Faculty of Life Science and Biotechnology, Kunming University of Science and Technology, Chenggong, 650500, Kunming, China.
Faculty of Life Science and Biotechnology, Kunming University of Science and Technology, Chenggong, 650500, Kunming, China.
Plant Sci. 2021 Apr;305:110829. doi: 10.1016/j.plantsci.2021.110829. Epub 2021 Jan 27.
Serine hydroxymethyltransferase 1 (SHMT1) is a key enzyme in the photorespiration pathway in higher plants. Our previous study showed that AtSHMT1 controls the assimilation of HCHO to sugars in Arabidopsis. The expression of SHMT1 was induced in Arabidopsis but was inhibited in tobacco under HCHO stress. To investigate whether the function of AtSHMT1 in the HCHO assimilation could be exerted in tobacco, AtSHMT1 was overexpressed alone (S5) or co-overexpressed (SF6) with Arabidopsis formate dehydrogenase (AtFDH) in leaves using a light-inducible promoter in this study. C NMR analyses showed that the C-metabolic flux from HCHO was introduced to sugar synthesis in SF6 leaves but not in S5 leaves. The increase in the production of metabolites via the original pathways was particularly greater in SF6 leaves than in S5 leaves, suggesting that co-overexpression of AtSHMT1 and AtFDH is more effective than overexpression of AtSHMT1 alone in the enhancement of HCHO metabolism in tobacco leaves. Consequently, the increase in HCHO uptake and resistance was greater in SF6 leaves than in S5 leaves. The mechanism underlying the role of overexpressed AtSHMT1 and AtFDH was discussed based on changes in photosynthetic parameters, chlorophyll content, antioxidant enzyme activity and the oxidative level in leaves.
丝氨酸羟甲基转移酶 1（SHMT1）是高等植物光呼吸途径中的关键酶。我们之前的研究表明，AtSHMT1 控制拟南芥中 HCHO 向糖的同化。在拟南芥中，SHMT1 的表达受到诱导，但在烟草中受到 HCHO 胁迫的抑制。为了研究 AtSHMT1 在 HCHO 同化中的功能是否可以在烟草中发挥作用，本研究使用光诱导启动子在叶片中单独（S5）或与拟南芥甲酸脱氢酶（AtFDH）共过表达（SF6）AtSHMT1。13C-NMR 分析表明，SF6 叶片中 HCHO 的 C-代谢通量被引入糖合成，但 S5 叶片中没有。通过原始途径增加代谢物的产生在 SF6 叶片中比在 S5 叶片中更为显著，表明 AtSHMT1 和 AtFDH 的共过表达比单独过表达 AtSHMT1 更有效地增强烟草叶片中 HCHO 的代谢。因此，SF6 叶片中 HCHO 的吸收和抗性增加大于 S5 叶片。根据光合参数、叶绿素含量、抗氧化酶活性和叶片氧化水平的变化，讨论了过表达 AtSHMT1 和 AtFDH 的作用机制。
