Ma Tengfei, Ma Haoli, Zhao Heming, Qi Huandong, Zhao Jie
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China.
BMC Plant Biol. 2014 Nov 18;14:299. doi: 10.1186/s12870-014-0299-y.
Xylogen, a chimeric arabinogalactan protein containing a non-specific lipid transfer protein domain, can promote xylem cell differentiation. No comprehensive study has been carried out on the XYLP gene family in rice. As a first step in research on this gene family and as a useful strategy in general, a genome-wide analysis of the OsXYLP gene family is thus needed.
In this study, we identified 21 XYLP genes from the rice genome and comprehensively analyzed their protein structures, phylogenetic relationships, chromosomal locations, and gene duplication status. Our results indicate that gene duplication has played major roles in the expansion of the OsXYLP gene family. We used expressed sequence tag, microarray, massively parallel signature sequencing, and quantitative real-time PCR data to analyze OsXYLP gene expression during various developmental stages and under abiotic stress conditions. We found that many OsXYLP genes are abundantly expressed in vascular tissues and seeds, with some genes regulated under hormonal or abiotic stresses. In addition, we identified knockout mutants of OsXYLP7 and OsXYLP16 and discovered that the mutant xylp7 has a defect in stem height.
We analyzed expression profiles of 21 XYLP genes and characterized the structures and evolutionary relationships of their proteins. Our results demonstrate that the rice XYLP gene family may play roles in plant vascular system development and hormone signaling. Among the 21 detected OsXYLPs, 19 are newly identified genes encoding arabinogalactan proteins. Our results provide comprehensive insights that will assist future research on the biological functions of the rice XYLP gene family.
木聚糖（Xylogen）是一种含有非特异性脂质转移蛋白结构域的嵌合阿拉伯半乳聚糖蛋白，可促进木质部细胞分化。目前尚未对水稻中的XYLP基因家族进行全面研究。因此，作为对该基因家族研究的第一步，也是一项通用的有效策略，有必要对水稻OsXYLP基因家族进行全基因组分析。
在本研究中，我们从水稻基因组中鉴定出21个XYLP基因，并对它们的蛋白质结构、系统发育关系、染色体定位和基因复制状态进行了全面分析。我们的结果表明，基因复制在水稻OsXYLP基因家族的扩展中发挥了主要作用。我们利用表达序列标签、微阵列、大规模平行签名测序和实时定量PCR数据，分析了OsXYLP基因在不同发育阶段和非生物胁迫条件下的表达情况。我们发现许多OsXYLP基因在维管组织和种子中大量表达，一些基因在激素或非生物胁迫下受到调控。此外，我们鉴定出了OsXYLP7和OsXYLP16的敲除突变体，并发现突变体xylp7的茎高存在缺陷。
我们分析了21个XYLP基因的表达谱，并对其蛋白质的结构和进化关系进行了表征。我们的结果表明，水稻XYLP基因家族可能在植物维管系统发育和激素信号传导中发挥作用。在检测到的21个OsXYLPs中，有19个是新鉴定的编码阿拉伯半乳聚糖蛋白的基因。我们的结果提供了全面的见解，将有助于未来对水稻XYLP基因家族生物学功能的研究。
