Developmental and molecular physiological evidence for the role of phosphoenolpyruvate carboxylase in rapid cotton fibre elongation.
Developmental and molecular physiological evidence for the role of phosphoenolpyruvate carboxylase in rapid cotton fibre elongation.
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DOI：
10.1093/jxb/erp299
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发表时间：
2010
影响因子：
6.9
通讯作者：
Ruan YL
中科院分区：
文献类型：
--
作者：
Li XR;Wang L;Ruan YL
棉纤维是毛发状的单细胞，在开花时从胚珠表皮开始延伸到几厘米。苹果酸以及钾和糖的积累被认为通过渗透调节和电荷平衡在纤维伸长中发挥重要作用。然而，缺乏支持或反对这一假设的证据。磷酸烯醇丙酮酸羧化酶（PEPC）是负责合成苹果酸的关键酶。本文研究了 PEPC 在棉纤维伸长中的潜在作用。从发育过程来看，快速伸长阶段的PEPC活性高于慢速伸长阶段的PEPC活性。从基因角度来看，PEPC 活性与纤维伸长率和最终达到的纤维长度呈正相关。重要的是，LiCl 抑制 PEPC 活性，降低其磷酸化状态，从而减少纤维长度。为了检查 PEPC 活性的分子基础，克隆了两个编码 PEPC 的 cDNA：GhPEPC1 和 2，它们代表了在棉纤维中表达的主要 PEPC 基因。 RT-PCR 分析显示，GhPEPC1 和 2 在快速延伸期高表达，但在慢速至终末延伸期表达较弱。原位杂交在 1 d 的幼纤维中检测到 GhPEPC1 和 2 的 mRNA，但在纤维起始之前的胚珠表皮中未检测到。总的来说，数据表明棉纤维伸长需要 PEPC 的高活性，这可能是通过 GhPEPC1 和 2 基因的表达实现的。
Cotton fibres are hair-like single-cells that elongate to several centimetres long after their initiation from the ovule epidermis at anthesis. The accumulation of malate, along with K+ and sugars, is thought to play an important role in fibre elongation through osmotic regulation and charge balance. However, there is a lack of evidence for or against such an hypothesis. Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme responsible for the synthesis of malate. The potential role of PEPC in cotton fibre elongation is examined here. Developmentally, PEPC activity was higher at the rapid elongation phase than that at the slow elongation stage. Genotypically, PEPC activity correlated positively with the rate of fibre elongation and the final fibre length attained. Importantly, suppression of PEPC activity by LiCl that reduces its phosphorylation status decreased fibre length. To examine the molecular basis underlying PEPC activity, two cDNAs encoding PEPC, GhPEPC1 and 2, were cloned, which represents the major PEPC genes expressed in cotton fibre. RT-PCR analyses revealed that GhPEPC1 and 2 were highly expressed at the rapid elongation phase but weakly at the slow-to-terminal elongation period. In situ hybridization detected mRNA of GhPEPC1 and 2 in 1 d young fibres but not in the ovule epidermis prior to fibre initiation. Collectively, the data indicate that cotton fibre elongation requires high activity of PEPC, probably through the expression of the GhPEPC1 and 2 genes.
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