Login / Signup

PHYTOCHROME-INTERACTING FACTORS (PIFs) are involved in starch degradation adjustment via inhibition of carbon metabolic regulator QUA-QUINE STARCH (QQS) in Arabidopsis.

Sang Woo LeeDasom ChoiHeewon MoonSujeong KimHajeong KangInyup PaikEnamul HuqDong Hwan Kim
Published in: The Plant journal : for cell and molecular biology (2023)
As sessile organism, plants daily encounter dynamic and challenging environments including abiotic/biotic stresses. The regulation of carbon and nitrogen allocations for the synthesis of plant proteins, carbohydrates, and lipids is fundamental for plant growth and adaption to its surroundings. Light, one of the essential environmental signals, exerts substantial impact on plant metabolism and resource partitioning (i.e. starch). However, it is not fully understood how light signaling affect carbohydrate production and allocation in plant growth and development. An orphan gene unique to Arabidopsis thaliana, named as QUA-QUINE STARCH (QQS) is involved in metabolic processes for partitioning of carbon and nitrogen among proteins and carbohydrates, thus influencing leaf, seed composition, and plant defense in Arabidopsis. In this study, we show that PHYTOCHROME-INTERACTING bHLH TRANSCRIPTION FACTORS (PIFs) including PIF4 is required to suppress QQS at the dawn period, thus preventing overconsumption of starch reserves. QQS expression is significantly de-repressed in pif4 and pifQ, while repressed by overexpression of PIF4, suggesting that PIF4 and its close homologs (PIF1, PIF3 and PIF5) act as negative regulators of QQS expression. In addition, we show that the evening complex including ELF3 is required for active expression of QQS, thus playing a positive role in starch catabolism during night period. Furthermore, QQS is epigenetically suppressed by DNA methylation machinery, whereas histone H3 K4 methyltransferases (e.g., ATX1, ATX2, and ATXR7) and H3 acetyltransferases (e.g., HAC1 and HAC5) are involved in expression of QQS. This study demonstrates that PIF light signaling factors help plants utilize optimal amounts of starch during night and prevent overconsumption of starch before starch biosynthesis in upcoming day.
Keyphrases