Changes of Leaf Membrane Fatty Acid Composition and Saturation Level of Warm‐Season Turfgrass during Drought Stress

Abstract

Although it is known that drought tolerance can be associated with membrane fatty acid (FA) unsaturation, a relevant study is lacking in zoysiagrass (Zoysia spp.) and St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze.]. Our objectives were (i) to substantiate that variation exists among species and genotypes for leaf tissue FA composition under well‐watered conditions; (ii) to evaluate the relationship between well‐watered leaf FA composition and turf performance under drought stress; and (iii) to determine if modifications in FA content occur during drought stress and if the changes associate with improved drought tolerance. Nine genotypes of three species were subjected to both controlled dry down and well‐watered conditions for 12 d in a greenhouse. Plants were evaluated for cumulative water use, transpiration response, turfgrass quality, and leaf FA composition (palmitic acid, stearic acid, palmitoleic acid, hexadecadienoic acid, oleic acid, linoleic acid, and linolenic acid). St. Augustinegrass had a constitutively higher unsaturation FA fraction than two zoysiagrass species, owing to its higher linolenic acid and low palmitic acid fractions. During dry down, relative FA contents remained stable and no early unsaturation alteration was found. Two genotypes, ‘UF182’ Japanese lawngrass (Z. japonica Steud.) and ‘Zeon’ manilagrass [Z. matrella (L.) Merr.], displayed an increase in unsaturated FAs when severe drought stress occurred (rapid decline in turfgrass quality), which was associated with good turfgrass quality and apparent drought tolerance. The result in zoysiagrass supports previous reports suggesting increased levels of linolenic acid under drought stress to be a defensive mechanism.

Physiological and Transcriptomic Analysis of Tree Peony (Paeonia section Moutan DC.) in Response to Drought Stress

“…In this transcriptome study, the upregulation of genes such as lipoxygenase gene (LOX), hydroperoxide dehydratase gene (CYP), and 12-oxophytodienoic acid reductase gene (ORP) in the alpha-linolenic acid metabolic pathway could also be seen. These all indicate that drought stress leads to a decrease in fatty acid content, and the results are the same as those of Zhang et al [44].…”

“…Among them, transketolase gene (TKL), ribose 5-phosphate isomerase A gene (RPI), fructose-1, 6-bisphosphatase I gene (FBP), and other genes in the pentose phosphate pathway can provide NADPH for fatty acid biosynthesis; 3-ketoacyl-CoA synthase gene (KCS), enoyl-CoA hydratase gene (ECH) and palmitoyl-protein thioesterase gene (PPT) in the fatty acid elongation pathway can play a role in the fatty acid biosynthesis pathway [43]. Moreover, drought stress induced an increase in linolenic acid levels, which stimulated the initiation of plant defense mechanisms [44]. In this transcriptome study, the upregulation of genes such as lipoxygenase gene (LOX), hydroperoxide dehydratase gene (CYP), and 12-oxophytodienoic acid reductase gene (ORP) in the alpha-linolenic acid metabolic pathway could also be seen.…”

Drought responses of above‐ground and below‐ground characteristics in warm‐season turfgrass

“…There is no evidence showing canopy characteristics such as leaf texture, density and vertical growth rate (Zhang et al., ) were attributed to its better drought resistance. Zeon was reported to increase the unsaturation level of its leaf membrane fatty acids when severe drought occurred (Zhang, Kenworthy, Unruh, Erickson, & MacDonald, ), which may contribute to its ability to delay leaf senescence or chlorophyll degradation under drought compared to Taccoa Green.…”

Mechanisms of Environmental Stress Tolerance in Turfgrass

“…Similarly, antioxidant enzyme activity, chlorophyll and proline content were variable within tall fescue species [78]. Moreover, evapotranspiration rate, transpiration sensitivity, soluble carbohydrate contents, H 2 O 2 content, fatty acid composition and antioxidant enzyme activity under drought stress were variable in different turfgrass species [79][80][81][82]. It was reported that the drought tolerance of Kentucky bluegrass was significantly higher than that of perennial ryegrasss [83].…”