Ha Chan Man, Jun Ji Hyung, Nam Hong Gil, Fletcher Jennifer C
Plant Gene Expression Center, US Department of Agriculture/University of California Berkeley, Albany, CA 94710, USA.
Plant Cell. 2007 Jun;19(6):1809-25. doi: 10.1105/tpc.107.051938. Epub 2007 Jun 29.
We report a novel function for BLADE-ON-PETIOLE1 (BOP1) and BOP2 in regulating Arabidopsis thaliana lateral organ cell fate and polarity, through the analysis of loss-of-function mutants and transgenic plants that ectopically express BOP1 or BOP2. 35S:BOP1 and 35S:BOP2 plants exhibit a very short and compact stature, hyponastic leaves, and downward-orienting siliques. We show that the LATERAL ORGAN BOUNDARIES (LOB) domain genes ASYMMETRIC LEAVES2 (AS2) and LOB are upregulated in 35S:BOP and downregulated in bop mutant plants. Ectopic expression of BOP1 or BOP2 also results in repression of class I knox gene expression. We further demonstrate a role for BOP1 and BOP2 in establishing the adaxial-abaxial polarity axis in the leaf petiole, where they regulate PHB and FIL expression and overlap in function with AS1 and AS2. Interestingly, during this study, we found that KANADI1 (KAN1) and KAN2 act to promote adaxial organ identity in addition to their well-known role in promoting abaxial organ identity. Our data indicate that BOP1 and BOP2 act in cells adjacent to the lateral organ boundary to repress genes that confer meristem cell fate and induce genes that promote lateral organ fate and polarity, thereby restricting the developmental potential of the organ-forming cells and facilitating their differentiation.
我们通过对功能缺失突变体以及异位表达BOP1或BOP2的转基因植物进行分析，报道了叶片柄上的叶片1（BOP1）和叶片柄上的叶片2（BOP2）在调节拟南芥侧生器官细胞命运和极性方面的新功能。35S:BOP1和35S:BOP2植株表现出非常矮小紧凑的株型、叶片上卷以及角果向下弯曲。我们发现，侧生器官边界（LOB）结构域基因不对称叶片2（AS2）和LOB在35S:BOP植株中上调，而在bop突变体植株中下调。BOP1或BOP2的异位表达也会导致I类knox基因表达受到抑制。我们进一步证明了BOP1和BOP2在叶片叶柄近轴-远轴极性轴建立中的作用，它们在其中调节PHB和FIL的表达，并且在功能上与AS1和AS2重叠。有趣的是，在这项研究中，我们发现KANADI1（KAN1）和KAN2除了在促进远轴器官特性方面的众所周知的作用外，还在促进近轴器官特性方面发挥作用。我们的数据表明，BOP1和BOP2在与侧生器官边界相邻的细胞中发挥作用，抑制赋予分生组织细胞命运的基因，并诱导促进侧生器官命运和极性的基因，从而限制器官形成细胞的发育潜能并促进其分化。
