Subgenus Ceratotropis Research Articles

Two New Species, Sectional Designations and New Combinations in Vigna Subgenus Ceratotropis (Piper) Verdc. (Leguminosae, Phaseoleae)

Two new species of Vigna L. subgenus Ceratotropis (Piper) Verdc., V aridicola and V tenuicaulis are described and illustrated. These two species are endemic to Sri Lanka and mainland Southeast Asia, respectively. Sectional designation and new species combinations are proposed.

Japanese Native <i>Vigna</i> Genetic Resources

This paper provides new information on the distribution of Japanese native Vigna species in the subgenus Ceratotropis. The azuki bean complex (Vigna angularis) in Japan consists of cultigen, wild, weed and complex population types. Population genetic studies of this complex based on AFLP and RAPD analyses have revealed clinal variation in Japan. Population analyses have also provided support for hypotheses related to the origin of weedy azuki bean. The complex population type displays greater genetic variation than other population types in the azuki bean complex. Thus complex populations are the logical focus for both in situ and ex situ conservation. The wild and weedy Vigna species of Japan are a potential source of useful traits for agriculture and agriculturally related industries. Currently V. riukiuensis (V. minima subsp. minor var. minor) is being used as a bridging species to enable gene transfer among sexually incompatible Vigna cultigens. The potential of the genus Vigna to become a genetic model to enhance the understanding and genetic improvement of the tropical grain legume cultigen group is discussed.

Direct shoot regeneration from cotyledonary nodes as a marker for genomic groupings within the Asiatic Vigna (subgenus Ceratotropis {Piper} Verdc.) species

In vitro culture of cotyledonary node (cn)explants, decapitated and intact seedlings of four different AsiaticVigna species (germinated and subcultured in MS-B5 mediumwith 1.0 mg l−1 BA) resulted in axillaryshoot formation only from the epigeal V. radiata and thehypogeal but allotetraploid V. glabrescens. The hypogealspecies V. angularis and V. umbellatafailed to exhibit this response. Shoot decapitation invivopromoted similar response only in V. radiata, indicatingthat in vitro culture in BA-supplemented medium isrequiredby V. glabrescens to achieve the same response.Histological observations of the cn explants from 4-d-oldin-vitro-germinated seedlings at d 0(inoculation day), d 4 and d 8 (after inoculation) revealed the formation ofprimary axillary shoots (pas) in both V. radiata andV. glabrescens. Secondary axillary branching at the baseofthe pas was observed at 8 d. Further examination by scanningelectron microscope (SEM) confirmed the presence of shoot buds enveloped by atleast two leaf primordia in the explants at d 0 in all epigeal species namelyV. radiata, V. mungo and V.aconitifolia together with the hypogeal but allotetraploidV. glabrescens. Consistently, these structures were absentin V. angularis and V. umbellata.Present histological and SEM observations support the previous findings ofAvenido and Hattori (Plant Cell Tissue Organ Cult, 1999) that the induction ornon-induction of shoots directly from the nodes of invitro-cultured cn explants is a new marker corresponding to thegenomic grouping within the Asiatic Vigna species. Basedonhybridization studies, Dana (Breeding Methods for Improvement of Crops, 1980)designates AA, A1A1 and A1A1/- toall epigeal, hypogeal and the hypogeal but allotetraploid AsiaticVigna species, respectively. Moreover, these findingsproved that the differential in vitro regenerationresponse(i.e., response to BA) arises from inherent anatomical and developmentaldifferences, and is supportive of the genomic grouping within subgenusCeratotropis of the genus vigna.

Comparative molecular mapping in Ceratotropis species using an interspecific cross between azuki bean (Vigna angularis) and rice bean (V. umbellata)

A genetic linkage map was developed with 86 F2 plants derived from an interspecific cross between azuki bean (Vigna angularis, 2n=2x=22) and rice bean (V. umbellata, 2n=2x=22). In total, 14 linkage groups, each containing more than 4 markers, were constructed with one phenotypic, 114 RFLP and 74 RAPD markers. The total map size was 1702 cM, and the average distance between markers was 9.7 cM. The loci showing significant deviation from the expected ratio clustered in several linkage groups. Most of the skewed loci were due to the predominance of rice bean alleles. The azuki-rice bean linkage map was compared with other available maps of Vigna species in subgenus Ceratotropis. Based on the lineage of the common mapped markers, 7 and 16 conserved linkage blocks were found in the interspecific map of azuki bean ×V. nakashimae and mungbean map, respectively. Although the present map is not fully saturated, it may facilitate gene tagging, QTL mapping and further useful gene transfer for azuki bean breeding.

