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Photo Res:曹坤芳等揭示植物合拢叶片是为自我保护

来源:中国科学报 2012-02-23 12:45




近日,国际著名杂志《光合作用研究》Photosynthesis Research 在线刊登了中科院版纳植物园研究者的研究成果“Regular PaperEvidence for leaf fold to remedy the deficiency of physiological photoprotection for photosystem II”,文章中,研究者揭示了植物叶片合拢是为自我保护。

在自然界中,某些阳生植物的叶片在强光下会合拢,例如薄叶羊蹄甲。但很多阳生植物的叶片并不具有这种合拢的特性。由于强光容易导致光系统II的损伤,叶片合拢可能是为了减少光的吸收和弥补光保护机制的不足。

为了验证这一假说,中科院版纳植物园生理生态组博士研究生黄伟在导师曹坤芳的指导下,对薄叶羊蹄甲(叶片合拢)和破布叶(叶片不合拢)的光合特征进行了测定,发现薄叶羊蹄甲中对光系统II起保护作用的两个重要途径(热耗散和环式电子传递)都要比破布叶弱。当这两种植物的叶片平展着接受强光处理后,薄叶羊蹄甲光系统II活性的丢失要比破布叶严重,这表明其叶片合拢是为了弥补植物对光系统II生理性光保护能力的不足。(生物谷Bioon.com)

Regular PaperEvidence for leaf fold to remedy the deficiency of physiological photoprotection for photosystem II

Wei Huang, Shi-Bao Zhang and Kun-Fang Cao

An interesting phenomenon is that some light-demanding plants fold their leaves when exposed to high light. Since high lightcould induce selective photodamage to photosystem II (PSII), we suggest that the leaves fold themselves to diminish the absorptionof light energy and remedy the deficiency of physiological photoprotection for PSII. To test this hypothesis, we determinedlight responses of non-photochemical quenching (NPQ) and cyclic electron flow (CEF) and the effect of high light on PSII activityin Microcos paniculata (non-foldable species) and Bauhinia tenuiflora (foldable species). Under high light B. tenuiflora showed much lower NPQ and CEF than M. paniculata. Meanwhile, the excess light energy that cannot be harmlessly dissipated in B. tenuiflora was more compared with that in M. paniculata. After exposure to a high light of 1,900 mol photons m2 s1 for 2 h, the maximum quantum yield of PSII, as estimated by variable to maximal fluorescence (Fv/Fm) decreased from 0.7 to 0.52 in the foldable species B. tenuiflora but was stable at 0.7 in the nonfoldable species M. paniculata. These results indicate that the foldable species B. tenuiflora has more sensitivity of PSII to high light stress than the nonfoldable species M. paniculata, partly as a result of less CEF and NPQ in B. tenuiflora. Our results suggest that sun leaves fold themselves under high light to remedy the deficiency of physiological photoprotectionfor PSII.

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