Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles

Abstract

BackgroundHigh temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d.ResultsCompared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system.ConclusionsTaken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1263-z) contains supplementary material, which is available to authorized users.

Reproductive success of soybean (Glycine max L. Merril) cultivars and exotic lines under high daytime temperature

“…The exine originates from the tapetum, and premature degeneration of the tapetal layer under high temperature stress might have affected the translocation of carbohydrates to developing pollen grains leading to abnormal exine ornamentation and loss of pollen viability (Djanaguiraman, Prasad, & Schapaugh, ; Djanaguiraman, Boyle, Welti, et al, ). Studies in sorghum have shown that apart from tapetum degeneration, high temperatures also induce accumulation of reactive oxygen species in pollen grains leading to loss of pollen viability (Djanaguiraman et al, ; Djanaguiraman, Boyle, Welti, et al, ; Prasad & Djanaguiraman, ). However, in pearl millet, the pistil is found to be more sensitive to high temperature than pollen grains (Djanaguiraman, Perumal, Ciampitti, et al, ).…”

“…Similar to this observation, Prasad et al (1999) in peanut; Aloni, Peet, Pharr, and Karni (2001) Figure 5). The exine originates from the tapetum, and premature degeneration of the tapetal layer under high temperature stress might have affected the translocation of carbohydrates to developing pollen grains leading to abnormal exine ornamentation and loss of pollen viability Djanaguiraman, Boyle, Welti, et al, 2018). Studies in sorghum have shown that apart from tapetum degeneration, high temperatures also induce accumulation of reactive oxygen species in pollen grains leading to loss of pollen viability (Djanaguiraman et al, 2014;Djanaguiraman, Boyle, Welti, et al, 2018;.…”

“…The SEM was operated in a vacuum, 5 kV, with a spot size of 3 and a pressure of 72.5 Pa. Images were taken at 3,000×; 12,000×; and 24,000× magnifications (Djanaguiraman, Boyle, Welti, Jagadish, & Prasad, ).…”

“…Images were taken at 3,000×; 12,000×; and 24,000× magnifications (Djanaguiraman, Boyle, Welti, Jagadish, & Prasad, 2018…”

VIL1, a Polycomb-associated protein, modulates high ambient temperature response via H3K27me3 and H2A.Z inArabidopsis thaliana

“…GO term analysis of cluster 7 shows enrichment of genes related to photosynthesis and response abiotic stimulus. It has been reported that photosynthetic activity is reduced at high ambient temperature in order to cope with the stress 26 . These results also suggest that vil1 fails to reduce photosynthetic activity at higher temperature unlike WT.…”