Different evolutionary patterns among intronless genes in maize genome

Intronless genes, as a characteristic feature of prokaryotes, are an important resource for the study of the evolution of gene architecture in eukaryotes. In the study, 14,623 (36.87%) intronless genes in maize were identified and the percentage is greater than that of other monocots and algae. The number of maize intronless genes on each chromosome has a significant linear correlation with the number of total genes on the chromosome and the length of the chromosomes. Intronless genes in maize play important roles in translation and energy metabolism. Evolutionary analysis revealed that 2601 intronless genes conserved among the three domains of life and 2323 intronless genes that had no homology with genes of other species. These two sets of intronless genes were distinct in genetic features, physical locations and function. These results provided a useful source to understand the evolutionary patterns of related genes and genomes and some intronless genes are good candidates for subsequent functional analyses specifically.