Cagliari Alexandro, Turchetto-Zolet Andreia Carina, Korbes Ana Paula, Maraschin Felipe Dos Santos, Margis Rogerio, Margis-Pinheiro Marcia
Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul, Brazil; Universidade Estadual do Rio Grande do Sul, Santa Cruz do Sul, Brazil.
Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
Genomics. 2014 May-Jun;103(5-6):380-7. doi: 10.1016/j.ygeno.2014.03.005. Epub 2014 Apr 2.
NF-Y is a conserved oligomeric transcription factor found in all eukaryotes. In plants, this regulator evolved with a broad diversification of the genes coding for its three subunits (NF-YA, NF-YB and NF-YC). The NF-YB members can be divided into Leafy Cotyledon1 (LEC1) and non-LEC1 types. Here we presented a comparative genomic study using phylogenetic analyses to validate an evolutionary model for the origin of LEC-type genes in plants and their emergence from non-LEC1-type genes. We identified LEC1-type members in all vascular plant genomes, but not in amoebozoa, algae, fungi, metazoa and non-vascular plant representatives, which present exclusively non-LEC1-type genes as constituents of their NF-YB subunits. The non-synonymous to synonymous nucleotide substitution rates (Ka/Ks) between LEC1 and non-LEC1-type genes indicate the presence of positive selection acting on LEC1-type members to the fixation of LEC1-specific amino acid residues. The phylogenetic analyses demonstrated that plant LEC1-type genes are evolutionary divergent from the non-LEC1-type genes of plants, fungi, amoebozoa, algae and animals. Our results point to a scenario in which LEC1-type genes have originated in vascular plants after gene expansion in plants. We suggest that processes of neofunctionalization and/or subfunctionalization were responsible for the emergence of a versatile role for LEC1-type genes in vascular plants, especially in seed plants. LEC1-type genes besides being phylogenetic divergent also present different expression profile when compared with non-LEC1-type genes. Altogether, our data provide new insights about the LEC1 and non-LEC1 evolutionary relationship during the vascular plant evolution.
核因子Y（NF-Y）是一种在所有真核生物中都存在的保守寡聚转录因子。在植物中，这种调节因子随着编码其三个亚基（NF-YA、NF-YB和NF-YC）的基因广泛多样化而进化。NF-YB成员可分为叶状子叶1（LEC1）型和非LEC1型。在此，我们进行了一项比较基因组研究，利用系统发育分析来验证植物中LEC型基因起源及其从非LEC1型基因中出现的进化模型。我们在所有维管植物基因组中鉴定出了LEC1型成员，但在变形虫、藻类、真菌、后生动物和非维管植物代表中未发现，这些生物仅呈现非LEC1型基因作为其NF-YB亚基的组成部分。LEC1和非LEC1型基因之间的非同义与同义核苷酸替换率（Ka/Ks）表明存在正选择作用于LEC1型成员，以固定LEC1特异性氨基酸残基。系统发育分析表明，植物LEC1型基因在进化上与植物、真菌、变形虫、藻类和动物的非LEC1型基因不同。我们的结果表明，LEC1型基因在植物基因扩增后起源于维管植物。我们认为，新功能化和/或亚功能化过程导致了LEC1型基因在维管植物，尤其是种子植物中发挥多种作用。与非LEC1型基因相比，LEC1型基因除了在系统发育上有差异外，还具有不同的表达谱。总之，我们的数据为维管植物进化过程中LEC1和非LEC1的进化关系提供了新的见解。
