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New Phytologist：拟南芥周质微管作用于种子黏液质结构建成

已有 4301 次阅读 2018-9-15 08:39 |个人分类:每日摘要|系统分类:论文交流

TRM4 is essential for cellulose deposition in Arabidopsis seed mucilage by maintaining cortical microtubule organization and interacting with CESA3

First author: Bo Yang; Affiliations: RWTH Aachen University (亚琛工业大学): Aachen, Germany

Corresponding author: Bo Yang

The differentiation of the seed coat epidermal (SCE) cells in Arabidopsis thaliana leads to the production of a large amount of pectin‐r ich (富含果胶的) mucilage (粘液质) and a thick cellulosic secondary cell wall. The mechanisms by which cortical microtubules (周质微管) are involved in the formation of these pectinaceous (含果胶的) and cellulosic cell walls are still largely unknown. Using a reverse genetic approach, we found that TONNEAU1 (TON1) recruiting motif 4 (TRM4) is implicated in cortical microtubule organization in SCE cells, and functions as a novel player in the establishment of mucilage structure. TRM4 is preferentially accumulated in the SCE cells at the stage of mucilage biosynthesis. The loss of TRM4 results in compact (紧实的) seed mucilage capsules, aberrant (异常的) mucilage cellulosic structure, short cellulosic rays (射线) and disorganized cellulose microfibrils (纤维素微纤丝) in mucilage. The defects could be rescued by transgene complementation of trm4 alleles. Probably, this is a consequence of a disrupted organization of cortical microtubules, observed using fluorescently tagged tubulin proteins (微管蛋白) in trm4 SCE cells. Furthermore, TRM4 proteins co‐aligned with microtubules and interacted directly with CELLULOSE SYNTHASE 3 in two independent assays. Together, the results indicate that TRM4 is essential for microtubule array organization and therefore correct cellulose orientation in the SCE cells, as well as the establishment of the subsequent mucilage architecture.

拟南芥种皮表皮（SCE）细胞会产生大量的富含果胶的粘液质和一层薄的纤维素次生细胞壁。周质微管在这些含果胶和纤维素的细胞壁形成过程中扮演着什么样的作用还不清楚。本文通过反向遗传学的方法发现TON1通过招募TRM4基序参与到SCE细胞中的周质微管排列，并且作为一种新的调控机制参与黏液质的结构建成。TRM4优先在黏液质生物合成阶段的SCE细胞中积累。TRM4缺失突变体会导致种子黏液荚更加紧实，黏液质纤维素结构出现异常，纤维素射线变短以及黏液质中纤维素微纤丝排列混乱。该突变体的异常表型可以通过转入trm4互补的等位基因所恢复。通过对trm4突变体SCE细胞利用微管蛋白作为标记进行荧光观测，作者推测这种突变体的异常表型可能是由于周质微管的排列混乱所导致的。此外，TRM4蛋白与微管共排列，并且在两个独立试验中均可以与纤维素合酶CESA3直接发生相互作用。综上，本文的研究结果显示TRM4蛋白对于微管的正常排列至关重要，进而保证了SCE细胞中纤维素的排列方向正确，以及随后黏液质结构的建立。