Basu D, Dehesh K, Schneider-Poetsch H J, Harrington S E, McCouch S R, Quail P H
Department of Plant and Microbial Biology, University of California, Berkeley 94720, USA.
Plant Mol Biol. 2000 Sep;44(1):27-42. doi: 10.1023/a:1006488119301.
Although sequences representing members of the phytochrome (phy) family of photoreceptors have been reported in numerous species across the phylogenetic spectrum, relatively few phytochrome genes (PHY) have been fully characterized. Using rice, we have cloned and characterized the first PHYC gene from a monocot. Comparison of genomic and cDNA PHYC sequences shows that the rice PHYC gene contains three introns in the protein-coding region typical of most angiosperm PHY genes, in contrast to Arabidopsis PHYC, which lacks the third intron. Mapping of the transcription start site and 5'-untranslated region of the rice PHYC transcript indicates that it contains an unusually long, intronless, 5'-untranslated leader sequence of 715 bp. PHYC mRNA levels are relatively low compared to PHYA and PHYB mRNAs in rice seedlings, and are similar in dark- and light-treated seedlings, suggesting relatively low constitutive expression. Genomic mapping shows that the PHYA, PHYB, and PHYC genes are all located on chromosome 3 of rice, in synteny with these genes in linkage group C (sometimes referred to as linkage group A) of sorghum. Phylogenetic analysis indicates that rice phyC is closely related to sorghum phyC, but relatively strongly divergent from Arabidopsis phyC, the only full-length dicot phyC sequence available.
尽管在整个系统发育谱的众多物种中都已报道了代表光受体植物色素（phy）家族成员的序列，但相对较少的植物色素基因（PHY）已得到充分表征。我们利用水稻克隆并鉴定了单子叶植物中的首个PHYC基因。基因组和cDNA的PHYC序列比较表明，水稻PHYC基因在蛋白质编码区含有三个内含子，这是大多数被子植物PHY基因的典型特征，而拟南芥PHYC则缺少第三个内含子。水稻PHYC转录本转录起始位点和5'非翻译区的定位表明，它含有一个异常长的、无内含子的715 bp的5'非翻译前导序列。与水稻幼苗中的PHYA和PHYB mRNA相比，PHYC mRNA水平相对较低，并且在黑暗处理和光照处理的幼苗中相似，表明其组成型表达相对较低。基因组定位显示，PHYA、PHYB和PHYC基因均位于水稻的3号染色体上，与高粱C连锁群（有时称为A连锁群）中的这些基因同线。系统发育分析表明，水稻phyC与高粱phyC密切相关，但与拟南芥phyC（唯一可用的全长双子叶植物phyC序列）相对差异较大。
