Abstract
High temperature is an important environmental factor that affects plant growth and crop yield. Potentilla fruticosa L. has a developed root system and characteristics of resistance to several stresses (e.g., high temperature, cold, drought) that are shared by native shrubs in the north and west of China. To investigate thermotolerance mechanisms in P. fruticosa, 3-year-old plants were subjected to a high temperature of 42°C for 1, 2, and 3 days respectively before analysis. Then, we studied changes in cell ultrastructure using electron microscopy and investigated physiological changes in the leaves of P. fruticosa. Additionally, we used isobaric tags for relative and absolute quantification (iTRAQ) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to study proteomic changes in P. fruticosa leaves after 3 d of 42°C heat stress. we found that the cell membrane and structure of chloroplasts, especially the thylakoids in P. fruticosa leaves, was destroyed by a high temperature stress, which might affect the photosynthesis in this species. We identified 35 up-regulated and 23 down-regulated proteins after the heat treatment. Gene Ontology (GO) analysis indicated that these 58 differentially abundant proteins were involved mainly in protein synthesis, protein folding and degradation, abiotic stress defense, photosynthesis, RNA process, signal transduction, and other functions. The 58 proteins fell into different categories based on their subcellular localization mainly in the chloroplast envelope, cytoplasm, nucleus, cytosol, chloroplast, mitochondrion and cell membrane. Five proteins were selected for analysis at the mRNA level; this analysis showed that gene transcription levels were not completely consistent with protein abundance. These results provide valuable information for Potentilla thermotolerance breeding.
Highlights
Plant growth and development are affected by a variety of biotic stress factors, such as bacterial infection, symbiotic or parasitic microbial infection, and abiotic stress factors, such as drought, flood, salinization, heat, cold, and mechanical damage
We found that leaf tips and leaf margins showed evidence of mild heat scorch after 1 d of heat stress (Fig 1B) and leaf margins had obvious evidence of heat scorch after 3 d (Fig 1D) compared to control. This indicated that the degree of leaf injury in P. fruticosa increased with extended exposure to heat stress
We found that mesophyll cells of P. fruticosa leaves were deformed under heat stress, and that the cells showed increased distortions on the second and third days of heat stress, indicating that the cell walls and membranes suffered serious injury under the high temperature (Fig 2C and 2D, Panels C and D in S1 Fig)
Summary
Plant growth and development are affected by a variety of biotic stress factors, such as bacterial infection, symbiotic or parasitic microbial infection, and abiotic stress factors, such as drought, flood, salinization, heat, cold, and mechanical damage. Adverse effects of stress on plants lead to a series of physiological changes in metabolic and biochemical processes that cause irreversible damage to growth and development [1, 2] and can result in plant death Of these various stress factors, high temperature damage to plants is important and affects plant growth and crop yields [1,2,3]. When exposed to a high temperature stress, plants generally respond through changes in cell structure, cell membrane permeability, cell osmotic adjustment, and photosynthetic activity [4] These stress responses can be examined by elucidating the changes in protein content (proteome) of cells. Characterization of the factors involved in stress response provides valuable information for use in resistance breeding in high-quality plant species
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