Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, Louisiana, United States of America.
PLoS One. 2011;6(12):e28624. doi: 10.1371/journal.pone.0028624. Epub 2011 Dec 9.
Plants contain an extensive family of PsbP-related proteins termed PsbP-like (PPL) and PsbP domain (PPD) proteins, which are localized to the thylakoid lumen. The founding member of this family, PsbP, is an established component of the Photosystem II (PS II) enzyme, and the PPL proteins have also been functionally linked to other photosynthetic processes. However, the functions of the remaining seven PPD proteins are unknown. To elucidate the function of the PPD5 protein (At5g11450) in Arabidopsis, we have characterized a mutant T-DNA insertion line (SALK_061118) as well as several RNAi lines designed to suppress the expression of this gene. The functions of the photosynthetic electron transfer reactions are largely unaltered in the ppd5 mutants, except for a modest though significant decrease in NADPH dehydrogenase (NDH) activity. Interestingly, these mutants show striking plant developmental and morphological defects. Relative to the wild-type Col-0 plants, the ppd5 mutants exhibit both increased lateral root branching and defects associated with axillary bud formation. These defects include the formation of additional rosettes originating from axils at the base of the plant as well as aerial rosettes formed at the axils of the first few nodes of the shoot. The root-branching phenotype is chemically complemented by treatment with the synthetic strigolactone, GR24. We propose that the developmental defects observed in the ppd5 mutants are related to a deficiency in strigolactone biosynthesis.
植物含有广泛的 PsbP 相关蛋白家族，称为 PsbP 样（PPL）和 PsbP 结构域（PPD）蛋白，它们定位于类囊体腔。该家族的创始成员 PsbP 是光系统 II（PS II）酶的一个组成部分，PPL 蛋白也与其他光合作用过程具有功能联系。然而，其余七个 PPD 蛋白的功能尚不清楚。为了阐明拟南芥 PPD5 蛋白（At5g11450）的功能，我们对一个 T-DNA 插入突变体（SALK_061118）和几个设计用于抑制该基因表达的 RNAi 系进行了特征描述。在 ppd5 突变体中，光合作用电子传递反应的功能基本没有改变，除了 NADPH 脱氢酶（NDH）活性略有但显著下降。有趣的是，这些突变体表现出明显的植物发育和形态缺陷。与野生型 Col-0 植物相比，ppd5 突变体表现出侧根分枝增加和与腋芽形成相关的缺陷。这些缺陷包括从植物基部腋芽形成的额外的莲座叶丛，以及在茎的前几个节点的腋芽形成的气生莲座叶丛。根分枝表型可以通过用合成的 Strigolactone GR24 处理来化学互补。我们提出，在 ppd5 突变体中观察到的发育缺陷与 Strigolactone 生物合成的缺陷有关。
