Tianjin Key Laboratory of Protein Science and Department of Plant Biology and Ecology, College of Life Sciences, Nankai University Tianjin, China.
Front Plant Sci. 2014 Jun 24;5:301. doi: 10.3389/fpls.2014.00301. eCollection 2014.
Carbon and nitrogen are essential components for plant growth. Although models of plant carbon and nitrogen metabolisms have long been established, certain gaps remain unfilled, such as how plants are able to maintain a flexible nocturnal starch turnover capacity over various light cycles, or how nitrogen remobilization is achieved during the reproductive growth stage. Recent advances in plant autophagy have shed light on such questions. Not only does autophagy contribute to starch degradation at night, but it participates in the degradation of chloroplast proteins and even chloroplasts after prolonged carbon starvation, thus help maintain the free amino acid pool and provide substrate for respiration. The induction of autophagy under these conditions may involve transcriptional regulation. Large-scale transcriptome analyses revealed that ATG8e belongs to a core carbon signaling response shared by Arabidopsis accessions, and the transcription of Arabidopsis ATG7 is tightly co-regulated with genes functioning in chlorophyll degradation and leaf senescence. In the reproductive phase, autophagy is essential for bulk degradation of leaf proteins, thus contributes to nitrogen use efficiency (NUE) both under normal and low-nitrogen conditions.
碳和氮是植物生长的必需组成部分。尽管植物碳氮代谢模型早已建立，但仍存在一些空白，例如植物如何能够在各种光周期下维持灵活的夜间淀粉周转率，或者在生殖生长阶段如何实现氮再利用。植物自噬的最新进展揭示了这些问题。自噬不仅有助于夜间淀粉的降解，而且在长期碳饥饿后还参与叶绿体蛋白甚至叶绿体的降解，从而有助于维持游离氨基酸池并为呼吸提供底物。在这些条件下诱导自噬可能涉及转录调控。大规模转录组分析表明，ATG8e 属于拟南芥品系共享的核心碳信号响应，并且拟南芥 ATG7 的转录与参与叶绿素降解和叶片衰老的基因紧密协同调节。在生殖阶段，自噬对于叶片蛋白的大量降解至关重要，因此有助于在正常和低氮条件下提高氮利用效率（NUE）。
