A large population of small chloroplasts in tobacco leaf cells allows more effective chloroplast movement than a few enlarged chloroplasts
A large population of small chloroplasts in tobacco leaf cells allows more effective chloroplast movement than a few enlarged chloroplasts
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DOI：
10.1104/pp.000588
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发表时间：
2002-05-01
期刊：
影响因子：
7.4
通讯作者：
Liu, JR
中科院分区：
文献类型：
--
作者：
Jeong, WJ;Park, YI;Liu, JR
我们通过引入NtFtsZ 1 -2（一种用于质体分裂的cDNA）产生了转基因烟草（Nicotiana tabacum cv Xanthi）植物，每个叶肉细胞仅含有一到三个扩大的叶绿体。这些植物被用来研究在叶肉细胞中具有大量的小叶绿体而不是少数放大的叶绿体的优点。尽管野生型和转基因植物之间的光合作用的组成部分和光合机制的超微结构的相似性，转基因植物在低和高光条件下的整体生长迟缓。在野生型植物中，叶绿体在弱光条件下向面位置移动，在强光条件下向侧面位置移动。然而，在转基因植物中，叶绿体重排在光条件下的反应并不明显。此外，转基因植物叶片在两种光照条件下的叶片透射率值变化都大大减少，表明叶绿体重排严重受阻。因此，在弱光条件下，扩大的叶绿体的不完整的面位置导致光能吸收减少。这反过来又会减少植物的生长。在强光条件下，由于增大的叶绿体轮廓位置不完整，吸收的光量超过光合利用能力，导致光合机构受到光损伤，生长下降。高等植物细胞中存在大量小的和/或快速移动的叶绿体，这使得叶绿体的趋光性更有效，因此，可以更有效地利用低入射光子通量密度。因此，在高入射光子通量密度下，光合机构免受损害。
We generated transgenic tobacco (Nicotiana tabacum cv Xanthi) plants that contained only one to three enlarged chloroplasts per leaf mesophyll cell by introducing NtFtsZ1-2, a cDNA for plastid division. These plants were used to investigate the advantages of having a large population of small chloroplasts rather than a few enlarged chloroplasts in a leaf mesophyll cell. Despite the similarities in photosynthetic components and ultrastructure of photosynthetic machinery between wild-type and transgenic plants, the overall growth of transgenic plants under low- and high-light conditions was retarded. In wild-type plants, the chloroplasts moved toward the face position under low light and toward the profile position under high-light conditions. However, chloroplast rearrangement in transgenic plants in response to light conditions was not evident. In addition, transgenic plant leaves showed greatly diminished changes in leaf transmittance values under both light conditions, indicating that chloroplast rearrangement was severely retarded. Therefore, under low-light conditions the incomplete face position of the enlarged chloroplasts results in decreased absorbance of light energy. This, in turn, reduces plant growth. Under high-light conditions, the amount of absorbed light exceeds the photosynthetic utilization capacity due to the incomplete profile position of the enlarged chloroplasts, resulting in photodamage to the photosynthetic machinery, and decreased growth. The presence of a large number of small and/or rapidly moving chloroplasts in the cells of higher land plants permits more effective chloroplast phototaxis and, hence, allows more efficient utilization of low-incident photon flux densities. The photosynthetic apparatus is, consequently, protected from damage under high-incident photon flux densities.