Unraveling Main Limiting Sites of Photosynthesis under Below- and Above-Ground Heat Stress in Cucumber and the Alleviatory Role of Luffa Rootstock.
Unraveling Main Limiting Sites of Photosynthesis under Below- and Above-Ground Heat Stress in Cucumber and the Alleviatory Role of Luffa Rootstock.
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DOI：
10.3389/fpls.2016.00746
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发表时间：
2016
影响因子：
5.6
通讯作者：
Zhou Y
中科院分区：
文献类型：
--
作者：
Li H;Ahammed GJ;Zhou G;Xia X;Zhou J;Shi K;Yu J;Zhou Y
光合作用是植物对温度最敏感的过程之一。虽然嫁接可以减轻高温胁迫的严重程度，但对高温胁迫下光合系统的主要受损部位以及砧木介导的耐热性的调控机制还知之甚少。本研究以黄瓜和丝瓜为试材，研究了根区高温（25/40°C）和气热（40/25°C）对黄瓜光合作用的影响，探讨了根区高温和气热对黄瓜光合作用的影响。结果表明，根际热胁迫主要通过降低Rubisco活性来抑制光合作用，而气生热胁迫主要通过抑制PSII受体侧来抑制光合作用。光吸收和利用的不平衡导致活性氧的积累，造成光合机构的破坏，形成恶性循环。相反，嫁接黄瓜耐热丝瓜砧木缓解热诱导的光合抑制和氧化胁迫，保持较高的根系活力，HSP 70的积累，和抗氧化潜力。
Photosynthesis is one of the most thermo-sensitive processes in plants. Although the severity of heat stress could be attenuated by grafting approach, the primary damaged site of photosynthesis system under heat stress and the regulatory mechanism of rootstock-mediated heat tolerance are poorly understood. In the current study, cucumber plants grafted onto their own roots and heat-tolerant luffa roots were exposed to root-zone heat (25/40°C) and aerial heat (40/25°C) individually and in combination (40/40°C) to understand the response of photosynthetic process by investigating energy absorption and distribution, electron transport in photosystem (PS) II and I, and CO2 assimilation. According to the results, root-zone heat stress inhibited photosynthesis mainly through decreasing Rubisco activity, while aerial heat stress mainly through inhibiting PSII acceptor side. The imbalance in light absorption and utilization resulted in accumulation of reactive oxygen species that caused damage to photosynthetic apparatus, forming a vicious cycle. On the contrary, grafting cucumber onto heat-tolerant luffa rootstock alleviated heat-induced photosynthetic inhibition and oxidative stress by maintaining higher root vitality, HSP70 accumulation, and antioxidant potential.