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Tree Physiology:微管蛋白在杨树叶片细胞壁中的作用

已有 3802 次阅读 2017-9-19 08:46 |个人分类:每日摘要|系统分类:论文交流|关键词:学者

Tubulins, rhythms and cell walls in poplar leaves: it’s all in the timing


First author:Scott A. Harding; Affiliations: University of Georgia (佐治亚大学): Athens, USA

Corresponding author: Chung-Jui Tsai


Plant cell walls exhibit architectural and compositional changes throughout their development and in response to external cues. While tubulins (微管蛋白) are involved in cell wall biogenesis, much remains unknown about the scope of their involvement (参与) during the orchestration of this resource-demanding process. A transgenic approach coupled with cell wall compositional analysis, RNA-seq and mining of publicly available diurnal gene expression data was used to assess the involvement of tubulins in poplar leaf cell wall biogenesis. Leaf cell walls of transgenic poplar lines with constitutive overexpression of α-tubulin (TUA) exhibited an increased abundance of homogalacturonan (同型半乳糖醛酸聚糖), along with a reduction in xylose (戊醛糖). These changes were traced to altered expression of UDP-glucuronic acid decarboxylase (GADC; UDP-葡萄糖醛酸脱羧酶) in the transgenic leaves. A model is postulated by which altered diurnal control of TUA through its constitutive overexpression led to a metabolic tradeoff affecting cellular utilization of GADC substrate UDP-glucuronic acid. While there were no effects on cellulose, hemicellulose or lignin abundance, subtle (微妙的) effects on hemicellulose composition and associated gene expression were noted. In addition, expression and enzymatic activity of pectin methylesterase (PME; 果胶甲酯酶) decreased in the transgenic leaves. The change is discussed in a context of increased levels of PME substrate homogalacturonan, slow stomatal kinetics (气孔动力学) and the fate of PME product methanol (甲醇). Since stomatal opening and closing depend on fundamentally contrasting microtubule (微管) dynamics, the slowing of both processes in the transgenic lines as previously reported appears to be directly related to underlying cell wall compositional changes that were caused by tubulin manipulation.


植物细胞壁在整个发育时期和响应外界环境时会改变其结构与组成。微管蛋白参与了细胞壁的生物合成,然而对于其还参与了哪些生物学的过程还所知甚少。本文利用转基因方法,结合细胞壁组成分析、RNA-seq及挖掘公共可利用的基因表达数据研究杨树叶片细胞壁生物合成中微管蛋白的作用。组成型过表达α-微管蛋白(TUA)的转基因杨树叶片表现出同型半乳糖醛酸聚糖积累的增加,同时戊醛糖含量的降低。这些改变可以追溯到转基因叶片中UDP-葡萄糖醛酸脱羧酶(GADC)基因表达的改变。通过过表达TUA改变其表达水平导致了植株代谢的平衡,进而影响了细胞内对GADC底物UDP-葡萄糖醛酸的利用。转基因中过表达TUA对于纤维素、半纤维素及木质素含量均无影响,但对于半纤维素的组成有微小影响,同时也注意到相关基因的表达水平的变化。另外,转基因植株中果胶甲酯酶表达及酶活有所降低。本文作者讨论了转基因植株中PME底物同型半乳糖醛酸聚糖含量升高、气孔动力的减缓以及PME产物甲醇的速率等问题。由于气孔开放与闭合基本取决于两侧微管动态的差异,转基因株系中这些生物学进程的减缓显然直接与由微管蛋白改变导致的潜在细胞壁组成的改变相关。


通讯:Chung-Jui Tsai (http://www.genetics.uga.edu/directory/chung-jui-tsai)


研究方向:利用转录组、代谢组、CRISPR基因组编辑、以及更多的传统的遗传学方法、生化及植物生理等手段来研究林木之所以为林木的原因,从基因家族进化和功能基因分化到生长发育重要基因的转基因研究。


doi: https://doi.org/10.1093/treephys/tpx104


Journal: Tree Physiology
Published data: September 12, 2017.


P.S. 欢迎关注微信公众号:微信号Plant_Frontiers


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