Hu Wei, Gao Min, Du Kang, Liu Yang, Xu Bingjie, Wang Youhua, Zhou Zhiguo, Zhao Wenqing
College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China.
Institute of Organic Dry Farming of Shanxi, Shanxi Agricultural University, Taiyuan, People's Republic of China.
Physiol Plant. 2023 Jan;175(1):e13866. doi: 10.1111/ppl.13866.
High temperatures and drought are expected to become more frequent in the future and last longer than ever before. To investigate their combined effect on leaves subtending cotton boll (LSCB), an experiment was conducted from 2016 to 2018 using a nonheat-tolerant cotton cultivar and a heat-tolerant cultivar. Two temperature regimes with ambient temperature (AT, 31.0/26.4°C) and elevated temperature (ET, 33.4/28.9°C, 2.5°C higher than AT) and three drought treatments with a soil relative water content (SRWC) of 75 ± 5%, 60 ± 5%, and 45 ± 5% were established repeatedly. ET decreased net photosynthetic rate (Pn), initial rubisco activity (4.1.1.39, RuBP) and cytosolicfructose-1,6-bisphosphatase (cy-FBPase; 3.1.3.11) activity, upregulated GhSuSyA, and GhSuSyD expressions, and increased SuSy (2.4.1.13) activity, which led to the decline of the final starch and sucrose contents. Moreover, RuBP, Pn, and starch content all decreased with drop in SRWC levels, but the cy-FBPase and SPS (2.4.1.14) activity increased, which in turn increased sucrose content. Under combined stresses, when the changing trends of ET and drought effects were the same, the decrease of Pn, RuBP, and starch content was greater than under single stress exposure. However, when the changing trends of ET and drought effects were adverse, the combined effects on indicators such as cy-FBPase, SuSy, sucrose content were mostly similar to drought stress. These results indicate that the effect of drought on carbohydrate metabolism in LSCB is more prominent than ET. Thus, the drought effect for carbohydrate metabolism in LSCB may need more attention than ET under combined heat and drought stress.
预计未来高温和干旱将变得更加频繁，且持续时间比以往任何时候都更长。为了研究它们对棉铃着生叶（LSCB）的综合影响，于2016年至2018年使用一个不耐热棉花品种和一个耐热品种进行了一项实验。反复设置了两种温度处理，即环境温度（AT，31.0/26.4°C）和高温（ET，33.4/28.9°C，比AT高2.5°C），以及三种干旱处理，土壤相对含水量（SRWC）分别为75±5%、60±5%和45±5%。ET降低了净光合速率（Pn）、初始核酮糖-1,5-二磷酸羧化酶（4.1.1.39，RuBP）活性和胞质果糖-1,6-二磷酸酶（cy-FBPase；3.1.3.11）活性，上调了GhSuSyA和GhSuSyD的表达，并增加了蔗糖合成酶（2.4.1.13）活性，这导致最终淀粉和蔗糖含量下降。此外，RuBP、Pn和淀粉含量均随SRWC水平的下降而降低，但cy-FBPase和蔗糖磷酸合成酶（SPS，2.4.1.14）活性增加，进而增加了蔗糖含量。在复合胁迫下，当ET和干旱效应的变化趋势相同时，Pn、RuBP和淀粉含量的下降幅度大于单一胁迫处理。然而，当ET和干旱效应的变化趋势相反时，对cy-FBPase、蔗糖合成酶、蔗糖含量等指标的复合效应大多与干旱胁迫相似。这些结果表明，干旱对LSCB碳水化合物代谢的影响比ET更显著。因此，在高温和干旱复合胁迫下，干旱对LSCB碳水化合物代谢的影响可能比ET更值得关注。
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