Разнообразие количественных оценок содержания ДНК в ядрах растений, их разброс, некоторые термины и понятия (геном, C-value, пангеном)

Abstract

As confirmation of the huge diversity of DNA content in the nuclei of plant cells, the boundary values of minimum and maximum parameters such as the number of chromosomes, varying in plants per haploid genome from two chromosomes to 480 (or even up to 720) chromosomes, as well as the "weight" sizes of genomes in picograms in the form of 1C-value with a range from 0.065 to 152.23 pg per haploid set of chromosomes. The importance of knowledge of the amount of DNA and the number of chromosomes for the implementation of projects for sequencing complete yet unknown plant genomes was noted. Examples of sequenced complete genomes of plants with very different sizes (less than 100 million bp and more than 30 billion bp) are also given. Attention is paid to the need to give the century-old term "genome" a new meaning, according to which it should already mean the entire amount of DNA in all chromosomes, regardless of ploidy, but not a haploid set, as before, since only the totality of all DNA (all alleles, both homologous and homeologous chromosomes) determines the vital status of a plant, and of any other eukaryotic organism. Attention is drawn to the fact that the concept of a "complete genome" includes various levels of their completeness from contigs and other draft quasi-haploid genomes to the so-called T2T genomes, which represent established nucleotide sequences chromosomally from "telomere to telomere". The most complete information about the organism can be given by the diploid genome, which is determined by the so-called phased assembly by haplotypes. At the same time, for plants and especially for cultivars of agricultural plants, as the reference genome should serve a pangenome that carries maximum information about the differences in nucleotide sequences characteristic of the sample under study. The use of plant pangenomic data in breeding will mark the transition to a new level of such work. Perhaps in the future, when the mass sequencing of truly complete diploid genomes in the T2T format begins, a new term will be needed for them, which could become "digenome" or briefly “dinome”.