QTL) analysis for Chl content of the top three leaves during the rice grain filling stage was performed in this study. A total of 61 QTLs for the Chl content at four development stages were identified. The QTLs had additive effects of 0.64-3.31 SPAD value with heritability ranging from 2.9 to 26.9 %. Twenty-seven pairs of epistatic interaction for Chl content were estimated and distributed on all 12 chromosomes. The detected QTLs and epistatic interactions were clustered in 15 intervals and expressed with spatial-temporal specificity. The QTLs for leaf senescence and their interactions were further estimated, indicating that the alleles delaying leaf senescence from japonica variety CJ06 exhibited more contribution than those from indica variety TN1. This study revealed that the QTLs for Chl content showed clear spatial-temporal specificity. QTL analysis also showed that more alleles that increased Chl content were contributed from japonica variety CJ06. Thus, the results in this study may help in the selection of the rice variety with delayed leaf senescence, and will improve understanding of the molecular basis of leaf senescence.