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背景：Increasing frequency of extreme summer high-temperature (HT) has become one of the most important limiting factors affecting tea production in China. 2-Amino-3-methylhexanoic acid (AMHA) is a unique natural plant inducer against HT stresses. 结果1：In this study, the field efficacy and physiological mechanism of AMHA for improving tea plant resistance against HT in the summer was studied using the temperature-sensitive tea cultivar “Longjing 43″. It was observed that field-grown tea plants treated with 100 or 1000 nM AMHA maintained erect and normal stems and foliage under HT stress. The optimal concentration of AMHA for counteracting HT in field-grown tea plants was 100 nM. 结果2：At three days after treatment (DAT), AMHA at 100 nM increased net photosynthetic rate Pn by 199% and stomatal conductance Gs of tea plants by 215% of tea plants. The fast chlorophyll a rise kinetics and JIP-test analysis further confirmed that AMHA improved the overall photosynthetic activity of photosystem II (PSII) mainly through enhancing the fraction of active oxygen evolving complex (OEC) centers, PSII energetic connectivity and electron transport efficiency. PIABS reflecting PSII overall activity in 100 nM AMHA-treated tea plants was increased by 95%, 51%, 39%, and 48% at 3, 5, 7, and 14 DAT, respectively, compared to mock. At the same dose, AMHA also increased osmotic adjustments for the rapid accumulation of amino acids and soluble sugars, which increased by 21% and 145% at 7 DAT, respectively. In addition, AMHA significantly enhanced the activities of peroxidase (POD), catalse (CAT) and superoxide dismutase (SOD), reducing oxidative damage on membrane lipids. Even at 14 DAT, 100 nM AMHA led to 50%, 75% and 19% increase in POD, CAT and SOD activity in tea plants relative to mock, respectively. 结论：Clearly, exogenous application of AMHA facilitated HT resistance by alleviating physiological damage in field-grown tea plants due to improved photosynthetic performance, osmotic adjustments and antioxidant enzyme activities.夏季极端高温（HT）频率的增加已成为影响中国茶叶生产的最重要限制因素之一。2-氨基-3-甲基己酸（AMHA）是一种独特的抗HT胁迫的天然植物诱导剂。在本研究中，利用温度敏感的茶树品种，研究了AMHA在夏季提高“龙井43”茶树耐高温性的田间效应和生理机制。据观察，在HT胁迫下，用100或1000 nM AMHA处理的大田茶树保持了直立和正常的茎和叶。在大田茶树中对抗HT的最佳AMHA浓度为100 nM。处理后3天（DAT），100 nM的AMHA使茶树的净光合速率Pn增加了199%，气孔导度Gs增加了215%。快速叶绿素a上升动力学和JIP测试分析进一步证实，AMHA主要通过提高活性氧演化复合体（OEC）中心的分数、PSII能量连通性和电子传输效率来提高光系统II（PSII）的整体光合活性。与模拟相比，100nM AMHA处理的茶树中PSII总活性的PIAS在3、5、7和14DAT时分别增加了95%、51%、39%和48%。在相同剂量下，AMHA还增加了氨基酸和可溶性糖的快速积累的渗透调节，在7DAT时分别增加了21%和145%。此外，AMHA显著提高了过氧化物酶（POD）、过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的活性，减少了膜脂质的氧化损伤。即使在14 DAT，100 nM AMHA也导致茶树中POD、CAT和SOD活性分别比模拟增加50%、75%和19%。显然，由于光合性能、渗透调节和抗氧化酶活性的提高，外源施用AMHA通过减轻田间种植茶树的生理损伤，促进了耐高温性。
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