Molecular cytogenetic characterization of common bean (Phaseolusvulgaris L.) accessions

Abstract

With an annual global production of approximately 25 million tons, the common bean (Phaseolus vulgaris L), a member of the genus Phaseolus, is one of the major protein sources used as food for humans. In this study, it was aimed to investigate the genome size of the common bean genetic resource collection (154 common bean accessions) in Turkey by flow cytometry (FCM) and determine whether geographical variables affected the genome size. In addition, the number and distribution of 5S and 45S ribosomal DNA loci were designated by performing a fluorescence in situ hybridization (FISH) analysis in some of the accessions. The FCM analyses revealed that the mean nuclear DNA content of the accessions varied from 1.28 pg2C-1 to 1.55 pg2C-1 (mean 1.35 pg2C-1), and the differences between these accessions were statistically significant (P < 0.01). Intraspecific variation in the genome size was determined, and a positive correlation was found between the altitude and genome size. However, latitude and longitude did not have any statistically significant effect on the genome size. In the principal coordinate analysis, the accessions were divided into 3groups. Based on the results of the FISH analysis performed on 5 different accessions with varying genome sizes, using 5S and 45S rDNA genes as probes, the number of 5S rDNA loci was 4 in the common bean and stable among the common bean accessions, while the number of 45S rDNA loci was highly polymorphic, varying between 6 and 16. Consequently, it was determined in the present study that the genetic resource collection of common bean had a wide variation in terms of genome size and genome organization.

Analysis of Nuclear DNA Content and Karyotype of Phaseolus vulgaris L.

“…The chromosome number in all genotypes was 2n = 2x = 22, confirming several previous results [17,[19][20][21][22][23][24][27][28][29][30]. The MTCL (Mean Total Chromosome Length) recorded in the studied genotypes varied from 15.65 ± 0.99 to 34.24 ± 0.35 micrometers (Table 2), which is almost similar to the previous study on nine genotypes of the common bean, who's MTCL was measured to be between 13.74 and 29.50 micrometers [24].…”

“…The results obtained from the current study area similar to some of these results and different from others. This may be due to the use of different methods, internal standards, and accessions or technical problems [42]; in many cases, these changes are related to different geographical and climatic conditions [29].…”

“…Many classical and molecular cytogenetic studies have been performed on this plant, but since these characteristics are variable under the influence of geographical and ecological factors [15,16], it seems necessary to study the characteristics of the nuclear and chromosomal genomes separately in each region. Several cytogenetic studies have been conducted to investigate the chromosomal structure of the common bean, which include chromosome analysis and cytogenetic maps [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Genome size information is an important issue in ploidy analysis, genome analysis, taxonomy, evolution, and breeding studies [31][32][33][34][35].…”

Phaseolus vulgaris mutants reveal variation in the nuclear genome

“…The study to determine whether geographical variables affected the genome size showed that the cultivars with high DNA content are better adapted to cold or temperate regions, while those with a lower DNA content are well adapted to hot, dry environments. Most of P. vulgaris cultivars were characterized by the mean nuclear DNA content 2C from 1.28 to 1.55 pg2C -1 , and the mean for species was calculated as 1.35 pg2C -1 ( Savas Tuna et al., 2020 ). Castagnaro et al.…”

“…Different techniques, internal standards, and accessions can account for the differences reported in genome size. The geographical location and distance may also be influential factors ( Wang et al., 2013 ; Savas Tuna et al., 2020 ).…”