5-氨基乙酰丙酸提高杜鹃和香樟叶片耐寒性效应

Promotive effect of 5-aminolevulinic acid on freezing tolerance of Rhododendron simsii and Cinnamomum camphora leaves

以杜鹃(Rhododendron simsii)和香樟(Cinnamomum camphora)两种园林植物为材料,利用英国Hansatech公司生产的M-PEA多功能植物效率分析仪检测了经50 mg·L^(-1) 5-氨基乙酰丙酸(5-ALA)溶液处理25 d后的离体叶片对-20°C低温胁迫10~30 min的响应,发现处理后的叶片可以维持较高的光化学效率(φP_o)和较低的光系统II(PSII)反应中心供体侧放氧复合体抑制程度(W_k)以及PSII反应中心最大关闭速率(M_o),处理后的叶片也具有较高的光合电子传递量子产额(φE_o)、有活性的反应中心密度(RC/CS)、PSI反应中心还原末端电子受体的效率(φR_o)以及光合性能指数(PI_(abs))。相反,低温胁迫降低杜鹃和香樟叶片PSI反应中心失去电子被氧化的速率(V_(PSI))以及从PSII反应中心传递过来的电子还原PSI反应中心的速率(V_(PSII-PSI)),且对后者的影响更大,似乎PSII电子传递对短时间急速低温胁迫更为敏感。本试验结果还表明,香樟叶片耐寒性高于杜鹃,而5-ALA对香樟耐寒性的促进效应比对杜鹃更明显。5-ALA作为一种新型植物生长调节剂,可以运用于提高园林植物耐低温能力,减轻冬季寒冷和春季倒春寒伤害。

The detached leaf chlorophyll fluorescence responses of Rhododendron simsii and Cinnamomum camphora which were pretreated with 5-aminolevulinic acid（5-ALA） solution at a dosage of 50 mg·L^（-1） for 25 d and treated at-20°C temperature for 10~30 min,were measured by a multifunctional plant efficiency analyzer（M-PEA）.The results show that the leaves which were pretreated by 5-ALA maintained higher levels of the maximal photochemical efficiency（φP_o）,but less inhibition of oxygen evolving complex activity at the donor side of PSII reaction centers（W_k） and the maximal close rate at the acceptor side of PSII reaction center（Mo）.5-ALA treatment significantly increased the quantum yield in photosynthetic electron transfer（φE_o）,the active reaction center density（RC/CS）,the efficiency to reduce the terminal electron acceptors of PSI reaction center（φR_o）,and therefore the capacity index based on the absorption（PIabs）.Conversely,low temperature stress impaired the reduction rate of PSI reaction center by the electrons transferred from PSII reaction center（V_（PSII-PSI）） more than the oxidation rate of PSI reaction center by the terminal electron acceptors（V_（PSI））.This means that the electron transfer of intersystem was more sensitive to short-term rapid freezing temperature than PSI itself.The results in the study show that the leaves of C.camphora were more freezing tolerance than those of R.simsii,and the improving effects by 5-ALA was more effective on C.camphora than R.simsii.Therefore,this new regulator may be applied in garden plant production to avoid injury by chilling stress at cold winter or cold spell in spring.