Xyloglucan endotransglycosylase/hydrolase genes in cotton and their role in fiber elongation
Xyloglucan endotransglycosylase/hydrolase genes in cotton and their role in fiber elongation
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DOI：
10.1007/s00425-010-1246-2
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发表时间：
2010-10-01
期刊：
影响因子：
4.3
通讯作者：
Allen, Randy D.
中科院分区：
文献类型：
--
作者：
Lee, Joohyun;Burns, Teresa H.;Allen, Randy D.
植物细胞壁延伸性部分地由木葡聚糖内切转糖基酶/水解酶（XTH）介导，所述酶能够切割并重新附着构成I型细胞壁的半纤维素基质的木葡聚糖聚合物。在拟南芥和其他植物中，XTH由相对较大的基因家族编码，这些基因家族以特定的空间和时间模式进行调控。通过对棉花表达序列标签（EST）数据库的计算机筛选，鉴定出23个与拟南芥XTH编码序列具有密切序列相似性的序列。对来自这些EST的全长棉花cDNA的分析允许主要基于它们的3'非翻译序列鉴定三种不同的GhXTH cDNA（表示为GhXTH 1、GhXTH 2和GhXTH 3）。三个GhXTH基因表达不同，GhXTH 1主要在伸长棉纤维中表达。在表达由CaMV 35 S启动子的转录控制下的GhXTH 1编码序列组成的转基因的转基因棉花植物中分析GhXTH 1在介导棉花纤维伸长中的功能。过表达GhXTH 1的植物具有增加的XTH活性，并且在温室和田间生长条件下产生比野生型棉花植物长15%至20%的成熟棉纤维。分离分析表明，35 S：：GhXTH 1基因在转基因棉花中为显性纤维长度等位基因。这些结果证实了GhXTH 1是伸长纤维中的主要XTH，并且其表达限制了棉纤维伸长。
Plant cell wall extensibility is mediated, in part, by xyloglucan endotransglycosylases/hydrolases (XTH) that are able to cleave and reattach xyloglucan polymers that make up the hemicelluloses matrix of type I cell walls. In Arabidopsis and other plants, XTHs are encoded by relatively large gene families that are regulated in specific spatial and temporal patterns. In silico screening of a cotton expressed sequence tag (EST) database identified 23 sequences with close sequence similarity to Arabidopsis XTH coding sequences. Analysis of full-length cotton cDNAs derived from these ESTs allow for the identification of three distinct GhXTH cDNAs (denoted GhXTH1, GhXTH2 and GhXTH3) based primarily on their 3' untranslated sequences. The three GhXTH genes were expressed differently with GhXTH1 predominantly expressed in elongating cotton fibers. The function of GhXTH1 in mediating cotton fiber elongation was analyzed in transgenic cotton plants that express a transgene consisting of the GhXTH1 coding sequence under transcriptional control of the CaMV 35S promoter. Plants that over-expressed GhXTH1 had increased XTH activity and produced mature cotton fibers that were between 15 and 20% longer than wild-type cotton plants under both greenhouse and field growth conditions. Segregation analysis showed that the 35S::GhXTH1 transgene acts as a dominant fiber length allele in transgenic cotton. These results confirm that GhXTH1 is the predominant XTH in elongating fibers and its expression limits cotton fiber elongation.