A correlation of nuclear DNA content and thin-layer chromatographic patterns in resolving genome relationships in Avena

Abstract

Relative amounts of nuclear deoxyribonucleic acid (DNA) from telophase root tip nuclei and thin-layer chromatographic patterns of alcohol-soluble compounds from dry leaves were determined for seven diploids: Avena clauda, A. pilosa, A. ventricosa, A. strigosa, A. hirtula, A. wiestii, A. longiglumis; four tetraploids: A. barbata, A. magna, A. abyssinica, A. vaviloviana; and four hexaploids: A. sterilis, A. fatua, A. byzantina, and A. sativa, in order to elucidate species relationships. Variation in nuclear DNA content was correlated with differences in genomic constitution; a few exceptions are considered to reflect chromosomal polymorphism. The average DNA value of the hexaploid species approximated the sum of the DNA value for A. magna and the theoretical value of the B genome. Chromatographic patterns showed distinct variations between species but little correlation between number of compounds and DNA content. Chromatographic patterns of hexaploids showed close similarity with those of diploids and tetraploids, except species with modified C genomes (A. clauda, A. pilosa, A. ventricosa) and A. longiglumis. It is considered that A. clauda, A. pilosa, A. ventricosa, and A. longiglumis did not participate in the evolution of polyploid taxa. From their chromatographic profiles, A. wiestii, A. abyssinica, A. vaviloviana, and A. byzantina are very closely related. Both A. magna and the AABB tetraploid species appear to share two genomes in common with the hexaploids. Hence, the genomic constitutions AADD and AABBDD have been proposed for A. magna and the hexaploids, respectively. Six compounds from ethanol leaf extracts of A. sativa were identified as three apigenins, luteolin, ferulic acid, and p-coumaric acid.

Genome size variation in the genus Avena

“…Based on averages within the A and C genome diploids, the difference in size is approximately 15%. This difference was also observed by Iiyama and Grant (1972), although the large variation among A genomes reported by these authors made this difference less striking, and the average difference that they reported was closer to 10%. The apparent divergence between the A and C sub-genomes is supported by previous studies showing major cytogenetic differences between A and C genome chromosomes that are most likely due to differences in repetitive DNA content (Fominaya et al 1988;Linares et al 1992;Jellen et al 1993).…”

“…An alternate (or additional) explanation could be that the unknown B and D genomes are actually smaller than the observed A genomes. The hypothesis that the B genome is smaller than the A genome was put forward by Iiyama and Grant (1972) for this reason, although this was also in support of a proposed AABBDD genome constitution for the hexaploid, which has been subsequently rejected. Polyploid genome downsizing has been observed in most angiosperms, and it is assumed to be a general trend (Kellogg and Bennetzen 2004;Pellicer et al 2010a).…”

“…Genome size has been estimated in 16 species of Avena (Bullen and Rees 1972;Iiyama and Grant 1972;Bennett and Smith 1976;Crosby et al 2014) excluding three that are considered to be homotypic with others in the Kew database (Baum 1977). Most estimates in the Kew database were provided by Bennett and Smith (1976) who made additional estimates and attempted to calibrate these with prior estimates.…”

Studies on Argemone. II. Impact of polyploidy and hybridity on some plant metabolites.

“…3, 16 and 32 characterise the profiles of the hybrid taxon. These results are similar to those obtained by Alston and Turner (1962) in Baptisia, Iiyama and Grant (1972) in Avena, Murray and Williams (1973) in Briza media, and Kohli and Denford (1977) in Potentilla. Origin of new compounds through hybridity can be explained on the basis of new gene combinations leading to novel expression.…”