Yamawaki Saori, Yamashino Takafumi, Nakanishi Hanayo, Mizuno Takeshi
School of Agriculture, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.
Biosci Biotechnol Biochem. 2011;75(8):1533-9. doi: 10.1271/bbb.110219. Epub 2011 Aug 7.
The developmental programs of Physcomitrella patens, a basal lineage of land plants, are regulated by phytohormones and light-signaling responses. In this study, our attention was focused on the HY5-family of transcription factors, which are known to play important roles immediately downstream of photoreceptors during the early photomorphogenesis of Arabidopsis thaliana. We retrieved two HY5-homologs, named PpHY5a and PpHY5b, from the whole genome sequence database of P. patens. Arabidopsis transgenic plants overproducing the basic leucine zipper (bZIP) domain of PpHY5a exhibited a phenotype of short hypocotyls, suggesting a functional relationship between PpHY5 and Arabidopsis HY5. A loss-of-function Δhy5a Δhy5b double mutant was defective in the vigorous protrusion of caulonema cells from the protonema networks of P. patens under light and dark conditions. These results suggest that the function of HY5-homologs in P. patens is evolutionarily conserved, and is implicated in a process of caulonema development.
小立碗藓是陆地植物的一个基部谱系，其发育程序受植物激素和光信号反应调控。在本研究中，我们将注意力集中在转录因子HY5家族上，已知该家族在拟南芥早期光形态建成过程中，在光感受器的直接下游发挥重要作用。我们从小立碗藓的全基因组序列数据库中检索到两个HY5同源物，命名为PpHY5a和PpHY5b。过量表达PpHY5a碱性亮氨酸拉链（bZIP）结构域的拟南芥转基因植物表现出下胚轴短的表型，这表明PpHY5与拟南芥HY5之间存在功能关系。功能缺失的Δhy5a Δhy5b双突变体在光照和黑暗条件下，从藓类原丝体网络中伸出的茎丝细胞强烈突出方面存在缺陷。这些结果表明，小立碗藓中HY5同源物的功能在进化上是保守的，并且与茎丝发育过程有关。