The effectiveness of evaluating wild species: searching for sources of resistance to bruchid beetles in the genus Vigna subgenus Ceratotropis

A species level germplasm collection representing 76% of known taxa in the genus Vigna subgenus Ceratotropis was evaluated for resistance to two species of bruchid beetles, Callosobruchus chinensis and C. maculatus. Seven taxa consisting of 29 accessions were found to be resistant to C. chinensis and 4 taxa consisting of 24 accessions were found to be resistant to C. maculatus. This compared with no resistant accessions being found in several hundred landrace accessions of mungbean, V. radiata var. radiata, in the same subgenus. Sometimes resistance was found in all accessions of a particular taxon, such as complete resistance to both C. chinensis and C. macualtus in V. umbellata. Other taxa showed intra taxon variation for resistance such as V. reflexo-pilosa andV. minima. The levels and patterns of resistance among taxa were diverse. The results suggest that various factors cause resistance to bruchid in the subgenus Ceratotropis. While the number of eggs laid on seeds generally reflected seed size, one small seeded cultivar of V. mungo var. mungo, black gram, had an unusually high number of eggs laid per seed. No correlation was found between seed size and levels of resistance. The species level germplasm collection, which reflects the core collection concept in trying to maximize genetic diversity in a limited number of accessions, has enabled a large number of potentially useful sources of resistance to bruchid beetles to be found efficiently.

Isoenzyme diversity and phylogenetic affinities among the African beans of the genus Vigna Savi (Fabaceae)

Electrophoretic variation of twelve enzymes encoded by 22 gene loci has been studied among 23 African and three Asian bean species of the genus Vigna by means of PAGE. Of the total of 190 electromorphs (putative allozymes), 118 were phylogenetically informative, i.e. shared by at least two species, and 72 were species-specific. Cladistic analysis of the allozyme data as unordered presence–absence characters revealed among the African Vigna species five major monophyletic groups. The species of the subgenus Haydonia appear on the cladogram as directly linked to the Asian outgroup species of the subgenus Ceratotropis, and basally paraphyletic to other African species which falled into two clades with two subclades. One major clade comprises species of the type section of type subgenus, with blue- and yellow-flowered species in separate subclades. The second major clade comprises species of the sections Reticulatae and Plectrotropis in one subclade, together with V. unguiculata of the section vs. subgenus Catiang as basally sister to them. The other subclade includes species of sections Macrodontae and Liebrechtsia of the type subgenus, together with V. kirkii of the subgenus Plectrotropis as basally sister to them. The allozyme-based phylogeny is largely congruent with the current delimitation of species into sections and subgenera by morphology, but with some important exceptions regarding the position of V. unguiculata, V. angivensis, V. kirkii and V. frutescens. Phenetic analysis with the UPGMA clustering revealed essentially the same major species groups and additionally provided information about the extent of genetic divergence between species.

Differences in shoot regeneration response from cotyledonary node explants in Asiatic Vigna species support genomic grouping within subgenus Ceratotropis (Piper) Verdc.

