Xylan synthesized by Irregular Xylem 14 (IRX14) maintains the structure of seed coat mucilage in Arabidopsis.
Xylan synthesized by Irregular Xylem 14 (IRX14) maintains the structure of seed coat mucilage in Arabidopsis.
复制标题
不规则木质部 14 (IRX14) 合成的木聚糖维持了拟南芥种皮粘液的结构。
DOI：
10.1093/jxb/erv510
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发表时间：
2016-03
影响因子：
6.9
通讯作者：
Kong Y
中科院分区：
文献类型：
--
作者：
Hu R;Li J;Wang X;Zhao X;Yang X;Tang Q;He G;Zhou G;Kong Y
IRX 14合成的木聚糖可能通过改变纤维素的结晶和组织来维持种皮的粘液结构。在分化过程中，拟南芥种皮表皮细胞合成并分泌大量的果胶粘液到质外体中，然后在吸胀时释放以包裹种子。在这项研究中，我们发现，不规则木质部14（IRX 14）的突变导致了由于木聚糖含量减少而导致的粘液凝聚力缺陷。IRX 14在种皮表皮细胞中特异性地检测到表达，当粘液多糖的积累停止时，在开花后13天（DPA）达到峰值表达。irx 14 -1种皮的切片显示粘液分泌细胞形态没有明显的结构变化。虽然粘液的总量与野生型（WT）相当，水溶性和粘附层之间的分区显着改变irx 14 -1，从粘附层的水溶性层的再分配。单糖组成分析显示，与WT相比，irx 14 -1水溶性和粘附性粘液中木糖含量显著降低。水溶性胶浆的大分子特性在irx 14 -1中被改变，损失了较大的聚合物组分。根据，糖组分析和斑点免疫印迹的种子粘液，使用特异性抗体的鼠李糖半乳糖醛酸聚糖I（RG I）和木聚糖证实的irx 14 -1粘液的超微结构的改变。同时，irx 14 -1胶浆中结晶纤维素含量降低。这些结果表明，IRX 14是种子粘液木聚糖的生物合成所必需的，其通过改变纤维素的结晶和组织在维持粘液结构中起着重要作用。
Xylan synthesized by IRX14 maintains seed coat mucilage structure potentially through altering the crystallization and organization of cellulose. During differentiation, the Arabidopsis seed coat epidermal cells synthesize and secrete large quantities of pectinaceous mucilage into the apoplast, which is then released to encapsulate the seed upon imbibition. In this study, we showed that mutation in Irregular Xylem 14 (IRX14) led to a mucilage cohesiveness defect due to a reduced xylan content. Expression of IRX14 was detected specifically in the seed coat epidermal cells, reaching peak expression at 13 days post-anthesis (DPA) when the accumulation of mucilage polysaccharides has ceased. Sectioning of the irx14-1 seed coat revealed no visible structural change in mucilage secretory cell morphology. Although the total amount of mucilage was comparable with the wild type (WT), the partition between water-soluble and adherent layers was significantly altered in irx14-1, with redistribution from the adherent layer to the water-soluble layer. The monosaccharide composition analysis revealed that xylose content was significantly reduced in irx14-1 water-soluble and adherent mucilage compared with the WT. The macromolecular characteristics of the water-soluble mucilage were modified in irx14-1 with a loss of the larger polymeric components. In accordance, glycome profiling and dot immunoblotting of seed mucilage using antibodies specific for rhamnogalacturonan I (RG I) and xylan confirmed the ultra-structural alterations in the irx14-1 mucilage. Meanwhile, the crystalline cellulose content was reduced in the irx14-1 mucilage. These results demonstrated that IRX14 was required for the biosynthesis of seed mucilage xylan, which plays an essential role in maintaining mucilage architecture potentially through altering the crystallization and organization of cellulose.