Overexpression of light-dependent PORA or PORB in plants depleted of endogenous POR by far-red light enhances seedling survival in white light and protects against photooxidative damage
Overexpression of light-dependent PORA or PORB in plants depleted of endogenous POR by far-red light enhances seedling survival in white light and protects against photooxidative damage
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DOI：
10.1046/j.1365-313x.1997.00649.x
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发表时间：
1997-09-01
期刊：
影响因子：
7.2
通讯作者：
Armstrong, GA
中科院分区：
文献类型：
--
作者：
Sperling, U;vanCleve, B;Armstrong, GA
结构上相关的光依赖性原叶绿素（Pchlide）氧化还原酶PORA和PORE介导的叶绿素（Chi）的生物合成中唯一的光需要的步骤在高等植物。相关证据表明，PORA和PORE的一些体内功能可能是独特的，包括PORA的假定光保护作用。例如，在非光氧化远红光（cFR）中生长的野生型拟南芥幼苗类似于在白色光（WL）中生长的那些幼苗，但是它们是黄色的，并且此后在WL中通常不呈绿色。这种缺陷伴随着可检测的PORA的缺乏和PORE表达水平的降低。在这里，直接的证据表明，存在的FOR，无论是作为PORA或孔，可以赋予植物的光保护。与野生型相比，在cFR中生长的转基因PORA或PORB过表达拟南芥幼苗的质体具有广泛的原板层体。在随后的转移到WL，POR-过表达的幼苗类囊体膜，积累大量的Chi和可行的通量率致死的野生型。有趣的是，绿化转基因幼苗的质体膜结构似乎取决于是否PORA或PORE已过量生产。在注量率从20到500 μ E m（-2）sec（-1）的情况下，POR过表达幼苗从cFR转移到WL，比野生型积累了大量的Chi。此外，允许最大Chi积累的WL注量率从野生型的8 μ E m（-2）sec（-1）增加到转基因幼苗的125 μ E m（-2）sec（-1）。FOR在cFR生长过程中的过度表达也与Pchlide（一种潜在致死性光敏剂）的稳态含量降低四倍相关。
The structurally related light-dependent protochlorophyllide (Pchlide) oxidoreductases PORA and PORE mediate the only light-requiring step in chlorophyll (Chi) biosynthesis in higher plants. Correlative evidence suggests that some in vivo functions of PORA and PORE may be unique, including a postulated photoprotective role for PORA. For example, wild-type Arabidopsis thaliana seedlings grown in non-photooxidative far-red light (cFR) resemble those grown in white light (WL), but they are yellow and do not green normally thereafter in WL. This defect is accompanied by the absence of detectable PORA and reduced levels of PORE expression. Here, direct evidence is provided that the presence of FOR, either as PORA or PORE, can confer photoprotection in plants. In contrast to the wild-type, the plastids of transgenic PORA- or PORB-overexpressing Arabidopsis seedlings grown in cFR possess extensive prolamellar bodies. Upon a subsequent shift to WL, POR-overexpressing seedlings develop thylakoid membranes, accumulate large amounts of Chi and are viable at fluence rates lethal to the wild-type. Intriguingly, the plastid membrane architectures of greening transgenic seedlings seem to depend on whether PORA or PORE has been overproduced. POR-overexpressing seedlings shifted from cFR to WL of fluence rates from 20 to 500 mu E m(-2) sec(-1) accumulate substantially higher amounts of Chi than does the wild-type. Furthermore, the WL fluence rate that permits maximal Chi accumulation increases from 8 mu E m(-2) sec(-1) in the wild-type to 125 mu E m(-2) sec(-1) in transgenic seedlings. FOR overexpression during growth in cFR also correlates with a fourfold decrease in the steady-state content of Pchlide, a potentially lethal photosensitizer.