【作者】 刘辉；

【导师】 郭延平；

【作者基本信息】 浙江大学 ， 果树学， 2005， 硕士

【摘要】 本论文以二年生杨梅（Myrica rubra Sieb. et Zucc.）荸荠种盆栽苗为试验材料,研究了在不同温度（25,12,2℃）和光强下(0,400μmol m^-2 s^-1)叶片的叶绿素荧光参数和D1蛋白的变化情况,探讨了光合机构对低温的响应机制;比较分析了与另一热带亚热带常绿果树温州蜜柑（Citrus unshiu Marc.）在低温光照(2℃400μmol m^-2 s^-1)下荧光参数的异同,为今后的栽培管理提供了理论依据。主要研究结果如下: 1.与25℃相比,12℃黑暗(0μmol·m^-2·s^-1)处理12h对杨梅叶片的叶绿素荧光参数影响较小,但在2℃黑暗下12h初始荧光Fo和反映无活性PSⅡ反应中心比例的（Fi-Fo）/（Fp-Fo）值上升,而PSⅡ的光化学效率Fv/Fm、光合电子传递速率ETR、PSⅡ的量子效率ΦPSⅡ和光化学猝灭系数qP下降,说明短期黑暗轻度低温对杨梅叶片PSⅡ反应中心几乎没有影响,而较严重的低温如2℃才对杨梅叶片PSⅡ反应中心产生伤害。 2.与25℃光照处理和12℃黑暗处理相比,12℃400μmol m^-2 s^-1光照处理12h的荧光参数Fv/Fm、ETR、ΦPSⅡ及qP下降,同时Fo、qN、（Fi-Fo）/（Fp-Fo）和E上升,说明低温诱导了杨梅叶片光抑制的发生。温度越低,光照的叠加效应越明显,低温光抑制越严重。 3.低温光抑制期间,叶片的过剩能量E和非光化学猝灭系数qN上升;加入蛋白质合成的抑制剂林可霉素和叶黄素循环的抑制剂DTT（二硫苏糖醇）后,明显加剧了低温光照对杨梅叶片PSⅡ反应中心的破坏。说明D1蛋白和叶黄素循环为主的热耗散可能在低温光辐射过程中对防御光抑制方面起着重要作用。 4.杨梅叶片经2℃400μmol·m^-2·s^-1低温处理后,在100μmol·m^-2·s^-1弱光下恢复的比较好,而在黑暗(0μmol·m^-2·s^-1)和中强光下(400、800μmol·m^-2·s^-1)均不能恢复。在有林可霉素和DTT条件下,即使在100μmol·m^-2·s^-1弱光下也不能恢复。 5.12℃黑暗处理12 h后的叶片,经SDS-PAGE电泳和Western blotting检测,发现D1蛋白含量基本没有明显变化;而12℃光照(400 μmol·m^-2·s^-1)处理后的D1蛋白含量明显下降。尽管2℃黑暗处理12 h的D1蛋白含量下降,但2℃光照(400 μmol·m^-2·s^-1)处理的D1蛋白含量下降更明显。此外,林可霉素素和DTT也加剧了D1的降解。 6.对杨梅和柑桔比较后发现,2℃低温光照(400 μmol·m^-2·s^-2)处理均导致杨梅和柑桔光抑制的发生并且2℃光照处理后柑桔叶片Fv/Fm下降程度要比杨梅的大,表明低温对柑桔叶片的损伤大于对杨梅叶片的损伤。更多还原

【Abstract】 In the present study, the potted plants of the two-year-old Myrica rubra were used to study the changes of chlorophyll fluorescence and the level of D1 protein in PS Ⅱ reaction centers in Myrica rubra leaves treated with different temperature (25, 12, 2℃) under irradiance levels (0, 400 μmol·m-2·s-1) for 12 hours, and the possible response mechanisms of effects of chilling stress on photosynthetic apparatus in Myrica rubra leaves were discussed. In addition, we compared the differences of chlorophyll fluorescence parameters between Myrica rubra leaves and Citrus unshiu leaves, another warm-climate plant under low temperature and light (2℃ 400 μmol m-2 s-1), affording academic foundation for cultivation management of Myrica rubra trees in furure. The main results of this study are as follows:1) Compared with 25℃ treatment , 12℃ 0 μmol·m-2·s-1 treatment for 12h had little effect on photosynthesis of Myrica rubra leaves, but exposure to 2℃ 0 μmol·m-2·s-1 resulted in increases in Fo (initial fluorescence), (Fi-Fo)/(Fp-Fo)(amount of inactive PS Ⅱ reaction centers) and the excess light energy E, but decreases in Fv/Fm (maximal photochemical efficiency of PSⅡ), ETR (linear electron transport rate), OPSⅡ(quantum yield of PSⅡ) and qP (photochemical quenching). These results indicated that short-term and low-grade chilling temperature almost had no effect on PSⅡ reaction centers in the dark, but severe chilling temperature (2℃) induced damage to PS Ⅱ reaction centers.2) Compared with 25 ℃ 400 μmol·m-2·s-1 and 12℃ 0 μmol·m-2·s-1 treatment, the Fv/Fm, ETR, OPS Ⅱ and qP decreased, but the Fo, (Fi-Fo)/(Fp-Fo) and the excess light energy E increased after treatment with 12℃ 400 μmol·m-2·s-1, suggesting that chilling temperature induced photoinhibition of photosynthesis of Myrica rubra leaves. The lower the temperature, the more significant effect of the light superposition and the more serious photoinhibition induced by chilling temperature.3) During the course of photoinhibition of photosynthesis of Myrica rubra leaves the excess light energy E and qN (non-photochemical quenching) increased; the photodamage to PSⅡ reaction centers was greatly enhanced in the presence of更多还原