LAZY3 plays a pivotal role in positive root gravitropism in Lotus japonicus
LAZY3 plays a pivotal role in positive root gravitropism in Lotus japonicus
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LAZY3在百脉根正向向地性中发挥关键作用
DOI：
10.1093/jxb/erz429
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发表时间：
2020-01-01
影响因子：
6.9
通讯作者：
Wu, Guojiang
中科院分区：
文献类型：
--
作者：
Chen, Yaping;Xu, Shaoming;Wu, Guojiang
LAZY1家族基因在植物茎和根向地性中都起重要作用。在这里，我们报道了一个日本莲花突变体，在主根和侧根中表现出负向地性反应。基于图谱的克隆鉴定突变基因LAZY3是LAZY1基因的功能同源基因。LAZY3基因的突变减少了主根向根极性生长素运输（PAT），并且对PAT抑制剂n -1-萘酞酸不敏感。此外，增强的绿色荧光蛋白标记LAZY3在日本松茸中的免疫定位显示LAZY3在根柱细胞的质膜上的极性定位。因此，我们认为LAZY3在石柱细胞中的极性定位可能是枇杷根中PAT的必要条件。LAZY3转录本在重力刺激后数小时内在根尖呈现不对称分布，而LAZY3植物在组成启动子下过表达LAZY3则恢复了根系的向地性反应。这些数据表明，根系的倾斜性取决于LAZY3的存在，而不是取决于其在根尖上的不对称表达。在lazy3背景下，其他LAZY基因的表达并不能挽救根的生长方向，说明lazy3基因在枇杷根向地性中起着明显的作用。
LAZY1 family genes play important roles in both shoot and root gravitropism in plants. Here we report a Lotus japonicus mutant that displays negative gravitropic response in primary and lateral roots. Map-based cloning identified the mutant gene LAZY3 as a functional ortholog of the LAZY1 gene. Mutation of the LAZY3 gene reduced rootward polar auxin transport (PAT) in the primary root, which was also insensitive to the PAT inhibitor N-1-naphthylphthalamic acid. Moreover, immunolocalization of enhanced green fluorescent protein-tagged LAZY3 in L. japonicus exhibited polar localization of LAZY3 on the plasma membrane in root stele cells. We therefore suggest that the polar localization of LAZY3 in stele cells might be required for PAT in L. japonicus root. LAZY3 transcripts displayed asymmetric distribution at the root tip within hours of gravistimulation, while overexpression of LAZY3 under a constitutive promoter in lazy3 plants rescued the gravitropic response in roots. These data indicate that root gravitropism depends on the presence of LAZY3 but not on its asymmetric expression in root tips. Expression of other LAZY genes in a lazy3 background did not rescue the growth direction of roots, suggesting that the LAZY3 gene plays a distinct role in root gravitropism in L. japonicus.