LEAFY controls Arabidopsis pedicel length and orientation by affecting adaxial-abaxial cell fate
LEAFY controls Arabidopsis pedicel length and orientation by affecting adaxial-abaxial cell fate
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DOI：
10.1111/j.1365-313x.2011.04836.x
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发表时间：
2012-03-01
期刊：
影响因子：
7.2
通讯作者：
Komeda, Yoshibumi
中科院分区：
文献类型：
--
作者：
Yamaguchi, Nobutoshi;Yamaguchi, Ayako;Komeda, Yoshibumi
花梗长度和方向（角度）有助于花序结构的多样性，并且对于花的最佳定位是重要的。然而，对花梗的发育知之甚少。我们先前描述了拟南芥CORYMBOSA 1（CRM 1）/BIG基因，它通过控制花梗伸长和方向来影响花序结构。在这里，我们进行了一个抑制筛选使用部分功能丧失等位基因crm 1 -13，以确定影响花梗发育的基因和途径。我们确定了一个亚型等位基因的分生组织身份调节LEAFY（LFY）的抑制。与此相一致，crm 1椎弓根LFY水平升高，LFY功能的条件性增益产生向下弯曲的椎弓根。类固醇激活的35 S：LFY-GR植物引起的皮质细胞长度的减少在远轴域和额外的缺陷与近轴化。进一步分析LFY功能的丧失表明，LFY是减少花梗基部近轴侧皮质细胞伸长所必需的。条件性LFY功能获得性花梗的缺陷与短梗细胞（BP）表达减少相关，而BP转录抑制因子不对称叶2（AS 2）和近轴细胞命运启动子REVOLUTA在LFY功能获得性花梗中高度异位表达。LFY绑定到AS 2上游的顺式调节区域，并且as 2突变部分抑制了由LFY活性增加引起的花梗长度和方向缺陷。这些数据表明，LFY活性促进近轴细胞的命运，因此适当的方向和长度的花梗部分直接激活AS 2的表达，抑制BP的表达。
Pedicel length and orientation (angle) contribute to the diversity of inflorescence architecture, and are important for optimal positioning of the flowers. However, relatively little is known about pedicel development. We previously described the Arabidopsis CORYMBOSA1 (CRM1)/BIG gene, which affects inflorescence architecture by controlling pedicel elongation and orientation. Here, we performed a suppressor screen using the partial loss-of-function allele crm1-13 to identify genes and pathways that affect pedicel development. We identified a hypomorph allele of the meristem identity regulator LEAFY (LFY) as the suppressor. Consistent with this, crm1 pedicels had elevated LFY levels and conditional gain of LFY function produced downward-bending pedicels. Steroid activation of 35S:LFY-GR plants caused a reduction in the cortical cell length in the abaxial domain and additional defects associated with adaxialization. Further analyses of loss of LFY function revealed that LFY is required for reduced cortical cell elongation at the adaxial side of the pedicel base. Defects in conditional LFY gain-of-function pedicels were correlated with decreased BREVIPEDICELLUS (BP) expression, while ASYMMETRIC LEAVES2 (AS2), a transcriptional repressor of BP, and REVOLUTA, a promoter of adaxial cell fate, were highly and ectopically expressed in LFY gain-of-function pedicels. LFY bound to cis-regulatory regions upstream of AS2, and as2 mutations partially suppressed the pedicel length and orientation defects caused by increased LFY activity. These data suggest that LFY activity promotes adaxial cell fate and hence the proper orientation and length of the pedicel partly by directly activating AS2 expression, which suppresses BP expression.