首页分享越冬期红叶石楠和桂花防御低温强光伤害的光保护机制

越冬期红叶石楠和桂花防御低温强光伤害的光保护机制

来源：花匠小妙招时间：2025-01-18 06:21

摘要：

位于亚热带地区的常绿植物在冬季常遭遇低温强光协同影响。低温限制了光合碳同化的进行，但强光仍能够被常绿植物叶片所吸收，因此越冬期的常绿植物存在潜在的光抑制风险。不同的常绿植物有着不同的越冬光保护策略，本研究以亚热带地区冬季生长型的红叶石楠（Photinia × fraseri）和冬季生长停滞型的桂花（Osmanthus fragrans）作为材料，研究了两种常绿植物阳生叶和阴生叶的叶绿素荧光和捕光色素分子内禀特性的差异，以探索亚热带地区常绿植物越冬光保护策略的选择。结果表明，红叶石楠和桂花均能够适应亚热带地区冬季低温强光环境，但2种常绿植物采取了不同的光保护策略。红叶石楠主要是通过降低捕光色素分子的实际光能吸收能力以减少光能的吸收，并维持相对较高的光化学能力和电子传递速率，从而保护光合机构免受低温强光伤害；同时，红叶石楠阳生叶又保持了相对较高的叶绿素含量和光化学效率，这将有利于温度回升后红叶石楠由光保护快速转换到碳同化为主的能量代谢。桂花则主要采用减少叶绿素含量和增强热耗散等逆转速度相对较慢的光保护策略为主。这也可能是亚热带地区红叶石楠冬季仍保持生长，而桂花生长停滞的主要原因。

关键词: 光保护策略, 常绿植物, 叶绿素荧光, 捕光色素分子内禀特性, 越冬期, 亚热带

Abstract:

Evergreen plants in subtropical region were suffered from the combination of low temperatures and high solar irradiances in winter. Low temperature inhibited photosynthetic CO2 assimilation， but light energy continued to be absorbed by green leaves. Therefore， there was a potential risk of photoinhibition to evergreens in overwintering. Different photoprotective strategies were observed in overwintering evergreens. The differences of the chorophyll fluorescence and intrinsic characteristics of light-harvesting pigment molecules of sun- and shading-leaves of Photinia × fraseri（growth type in winter） and Osmanthus fragrans（growth stagnant type in winter） were compared with during overwintering， to explore the choice of photoprotective strategies of overwintering evergreens in the subtropical region. Both P. × fraseri and O. fragrans in the subtropical region adapted to the low temperature with high light condition of winter. However， there were different photoprotective strategies in two evergreens. The absorption of light energy decreased in P. × fraseri ， the actual absorption capacity of light-harvesting pigment molecules reduced， and high photochemical capacity and electron transport rate maintained， which would protect photosynthetic apparatus against damage due to low temperature with high light in winter. Meanwhile， high chlorophyll content and photochemical efficiencymaintained in P. × fraseri， which would be conducive to the rapid conversion of energy metabolism pathway from photoprotection to carbon assimilation when temperature rises during overwintering. Different from photoprotective strategy of P. × fraseri， O. fragrans mainly adopted relatively slow reversal photoprotective strategies such as reducing chlorophyll content and enhancing energy dissipation. That could be the main reason that P. × fraseri still maintained growth， while O. fragrans was stagnant in the subtropical region in winter.

Key words: photoprotective strategy, evergreen, chorophyll fluorescence, intrinsic characteristics of light-harvesting pigment molecules, overwintering, subtropical region

中图分类号:

Q945.79