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Ancestry of KNOX genes revealed by bryophyte ( Physcomitrella patens ) homologs
Author(s) -
Champagne Connie E. M.,
Ashton Neil W.
Publication year - 2001
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2001.00076.x
Subject(s) - physcomitrella patens , biology , gene , bryophyte , genetics , phylogenetic tree , gene duplication , bryopsida , plant evolution , homology (biology) , homeobox , gene family , genome , botany , gene expression , mutant
Summary• Structural and phylogenetic studies of KNOXgenes identified in the bryophytePhyscomitrella patensare reported here, to provide insights into the evolution of class 1 and class 2KNOX genes. • Three KNOTTED1‐like homeobox (KNOX) genomic clones were isolated and sequenced fromP. patens . Corresponding cDNAs from a library, prepared from mRNA transcripts isolated from gametophytic tissues, were also sequenced. • Conceptual translation and analysis of the bryophyte coding sequences revealed a domain pattern and secondary structures typical of higher plant KNOX proteins. Intron number and positions within the genes were also highly conserved between moss and angiosperm loci, providing further support for their homology. Structural and phylogenetic analyses indicated that moss clones ( MKN2andMKN4) represent class 1KNOXgenes and the remaining clone (MKN1–3) is a class 2KNOX gene. • We conclude that the observed protein domain pattern is encoded by homeobox genes that evolved after separation of the plant lineage from that of fungi and animals, and must have been present in the common ancestor to mosses and seed plants. It is proposed that gene duplication and diversification, which created class 1 and 2 KNOXgene subfamilies, occurred after separation of this common ancestor from its algal progenitor (since a characterized algalKNOX gene cannot be assigned to class 1 or 2), but before the moss and higher plant lineages diverged.