粳稻叶绿素含量QTL与其合成降解相关基因的比较分析

Comparison between QTLs for Chlorophyll Content and Genes Controlling Chlorophyll Biosynthesis and Degradation in Japonica Rice (Oryza sativa L.)

为剖析水稻叶绿素不同时期的表达规律及后期持绿的遗传机制,以沈农265和丽江新团黑谷的粳-粳交重组自交系为材料,对水稻分蘖期、抽穗期和成熟期的叶绿素含量以及生育后期的持绿能力进行QTL定位分析。检测到5个控制分蘖期叶绿素含量的QTL、7个控制水稻抽穗期叶绿素含量的QTL和10个控制成熟期叶绿素含量的QTL,分布在除第5染色体以外的11条染色体上。比较它们与编码叶绿素合成及降解过程中的重要酶的基因发现,虽然生育前期检测到的QTL较少,但对应的叶绿素合成降解相关基因却较多。随生育期的推移,检测到的QTL数目增多,但对应的叶绿素合成降解相关基因却减少。暗示生育前期大多数叶绿素合成(降解)相关基因表达的水平差异不大,后期控制叶绿素合成降解的个别关键基因表达水平增加。并以此为基础提出了叶片生育后期持绿的两种可能遗传基础。

To understand the expression patterns of chlorophyll content related genes at different stages and genetic mechanisms of stay-green at later stage, we analyzed the QTLs controlling chlorophyll content at the stages of tillering, heading and maturity by employing 126 recombinant inbred lines （RILs） derived from a cross between two japonica rice cultivars, Shennong 265 and Lijiangxintuanheigu. Five, seven, and ten QTLs controlling chlorophyll contents at tillering stage, heading stage and maturity stage were detected, respectively. They were distributed on all rice chromosomes except chromosome 5. Comparison of the QTLs and the genes underlying the key enzymes of chlorophyll biosynthesis and degradation revealed that relatively more QTLs de-tected at earlier stage co-located with the genes related to chlorophyll biosynthesis and degradation. With the growth stage going on, more QTLs were detected but only a few of them involved in chlorophyll biosynthesis and degradation. The results suggested that the expression level of most genes related to chlorophyll biosynthesis （degradation） had no difference at earlier stage but specific key genes increased at later stage. And two possible genetic bases for stay-green were proposed.