Chill-induced decrease in capacity of RuBP carboxylation and associated H2O2 accumulation in cucumber leaves are alleviated by grafting onto figleaf gourd.
Chill-induced decrease in capacity of RuBP carboxylation and associated H2O2 accumulation in cucumber leaves are alleviated by grafting onto figleaf gourd.
复制标题
通过嫁接到无花果葫芦上，可以缓解寒冷引起的黄瓜叶中 RuBP 羧化能力的下降和相关的 H2O2 积累。
作者：
背景和目标
冷害导致冷敏品种黄瓜(Cucumis Sativus)Rubisco含量显著降低，活性氧(ROS)生成量增加。根在耐受性调节中的作用尚不清楚。本研究以耐冷性较强的无花果(Cucurbita Fumfolia)为试材，通过嫁接黄瓜植株，研究了根在黄瓜地上部功能调控及相关的根冠通讯中的作用。
方法
在14摄氏度或7摄氏度的冷藏和随后的恢复过程中，使用红外气体分析仪与脉冲幅度荧光仪相结合来测量气体交换和叶绿素荧光。同时，用分光光度法测定了Rubisco的含量、活性和ROS的产生。用酶联免疫吸附试验测定了木质部汁液中脱落酸和细胞分裂素的浓度。
主要成果和结论
根逐渐冷却时，嫁接植株对CO2同化的光饱和速率(A(Sat))显著高于自根植株，而地上部分冷却时差异不显著。7℃冷藏不可逆转地降低了A(Sat)，并显著降低了最大羧化活性、Rubisco含量和初始Rubisco活性。然而，嫁接植物表现出较弱的抑制作用，同时水-水循环中的电子通量降低。嫁接植株抗氧化酶活性较高，ROS产生较少。此外，自根植物木质部汁液中ABA浓度升高48.4倍，细胞分裂素浓度下降91.5%。相比之下，嫁接植株的ABA和细胞分裂素浓度分别增加了10.5倍和36.9%。低温后嫁接植株的生长也得到了改善。这些结果表明，一些来自抗冷根的信号(即ABA和细胞分裂素)保护了低温敏感植物的叶片光合作用。
BACKGROUND AND AIMS
Chilling results in a significant decrease in Rubisco content and increased generation of reactive oxygen species (ROS) in cucumber (Cucumis sativus), a chilling-sensitive species. The role of roots in the regulation of the tolerance is unknown. Here, cucumber plants grafted onto figleaf gourd (Cucurbita ficifolia), a chilling-tolerant species were used to study the role of roots in the regulation of shoot functioning and the associated root-to-shoot communication.
METHODS
Gas exchange and chlorophyll fluorescence were measured using an infrared gas analyser combined with a pulse amplitude fluorimeter during chilling at 14 degrees C or 7 degrees C and subsequent recovery. At the same time, Rubisco content and activity and ROS generation were spectrophotometrically assayed. Abscisic acid and cytokinin concentrations in xylem sap were also determined by enzyme-linked immunosorbent assay.
KEY RESULTS AND CONCLUSIONS
Grafted plants showed a significantly higher light-saturated rate of CO(2) assimilation (A(sat)) than own-rooted plants when roots were gradually cooled, but no differences were detected when shoots were cooled. Chill at 7 degrees C irreversibly reduced A(sat), and significantly decreased maximum carboxylation activity, Rubisco content and initial Rubisco activity. However, grafted plants showed weaker inhibition, together with decreased electron flux in the water-water cycle. Higher activity of antioxidant enzymes with less ROS production was found in grafted plants. In addition, ABA concentration increased by 48.4-fold whilst cytokinin concentration decreased by 91.5% in the xylem sap of own-rooted plants after exposure to a 7 degrees C chill. In comparison, ABA and cytokinin concentrations increased by 10.5-fold and 36.9%, respectively, for the grafted plants. Improved plant growth was also observed in grafted plants after the chill. These results suggest that some signals coming from chilling-resistant roots (i.e. ABA and cytokinins) protect leaf photosynthesis in shoots of chilling-sensitive plants.
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