Sugars are the key regulatory molecules that impact diverse biological processes in plants. Hexokinase, the key rate-limiting enzyme in hexose metabolism, takes part in the first step of glycolytic pathway. Acting as a sensor that mediates sugar regulation, hexokinase has been proved to play significant roles in regulating plant growth and development. Here, we isolated a hexokinase gene SlHXK1 from tomato. Its transcript levels were higher in flowers and leaves than in other organs and decreased during leaf and petiole development. SlHXK1-RNAi lines displayed advanced leaf senescence and stunted plant growth. Physiological features including plant height, leaf length, thickness and size, the contents of chlorophyll, starch and MDA, and hexokinase activity were dramatically altered in SlHXK1-RNAi plants. Dark-induced leaf senescence were advanced and the transcripts of senescence-related genes after darkness treatment were markedly increased in SlHXK1-RNAi plants. RNA-seq and qRT-PCR analyses showed that the transcripts of genes related to plant hormones, photosynthesis, chloroplast development, chlorophyll synthesis and metabolism, cellular process, starch and sucrose metabolism, and senescence were significantly altered in SlHXK1-RNAi plants. Taken together, our data demonstrate that SlHXK1 is a significant gene involved in leaf senescence and plant growth and development in tomato through affecting starch turnover.

中文翻译：

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抑制己糖激酶基因 SlHXK1 导致番茄叶片衰老加速和植物生长发育迟缓

糖是影响植物多种生物过程的关键调节分子。己糖代谢的关键限速酶己糖激酶参与糖酵解途径的第一步。作为介导糖调节的传感器，己糖激酶已被证明在调节植物生长发育中发挥重要作用。在这里，我们从番茄中分离了己糖激酶基因 SlHXK1。其转录水平在花和叶中高于其他器官，并在叶和叶柄发育期间降低。SlHXK1-RNAi 系显示出晚期叶片衰老和植物生长受阻。SlHXK1-RNAi 植物的生理特征，包括株高、叶长、厚度和大小、叶绿素、淀粉和 MDA 的含量以及己糖激酶活性都发生了显着变化。SlHXK1-RNAi植物中黑暗诱导的叶片衰老提前，黑暗处理后衰老相关基因的转录显着增加。RNA-seq 和 qRT-PCR 分析表明，SlHXK1-RNAi 植物中与植物激素、光合作用、叶绿体发育、叶绿素合成和代谢、细胞过程、淀粉和蔗糖代谢以及衰老相关的基因转录本显着改变。综上所述，我们的数据表明 SlHXK1 是一个重要的基因，通过影响淀粉周转而参与番茄叶片衰老和植物生长发育。SlHXK1-RNAi 植物的叶绿体发育、叶绿素合成和代谢、细胞过程、淀粉和蔗糖代谢以及衰老发生了显着改变。综上所述，我们的数据表明 SlHXK1 是一个重要的基因，通过影响淀粉周转而参与番茄叶片衰老和植物生长发育。SlHXK1-RNAi 植物的叶绿体发育、叶绿素合成和代谢、细胞过程、淀粉和蔗糖代谢以及衰老发生了显着改变。综上所述，我们的数据表明 SlHXK1 是一个重要的基因，通过影响淀粉周转而参与番茄叶片衰老和植物生长发育。