School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
Plant Sci. 2019 Oct;287:110191. doi: 10.1016/j.plantsci.2019.110191. Epub 2019 Jul 15.
As an extracellular arabinogalactan protein (AGP) containing a non-specific lipid transfer protein (nsLTP) domain, xylogen mediates the local intercellular communication required for tracheary element (TE) differentiation in Zinnia cell culture. Although XYLP (xylogen-like protein) gene families have been reported in Arabidopsis and rice, no comprehensive analysis has been performed in woody plants. In this work, 31 XYLP genes in five phylogenetic groups were identified from Populus trichocarpa genome and a comprehensive bioinformatic analysis including gene and protein structures, chromosomal locations and duplication events were conducted. In-silico data and qRT-PCR results indicated that PtXYLP1 is predominantly expressed in poplar apex, young leaves and roots, while PtXYLP2 is uniformly expressed across a variety of tissues with a low abundance. Analysis on PtXYLP1pro:GUS and PtXYLP2pro:GUS in Arabidopsis revealed their differential expression patterns during seed germination and specific inductions by exogenously applied phytohormones including auxin, cytokinin and GA. When overexpressed in Arabidopsis, PtXYLP1 but not PtXYLP2 resulted in cotyledons with defective venation patterns and interrupted secondary (2°) vein loops, which phenotype was underpinned by the down-regulation of genes indispensably required by embryonic venation development at procambium and/or vessel level.
作为一种含有非特异性脂质转移蛋白 (nsLTP) 结构域的细胞外阿拉伯半乳聚糖蛋白 (AGP)，木葡聚糖介导了泽兰细胞培养中需要进行木质部分化的细胞间局部通讯。尽管在拟南芥和水稻中已经报道了 XYLP（木葡聚糖样蛋白）基因家族，但在木本植物中尚未进行全面分析。在这项工作中，从杨树基因组中鉴定了五个进化群的 31 个 XYLP 基因，并进行了包括基因和蛋白质结构、染色体位置和重复事件的综合生物信息学分析。计算机数据和 qRT-PCR 结果表明，PtXYLP1 在杨树顶端、幼叶和根部表达丰富，而 PtXYLP2 在各种组织中均匀表达，丰度较低。对 PtXYLP1pro:GUS 和 PtXYLP2pro:GUS 在拟南芥中的分析表明，它们在种子萌发过程中的表达模式不同，并且对外源施加的植物激素如生长素、细胞分裂素和 GA 具有特异性诱导作用。在拟南芥中过表达时，PtXYLP1 而非 PtXYLP2 导致子叶的叶脉模式出现缺陷，并且次级（2°）叶脉环中断，这种表型是由胚胎叶脉发育过程中在原形成层和/或脉管水平上必不可少的基因下调所支撑的。
