Abstract
Stipa purpurea, an endemic forage species on the Tibetan Plateau, is highly resistant to cold and drought, but the mechanisms underlying its responses to drought stress remain elusive. An understanding of such mechanisms may be useful for developing cultivars that are adaptable to water deficit. In this study, we analyzed the physiological and proteomic responses of S. purpurea under increasing drought stress. Seedlings of S. purpurea were subjected to a drought gradient in a controlled experiment, and proteins showing changes in abundance under these conditions were identified by two-dimensional electrophoresis followed by mass spectrometry analysis. A western blotting analysis was conducted to confirm the increased abundance of a heat-shock protein, NCED2, and a dehydrin in S. purpurea seedlings under drought conditions. We detected carbonylated proteins to identify oxidation-sensitive proteins in S. purpurea seedlings, and found that ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO) was one of the oxidation-sensitive proteins under drought. Together, these results indicated drought stress might inhibit photosynthesis in S. purpurea by oxidizing RuBisCO, but the plants were able to maintain photosynthetic efficiency by a compensatory upregulation of unoxidized RuBisCO and other photosynthesis-related proteins. Further analyses confirmed that increased abundance of antioxidant enzymes could balance the redox status of the plants to mitigate drought-induced oxidative damage.
Highlights
Global warming during the last 100 years has caused substantial changes in temporal and spatial precipitation patterns in many parts of the world [1]
Because drought is one the main stress factors limiting plant growth on the Tibetan Plateau, we examined the proteomic profile of S. purpurea to identify the key intrinsic response to drought stress under laboratory conditions
These results suggest that the drought treatment enhanced the potential of S. purpurea to tolerate further drought
Summary
Global warming during the last 100 years has caused substantial changes in temporal and spatial precipitation patterns in many parts of the world [1]. The Tibetan Plateau, sometimes called “the roof of the world”, is an important region for studying plants’ responses to such. Proteomic Analysis of S. purpurea under Drought changes. This is partly because of its extreme altitude (average elevation, >4000 m), and partly because annual precipitation gradually declines from approximately 700 mm to 50 mm from the southeast to the northwest across the Plateau, with accompanying changes in ecosystem types from alpine marsh, grassland, or coniferous forest to alpine or polar desert [2]. Tree-line data indicate that extreme drought conditions have progressed into the northwest part of the Tibetan Plateau over the past 300 years [3]. Water has become an even scarcer commodity in this region
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