The interaction between plastocyanin and photosystem I is inefficient in transgenic Arabidopsis plants lacking the PSI-N subunit of photosystem I
The interaction between plastocyanin and photosystem I is inefficient in transgenic Arabidopsis plants lacking the PSI-N subunit of photosystem I
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DOI：
10.1046/j.1365-313x.1999.00419.x
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发表时间：
1999-03-01
期刊：
影响因子：
7.2
通讯作者：
Scheller, HV
中科院分区：
文献类型：
--
作者：
Haldrup, A;Naver, H;Scheller, HV
光系统I （PSI）的PSI- n亚基仅限于高等植物，是唯一完全位于类囊体腔内的亚基。研究了PSI- n亚基在反义和共抑制转基因拟南芥植株PSI复合体中的作用。鉴定出几条没有检测到PSI-N水平的品系。缺乏PSI- n的植株组装了功能性PSI复合体，能够进行光自养生长。在琼脂培养基上生长数周后，植株褪绿，发育明显变慢。然而，在最佳生长条件下，尽管一些光合参数受到影响，但未添加PSI-N的植株在视觉上与野生型无法区分。在转化体中，电子从质体青素转移到PSI氧化反应中心P700（+）的二阶速率常数仅为野生型值的55%，稳态NADP（+）还原也有类似程度的下降。叶片水平的析氧量子产率和PSII光化学量子产率比野生型低10%左右。光化学荧光猝灭也有类似程度的降低。因此，PSI在分子水平上的活性降低了40-50%，而在整个植株水平上的活性则不那么显著。部分原因是在缺乏PSI- n的植物中PSI含量增加了17%。
The PSI-N subunit of photosystem I (PSI) is restricted to higher plants and is the only subunit located entirely in the thylakoid lumen. The role of the PSI-N subunit in the PSI complex was investigated in transgenic Arabidopsis plants which were generated using antisense and cosuppression strategies. Several lines without detectable levels of PSI-N were identified. The plants lacking PSI-N assembled a functional PSI complex and were capable of photoautotrophic growth. When grown on agar media for several weeks the plants became chlorotic and developed significantly more slowly. However, under optimal growth conditions, the plants without PSI-N were visually indistinguishable from the wild-type although several photosynthetic parameters were affected. In the transformants, the second-order rate constant for electron transfer from plastocyanin to P700(+), the oxidized reaction centre of PSI, was only 55% of the wild-type value, and steady-state NADP(+) reduction was decreased to a similar extent. Quantum yield of oxygen evolution and PSII photochemistry were about 10% lower than in the wild-type at leaf level. Photochemical fluorescence quenching was lowered to a similar extent. Thus, the 40-50% lower activity of PSI at the molecular level was much less significant at the whole-plant level. This was partly explained by a 17% increase in PSI content in the plants lacking PSI-N.