Abstract
Drought is a major environmental stress that limits growth and development of cool-season annual grasses. Drought transcriptional profiles of resistant and susceptible lines were studied to understand the molecular mechanisms of drought tolerance in annual ryegrass (Lolium multiflorum L.). A total of 4718 genes exhibited significantly differential expression in two L. multiflorum lines. Additionally, up-regulated genes associated with drought response in the resistant lines were compared with susceptible lines. Gene ontology enrichment and pathway analyses revealed that genes partially encoding drought-responsive proteins as key regulators were significantly involved in carbon metabolism, lipid metabolism, and signal transduction. Comparable gene expression was used to identify the genes that contribute to the high drought tolerance in resistant lines of annual ryegrass. Moreover, we proposed the hypothesis that short-term drought have a beneficial effect on oxidation stress, which may be ascribed to a direct effect on the drought tolerance of annual ryegrass. Evidence suggests that some of the genes encoding antioxidants (HPTs, GGT, AP, 6-PGD, and G6PDH) function as antioxidant in lipid metabolism and signal transduction pathways, which have indispensable and promoting roles in drought resistance. This study provides the first transcriptome data on the induction of drought-related gene expression in annual ryegrass, especially via modulation of metabolic homeostasis, signal transduction, and antioxidant defenses to improve drought tolerance response to short-term drought stress.
Highlights
Water availability plays a significant role in the transportation of metabolites and enzymatic reactions in plants, and plays roles in the hydrolytic breakdown of proteins, lipids, and carbohydrates (Bewley and Black, 1994; Białecka and Kêpczyñski, 2010)
To investigate the effects of drought stress resulting in oxidative stress in two L. multiflorum lines, enzyme change was quantified after plants were treated with drought stress for 1 or 2 h
A lower H2O2 concentration in drought-tolerant lines could be due to the higher activity of the enzymatic activities of catalases (CAT), superoxide dismutase (SOD), dehydroascorbate reductase (DHAR), and monodehydroasorbate reductase (MDHAR; Figures 1D–H)
Summary
Water availability plays a significant role in the transportation of metabolites and enzymatic reactions in plants, and plays roles in the hydrolytic breakdown of proteins, lipids, and carbohydrates (Bewley and Black, 1994; Białecka and Kêpczyñski, 2010). The metabolite changes contribute to the number of drought-responsive genes when the plant is under abiotic stress. A number of genes are known to be related to early response to stress, and are thought to be involved in metabolic processes possessing adaptation capacity to abiotic stress (Puranik et al, 2011). The identification such genes has been suggested as representing a promising approach toward the improvement of drought tolerance in crops (Munns, 2005). Responsive genes have been identified through high-throughput sequencing technology, which is a powerful method that is used to analyze changes in cell morphology, gene expression, and physiological and biochemical metabolism for plants under abiotic and biotic stress (Lan et al, 2012)
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