期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 72, 期 7, 页码 2627-2641出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/eraa604
关键词
Blue light; cryptochrome; HY5; Solanum lycopersicum; starch degradation; sugar accumulation; tomato
资金
- National Key Research and Development Program of China [2019YFD1000300]
- Modern Agro-industry Technology Research System of China [CARS-25-02A]
- National Natural Science Foundation of China [31825023]
- Key Research and Development Program of Zhejiang [2018C0210]
The study reveals that the blue light signal plays a critical role in regulating starch accumulation in tomato chloroplasts through the CRY1a-mediated HY5 transcription factor, affecting starch degradation. HY5 directly binds to the promoters of starch degradation-related genes, activating their transcription and impacting the accumulation of starch and soluble sugars.
Starch is the major storage carbohydrate in plants, and its metabolism in chloroplasts depends mainly on light. However, the mechanism through which photoreceptors regulate starch metabolism in chloroplasts is unclear. In this study, we found that the cryptochrome 1a (CRY1a)-mediated blue light signal is critical for regulating starch accumulation by inducing starch degradation through the transcription factor HY5 in chloroplasts in tomato. cry1a mutants and HY5-RNAi plants accumulated more starch and presented lower transcript levels of starch degradation-related genes in their leaves than wild-type plants. Blue light significantly induced the transcription of starch degradation-related genes in wild-type and CRY1a- or HY5-overexpressing plants but had little effect in cry1a and HY5-RNAi plants. Dual-luciferase assays, electrophoretic mobility shift assays, and chromatin immunoprecipitation-qPCR revealed that HY5 could activate the starch degradation-related genes PWD, BAM1, BAM3, BAM8, MEX1, and DPE1 by directly binding to their promoters. Silencing of HY5 and these starch degradation-related genes in CRY1a-overexpressing plants led to increased accumulation of starch and decreased accumulation of soluble sugars. The findings presented here not only deepen our understanding of how light controls starch degradation and sugar accumulation but also allow us to explore potential targets for improving crop quality.
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