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Bulletin of Botanical Research ›› 2021, Vol. 41 ›› Issue (1): 53-59.doi: 10.7525/j.issn.1673-5102.2021.01.007

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Effects of 24-Epibrassinolide on the Chlorophyll Fluorescence Transient in Leaves of Pepper under Drought Stress

Wen-Hai HU1,2, Xiao-Hong YAN1,2, Xiao-Hong LI1,2, Zao-Gui CAO1   

  1. 1.School of Life Sciences,Jingganshan University,Ji’an 343009
    2.Key Laboratory for Biodiversity Science and Ecological Engineering,Jingganshan University,Ji’an 343009
  • Received:2020-01-02 Online:2021-01-20 Published:2021-01-05
  • About author:HU Wen-Hai(1973—),male,Professor,Doctor, majoring in the Horticultural Plant Physiology and Ecology.
  • Supported by:
    National Natural Science Foundation of China(31460513)


In order to investigate the role of exogenous 24-epibrassinolide(EBR) in improving drought tolerance in pepper (Capsicum annuum L. cv.Chaola 9), the chlorophyll fluorescence transient curve(OJIP) was examined in plants under drought stress(15% PEG6000). Drought reduced the photochemical efficiency and photosynthetic performance of pepper leaves, and induced photoinhibition. Drought not only disrupted the oxygen-evolving complex(OEC), but also impaired the PSⅡ reaction and acceptor side of PSⅡ, which inhibited the photosynthetic electron transportation. Drought decreased the number of active PSⅡ reaction centers per unit area. Drought also decreased the specific energy fluxes per unit area for absorption(ABS/CS), trapping(TRo/CS), electron transport(ETo/RC), but increased dissipation energy fluxes per unit area(DIo/CS). These results indicated that drought initiated defense mechanism by decreasing the absorption and transportation of light energy by reversible deactiveation of PSⅡ, and reducing the accumulation of excess excitation energy by promoting heat dissipation. EBR treatment improved the electron transport of PSⅡ acceptor side, alleviated the drought-induced decrease of active reaction center per unit area, optimized the process of photosynthetic electron transport, maintained high heat dissipation capacity in pepper leaves under drought, and alleviated drought-induced photoinhibition. In conclusion, EBR could optimize photochemical efficiency and photosynthetic performance, and protect the photosynthetic electron transport chain and PSⅡ reaction center in pepper leaves under drought stress.

Key words: pepper(Capsicum annuum L.), drought stress, 24-epibrassinolide, chlorophyll fluorescence transient

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