5-氨基乙酰丙酸(ALA)提高两种园林植物叶片耐热性效应

Effect of 5-Aminolevulinic Acid on Leaf Heat Tolerance in Ligustrum japonicum and Spiraea japonica

摘要: 本试验以金森女贞和金山绣线菊为材料，利用M-PEA多功能植物效率仪检测了叶面喷施50 mg/L 5-氨基乙酰丙酸(ALA) 25 d后离体叶片对高温逆境的适应性，发现ALA处理叶片在50℃高温处理不同时间后仍能保持一定光化学效率，降低PSII反应中心供体侧放氧复合体受抑程度，维持PSII反应中心较高的开放程度以及用于光合电子传递的量子产额和有活性的反应中心密度，提高了PSI反应中心最大光化学效率，从而保证了较高的光合性能指数。PSI反应中心电子氧化速率(V_PSI)对高温胁迫不敏感，而PSII与PSI之间的电子传递速率(V_PSII-PSI)对高温胁迫相当敏感，ALA对高温下两种园林植物叶片V_PSII-PSI有较高的保护效应。以上结果说明，ALA可以提高园林植物耐高温能力。这为其在炎热夏季园林生产中应用提供了理论依据。本研究还表明，金山绣线菊的耐热性高于金森女贞，ALA对金森女贞耐热性的促进效应在短时间高温胁迫下便可体现出来，而对金山绣线菊耐热性的促进效应需要较长时间才能体现出来。

Abstract: The detached leaf chlorophyll fluorescence responses of Ligustrum japonicum and Spiraea japonica which were pretreated with 5-aminolevulinic acid (ALA) solution at a dosage of 50 mg∙L−1 for 25 d and treated at 50˚C temperature for 30~90 min, were measured by a multifunctional plant efficiency analyzer (M-PEA). The results show that the leaves which were pretreated by ALA maintained higher levels of the maximal photochemical efficiency (F_v/F_m), but less inhibition of oxygen evolving complex activity at the donor side of PSII reaction centers (Vk) and the maximal close rate at the acceptor side of PSII reaction center (Mo). ALA treatment significantly increased the quantum yield in photosynthetic electron transfer (φEo), the active reaction center density (RC/CS), the efficiency to reduce the terminal electron acceptors of PSI reaction center (φRo), and therefore the capacity index based on the absorption (PI_abs). Conversely, high 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 heat stress than PSI itself. The results in the study show that the leaves of S. japonica were more heat tolerance than those of L. japonicum, and the improving effects by ALA were effective at the early stage of heat stress on L. japonicum while at the later stage on S. japonica. Therefore, this new regulator may be applied in garden plant production to protect heat stress in high temperature summer.