The efficiency of any plant regeneration system lies in part in its wide applicability to diverse genotypes. In Asiatic Vigna, cotyledon and cotyledonary node explants from 4-day-old seedlings of 27 genotypes were cultured in a medium consisting of MS salts, B5 vitamins, 3.0% sucrose and 1.0 mg l-1 BA. Direct and efficient multiple shoot regeneration (80–100%) from the cotyledonary nodes was obtained in all epigeal species namely radiata, mungo, aconitifolia, subspecies radiata var. sublobata, mungo var. silvestris and in the hypogeal but allotetraploid glabrescens. In contrast, two other hypogeal species V. angularis and V. umbellata failed to initiate shoots from the nodes. However, adventititious shoots developed at the basipetal cut (hypocotyl) in 35–67% of V. angularis explants. These results provide evidence in support of the existing genomic grouping within subgenus Ceratotropis, which designates AA, A1A1 and A1A1/- to epigeal, hypogeal and the allotetraploid species, respectively. Mean shoot production ranged from 3.3 to 10.4 shoots per explant during the first subculture and varied significantly among the responsive genotypes within 4 species. Additional shoots were obtained in all genotypes after subsequent subculture. However, cotyledons were not as regenerable as cotyledonary node explants. Although significant differences in rooting were observed among the shoots of the 15 genotypes, the response was generally higher in MS basal medium (MSO) than in MS with 1.0 mg l-1 IAA. Regenerated plants were successfully transferred to soil (50–100% survival rate) and all surviving plants were reproductively fertile.

Phylogenetic relationships of the subgenus Ceratotropis based on random amplified polymorphic DNA

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2020 Impact Factor: 0.515The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.

Species relationships in the subgenus Ceratotropis (genus Vigna) as revealed by RAPD analysis

The genetic variation among 23 accessions of 5 species in the subgenus Ceratotropis, genus Vigna, were investigated by random amplified polymorphic DNA (RAPD) analysis. A total of 404 fragments amplified with 24 primers were scored and analyzed by cluster analysis. The accessions used were separated into two main groups with an average of 70% differences. Within the main groups, five subgroups were recognized, which are in complete agreement with taxonomic species. Wild forms were always grouped with their most closely related cultivated forms and they showed variation in each species. The largest intraspecific variation was found in V. radiata (mungbean), in which wild forms (V. radiata var. sublobata) were highly different from each other and from cultivated forms. V. angularis (adzuki bean) showed the least variation and thus, was probably differentiated in relatively recent times.

Phylogenetic Analysis of the Subgenus Ceratotropis(genus Vigna) and an Assumption of the Progenitor of Azuki Bean Using Isozyme Variation.

In order to understand the phylogenetic relationships of azuki bean (Vigna angularis ) and its related species, isozyme variation of nine taxa belonging to the subgenus Ceratotropis (genus Vigna : Fabaceae) and two outgroup species (V. unguiculata. V. vexillata ) was evaluated us-ing twelve enzyme systems. Isozyme variation among accessions in each species was very low. An UPGMA phenogram indicated the occurrence of three distinct groups of species in the subgenus Ceratotropis. The first group consisted of three races of azuki bean. The second group consisted of V. nakashimae. V. minima var.

Molecular taxonomic relationships in the genus Vigna based on RFLP analysis

The taxonomy of the genus Vigna has been primarily based on morphological attributes. We have used 27 genomic clones from soybean, common bean, mungbean and cowpea to examine restriction fragment length polymorphism (RFLP) among 44 accessions of different species belonging to four subgenera of the genus Vigna. One accession each of common bean (Phaseolus vulgaris) and soybean (Glycine max) was included in the study. Total DNA from the various genotypes was digested with one restriction enzyme (Eco RV). Results of a numerical taxonomic analysis showed a high level of genetic variation within the genus with a remarkably higher amount of variation associated with Vigna sp. from Africa relative to those from Asia. The distinctness of the Asiatic grams in subgenus Ceratotropis, cowpea in section Catiang, bambara groundnut (V. subterranean) and members of the subgenus Plectotropis was elucidated by this study. Members of the subgenus Plectotropis were closer in genome homology to those of subgenus Vigna section Catiang than to those of subgenus Ceratotropis. The relative positions of some genotypes to one another on the dendrogram and minimum spanning tree were discussed in regard to hybridisations aimed generating well-saturated genomic maps and interspecies transfer of desirable genes.

Isoenzyme Variation in Asian Beans

AbstractElectrophoretic variation of isoenzyme characters encoded by 20 gene loci has been studied in 9 species of Asian beans, comprising subgenus Ceratotropis of the genus Vigna. Four species of hypogeal germination type, V. angularis, V. umbellata, V. dalzelliana and V. minima, are shown to form a distinct monophyletic group in the subgenus, sharing common electromorphs of two major isoenzymes of aspartate aminotransferase. V. glabrescens is confirmed to be an allotetraploid derivate of two diploids closely related to V. radiata and V. umbellata, but divergent from their contemporary accessions analyzed. V. trilobata is the most variable species of the subgenus in isoenzyme characters. It reveals intraspecific differentiation at several isoenzyme loci correlated with the seed morphology and geographical localization.

