Irregular xylem 7 (IRX7) is required for anchoring seed coat mucilage in Arabidopsis
Irregular xylem 7 (IRX7) is required for anchoring seed coat mucilage in Arabidopsis
复制标题
拟南芥种皮粘液的锚定需要不规则木质部 7 (IRX7)
DOI：
10.1007/s11103-016-0493-4
复制
发表时间：
2016-09-01
影响因子：
5.1
通讯作者：
Kong, Yingzhen
中科院分区：
文献类型：
--
作者：
Hu, Ruibo;Li, Junling;Kong, Yingzhen
在种皮分化过程中，种皮表皮细胞合成大量粘液。该过程是研究植物细胞壁生物合成和修饰的理想模型系统。在这项研究中，我们表明，不规则木质部7（IRX 7）的突变导致的缺陷，由于减少木聚糖生物合成的粘液粘附。IRX 7在花后4 ~ 13 d表达，13 d表达量最高。irx 7的种皮表皮细胞在分化过程中没有表现出异常的形态，这些细胞合成和沉积了与野生型（WT）细胞相同量的粘液。然而，与WT相比，irx 7中水溶性与粘附性粘液层的分布显著改变。与WT相比，在irx 7水溶性和粘附性粘液中木糖的量和木聚糖的糖基连接的程度都显著降低。水溶性胶浆的聚合物结构在irx 7中改变，WT中存在的较高分子量聚合物组分完全丧失。相应地，全种子免疫标记试验和斑点免疫分析提取的粘液表明，在irx 7粘液的鼠李糖半乳糖醛酸聚糖I（RG I）和木聚糖表位的显着变化。此外，irx 7胶浆中的结晶纤维素含量显著降低。综上所述，这些结果表明，由IRX 7合成的木聚糖在维持种皮粘液的粘附性方面起着至关重要的作用，并且其结构作用可能通过其与纤维素的相互作用来实现。
Large quantities of mucilage are synthesized in seed coat epidermis cells during seed coat differentiation. This process is an ideal model system for the study of plant cell wall biosynthesis and modifications. In this study, we show that mutation in Irregular Xylem 7 (IRX7) results in a defect in mucilage adherence due to reduced xylan biosynthesis. IRX7 was expressed in the seeds from 4 days post-anthesis (DPA) to 13 DPA, with the peak of expression at 13 DPA. The seed coat epidermis cells of irx7 displayed no aberrant morphology during differentiation, and these cells synthesized and deposited the same amount of mucilage as did wild type (WT) cells. However, the distribution of the water-soluble vs. adherent mucilage layers was significantly altered in irx7 compared to the WT. Both the amount of xylose and the extent of glycosyl linkages of xylan was dramatically decreased in irx7 water-soluble and adherent mucilage compared to the WT. The polymeric structure of water-soluble mucilage was altered in irx7, with a total loss of the higher molecular weight polymer components present in the WT. Correspondingly, whole-seed immunolabeling assays and dot-immunoassays of extracted mucilage indicated dramatic changes in rhamnogalacturonan I (RG I) and xylan epitopes in irx7 mucilage. Furthermore, the crystalline cellulose content was significantly reduced in irx7 mucilage. Taken together, these results indicate that xylan synthesized by IRX7 plays an essential role in maintaining the adhesive property of seed coat mucilage, and its structural role is potentially implemented through its interaction with cellulose.