Expansins are involved in cell growth mediated by abscisic acid and indole-3-acetic acid under drought stress in wheat

Abstract

Expansin protein is a component of the cell wall generally accepted to be the key regulator of cell wall extension during plant growth. Plant hormones regulate expansin gene expression as well as plant growth during drought stress. However, the relationship between expansin and plant hormone is far from clear. Here, we studied the involvement of expansin in plant cell growth mediated by the hormones indole-3-acetic acid (IAA) and abscisic acid (ABA) under osmotic stress which was induced by polyethylene glycol (PEG)-6000. Wheat coleoptiles from a drought-resistant cultivar HF9703 and a drought-sensitive cultivar 921842 were used to evaluate cell growth and expansin activity. Osmotic stress induced the accumulation of ABA. ABA induced expansin activity mainly by enhancing expansin expression, since ABA induced cell wall basification via decreasing plasma membrane H(+)-ATPase activity, which was unfavorable for expansin activity. Although ABA induced expansin activity and cell wall extension, treatment with exogenous ABA and/or fluridone (FLU, an ABA inhibitor) suggested that ABA was involved in the coleoptile growth inhibition during osmotic stress. IAA application to detached coleoptiles also enhanced coleoptile growth and increased expansin activity, but unlike ABA, IAA-induced expansin activity was mainly due to the decrease of cell wall pH by increasing plasma membrane H(+)-ATPase activity. Compared with drought-sensitive cultivar, the drought-resistant cultivar could maintain greater expansin activity and cell wall extension, which was contributive to its resultant faster growth under water stress.

Gene expression changes in response to drought stress in Ilex paraguariensis leaves

“…There is increasing evidence demonstrating that expansins are involved in the responsive mechanisms of plant species to water stress (Dai et al, 2012;Zhao et al, 2012;Barcia et al, 2014). Recently, Zhou et al (2015) have suggested that water stress inhibits leaf growth; however, changes in expansin activity and cell wall susceptibility to expansin during times of water deficit could increase the growth rate after rehydration.…”

AtEXP2 Is Involved in Seed Germination and Abiotic Stress Response in Arabidopsis

“…In addition to the regulation by phytohormones, expansin genes are also differentially regulated by various environmental cues [54], such as abiotic stresses including salt stress, heat stress, drought stress, and water stress [30], [37], [43], [70]. Here we tested the germination phenotype of exp2 and the overexpression line in response to salt stress and osmotic stress, and we found that exp2 mutant exhibited hypersensitivity to salt stress and osmotic stress compared to wild type, while the overexpression line showed reduced sensitivity to these stress treatments and revealed enhanced tolerance to stress to a certain extent.…”

“…The extensive occurrence of the expansins superfamily in plants suggests that expansins play multiple roles during the plant life cycle [14]–[15], and in the past several decades numerous studies have accumulated evidence about their involvement in diverse developmental processes, including seed germination [16]–[17], seedling morphogenesis [18], root architecture [19]–[26], leaf development [27]–[30], fruit ripening [31]–[32], stoma opening [33]–[34], pollination [35], abscission, stress responses [36]–[43] and others. However, those characterized expansins only represent a small proportion of the expansins superfamily in the plant kingdom, and the individual functions of other expansin coding genes still remains to be elucidated.…”

HDG11 upregulates cell-wall-loosening protein genes to promote root elongation in Arabidopsis

“…It has been found that most hormones that affect the root development seem to act ultimately by modulating auxin activity (Moubayidin et al , 2010; Perilli et al , 2012). Hormones control root development in many ways, one of which is that hormones can change the expression of root cell-wall-loosening protein genes or the activity of cell-wall-loosening proteins (Jan et al , 2004; Liu et al , 2007; Zhao et al , 2012). Regulated cell expansion allows plants to adapt their morphogenesis to survive in different environmental conditions.…”