Abstract
Tree peony (Paeonia section Moutan DC.) is a famous ornamental plant, and P. ostii has been used for seed oil production in China because it is rich in α-linolenic acid. P. ostii has some resistance to drought, but lack of water can severely hinder its growth and development in arid areas. In order to clarify drought stress induced physiological and molecular changes of P. ostia, its physiological and transcriptomic analyses were performed under drought stress, and we found that P. ostii leaves drooped significantly 12 days after treatment and observed a significant increase in all detected physiological indices in response to drought treatment except leaf water content, chlorophyll, and carotenoid content. Meanwhile, the activity of three antioxidant enzymes basically increased under drought treatment. Moreover, drought treatment significantly reduced photosynthetic and chlorophyll fluorescence parameters except non-photochemical quenching (qN), and maintained more intact mesophyll cell structures. Additionally, many differentially expressed genes (DEGs) were found by transcriptome sequencing, which play an important role in P. ostia drought tolerance by controlling a variety of biological processes, including the reactive oxygen species (ROS) system, chlorophyll degradation and photosynthetic competency, fatty acid metabolism, proline metabolism, biosynthesis of secondary metabolism, and plant hormone metabolism. These results provide a better understanding of P. ostii responses to drought stress.
Highlights
Drought stress is a type of water stress that is due mainly to the lack of an effective water supply for plants in soil or air, which affects normal plant growth
When P. ostii was stressed with continuous drought, the leaves wilted on day 8 and drooped
Observation of transmission electron microscopy in this study showed that P. ostii chloroplast structure was destroyed under drought stress, which revealed that the destroyed chloroplast structure was another reason for the decreased photosynthesis rate (Pn)
Summary
Drought stress is a type of water stress that is due mainly to the lack of an effective water supply for plants in soil or air, which affects normal plant growth. The effects of drought stress on plant growth and development are growing. Drought stress directly affects plant morphological structure, especially in the nutritive growth stage [1]. Reduced leaf expansion is beneficial for plants under drought conditions, as reduced leaf area leads to reduced transpiration [3]. Reducing shoot growth and correspondingly increasing root growth can alleviate the damage to plants under drought stress. This is beneficial for the roots to extract more water from deep soil [3]. Drought stress can have a significant impact on plants during reproductive growth. Moderate drought can promote flower bud differentiation, but excessive drought stress will reduce the number of flowers and promote the degradation of flower
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