ARS | Publication request: GC COMPOSITION AND CODON USAGE IN GENES OF INBREEDING AND OUTCROSSING TRITICEAE SPECIES

Submitted to: Wheat Genetics International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2003
Publication Date: September 1, 2003
Citation: Akhunov, E.D., David, J.L., Chao, S., Lazo, G.R., Anderson, O.D., Qi, L., Echalier, B., Gill, B.S., Linkiewicz, A.M., Dubcovsky, J., Miftahudin, Gustafson, J.P., La Rota, M., Sorrells, M.E., Zhang, D., Nguyen, H.T., Hossain, K., Kianian, S.F., Peng, J., Lapitan, N.V., Sidhu, D., Gill, K.S., Mcguire, P.E., Qualset, C.O., Dvorak, J. 2003. Gc composition and codon usage in genes of inbreeding and outcrossing triticeae species. In: Proceedings of International Wheat Genetics Symposium, September 1-6, 2003, Paestum, Italy. p. 203-206.

Technical Abstract: Wheat chromosomes are characterized by a steep gradient of recombination rate along chromosome arms. The mating system of Triticeae species varies from outcrossing to almost complete selfing. A relevant question is how these two important factors affect the gene composition. Wheat contigs were analyzed to assess how codon usage was related to coding sequence length, level of gene expression, recombination rate in gene vicinity, and mating system. In Triticum aestivum, codon usage was positively correlated with recombination rate and gene expression level and negatively correlated with length of coding sequence. Codons in genes with biased codon usage were more GC-rich in silent position than codons in genes with non-biased codon usage. A mutation bias towards GC was suspected in high recombination regions. Genes in the inbreeding T. monococcum use codons with lower GC content than genes in two outcrossing species, Aegilops speltoides and Secale cereale. A GC gradient has been observed from the 5' end towards the 3' end along the coding sequences. This gradient was steeper in the outcrossing species than in the inbreeding species. These findings suggest that variation in the strength of direct and indirect selection impact the composition of genes across chromosomes and among Triticeae species differing in mating systems.