Phan Jana L, Tucker Matthew R, Khor Shi Fang, Shirley Neil, Lahnstein Jelle, Beahan Cherie, Bacic Antony, Burton Rachel A
Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA 5064, Australia.
Australian Research Council Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Parkville Campus, VIC 3010, Australia.
J Exp Bot. 2016 Dec;67(22):6481-6495. doi: 10.1093/jxb/erw424.
Xylans are the most abundant non-cellulosic polysaccharide found in plant cell walls. A diverse range of xylan structures influence tissue function during growth and development. Despite the abundance of xylans in nature, details of the genes and biochemical pathways controlling their biosynthesis are lacking. In this study we have utilized natural variation within the Plantago genus to examine variation in heteroxylan composition and structure in seed coat mucilage. Compositional assays were combined with analysis of the glycosyltransferase family 61 (GT61) family during seed coat development, with the aim of identifying GT61 sequences participating in xylan backbone substitution. The results reveal natural variation in heteroxylan content and structure, particularly in P. ovata and P. cunninghamii, species which show a similar amount of heteroxylan but different backbone substitution profiles. Analysis of the GT61 family identified specific sequences co-expressed with IRREGULAR XYLEM 10 genes, which encode putative xylan synthases, revealing a close temporal association between xylan synthesis and substitution. Moreover, in P. ovata, several abundant GT61 sequences appear to lack orthologues in P. cunninghamii. Our results indicate that natural variation in Plantago species can be exploited to reveal novel details of seed coat development and polysaccharide biosynthetic pathways.
木聚糖是植物细胞壁中含量最丰富的非纤维素多糖。多种木聚糖结构在生长和发育过程中影响组织功能。尽管自然界中木聚糖含量丰富，但控制其生物合成的基因和生化途径的细节仍不清楚。在本研究中，我们利用车前属植物的自然变异来研究种皮黏液中杂木聚糖组成和结构的变异。在种皮发育过程中，将成分分析与糖基转移酶家族61（GT61）的分析相结合，目的是鉴定参与木聚糖主链取代的GT61序列。结果揭示了杂木聚糖含量和结构的自然变异，特别是在卵叶车前和康宁汉姆车前中，这两个物种显示出相似数量的杂木聚糖，但主链取代模式不同。对GT61家族的分析确定了与不规则木质部10基因共表达的特定序列，该基因编码假定的木聚糖合酶，揭示了木聚糖合成与取代之间密切的时间关联。此外，在卵叶车前中，几个丰富的GT61序列在康宁汉姆车前中似乎缺乏直系同源物。我们的结果表明，车前属植物的自然变异可用于揭示种皮发育和多糖生物合成途径的新细节。
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