Imlay Eleanor E, Jeon Hyung-Woo, Byrne Mary E
School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
J Exp Bot. 2025 Sep 17;76(14):4014-4026. doi: 10.1093/jxb/eraf174.
Arabidopsis thaliana has simple spatulate to obovate shaped leaves, with subtle serrations along the margin. The BEL1-like homeodomain transcription factors (BLH) SAWTOOTH1 and SAWTOOTH2, and the class II KNOTTED1-like homeobox (KNOXII) KNAT3 are suppressors of serration outgrowths. Double saw1 saw2 mutants have enhanced serrations and knat3 single mutants have a subtle increase in serrations relative to the wild type. However, the relationship between these homeodomain proteins is unclear. Here we show that SAW1, SAW2, and KNAT3 have overlapping expression patterns on the adaxial side of the leaf and saw1 saw2 knat3 triple mutants show greatly enhanced leaf serration relative to the saw1 saw2 double mutant and knat3 single mutant. KNAT3 expressed in the adaxial leaf from the endogenous promoter suppresses the saw1 saw2 knat3 phenotype, whereas ectopic expression throughout the leaf or in the abaxial domain enhances the triple mutant serration phenotype. This ectopic KNAT3 activity can be modified by ectopic expression of SAW1. These results demonstrate that the adaxial-abaxial domain specificity of BLH and KNOXII homeodomain proteins has consequences for serration geometry.
拟南芥具有简单的匙形至倒卵形叶片，叶缘有细微锯齿。BEL1类同源异型域转录因子（BLH）锯齿1（SAWTOOTH1）和锯齿2（SAWTOOTH2）以及II类类KNOTTED1同源异型框（KNOXII）KNAT3是锯齿生长的抑制因子。saw1 saw2双突变体的锯齿增强，而knat3单突变体相对于野生型的锯齿有细微增加。然而，这些同源异型域蛋白之间的关系尚不清楚。在这里，我们表明SAW1、SAW2和KNAT3在叶片近轴侧具有重叠的表达模式，并且saw1 saw2 knat3三突变体相对于saw1 saw2双突变体和knat3单突变体表现出大大增强的叶片锯齿。从内源性启动子在叶片近轴侧表达的KNAT3抑制saw1 saw2 knat3表型，而在整个叶片或远轴域中的异位表达增强了三突变体的锯齿表型。这种异位的KNAT3活性可以通过SAW1的异位表达来改变。这些结果表明，BLH和KNOXII同源异型域蛋白的近轴-远轴域特异性对锯齿形态有影响。
