366회 Expansins, Hairs, and Cell Patterning

366회

연사 :  조 형 택, 충남대학교 생물학과

제목:  Expansins, Hairs, and Cell Patterning

Abstract

 Two topics will be presented in today's talk. The first one is about the study on Arabidopsis expansins. The regulation of root hair-specific genes and hair cell patterning is the second topic.   Rigid cell walls are the limiting factor for a plant cell to increase its volume. Expansins are unique wall proteins capable of loosening the cell wall, where the mechanism includes non-destructive activities unlike hydrolytic enzymes such as cellulases. Thirty six expansin and expansin-related genes are found in Arabidopsis. The promoter-marker expression study showed that Arabidopsis expansins express in diverse tissue types, indicating their specified functions during plant development. The modulation of expansin expression also could alter the plant cell growth and organ morphogenesis. Two (AtEXP7 and AtEXP18) of these Arabidopsis expansin genes are expressed specifically in the root hair cell whose differentiation is known to depend on the position relative to underlying cortical cells. The root hair expansin genes start to express immediately before the hair bulges out, implying their role during hair initiation. Moreover, their expression pattern is consistent with the regulation of root hair formation by transcription factors determining the epidermal fate and also by environment/hormone factors. The cis-element, responsible for the root hair specificity and hormone inducibility of these root hair genes, was identified by promoter analyses. Yeast one-hybrid screening of the root cDNA library revealed a putative transcription factor that is able to bind the cis-element. As orthologous genes to AtEXP7 are seen in many different plants, a comparative study is under process to find the evolutionarily conserved regulatory pathway of these orthologous genes.