欧亚国际

己糖激酶 (HXK)是参与到蔗糖感知的蔗糖磷化酶。较近表明在每年栽种的西红柿和拟南芥护卫细胞中HXK介导了气孔关闭并通过蒸腾协调了光合作用。要检查HXK在多年生植物中控制气孔运动的作用，我们培育了表达 KST1拟南芥HXK1(AtHXK1) 基因的柑橘，该基因为护卫细胞特异启动子。柑橘植物中护卫细胞中KST1 的表达可通过使用GFP报告基因验证。柑橘保卫细胞AtHXK1的表达降低了气孔导度和蒸腾且未对光合速率造成影响，从而提升了水利用效率。光强度以及湿度对气孔行为的影响通过检测柑橘植物近根叶加以检查。较佳强度光合有效辐射以及低湿度了 AtHXK1表达叶片的气孔关闭，协助蔗糖调控柑橘气孔。结果揭示HXK协调了光合和蒸腾作用，刺激了一年生和多年生植物的气孔关闭。

关键词：蔗糖、己糖激酶，气孔，蒸腾，水利用效率，柑橘近根叶，湿度，光强

Expression  of Arabidopsis Hexokinase  in Citrus Guard Cells Controls Stomatal  Aperture  and Reduces Transpiration Hexokinase  

(HXK) is a sugar-phosphorylating  enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration  in the annual species  tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1) under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing  leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

Keywords: sugar, hexokinase,  stomata, transpiration, water-use efficiency, citrus rooted leaves, humidity, light intensity