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Enhanced thermal-tolerance of photosystem II by elevating root zone temperature in Prunus mira koehne seedlings

作　　者：Hai-Ping Hao, Chuang-Dao Jiang, Shou-Ren Zhang, Yu-Dan Tang, Lei Shi
影响因子：2.773
刊物名称：Plant and Soil
出版年份：2011
卷：DOI: 10.1007/s11104-011-1037-y  期：  页码：

论文摘要：

     Background and aims In the field, high ambient temperature inevitably leads to high root zone temperature, especially for seedlings. It is reported that maintaining a non-stressful root temperature is beneficial to improving tolerance of shoot to heat stress. However, our recent studies found that 1-yearold seedlings of smooth-pit peach grew poorly at nonstressful root zone temperature under field conditions in summer. To explore the mechanisms underlying the observations, we studied the physiological responses of seedlings of smooth-pit peach (Prunus mira Koehne), a heat-sensitive species, to high ambient temperatures (37 and 42°C) under varying root zone temperatures.
Methods One-year-old seedlings of smooth-pit peach were divided into two groups subjected to two temperatures: non-stressful root temperature (25±2°C, NRT), and high root zone temperature (HRT). The root and ambient temperatures were controlled by a root zone temperature chamber and light incubator. During this process, the responses of leaf water status (RWC), chlorophyll a fluorescence, activities of antioxidant enzymes, and abscisic acid (ABA) content to high ambient temperature were investigated.
Results Under the high ambient temperature, seedlings exposed to NRT had higher RWC than those subjected to HRT. Interestingly, high ambient temperature induced more severely damage to the primary photochemistry of photosystem II (PSII) in seedlings under NRT than those under HRT. These results were consistent with the results of activities for antioxidant enzymes. Seedlings exposed to NRT exhibited a significantly lower leaf ABA contents than those exposed to HRT under high ambient temperatures. Further studies demonstrated that, in seedlings treated with NRT, exogenous application of ABA enhanced the activities of antioxidant enzymes and significantly alleviated the damage to the primary photochemistry of PSII caused by high ambient temperature.
Conclusions Our findings demonstrate that exposure of smooth-pit peach seedlings to non-stressful root temperature maintained leaf water status under high ambient temperature, but it enhanced the sensitivity of PSII to heat stress. The enhanced accumulation of ABA in leaves of smooth-pit peach seedlings triggered by HRT may contribute to the improvement of the thermo-tolerance of PSII.
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