Abstract
During evolution, various processes such as duplication, divergence, recombination, and many other events leads to the evolution of new genes with novel functions. These evolutionary events, thus significantly impact the evolution of cellular, physiological, morphological, and other phenotypic trait of organisms. While evolving, eukaryotes have acquired large number of genes from the earlier prokaryotes. This work is focused upon identification of old “prokaryotic” proteins in Arabidopsis and Oryza sativa genome, further highlighting their possible role(s) in the two genomes. Our results suggest that with respect to their genome size, the fraction of old “prokaryotic” proteins is higher in Arabidopsis than in Oryza sativa. The large fractions of such proteins encoding genes were found to be localized in various endo-symbiotic organelles. The domain architecture of the old “prokaryotic” proteins revealed similar distribution in both Arabidopsis and Oryza sativa genomes showing their conserved evolution. In Oryza sativa, the old “prokaryotic” proteins were more involved in developmental processes, might be due to constant man-made selection pressure for better agronomic traits/productivity. While in Arabidopsis, these proteins were involved in metabolic functions. Overall, the analysis indicates the distinct pattern of evolution of old “prokaryotic” proteins in Arabidopsis and Oryza sativa.
Highlights
Evolution is a process that results in change in the frequency of alleles within a gene pool, across generations
In Oryza sativa, the minimum number of old “prokaryotic” protein encoding genes was observed on chromosome XI and XII (29%) while maximum number of these was observed on chromosome III and II (37 and 36%, respectively)
Our results showed that in Oryza sativa, old “prokaryotic” proteins were involved in metabolic and developmental process and abiotic and biotic stress response while in Arabidopsis large number of old “prokaryotic” proteins were involved in the metabolic processes
Summary
Evolution is a process that results in change in the frequency of alleles within a gene pool, across generations. It enables species to cope up with various environmental conditions, both abiotic and biotic (Helena and Sue Barnes, 1989) These phenotypic variations are the result of genome evolution which takes place through various processes such as mutations, transfer of genes and genomes between species, amplification and mobility of DNA, and amplification and homogenization of tandemly repeated DNA sequences. Genes which come from the unrelated genomes are considered as probable case of lateral gene transfer This is the most common mechanism for gene induction in prokaryotes, and has been reported in genomes of cellular organelles such as mitochondria, chloroplasts, and nucleus in eukaryotes (Roger, 1999). The evolution process in the eukaryotes occurs via loss of genes and appearance of new genes leading to the evolution of new proteins (Koonin et al, 2004; Miller and Ball, 2008)
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