Abstract
After maize seedlings grown in full-strength Hoagland solution for 20 days were exposed to 20% polyethylene glycol (PEG)-stimulated water deficiency for two days, plant height, shoot fresh and dry weights, and pigment contents significantly decreased, whereas malondialdehyde (MDA) content greatly increased. Using transmission electron microscopy, we observed that chloroplasts of mesophyll cells in PEG-treated maize seedlings were swollen, with a disintegrating envelope and disrupted grana thylakoid lamellae. Using two-dimensional gel electrophoresis (2-DE) method, we were able to identify 22 protein spots with significantly altered abundance in the leaves of treated seedlings in response to water deficiency, 16 of which were successfully identified. These protein species were functionally classified into signal transduction, stress defense, carbohydrate metabolism, protein metabolism, and unknown categories. The change in the abundance of the identified protein species may be closely related to the phenotypic and physiological changes due to PEG-stimulated water deficiency. Most of the identified protein species were putatively located in chloroplasts, indicating that chloroplasts may be prone to damage by PEG stimulated-water deficiency in maize seedlings. Our results help clarify the molecular mechanisms of the responses of higher plants to severe water deficiency.
Highlights
Water deficiency is one of the most important environmental stresses limiting plant growth and crop yield [1]
After two days of polyethylene glycol (PEG)-stimulated water deficiency, the seedlings showed significant decreases in plant height, relative water content (RWC) of leaf, fresh weight (FW) and dry weight (DW) of shoot compared to controls by 20.8%, 28.4%, 28.9%, and 15.1%, respectively (Figure 1B–E)
A severe water deficiency was induced by 20% PEG-stimulated stress, which greatly inhibited the growth of maize seedlings
Summary
Water deficiency is one of the most important environmental stresses limiting plant growth and crop yield [1]. Physiological responses to water deficiency have been intensively studied, a thorough molecular understanding of the responses in plants could help explore patterns of biological response and identify genes or proteins involved in tolerance to water deficiency [3]. Water deficiency occurs most frequently at the seedling stage [10] and the few proteomic studies have been mainly performed at temporary water stress in this species [11,12]. A comparative proteomic approach was conducted to identify physiological and proteomic changes in the leaf of maize seedlings suffering PEG-stimulated water deficiency. Results from this study could be helpful for further understanding the molecular mechanism of severe water deficiency in maize. Emphasis was placed on target proteins that may play crucial roles in protecting cellular metabolism from water deficiency
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