Comparative molecular cytogenetic characterization of five wild Vigna species (Fabaceae)

Abstract

To extend our knowledge on karyotype variation of the genus Vigna Savi, 1824, the chromosomal organization of rRNA genes and fluorochrome banding patterns of five wild Vigna species were studied. Sequential combined PI (propidium iodide) and DAPI (4',6-diamidino-2-phenylindole) (CPD) staining and fluorescence in situ hybridization (FISH) with 5S and 45S rDNA probes were used to analyze the karyotypes of V. luteola (Jacquin, 1771) Bentham, 1959, V. vexillata (Linnaeus, 1753) A. Richard, 1845, V. minima (Roxburgh, 1832) Ohwi & H. Ohashi, 1969, V. trilobata (Linnaeus, 1753) Verdcourt, 1968, and V. caracalla (Linnaeus, 1753) Verdcourt,1970. For further phylogenetic analysis, genomic in situ hybridization (GISH) with the genomic DNA of V. umbellata (Thunberg, 1794) Ohwi & H.Ohashi, 1969 onto the chromosomes of five wild Vigna species was also performed. Detailed karyotypes were established for the first time using chromosome measurements, fluorochrome bands, and rDNA-FISH signals. All species had chromosome number 2n = 2x = 22, and symmetrical karyotypes that composed of only metacentric or metacentric and submetacentric chromosomes. CPD staining revealed all 45S rDNA sites in the five species analyzed, (peri)centromeric GC-rich heterochromatin in V. luteola, V. trilobata and V. caracalla, interstitial GC-rich and pericentromeric AT-rich heterochromatin in V. caracalla. rDNA-FISH revealed two 5S loci in V. caracalla and one 5S locus in the other four species; one 45S locus in V. luteola and V. caracalla, two 45S loci in V. vexillata and V. trilobata, and five 45S loci in V. minima. The karyotypes of the studied species could be clearly distinguished by the karyotypic parameters, and the patterns of the fluorochrome bands and the rDNA sites, which revealed high interspecific variation among the five species. The V. umbellata genomic DNA probe produced weak signals in all proximal regions of V. luteola and all (peri)centromeric regions of V. trilobata. The combined data demonstrate that distinct genome differentiation has occurred among the five species during evolution. The phylogenetic relationships between the five wild species and related cultivated species of Vigna are discussed based on our present and previous molecular cytogenetic data.

Analysis of CMA-DAPI bands and preparation of fluorescent karyotypes in thirty Indian cultivars of Lens culinaris

“…Nonetheless, occurrence of centromeric CMA + or DAPI + bands along with nucleolar CMA + /DAPI + or CMA 0 bands certainly advocate atypical heterochromatin composition in Lens. The non-uniform composition and rearrangements of heterochromatin had been observed repeatedly in Pailionoideae species (Moscone et al 1999;Souza and Benko-Iseppon 2004;Pedrosa-Harand et al 2006;Mondin and Aguiar-Perecin 2011;She et al 2020), which becomes apparent in our study once again.…”

“…However, we found that the intensity of the nucleolar CMA signals (type A) varies in certain cultivars, suggesting differences in NORs that influence affinity towards the stain. Intraspecific rDNA variation has been thoroughly worked out in Phaseolus (Moscone et al 1999;Pedrosa-Harand et al 2006) and Vigna (Bortoleti et al 2012;She et al , 2020 of Papilionoideae. A number of factors such as transposition, unequal crossing over, inversion or locus duplication, had been suggested to drive NOR variation in plant groups, including Papilionoideae (Moscone et al 1999;Chung et al 2008;Raskina et al 2008).…”

“…However, in case of L. culinaris and related species, AT heterochromatic regions were mapped by repetitive sequence probe FISH (Galasso et al 2001;Galasso 2003). Also in Papilionoideae, AT rich heterochromatin at centromere and pericentromeric regions are reported in Vigna (Bortoleti et al 2012;She et al 2020), Lablab and Arachis (Silvestri et al 2020). Nonetheless, occurrence of centromeric CMA + or DAPI + bands along with nucleolar CMA + /DAPI + or CMA 0 bands certainly advocate atypical heterochromatin composition in Lens.…”

Karyotype analysis of three species of Allium (Amaryllidaceae) from Thailand

“…Such discrepancies in karyotype formula were probably due to differences in analyzed materials and mitotic stages used, and difficulty in identifying chromosomes using the classical staining technique before (She et al 2015a(She et al , 2015b(She et al , 2017(She et al , 2020. This observed difference could mainly be related to variation in the chromosome condensation levels of measured cells (She et al 2015a(She et al , 2020.…”

“…Such discrepancies in karyotype formula were probably due to differences in analyzed materials and mitotic stages used, and difficulty in identifying chromosomes using the classical staining technique before (She et al 2015a(She et al , 2015b(She et al , 2017(She et al , 2020. This observed difference could mainly be related to variation in the chromosome condensation levels of measured cells (She et al 2015a(She et al , 2020. Therefore, differences in the chromosome structures due to the variation in morphology of Allium species, such as variation in cloves of both variations garlic, in size and color of both variation onion (Table 1) and because of the effects of environmental factors such as water, air, soil and maybe nutrients (Saensouk and Saensouk 2021a, b).…”