Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
J Plant Physiol. 2018 Dec;231:271-276. doi: 10.1016/j.jplph.2018.10.008. Epub 2018 Oct 11.
Global climate warming has a crucial impact on many terrestrial ecosystems, including temperate steppe. In addition, phosphate deficiency is known to be the common deficiency in soils worldwide due to the low availability of the phosphate nutrient in the form of inorganic phosphate anions (Pi). Consequently, in the future, land plants are likely to simultaneously encounter heat stress and phosphate deficiency more frequently. Sheepgrass 〔Leymus chinensis (Trin.) Tzvel〕is a dominant perennial forage plant highly significant to grass productivity of Eurasian temperate grasslands. Though effects of environmental stress including drought and Pi starvation have been studied, the combined eff ;ects of phosphate deficiency and heat stress on plant physiology remain largely unclear. Here, we investigated the combined eff ;ects of heat stress and phosphate deficiency on above-ground tissue growth and photochemical properties of L. chinensis using in vivo chlorophyll fluorescence spectroscopy. We observed remarkable phenotypic alterations of reduced shoot growth and considerable leaf chlorosis in L. chinensis seedlings under the combined stress condition. Also, we compared changes in photochemical activity between the control and the corresponding stressed seedlings. Based on chlorophyll fluorescence analysis, impairment of PSI was more severe than that of PSII in the seedlings treated with the combined stress. Compared to the control, PSI and PSII activity decreased up to 35.5% and 30%, respectively, under the combined-stress condition. Moreover, our data show that the decreased photosynthetic activity is not the sum of the single-stressed conditions. These results combined with the distinction of other photochemical parameters indicate that a complex interaction between Pi-deficiency and heat stress may exist in the forage plant.
全球气候变暖对包括温带草原在内的许多陆地生态系统产生了至关重要的影响。此外，由于无机磷酸根离子（Pi）形式的磷营养物质的可用性低，全世界的土壤普遍存在磷缺乏的问题。因此，在未来，陆地植物可能更频繁地同时遇到热胁迫和磷缺乏的问题。羊草（Leymus chinensis (Trin.) Tzvel）是一种优势多年生饲用植物，对欧亚大陆温带草原的草产量具有重要意义。尽管已经研究了包括干旱和 Pi 饥饿在内的环境胁迫的影响，但磷缺乏和热胁迫对植物生理学的综合影响在很大程度上仍不清楚。在这里，我们使用活体叶绿素荧光光谱法研究了热胁迫和磷缺乏对羊草地上组织生长和光化学特性的综合影响。我们观察到，在复合胁迫条件下，羊草幼苗的地上组织生长和叶片明显变绿。此外，我们比较了对照和相应胁迫幼苗之间光化学活性的变化。基于叶绿素荧光分析，与 PSII 相比，PSI 在处理复合胁迫的幼苗中受到的损伤更为严重。与对照相比，PSI 和 PSII 的活性分别下降了 35.5%和 30%。此外，我们的数据表明，降低的光合作用活性不是单一胁迫条件的总和。这些结果结合其他光化学参数的差异表明，在饲用植物中，Pi 缺乏和热胁迫之间可能存在复杂的相互作用。
