Arabinogalactan protein polysaccharide chains are required for normal biogenesis of plasmodesmata
Arabinogalactan protein polysaccharide chains are required for normal biogenesis of plasmodesmata
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DOI：
10.1111/tpj.16061
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发表时间：
2022-12-29
期刊：
影响因子：
7.2
通讯作者：
Ogawa-Ohnishi, Mari
中科院分区：
文献类型：
--
作者：
Okawa, Ryoya;Hayashi, Yoko;Ogawa-Ohnishi, Mari
阿拉伯半乳聚糖蛋白（AGPs）是一类植物特异性的胞外蛋白聚糖，其特征是富含半乳糖的大而复杂的多糖链。然而，AGP基因的高度冗余性阻碍了对AGP功能的阐明。为了揭示AGPs在拟南芥中尚未探索的作用，使用了Hyp O-半乳糖基转移酶（HPGT）的突变体，所述Hyp O-半乳糖基转移酶（HPGT）是催化Hyp-linked阿拉伯半乳聚糖链生物合成的共同初始步骤的关键酶。在这里，我们表明，使用hpgt 1，2，3三重突变体，减少功能性的AGPs导致气孔图案缺陷，其中两个或多个气孔聚集在一起。这种缺陷是由于增加和失调的共质体运输后，胞间连丝结构的变化，使高渗透性的复杂分支胞间连丝与腔在分支部分增加的突变体。我们还发现hpgt 1，2，3突变导致细胞壁中纤维素的减少和果胶的积累，从而控制细胞壁的孔隙度。我们的研究结果强调了AGPs在胞间连丝的正确生物发生中的重要性，可能是通过调节胞间连丝周围的细胞壁特性起作用。
Arabinogalactan proteins (AGPs) are a plant-specific family of extracellular proteoglycans characterized by large and complex galactose-rich polysaccharide chains. Functional elucidation of AGPs, however, has been hindered by the high degree of redundancy of AGP genes. To uncover as yet unexplored roles of AGPs in Arabidopsis, a mutant of Hyp O-galactosyltransferase (HPGT), a critical enzyme that catalyzes the common initial step of Hyp-linked arabinogalactan chain biosynthesis, was used. Here we show, using the hpgt1,2,3 triple mutant, that a reduction in functional AGPs leads to a stomatal patterning defect in which two or more stomata are clustered together. This defect is attributed to increased and dysregulated symplastic transport following changes in plasmodesmata structure, such that highly permeable complex branched plasmodesmata with cavities in branching parts increased in the mutant. We also found that the hpgt1,2,3 mutation causes a reduction of cellulose in the cell wall and accumulation of pectin, which controls cell wall porosity. Our results highlight the importance of AGPs in the correct biogenesis of plasmodesmata, possibly acting through the regulation of cell wall properties surrounding the plasmodesmata.