Anthocyanin pigmentation in seedlings of selected species of Phaseolus and Vigna (Fabaceae)

Seedlings of 31 taxa of Phaseolus and Vigna were grown in light (cool-white fluorescent, 600 lx) at 20 °C under a 16-h photoperiod. Anthocyanin pigmentation was present in all 9 taxa (6 species) of Phaseolus and in 22 taxa (12 species) of Vigna. Pigmentation appeared in less than 1 week and was usually intense in Phaseolus seedlings. Most Vigna seedlings required a longer period to develop a paler color. Malvidin was the major aglycone in five of the species of Phaseolus examined, whereas delphinidin and cyanidin were major aglycones in three species of Vigna. Anthocyanins were located in the subepidermal layer of the stem and hypocotyl of all taxa except two, P. vulgaris cv. Royalty and P. coccineus, both of which had pigment in the epidermal layer instead. Three Vigna species, V. longifolia (subgenus Lasiopron) and V. adenantha and V. caracalla (subgenus Sigmoidotropis), also had pigment in cortical cells. Anthocyanoplasts were evident only in members of the subgenus Ceratotropis. Numerical analysis of the anthocyanin data placed Vigna longifolia in association with members of Vigna subgenus Vigna, but the two species of Vigna subgenus Sigmoidotropis associated closely with members of the genus Phaseolus. It is concluded that several aspects of seedling anthocyanin pigmentation, when present, can provide additional data useful to the taxonomy of the Phaseolus–Vigna complex. Characters of interest include speed of the photoresponse, tissue site of pigmentation, chemical nature of the pigments, and presence or absence of anthocyanoplasts.

Evolution of Grain Legumes. III. Pulses in the Genus Vigna

SUMMARYThe genus Vigna includes seven species of pulse, two African and five Asian. While the Asian species are within the subgenus Ceratotropis, the two African species are in different sections of the subgenus Vigna, namely Catjang (V. unguiculata) and Vigna (V. subterranea). Limited gene flow is possible within subgenus Ceratotropis, but none has as yet been demonstrated between subgenera nor between sections within subgenus Vigna. Parallel evolutionary trends are apparent in all species, with considerable increase in seed and pod size. Erect bush forms have evolved in all cultigens except V. aconitifolia and V. subterranea. The former has not apparently changed much in vegetative form under domestication, while the geocarpy of the latter precludes erect growth. Future prospects for the Asiatic grams would be better if yield levels could be improved. The cowpea is likely to remain an important crop at present levels of performance although there is room for improvement. There seems little immediate prospect of expanded ground bean production under existing conditions.

Flavonoids of someVigna-plants in leguminosae

Flavonoids in five lines ofVigna mungo, fifteen lines ofV. radiata var.radiata and two lines ofV. radiata var.sublobata, which belong to the subgenus Ceratotropis, were examined. In hypocotyls, seed-coats and mature leaves of those plants, twelve kinds of flavonoid including three anthocyanins, two leucoanthocyanins, two glycoflavones and five flavonol glycosides were found, and their distribution pattern in twenty-two lines of the legumes is discussed. The leaves ofV. radiata var.radiata and var.sublobata contained the glycosides (mainly rutin) of both quercetin and kaempferol, while those ofV. mungo contained only kaempferol glycosides, with robinin as the predominant pigment, and the purple-red hypocotyls of the former group contained delphinidin 3-p-coumaroylglucoside, while those of the latter contained cyanidin 3-glucoside, although delphinidin 3-glucoside was commonly found in all of the plants. With the exception of two lines, all of the seed-coats examined contained in common four compounds of vitexin, isovitexin, leucocyanidin and leucodelphinidin, whereas in addition to these pigments the black seed-coats ofV. mungo andV. radiata var.sublobata TC 1965 contained delphindin 3-glucoside.