Adaxial-abaxial patterning: a novel function of the GABA shunt.

Adaxial-abaxial patterning in lateral organ development is important for proper tissue differentiation and the entire shape of the organs. Although many transcriptional regulators are known to be involved in adaxial-abaxial patterning, the molecular mechanisms of the initial step of adaxial-abaxial polarity formation are still unclear. To determine these mechanisms, we have been analyzing the abaxial-specific expression of FILAMENTOUS FLOWER (FIL), which encodes a putative transcription factor. Recently, we found that the enf1 mutant, which has a mutation in the succinicsemialdehyde (SSA)-degrading enzyme, reduces the robustness of FIL expression patterning and has abnormally shaped leaves. ( 1) Here, we show that the transcriptomic data of enf1 provide more information on the relationship between SSA and adaxial-abaxial patterning, and we discuss the novel metabolic pathways of SSA production and the potential that the enf1 mutant represents a new tool in research on adaxial-abaxial polarity formation.