Li Juanxia, Bai Xiaoming, Ran Fu, Zhi Yuchi, Gao Dongdong, Fang Yao, Cheng Jialong, Chai Xueting, Li Ping, Chen Hui
College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, 730070, China; Key Laboratory of Grassland Ecosystem (Ministry of Education), Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
Plant Physiol Biochem. 2024 Dec;217:109238. doi: 10.1016/j.plaphy.2024.109238. Epub 2024 Oct 24.
Drought and cold stresses co-occur in nature, and significantly limited agricultural productivity in northwest China. Their effects on plant photosynthesis, physiology and biochemistry, and microstructure have been extensively studied, but their combined stress mechanisms remain unclear. Therefore, growth chamber experiments were conducted using the Annual bluegrass (Poa annua) with the 'HZ' and 'ZQ' germplasms, our goal was to clarify the responses of leaves to cold (C), drought (D), and combined (D&C) stresses in the morphology, photosynthesis, physiology and biochemistry, and microstructure. The results showed that three stress types significantly suppressed growth, reduced photosynthetic pigments, photosynthetic capacity, and photosynthetic enzyme activities, with 'ZQ' being more sensitive than 'HZ'. C stress (12/36 h) improved chlorophyll fluorescence parameters in 'HZ' (except for photochemical quenching coefficient), while D and D&C stresses diminished these parameters of both germplasms. Under single and combined stresses, leaf thickness and cuticle thickness generally increased then decreased with stress duration, except for 'ZQ' under D stress. D stress increased reactive oxygen species, relative conductivity, malondialdehyde content and stomatal density, while inhibited stomatal size. Conversely, C stress exacerbated the negative effects of drought on these traits. The D&C stress enhanced antioxidant enzyme activity and proline content, which were similar to the responses to D stress, except for 'ZQ' under D&C stress. After 24 h of stress relief, the recoveries degree of most traits in plant under D and D&C stresses were similar, with 'HZ' recovering more than 'ZQ'. This study indicated drought played a dominant role in combined stress. However, some unique responses could not be inferred from the superimposed effects of some single stresses.
干旱和寒冷胁迫在自然界中同时发生，严重限制了中国西北地区的农业生产力。它们对植物光合作用、生理生化及微观结构的影响已得到广泛研究，但其复合胁迫机制仍不清楚。因此，利用“HZ”和“ZQ”种质的一年生早熟禾进行了生长室试验，目的是阐明叶片在形态、光合作用、生理生化及微观结构方面对寒冷（C）、干旱（D）及复合（D&C）胁迫的响应。结果表明，三种胁迫类型均显著抑制生长，降低光合色素、光合能力及光合酶活性，“ZQ”比“HZ”更敏感。C胁迫（12/36小时）提高了“HZ”的叶绿素荧光参数（除光化学猝灭系数外），而D和D&C胁迫降低了两种种质的这些参数。在单一和复合胁迫下，叶片厚度和角质层厚度一般随胁迫持续时间先增加后降低，但D胁迫下的“ZQ”除外。D胁迫增加了活性氧、相对电导率、丙二醛含量及气孔密度，同时抑制气孔大小。相反，C胁迫加剧了干旱对这些性状的负面影响。D&C胁迫增强了抗氧化酶活性和脯氨酸含量，这与对D胁迫的响应相似，但D&C胁迫下的“ZQ”除外。胁迫解除24小时后，D和D&C胁迫下植物大多数性状的恢复程度相似，“HZ”的恢复程度高于“ZQ”。本研究表明干旱在复合胁迫中起主导作用。然而，一些独特的响应无法从某些单一胁迫的叠加效应中推断出来。
