Chlorophyll formation and photosynthetic activity in rice mutants with alterations in hydrogenation of the chlorophyll alcohol side chain
Chlorophyll formation and photosynthetic activity in rice mutants with alterations in hydrogenation of the chlorophyll alcohol side chain
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DOI：
10.1016/j.plantsci.2003.10.014
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发表时间：
2004-03
期刊：
影响因子：
5.2
通讯作者：
M. Shibata;Takashi Mikota;A. Yoshimura;N. Iwata;M. Tsuyama;Y. Kobayashi
中科院分区：
文献类型：
--
作者：
M. Shibata;Takashi Mikota;A. Yoshimura;N. Iwata;M. Tsuyama;Y. Kobayashi
通过用N-甲基-N-亚硝基脲处理受精卵细胞，从水稻植物(Oryza sativa L.)中获得了积累用不完全还原醇酯化的叶绿素a和b的核基因突变体M134和M249，例如香叶基香叶醇、二氢香叶基香叶醇和四氢香叶基香叶醇。在突变体和野生型植物的变绿和完全发育的叶子中测量叶绿素形成和光合作用活性。在黄化幼苗的光照下，香叶基香叶基叶绿素a是在野生型、M134和M249的叶子变绿的早期阶段中唯一可检测到的酯化色素。经过长时间的光照，M134 显示优先积累香叶基香叶基叶绿素 a 和 b，而 M249 积累了所有六种中间体，推测这些中间体参与叶绿素醇侧链从香叶基香叶醇到植醇的三步还原。叶绿素形成的时间进程表明，遗传阻断发生在M134中从香叶基香叶醇到二氢香叶基香叶醇的侧链还原以及M249中从四氢香叶基香叶醇到植醇的还原。当幼苗在弱光条件下生长时，在完全发育的叶子中以氧气释放测量的光合活性显示野生型和突变体之间没有大的差异。然而，当幼苗暴露在强光下时，两种突变体的叶片叶绿素含量逐渐下降，并且光合活性丧失。这些结果表明，光合作用的发生无需将香叶基香叶醇侧链还原为植醇，但需要植醇部分来防止叶片在光胁迫条件下发生失绿症。
The nuclear gene mutants M134 and M249 that accumulate chlorophyllides a and b esterified with incompletely reduced alcohol, such as geranylgeraniol, dihydrogeranylgeraniol, and tetrahydrogeranylgeraniol, were obtained from rice plants (Oryza sativa L.) by treatment of fertilized egg cells with N-methyl-N-nitrosourea. Chlorophyll formation and photosynthetic activity were measured in both greening and fully developed leaves of the mutants and wild-type plants. On illumination of etiolated seedlings, geranylgeranyl-chlorophyll a was the only esterified pigment detectable during the early phase of greening in the leaves of wild-type, M134, and M249. Upon prolonged illumination, M134 showed preferential accumulation of geranylgeranyl-chlorophylls a and b, and M249 accumulated all six intermediates presumed to be involved in the three-step reduction of the chlorophyll alcohol side chain from geranylgeraniol to phytol. The time courses of chlorophyll formation suggest that genetic blocking occurred in reduction of the side chain from geranylgeraniol to dihydrogeranylgeraniol in M134 and the reduction from tetrahydrogeranylgeraniol to phytol in M249. When seedlings were grown under low light conditions, the photosynthetic activity measured as oxygen evolution in fully developed leaves showed no large difference between wild-type and mutant. However, on exposure of seedlings to high light, leaf chlorophyll content decreased gradually, and photosynthetic activity was lost in both mutants. These results suggest that photosynthesis occurs without reduction of the geranylgeraniol side chain to phytol, but the phytol moiety is required to prevent leaves from chlorosis under light-stressed conditions.