温度和光照对莫索湾地区两种典型短命植物光合系统的损伤特征研究

Damage characteristics of photosynthetic system of two typical ephemeral plants in Mosuowan area caused by temperature and light

关键词:  短命植物, 光合作用, 光保护, 光抑制, 联合胁迫

Key words:  ephemeral plants, photosynthesis, photoprotection, photoinhibition, combined stress

摘要:

为探究莫索湾地区2种优势短命植物对光照和温度的光合适应机制,该文测定了卷果涩芥(Malcolmia scorpioides)和硬萼软紫草(Arnebia decumbens)在不同温度下(25～60 ℃)及恒定常温(25 ℃)与胁迫高温(50 ℃)下不同光强间(80～400 μmol·m^-2·s^-1)的叶绿素荧光参数,以探讨其光损伤情况和光合活性变化。结果表明:(1)随温度升高,2种短命植物的光合效率和电子传递速率先升后降,40 ℃时达到最高值,其后快速下降,并伴随着光系统Ⅱ(PS Ⅱ)非调节性能量耗散的量子产量 [Y(NO)]和光系统I(PS I)受体端热耗散效率 [Y(NA)]的上升,受体端激发压积累,光合系统受损。(2)在80～400 μmol·m^-2·s^-1的光照范围内,常温下,光合效率随光照强度增加而增加; 而高温下,光照与高温对植物产生了联合胁迫,造成光合活性下降,PS Ⅱ调节性能量耗散的量子产量 [Y(NPQ)]降低,并且当光强达320 μmol·m^-2·s^-1时,环式电子传递流逐渐消失。综上所述,一定范围内的光照和温度能够提升2种短命植物的光合活性,激活热耗散和环式电子传递流,减少光抑制,但温度增加及高温下光强的增加会使2种短命植物的适应能力减弱,光保护机制消失,其主要原因为PS I受体侧激发压积累和调节性热耗散保护能力不足使植物光合系统受损。

Abstract:

To explore the photosynthetic system adaptation mechanism of two dominant ephemeral plants, including Malcolmia scorpioides and Arnebia decumbens, to light and temperature, this study measured the chlorophyll fluorescence parameters and discussed their light damage and the change of photosynthetic activities under different temperatures(25-60 ℃)and constant room temperature(25 ℃)and high temperature and different illumination(80-400 μmol·m^-2·s^-1). The results were as follows:(1)The photosynthetic efficiency and electron transport rate increased first and then decreased with the increase of temperature, reached the highest value at 40 ℃ and then rapidly decreased, the quantum yield of non-regulated energy dissipation in PS Ⅱ [Y(NO)] and PS I receptor side heat dissipation efficiency [Y(NA)] increased, and the photosynthetic system was damaged due to the accumulation of excitation pressure at the receptor terminal.(2)Under the light range of 80-400 μmol·m^-2·s^-1 and room temperature, the photosynthetic efficiency increased with the enhancement of light intensity; under high temperature, the combined stress of light and high temperature on plants descended the photosynthetic activities of plants and the quantum yield of regulatory energy dissipation in PS Ⅱ [Y(NPQ)], and when the light intensity reached 320 μmol·m^-2·s^-1, the ring electron transport flow disappeared. In conclusion, light and temperature within a certain range can improve the photosynthetic activity, activate heat dissipation and ring electron transport flow and reduced photoinhibition. However, with the increase of temperature and light intensity at high temperature, the adaptation ability of the two ephemeral plants decrease and the photoprotective mechanism disappeared. The main reason is the accumulation of PS I receptor side excitation pressure and the failure of regulatory heat dissipation.