Akoumianaki-Ioannidou Anastasia, Georgakopoulos John H, Fasseas Costas, Argyroudi-Akoyunoglou Joan H
Department of Crop Science, Floriculture and Landscape Architecture Laboratory, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece.
J Photochem Photobiol B. 2004 Feb 20;73(3):149-58. doi: 10.1016/j.jphotobiol.2003.11.007.
We studied photoacclimation in Spathiphyllum grown at an irradiance of 40 or 420 micromol/m2 s (LL or HL, respectively). All parameters studied responded to acclimation. Leaves at LL, in contrast to HL, were thinner and oriented perpendicular to the incident light, had more chlorophyll per g f w, fewer stomata on the upper leaf surface and a reduced layer of mesophyll cells. Their chloroplasts at HL had wider grana with less thylakoids per granum, and better organized photosystems than at LL. PSI and PSII activities per mg chlorophyll ( Vmax ), and PSI and PSII content (total activity per g f w), were lower at LL than at HL and so was the light requirement for saturation of the PSI or PSII partial photoreactions, suggesting that fewer photosystems with larger antenna size prevail at LL, but many more with smaller antenna size at HL. Analysis of chlorophyll distribution among the thylakoid pigment-protein complexes showed less antenna chlorophyll serving PSII (CPa+LHCP1+LHCP3) than that serving PSI (CPIa+CPI+LHCP2) at LL as compared to HL, and thus a lower PSII/PSI ratio at LL, in agreement with the general finding that LL plants, with larger PSII antenna size, have lower PSII/PSI ratio. The increase in PSI antenna size at LL was correlated with the increase in the distribution of chlorophyll in pigment-protein complexes serving PSI, and a very large chlorophyll/protein molar ratio in the isolated CPI complex. On the other hand, the PSII antenna chlorophyll (CPa+LHCP1+LHCP3) on a g f w basis, and the chlorophyll a/b ratio remained more or less constant at LL or HL. This may reflect our finding that Spathiphyllum contains mainly the 27 kDa inner LHCII antenna protein, the size of which remains unaffected by photoacclimation. The increase in the distribution of chlorophyll in pigment-protein complexes serving PSII at HL, therefore, reflects the higher population of PSII at HL. Very high PSI activity was found at HL, which we attribute to the highly organized small in size PSI.
我们研究了在40或420微摩尔/平方米·秒(分别为低光照或高光照)辐照度下生长的白鹤芋的光适应情况。所有研究参数均对光适应有响应。与高光照相比,低光照下的叶片更薄,且与入射光垂直,每克鲜重的叶绿素含量更高,叶片上表面的气孔更少,叶肉细胞层更薄。高光照下其叶绿体的基粒更宽,每个基粒中的类囊体更少,且光系统比低光照下组织得更好。每毫克叶绿素的PSI和PSII活性(Vmax)以及PSI和PSII含量(每克鲜重的总活性)在低光照下比高光照下更低,PSI或PSII部分光反应达到饱和所需的光照也是如此,这表明在低光照下以较大天线尺寸为主的光系统较少,而在高光照下以较小天线尺寸为主的光系统更多。对类囊体色素 - 蛋白质复合物中叶绿素分布的分析表明,与高光照相比,低光照下为PSII服务的天线叶绿素(CPa + LHCP1 + LHCP3)比为PSI服务的(CPIa + CPI + LHCP2)少,因此低光照下PSII/PSI比值更低,这与一般发现一致,即具有较大PSII天线尺寸的低光照植物的PSII/PSI比值较低。低光照下PSI天线尺寸的增加与为PSI服务的色素 - 蛋白质复合物中叶绿素分布的增加以及分离的CPI复合物中非常高的叶绿素/蛋白质摩尔比相关。另一方面,以每克鲜重计的PSII天线叶绿素(CPa + LHCP1 + LHCP3)以及叶绿素a/b比值在低光照或高光照下或多或少保持恒定。这可能反映了我们的发现,即白鹤芋主要含有27 kDa的内部LHCII天线蛋白,其大小不受光适应的影响。因此,高光照下为PSII服务的色素 - 蛋白质复合物中叶绿素分布的增加反映了高光照下PSII的数量更多。在高光照下发现了非常高的PSI活性,我们将其归因于高度组织化且尺寸较小的PSI。