Molecular evolution of receptor-like kinase genes in hexaploid wheat. Independent evolution of orthologs after polyploidization and mechanisms of local rearrangements at paralogous loci1

• Published in: Plant physiology (Bethesda) Vol. 125; no. 3; pp. 1304 - 1313
• Main Authors: FEUILLET, Catherine, PENGER, Anja, GELLNER, Klaus, MAST, Austin, KELLER, Beat
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.03.2001
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Classical and quantitative genetics. Population genetics. Molecular genetics; Fundamental and applied biological sciences. Psychology; Generalities. Genetics. Plant material; Genes. Genome; Genetics and breeding of economic plants; Molecular and cellular biology; Molecular genetics; Monocotyledones; Polyploidy; Hexaploidy; Enzyme; Transferases; Phylogenetic tree; Interspecific comparison; Biological evolution; Cereal crop; Mechanism; Gramineae; Protein kinase; Angiospermae; Gene rearrangement; Spermatophyta; Molecular biology; Genome; Triticum aestivum; Biological receptor
• ISSN: 0032-0889; 1532-2548

Hexaploid wheat is a young polyploid species and represents a good model to study mechanisms of gene evolution after polyploidization. Recent studies at the scale of the whole genome have suggested rapid genomic changes after polyploidization but so far the rearrangements that have occurred in terms of gene content and organization have not been analyzed at the microlevel in wheat. Here, we have isolated members of a receptor kinase ( Lrk ) gene family in hexaploid and diploid wheat, Aegilops tauschii , and barley ( Hordeum vulgare ). Phylogenetic analysis has allowed us to establish evolutionary relationships (orthology versus paralogy) between the different members of this gene family in wheat as well as with Lrk genes from barley. It also demonstrated that the sequences of the homoeologous Lrk genes evolved independently after polyploidization. In addition, we found evidence for gene loss during the evolution of wheat and barley. Analysis of large genomic fragments isolated from nonorthologous Lrk loci showed a high conservation of the gene content and gene organization at these loci on the homoeologous group 1 chromosomes of wheat and barley. Finally, sequence comparison of two paralogous fragments of chromosome 1B showed a large number of local events (sequence duplications, deletions, and insertions), which reveal rearrangements and mechanisms for genome enlargement at the microlevel.