Abstract
Secondary walls are synthesized only in cells of limited tissues such as stem, hypocotyl, anther and silique. In the course of systematic functional analysis of NAC transcription factors, we found that NST1, NST2 and NST3 (=SND1) transcription factors are key regulators for secondary wall synthesis. The nst1 nst2 double T-DNA tagged line showed indehiscent anther due to loss of secondary wall in anther endocecium, while nst1 nst3 double T-DNA tagged line could not stand erect and showed indehiscent silique due to complete loss of secondary walls in stem, hypocotyl and silique except in vascular vessels. On the contrary, ectopic expression of NSTs induced ectopic secondary wall synthesis in various above-ground organs. We concluded that NST transcription factors are master regulators of secondary wall synthesis in plants. However, factors functioning in downstream and upstream of NSTs are still obscure. We will discuss about this issue incorporating recent topics.
