Mathews S, Sharrock R A
Department of Biology, Montana State University, USA.
Mol Biol Evol. 1996 Oct;13(8):1141-50. doi: 10.1093/oxfordjournals.molbev.a025677.
The phytochrome nuclear gene family encodes photoreceptor proteins that mediate developmental responses to red and far red light throughout the life of the plant. From studies of the dicot flowering plant Arabidopsis, the family has been modeled as comprising five loci, PHYA-PHYE. However, it has been shown recently that the Arabidopsis model may not completely represent some flowering plant groups because additional PHY loci related to PHYA and PHYB of Arabidopsis apparently have evolved independently several times in dicots, and monocot flowering plants may lack orthologs of PHYD and PHYE of Arabidopsis. Nonetheless, the phytochrome nucleotide data were informative in a study of organismal evolution because the loci occur as single copy sequences and appear to be evolving independently. We have continued our investigation of the phytochrome gene family in flowering plants by sampling extensively in the grass family. The phytochrome nuclear DNA data were cladistically analyzed to address the following questions: (1) Are the data consistent with a pattern of differential distribution of phytochrome genes among monocots and higher dicots, with homologs of PHYA, B, C, D, and E present in higher dicots, but of just PHYA, B, and C in monocots, and (2) what phylogenetic pattern within Poaceae do they reveal? Results of these analyses, and of Southern blot experiments, are consistent with the observation that the phytochrome gene family in grasses comprises the same subset of loci detected in other monocots. Furthermore, for studies of organismal phylogeny in the grass family, the data are shown to provide significant support for relationships that are just weakly resolved by other data sets.
光敏色素核基因家族编码光受体蛋白，这些蛋白在植物的整个生命周期中介导对红光和远红光的发育反应。通过对双子叶开花植物拟南芥的研究，该家族被建模为包含五个基因座，即PHYA - PHYE。然而，最近的研究表明，拟南芥模型可能无法完全代表某些开花植物类群，因为与拟南芥的PHYA和PHYB相关的额外PHY基因座在双子叶植物中显然已经独立进化了几次，而且单子叶开花植物可能缺乏拟南芥PHYD和PHYE的直系同源基因。尽管如此，光敏色素核苷酸数据在一项生物进化研究中提供了有用信息，因为这些基因座以单拷贝序列形式存在，并且似乎是独立进化的。我们通过在禾本科中广泛取样，继续对开花植物中的光敏色素基因家族进行研究。对光敏色素核DNA数据进行了分支分析，以解决以下问题：（1）这些数据是否与单子叶植物和高级双子叶植物之间光敏色素基因的差异分布模式一致，即高级双子叶植物中存在PHYA、B、C、D和E的同源物，而单子叶植物中仅存在PHYA、B和C的同源物；（2）它们在禾本科中揭示了什么样的系统发育模式？这些分析以及Southern杂交实验的结果与以下观察结果一致，即禾本科中的光敏色素基因家族包含在其他单子叶植物中检测到的相同基因座子集。此外，对于禾本科生物系统发育的研究，这些数据被证明为其他数据集解析得很弱的关系提供了重要支持。
