摘要
用荧光动力学的方法研究了碱性盐Na2CO3胁迫下星星草幼苗叶片PSⅡ光能利用和耗散与培养基质渗透势的关系。结果发现在大于-4bar的胁迫下,PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在光化学效率(Fv/Fo)、PSⅡ实际光化学效率(ΦPSⅡ)以及开放的PSⅡ反应中心有效光化学效率(Fv′/Fm′)的变化不大;然而在小于-4barNa2CO3胁迫下,Fv/Fm、Fv/Fo和Fv′/Fm′均随着渗透势的增大而增大,而ΦPSⅡ、电子传递速率(ETR)、光化学速率、捕光色素吸收的光能被用于热耗散的相对份额及热耗散速率则随着渗透势的增大而减小。这些研究结果说明星星草幼苗在Na2CO3胁迫所导致的不同的渗透胁迫下(小于-4bar和大于-4bar)其过剩光能的耗散机制可能不同,大于-4bar的胁迫下可能存在精细的渗透调节机制,而在高强度的Na2CO3所导致的渗透胁迫下具有与其它植物不同的保护机制,可能通过两条途径耗散过剩的光能,一方面通过增加捕光色素吸收的光能被用于热耗散的相对份额及热耗散速率;另一方面通过增大ΦPSⅡ、光化学速率、ETR,增强假循环式光合磷酸化过程,而由此引起的活性氧的增加则通过体内较高活性的保护酶系统来清除,以保护光合器官免受过剩光能的损伤。
Method of fluorescence induction kinetics was used to investigate the relationship between light energy utilization and dissipation of PS Ⅱ of Puccinellia tenuiflora seedlings and osmotic potential of culture solution under Na2CO3 stress. It was found that the changes of maximal photochemical efficiency of PS Ⅱ （Fv/Fm）, potential photochemical efficiency （Fv/Fo）, actual photochemical efficiency of PS Ⅱ in the light （φPS Ⅱ ） and photochemical efficiency of PSⅡ in the light （Fv＇/Fm＇） were not obvious in an osmotic potential higher than -4 bar. At the same time, Fv/Fm, Fv/Fo, Fv＇/Fm＇ increased along with the osmotic potential lower than -4 bar; nevertheless φPS Ⅱ , electron transferrate （ ETR）, photochemical efficiency, heat dissipation and heat dissipation rate decreased. The results showed that the dissipation mechanism of surplus of light energy of P. tenuiflora seedlings may be various in different osmotic potential induced by Na2 CO3 stress （lower than - 4 bar and higher than - 4 bar）, and there may be a refined osmotic regulation mechanism under osmotic potential higher than - 4 bar. Furthermore, in high osmotic stress induced by Na2 CO3, the safeguard mechanism of P. tenuiflora was different from that of other plants, they dissipated surplus light energy via two approach： increasing light energy absorbed by light-harvesting pigment that used in heat dissipation and heat dissipation rate; increasing φPS Ⅱ , ETR and photochemical efficiency, and building up fake circulate photosynthetic phosphorylation, which resulted in the augment of active oxygen eliminated by antioxidant enzymes system. In this way do P. tenuiflora protect photosynthetic apparatus from the damage of surplus of light energy.
出处
《生态学报》
CAS
CSCD
北大核心
2006年第1期115-121,共7页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(30270234)~~
关键词
星星草
Na2CO
胁迫
渗透势
叶绿素荧光动力学
PSⅡ光能利用
PSⅡ光能耗散
Puccinellia tenuiflora
Na2CO3 stress
osmotic potential
chlorophyll fluorescence kinetics
light energy utilization of PS Ⅱ
lightenergy dissipation of PS Ⅱ
