School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
Plant J. 2013 Apr;74(2):294-309. doi: 10.1111/tpj.12121. Epub 2013 Mar 1.
A family of six genes encoding acyl-CoA-binding proteins (ACBPs), ACBP1-ACBP6, has been characterized in Arabidopsis thaliana. In this study, we demonstrate that ACBP1 promotes abscisic acid (ABA) signaling during germination and seedling development. ACBP1 was induced by ABA, and transgenic Arabidopsis ACBP1-over-expressors showed increased sensitivity to ABA during germination and seedling development, whereas the acbp1 mutant showed decreased ABA sensitivity during these processes. Subsequent RNA assays showed that ACBP1 over-production in 12-day-old seedlings up-regulated the expression of PHOSPHOLIPASE Dα1 (PLDα1) and three ABA/stress-responsive genes: ABA-RESPONSIVE ELEMENT BINDING PROTEIN1 (AREB1), RESPONSE TO DESICCATION29A (RD29A) and bHLH-TRANSCRIPTION FACTOR MYC2 (MYC2). The expression of AREB1 and PLDα1 was suppressed in the acbp1 mutant in comparison with the wild type following ABA treatment. PLDα1 has been reported to promote ABA signal transduction by producing phosphatidic acid, an important lipid messenger in ABA signaling. Using lipid profiling, seeds and 12-day-old seedlings of ACBP1-over-expressing lines were shown to accumulate more phosphatidic acid after ABA treatment, in contrast to lower phosphatidic acid in the acbp1 mutant. Bimolecular fluorescence complementation assays indicated that ACBP1 interacts with PLDα1 at the plasma membrane. Their interaction was further confirmed by yeast two-hybrid analysis. As recombinant ACBP1 binds phosphatidic acid and phosphatidylcholine, ACBP1 probably promotes PLDα1 action. Taken together, these results suggest that ACBP1 participates in ABA-mediated seed germination and seedling development.
在拟南芥中，已经鉴定出了一个编码酰基辅酶 A 结合蛋白（ACBPs）的六个基因家族，ACBP1-ACBP6。在这项研究中，我们证明了 ACBP1 在萌发和幼苗发育过程中促进脱落酸（ABA）信号转导。ACBP1 被 ABA 诱导，过表达 ACBP1 的转基因拟南芥在萌发和幼苗发育过程中对 ABA 的敏感性增加，而 acbp1 突变体在这些过程中对 ABA 的敏感性降低。随后的 RNA 分析表明，在 12 天大的幼苗中过表达 ACBP1 会上调 PHOSPHOLIPASE Dα1（PLDα1）和三个 ABA/应激响应基因的表达：ABA-RESPONSIVE ELEMENT BINDING PROTEIN1（AREB1）、RESPONSE TO DESICCATION29A（RD29A）和 bHLH-TRANSCRIPTION FACTOR MYC2（MYC2）。与野生型相比，在 ABA 处理后，acbp1 突变体中 AREB1 和 PLDα1 的表达受到抑制。已经报道 PLDα1 通过产生磷脂酸来促进 ABA 信号转导，磷脂酸是 ABA 信号中的一种重要脂质信使。通过脂质谱分析，发现与 acbp1 突变体相比，ACBP1 过表达系的种子和 12 天大的幼苗在 ABA 处理后积累了更多的磷脂酸。双分子荧光互补测定表明，ACBP1 在质膜上与 PLDα1 相互作用。酵母双杂交分析进一步证实了它们的相互作用。由于重组 ACBP1 结合磷脂酸和磷脂酰胆碱，因此 ACBP1 可能促进 PLDα1 的作用。综上所述，这些结果表明 ACBP1 参与了 ABA 介导的种子萌发和幼苗发育。
