Abstract
Flag leaves (FL) and second leaves (SL) in rice show differential aging patterns during monocarpic senescence. Coordination of aging programs between FL and SL is important for grain yield and quality. However, the molecular bases for differential aging programs between FL and SL have not been systematically explored in rice. Here, we performed mRNA-sequencing of FL and SL at six time points during grain-filling and identified four molecular bases for differential aging programs between FL and SL: phenylpropanoid biosynthesis, photosynthesis, amino acid (AA) transport, and hormone response. Of them, photosynthesis (carbon assimilation) and AA transport (nitrogen remobilization) predominantly occurred in FL and SL, respectively, during grain-filling. Unlike other molecular bases, AA transport showed consistent differential expression patterns between FL and SL in independent samples. Moreover, long-distance AA transporters showed invariant differential expression patterns between FL and SL after panicle removal, which was consistent to invariant differential nitrogen contents between FL and SL after panicle removal. Therefore, our results suggest that the supplies of carbon and nitrogen to seeds is functionally segregated between FL and SL and that long-distance AA transport is an invariant core program for high nitrogen remobilization in SL.
Highlights
In cereal crops, nutrients are predominantly transported to grains from leaves
In preliminary analyses of the Dongjin (Oryza sativa L. ssp. japonica) variety, which has been widely used for genetic analyses[34], differential patterns of Chl degradation were observed between flag leaves (FL) and second leaves (SL) during grain-filling
Because this is a hallmark feature of leaf senescence, we used this variety for further experiments in this study
Summary
Nutrients are predominantly transported to grains from leaves. In rice, leaves provide grains with carbon (C) and nitrogen (N) mainly through assimilation and remobilization, respectively[1,2,3]. On the other hand, delayed senescence can decrease protein content (grain quality) in grains by delaying up-regulation of N remobilization, whereas accelerated senescence can increase protein content[9,10,11] These data indicate that leaf senescence is crucial for determining both yield and quality of grains during the grain-filling period. Gene expression profiling of flag leaves (FL) from vegetative to senescence stages has identified www.nature.com/scientificreports/ These studies were performed mostly in FL only. These analyses revealed SAGs with shared and differential patterns of expression changes during grain-filling. Among differential senescence programs, changes after panicle removal were used to distinguish invariable core senescence programs from variable senescence programs
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
