School of Biological Science and Engineering, Shaanxi University of Technology, Hanzhong 732001, China.
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Int J Mol Sci. 2021 Aug 29;22(17):9365. doi: 10.3390/ijms22179365.
Cucumber ( L.), an important vegetable plant species, is susceptible to low temperature stress especially during the seedling stage. Vacuolar invertase (VI) plays important roles in plant responses to abiotic stress. However, the molecular and biochemical mechanisms of VI function in cucumber, have not yet been completely understood and VI responses to low temperature stress and it functions in cold tolerance in cucumber seedlings are also in need of exploration. The present study found that hexose accumulation in the roots of cucumber seedlings under low temperature stress is closely related to the observed enhancement of invertase activity. Our genome-wide search for the vacuolar invertase (VI) genes in cucumber identified the candidate VI-encoding gene . Expression profiling of showed that it was mainly expressed in the young roots of cucumber seedlings. In addition, transcriptional analysis indicated that expression could respond to low temperature stress. Recombinant CsVI1 proteins purified from and leaves could hydrolyze sucrose into hexoses. Further, overexpression of in cucumber plants could increase their hexose contents and improve their low temperature tolerance. Lastly, a putative cucumber invertase inhibitor was found could form a complex with CsVI1. In summary, these results confirmed that CsVI1 functions as an acid invertase involved in hexose accumulation and responds to low temperature stress in cucumber seedlings.
黄瓜（L.）是一种重要的蔬菜植物物种，特别在幼苗期易受到低温胁迫的影响。液泡转化酶（VI）在植物应对非生物胁迫中起着重要作用。然而，VI 在黄瓜中的分子和生化机制尚未完全阐明，VI 对低温胁迫的响应及其在黄瓜幼苗抗寒性中的功能也需要进一步探索。本研究发现，低温胁迫下黄瓜幼苗根系中己糖的积累与观察到的转化酶活性增强密切相关。我们对黄瓜液泡转化酶（VI）基因的全基因组搜索鉴定了候选的 VI 编码基因 。 表达谱分析表明，它主要在黄瓜幼苗的幼根中表达。此外，转录分析表明 可以响应低温胁迫。从 和 叶片中纯化的重组 CsVI1 蛋白可以将蔗糖水解成己糖。此外，在黄瓜植物中过表达 可以增加其己糖含量并提高其耐低温性。最后，发现一种假定的黄瓜转化酶抑制剂可以与 CsVI1 形成复合物。总之，这些结果证实 CsVI1 作为一种酸性转化酶参与了黄瓜幼苗中己糖的积累，并对低温胁迫做出响应。
