Study on the photoprotective functions of rhodoxanthin accumulated in the needles of Cryptomeria japonica and Chamaecyparis obtusa

为了阐明紫紫红质的光保护作用，进行了以下五个实验。在第一个实验中，比较了野生型和缺乏紫红质积累能力的突变体。与野生型相比，突变体的最大光合速率、Fv/Fm值、叶绿素含量和光合相关蛋白水平均显著降低。(2)在第二个实验中，比较了在四种不同光照强度下生长的树苗。结果表明，在冬季，Fv/Fm的下降与紫青素的增加和DEPS的增加之间存在着一定的关系。高光强下的幼苗积累了大量的紫红质。(3)第三个试验比较了四个不同海拔高度成年树针叶的日照量。虽然Fv/Fm值随海拔升高而降低，但不同海拔之间的红黄素水平没有差异。但不同海拔高度的红黄素积累和消失的时间不同。(4)在第四个实验中，研究了紫紫红质消失的过程。Fv/Fm值低于最大水平，即使玉米黄质已完全再转化为紫黄质。海拔越高，玉米黄质消失时的Fv/Fm值与最大值之间的差异越大，说明海拔越高的树木光害越严重。(5)第五个试验对不同地区的优树进行了比较。不同优树间的红黄素含量差异显著，遗传差异小于环境差异。

In order to elucidate the photoprotective role of rhodoxanthin, following five experiments were conducted. In the first experiment the wild type and the mutant lacking the ability of rhodoxanthin accumulation were compared. The maximum photosynthetic rates and the Fv/Fm values, chlorophyll contents, and the levels of photosynthesis related proteins decreased more significantly in the mutant than in the wild type. (2) In the second experiment, the saplings grown in four different light intensities were compared. The relationships among the decrease in Fv/Fm, the increase in rhodoxanthin and the increase in DEPS were observed during the winter. The saplings under the higher light intensities accumulated large amount of rhodoxanthin. (3) In the Third experiment the sun exposed needles of the mature trees grown in four different altitudes were compared. Although the values of Fv/Fm were more decreased in the higher altitudes, the levels of rhodoxanthin were not differed among the altitudes. However, the timing of the accumulation and disappearance of rhodoxanthin were differed among the altitudes. (4) In the fourth experiment, the process of rhodoxanthin disappearance were examined. The values of Fv/Fm were lower than maximum level, even when the zeaxanthin had perfectly re-converted to violaxanthin. The differences in the Fv/Fm values between the maximum value and the value when zeaxanthin had disappeared were greater in the higher altitude, indicated that the trees grown in higher altitude were more severely photo-damaged. (5) In the fifth experiment, the plus-trees selected from different regions were compared. The level of rhodoxanthin were significantly differed among the plus trees, the difference attributed to the genetic difference were smaller than that attributed to environmental differences.