Genetic mechanisms of progressive evolution and speciation in plants: Gene multiplication as a way of an adequate response of the genome to the action of environmental factors

Abstract

One of the mechanisms related to the progressive evolution of plants probably is gene duplications. Paralogous and orthologous gene copies can appear in the genome either as a result of whole genome duplication (WGD), or after segmental or tandem duplications. The proportion of duplicated genes among the protein-coding genes in plant genomes is high (64 % on average), but it is several times less than would be expected if all genes duplicated during WGD were preserved - all plant genomes in that or otherwise lost some of the duplicated genes and transposons. Due to the need to respect the gene dose, for duplicated genes resulting from WGD, the rule applies: genes whose products work as part of multiprotein complexes are preserved, genes following the rule “one gene - one enzyme” prefer a monogenic existence. On the contrary, if duplicated copies of genes appeared in the genome as a result of tandem or segmental duplication, then in the first place, for the same reason, “extra” copies of the genes of the components of heteromeric complexes are lost. The role of tandem duplications in plant evolution, apparently, consists primarily in the fact that they correct the results of the distribution of alleles that remains in the genome of a polyploid or diploid as a result of processes of secondary diploidization and fractionation of neopolyploid genomes, stochastic changes in the set of alleles in comparison with stabilized (passed a long selection).