VAN4 encodes a putative TRS120 that is required for normal cell growth and vein development in Arabidopsis.
VAN4 encodes a putative TRS120 that is required for normal cell growth and vein development in Arabidopsis.
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DOI：
10.1093/pcp/pcu012
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发表时间：
2014-04
影响因子：
4.9
通讯作者：
S. Naramoto;Tomasz Nodzyłski;Tomoko Dainobu;Hirotomo Takatsuka;Teruyo Okada;J. Friml;H. Fukuda
中科院分区：
文献类型：
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作者：
S. Naramoto;Tomasz Nodzyłski;Tomoko Dainobu;Hirotomo Takatsuka;Teruyo Okada;J. Friml;H. Fukuda
在被子植物中，叶脉形成了复杂的模式，但这一过程的机制在很大程度上是未知的。为了阐明控制静脉模式形成的分子机制，我们先前分离了显示静脉不连续性的血管网络缺陷（van）突变体。在这里，我们报道了van4突变体的表型分析，并鉴定和表征了van4基因。详细的表型分析表明，van4突变体在原形成层细胞分化和随后的维管细胞分化中存在缺陷。在van4突变体中观察到茎和根细胞生长减少，这表明van4的功能对细胞生长和脉络连续性的建立很重要。与这些表型一致，VAN4基因在维管细胞和分生组织细胞中强烈表达。VAN4编码一个推测的TRS120，这是一个已知的鸟嘌呤核苷酸交换因子（GEF），参与调节Rab GTPase的囊泡运输，以及一个已知的系带因子，决定膜融合的特异性。VAN4蛋白定位于反式高尔基网络/早期核内体（TGN/EE）。在van4突变体中观察到生长素外排载体PIN蛋白的异常再循环。这些结果表明，van4介导的TGN胞吐作用在植物维管发育和茎、根细胞生长中起着重要作用。我们将VAN4鉴定为推测的TRS120，这表明Rab GTPases（除了ARF GTPases）对于持续的维管发育至关重要，并进一步证明了泡泡运输在叶片维管形成中的重要性。
Leaf venation develops complex patterns in angiosperms, but the mechanism underlying this process is largely unknown. To elucidate the molecular mechanisms governing vein pattern formation, we previously isolated vascular network defective (van) mutants that displayed venation discontinuities. Here, we report the phenotypic analysis of van4 mutants, and we identify and characterize the VAN4 gene. Detailed phenotypic analysis shows that van4 mutants are defective in procambium cell differentiation and subsequent vascular cell differentiation. Reduced shoot and root cell growth is observed in van4 mutants, suggesting that VAN4 function is important for cell growth and the establishment of venation continuity. Consistent with these phenotypes, the VAN4 gene is strongly expressed in vascular and meristematic cells. VAN4 encodes a putative TRS120, which is a known guanine nucleotide exchange factor (GEF) for Rab GTPase involved in regulating vesicle transport, and a known tethering factor that determines the specificity of membrane fusion. VAN4 protein localizes at the trans-Golgi network/early endosome (TGN/EE). Aberrant recycling of the auxin efflux carrier PIN proteins is observed in van4 mutants. These results suggest that VAN4-mediated exocytosis at the TGN plays important roles in plant vascular development and cell growth in shoot and root. Our identification of VAN4 as a putative TRS120 shows that Rab GTPases are crucial (in addition to ARF GTPases) for continuous vascular development, and provides further evidence for the importance of vesicle transport in leaf vascular formation.