Ivanov A G, Morgan R M, Gray G R, Velitchkova M Y, Huner N P
Department of Plant Sciences, University of Western Ontario, London, Canada.
FEBS Lett. 1998 Jul 3;430(3):288-92. doi: 10.1016/s0014-5793(98)00681-4.
Exposure of winter rye leaves grown at 20 degrees C and an irradiance of either 50 or 250 micromol m(-2) s(-1) to high light stress (1600 micromol m(-2) s(-1), 4 h) at 5 degrees C resulted in photoinhibition of PSI measured in vivo as a 34% and 31% decrease in deltaA820/A820 (P700+). The same effect was registered in plants grown at 5 degrees C and 50 micromol m(-2) s(-1). This was accompanied by a parallel degradation of the PsaA/PsaB heterodimer, increase of the intersystem e- pool size as well as inhibition of PSII photochemistry measured as Fv/Fm. Surprisingly, plants acclimated to high light (800 micromol m(-2) s(-1)) or to 5 degrees C and moderate light (250 micromol m(-2) s(-1)) were fully resistant to photoinhibition of PSI and did not exhibit any measurable changes at the level of PSI heterodimer abundance and intersystem e- pool size, although PSII photochemistry was reduced to 66% and 64% respectively. Thus, we show for the first time that PSI, unlike PSII, becomes completely resistant to photoinhibition when plants are acclimated to either 20 degrees C/800 micromol m(-2) s(-1) or 5 degrees C/250 micromol m(-2) s(-1) as a response to growth at elevated excitation pressure. The role of temperature/light dependent acclimation in the induction of selective tolerance to PSI photoinactivation is discussed.
将在20摄氏度、光照强度为50或250微摩尔·米⁻²·秒⁻¹条件下生长的冬黑麦叶片，在5摄氏度时置于高光胁迫（1600微摩尔·米⁻²·秒⁻¹，4小时）下，体内测量的PSI光抑制表现为ΔA820/A820（P700⁺）分别下降34%和31%。在5摄氏度和50微摩尔·米⁻²·秒⁻¹条件下生长的植株中也观察到了同样的效果。这伴随着PsaA/PsaB异二聚体的平行降解、电子传递链中电子库大小的增加以及以Fv/Fm衡量的PSII光化学的抑制。令人惊讶的是，适应高光（800微摩尔·米⁻²·秒⁻¹）或5摄氏度和中等光照（250微摩尔·米⁻²·秒⁻¹）的植株对PSI光抑制完全抗性，并且在PSI异二聚体丰度和电子传递链中电子库大小水平上没有表现出任何可测量的变化，尽管PSII光化学分别降至66%和64%。因此，我们首次表明，与PSII不同，当植物适应20摄氏度/800微摩尔·米⁻²·秒⁻¹或5摄氏度/250微摩尔·米⁻²·秒⁻¹以应对升高的激发压力下的生长时，PSI对光抑制变得完全抗性。讨论了温度/光照依赖性适应在诱导对PSI光失活的选择性耐受性中的作用。
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