过表达棉花葡萄糖醛酸激酶基因GbGlcAK促进拟南芥细胞伸长

Overexpression of a Cotton Glucuronokinase Gene GbGlcAK Promotes Cell Elongation in Arabidopsis thaliana

纤维品质改良一直是棉花育种的重要目标。基于纤维不同发育时期的RNA-seq数据,发现1个在海岛棉和陆地棉间差异表达的葡萄糖醛酸激酶基因(glucuronic acid kinase/glucuronokinase,GlcAK)。从海岛棉(Gossypium barbadense)Pima90-53纤维中克隆了GbGlcAK,其ORF为1101 bp,编码366个氨基酸。GbGlcAK具有GHMP激酶N和C结构域,为GHMP超家族成员,属于可溶性非分泌蛋白,与拟南芥GlcAK亲缘关系最近。亚细胞定位结果显示GbGlcAK分布在细胞质中。超表达GbGlcAK的拟南芥叶表皮毛、下胚轴、下胚轴细胞和根的长度较野生型均极显著增加,UDP-D-GlcA代谢相关基因表达量增加,果胶含量显著增加,说明过表达GbGlcAK能够上调UDP-D-GlcA代谢通路相关基因的表达从而提高果胶含量,进而促进细胞伸长,这为进一步研究GbGlcAK在棉纤维发育中的功能提供了参考。

Fiber quality improvement is an important objective for cotton breeding.A differentially expressed gene GlcAK(glucuronic acid kinase/glucuronokinase)between sea island and upland cotton was identified based on RNA-seq data from different stages of fiber development.In this study,GbGlcAK(Gossypium barbadense GlcAK)with 1101 bp of ORF was cloned from the fibers of sea island cotton Pima 90-53,which encoded 366 amino acids.GbGlcAK had the structure domain of GHMP kinases N and C domain and belonged to the GHMP superfamily.GbGlcAK was a soluble and non-secretory protein.In terms of phyletic evolution,GbGlcAK was most closely related to GlcAK from A.thaliana.Subcellular localization results showed that GbGlcAK was distributed in the cytoplasm.Compared with the wild type,the transgenic A.thaliana lines possessed significantly longer leaf trichomes,hypocotyls,hypocotyl cells and roots.The expression of uridine diphosphate-D-glucuronic acid(UDP-D-GlcA)metabolic related genes were upregulated,and the pectin content was also significantly increased in the transgenic lines.These results suggested that overexpression of GbGlcAK in A.thaliana up-regulated UDP-D-GlcA metabolic pathway,thereby increased pectin content and promoted cell elongation.Our study provided references for further exposing the function of GbGlcAK in cotton fiber development.