Abstract Honeysuckle (Lonicera japonica Thunb.) is a traditional Chinese medicinal crop and belongs to the glycophyte with certain salt tolerance. This study aimed to deeply dissect its salt adaptability by contrasting photosynthesis, photoinhibition and oxidative damage under moderate and severe iso-osmotic salt (150 and 300 mM NaCl) and drought (19.3 % and 28 % PEG-6000) stresses with hydroponic protocol. Photosynthesis was more susceptible to drought stress than iso-osmotic salt stress in honeysuckle according to drought-induced greater decrease in photosynthetic rate. In contrast to salt-induced mild PSⅡ and PSI photoinhibition, severe photosystem II (PSⅡ) and photosystem I (PSI) photoinhibition arose upon iso-osmotic drought stress, indicated by greater decreased the maximal photochemical efficiency of PSⅡ and PSI and remarkable loss of their reaction center proteins. However, PSⅡ and PSI interaction hardly contributed to salt stability of photosynthetic apparatus because of salt-induced finite restriction on electron flow from PSⅡ to PSI. Consistent with photosystems photoinhibition, leaf lipid peroxidation, H2O2 production and electrolyte leakage were elevated much greater by drought stress than iso-osmotic salt stress, confirming drought-induced severe oxidative stress in honeysuckle. Furthermore, the principal components analysis comprehensively showed higher salt adaptability in honeysuckle due to larger cluster separation upon drought stress than iso-osmotic salt stress. As an apparent reason, honeysuckle could prevent drought-induced tremendous leaf water loss upon iso-osmotic salt stress, and had a capacity to dispose accumulated Na+. Therefore, honeysuckle resembles halophytes in this respect and seems appropriate for planting in coastal saline land.

中文翻译：

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对比等渗盐和干旱胁迫下金银花 (Lonicera japonica Thunb.) 的光合作用、光抑制和氧化损伤

摘要 金银花（Lonicera japonica Thunb.）是中药材，属于具有一定耐盐性的糖生植物。本研究旨在通过对比中度和重度等渗盐（150 和 300 mM NaCl）和干旱（19.3 % 和 28 % PEG-6000）胁迫与水培协议下的光合作用、光抑制和氧化损伤，深入剖析其盐适应性。根据干旱引起的光合速率下降幅度更大，金银花中的光合作用比等渗盐胁迫更容易受到干旱胁迫的影响。与盐诱导的轻度 PSⅡ 和 PSI 光抑制相反，等渗干旱胁迫产生了严重的光系统 II (PSⅡ) 和光系统 I (PSI) 光抑制，PSⅡ和PSI的最大光化学效率降低，反应中心蛋白损失显着。然而，PSⅡ和PSI的相互作用对光合装置的盐稳定性几乎没有贡献，因为盐诱导的电子流从PSⅡ到PSI的有限限制。与光系统​​光抑制、叶片脂质过氧化、H2O2 产生和电解质泄漏相一致，干旱胁迫比等渗盐胁迫显着提高，证实了干旱引起的金银花严重氧化胁迫。此外，主成分分析综合表明，由于干旱胁迫下的簇分离比等渗盐胁迫更大，金银花的盐适应性更高。作为一个明显的原因，金银花可以防止等渗盐胁迫下干旱引起的大量叶片失水，并具有处理积累的 Na+ 的能力。因此，金银花在这方面类似于盐生植物，似乎适合在沿海盐碱地种植。