Leaf Lipid Alterations in Response to Heat Stress of Arabidopsis thaliana

Abstract

<jats:p>In response to elevated temperatures, plants alter the activities of enzymes that affect lipid composition. While it has long been known that plant leaf membrane lipids become less unsaturated in response to heat, other changes, including polygalactosylation of galactolipids, head group acylation of galactolipids, increases in phosphatidic acid and triacylglycerols, and formation of sterol glucosides and acyl sterol glucosides, have been observed more recently. In this work, by measuring lipid levels with mass spectrometry, we confirm the previously observed changes in Arabidopsis thaliana leaf lipids under three heat stress regimens. Additionally, in response to heat, increased oxidation of the fatty acyl chains of leaf galactolipids, sulfoquinovosyldiacylglycerols, and phosphatidylglycerols, and incorporation of oxidized acyl chains into acylated monogalactosyldiacylglycerols are shown. We also observed increased levels of digalactosylmonoacylglycerols and monogalactosylmonoacylglycerols. The hypothesis that a defect in sterol glycosylation would adversely affect regrowth of plants after a severe heat stress regimen was tested, but differences between wild-type and sterol glycosylation-defective plants were not detected.</jats:p>

Heat stress elicits remodeling in the anther lipidome of peanut

“…Muller et al 21,22 reported that the accumulation of TAG species, particularly those with polyunsaturated acyl chains, is a heat-response mechanism. The TAG formed in peanut anthers under HT contained all the major fatty acids but was less enriched in 18:3 than in the other major fatty acids, in contrast to the results in Arabidopsis [21][22][23][24] . Essentially no TAG(18:3/18:3/18:3) was accumulated under HT in peanut anthers (Fig.…”

“…5 and Supplementary Table S3). This is in contrast to data from Arabidopsis leaves and seedlings, where 18:3/18:3/18:3 levels are highly increased in leaves under short-term heat stress [21][22][23][24] . SPT 06-07 had a larger percent increase under HT than Bailey for most TAG species (Fig.…”

“…The lack of increase in the TAG(16:0/16:0/16:0) species may be because a significant portion of high-melting 16:0 component remains in polar lipids in order to stabilize membranes at HT. The lack of much increase in TAG(18:3/18:3/18:3) in most genotypes at HT is in contrast to the large increases seen in TAG(18:3/18:3/18:3) in Arabidopsis seedlings and leaves and in wheat leaves 13,[21][22][23][24] . Muller et al 21,22 reported that the accumulation of TAG species, particularly those with polyunsaturated acyl chains, is a heat-response mechanism.…”

“…Genotype was the split-plot factor with four replications per level arranged as a randomized complete block design within the whole-plot Figure 10. A lipid metabolic pathway map based on previously published information and results from the present study 14,23,24,[59][60][61][62] . Dashed arrows indicate multi-step conversions.…”

Head-Group Acylation of Chloroplast Membrane Lipids

“…Biotic and abiotic stresses result in dramatic fluctuations in chloroplast lipid levels, with head-group acylation being strongly enhanced by stress ( Figure 3 ). Whereas wounding and freeze-thaw treatments have been shown to increase the level of acylated lipids in a number of plant species, most studies of stress effects on chloroplast lipid acylation have been done in Arabidopsis thaliana [ 7 , 8 , 10 , 16 , 20 , 22 , 23 , 28 , 33 ]. The pattern of acylated chloroplast lipid accumulation varies as a function of the particular stress applied to Arabidopsis plants.…”