Breeding in bambara groundnut (Vigna subterranea (L.) Verdc): strategic considerations

Bambara groundnut (Vigna subterranea (L.) Verdc.) has a large number of landraces throughout Africa where small-scale farmers have preserved its genetic diversity on-farm. To date, the full genetic diversity of the crop remains largely unexploited. Until recently bambara groundnut never received any appreciable research effort, especially for its genetic improvement. Until then, only selection breeding was practised in which existing landraces were evaluated and their seeds multiplied. However, no new combinations resulting from hybridisation had ever been produced. Recently, collaborative research efforts involving partners from Africa and Europe have produced the first crosses of bambara groundnut. The creation of these crosses is a significant scientific and practical achievement and opens up the possibility of breeding true varieties of this crop. This paper shows how different strategies have been combined to establish the basis of a strategic breeding programme in bambara groundnut. The paper also illustrates the use of landraces in the bambara groundnut breeding programme, as an example of the contribution that landraces can make to increasing productivity in marginal environments and the conservation of a crop’s genetic resources on-farm

Genetic diversity in bambara groundnut (Vigna subterranea (L.) verdc.) as revealed by phenotypic descriptors and DArT marker analysis

Genetic diversity of a Bambara groundnut germplasm representing accessions from 25 African countries, maintained at the International Institute of Tropical Agriculture (IITA; Nigeria) was evaluated based on seed patterns, qualitative characters, quantitative traits and Diversity Arrays Technique (DArT) markers. The study aimed at identifying important descriptors for germplasm conservation, validating the crop’s geographical centre of origin and facilitating the utilization of existing genetic resources. Frequencies and diversity indices of seven types of seed patterns, 12 qualitative and 28 quantitative traits were evaluated for 124 representative accessions and were analyzed by region to elucidate the geographic distribution of descriptor states. In addition, individual plant samples from a subset of 40 landrace accessions were analyzed by assessing 554 DArT markers. Both the phenetic tree constructed from the qualitative and quantitative descriptors and the population structure derived from DArT marker analysis suggested a relatively high genetic diversity among accessions. Higher genetic diversity was observed for the Cameroon/Nigeria region relative to other regions, in agreement with the hypothesis that this region is the centre of origin for Bambara groundnut. Use of an extensive and diverse range of germplasm and an approach that integrated morphological and quantitative descriptors with DNA markers that represent wide genomic coverage offered a powerful way to make inferences about crop germplasm, in support of crop-improvement programs

Homozygosity mapping and targeted sanger sequencing reveal genetic defects underlying inherited retinal disease in families from pakistan

Contains fulltext : 152997.PDF (publisher's version ) (Open Access)BACKGROUND: Homozygosity mapping has facilitated the identification of the genetic causes underlying inherited diseases, particularly in consanguineous families with multiple affected individuals. This knowledge has also resulted in a mutation dataset that can be used in a cost and time effective manner to screen frequent population-specific genetic variations associated with diseases such as inherited retinal disease (IRD). METHODS: We genetically screened 13 families from a cohort of 81 Pakistani IRD families diagnosed with Leber congenital amaurosis (LCA), retinitis pigmentosa (RP), congenital stationary night blindness (CSNB), or cone dystrophy (CD). We employed genome-wide single nucleotide polymorphism (SNP) array analysis to identify homozygous regions shared by affected individuals and performed Sanger sequencing of IRD-associated genes located in the sizeable homozygous regions. In addition, based on population specific mutation data we performed targeted Sanger sequencing (TSS) of frequent variants in AIPL1, CEP290, CRB1, GUCY2D, LCA5, RPGRIP1 and TULP1, in probands from 28 LCA families. RESULTS: Homozygosity mapping and Sanger sequencing of IRD-associated genes revealed the underlying mutations in 10 families. TSS revealed causative variants in three families. In these 13 families four novel mutations were identified in CNGA1, CNGB1, GUCY2D, and RPGRIP1. CONCLUSIONS: Homozygosity mapping and TSS revealed the underlying genetic cause in 13 IRD families, which is useful for genetic counseling as well as therapeutic interventions that are likely to become available in the near future

Desenvolvimento foliar das culturas da soja e do feijão e de plantas daninhas Leaf development of soybean and bean crops and weeds

Objetivou-se, neste trabalho, comparar a taxa de emissão e expansão das folhas, duração da área foliar (DAF) e o coeficiente de extinção (k) para as culturas da soja e do feijão e para as espécies de plantas daninhas Euphorbia heterophylla sensível e Euphorbia heterophylla resistente aos herbicidas inibidores da enzima ALS, Bidens pilosa e Desmodium tortuosum. O experimento foi desenvolvido a campo, em um Argissolo Vermelho-Amarelo, no período de outubro de 2000 a março de 2001. Cada espécie vegetal constou de um tratamento. O delineamento experimental utilizado foi o de blocos ao acaso com quatro repetições. As medições da radiação fotossinteticamente ativa (RFA) foram realizadas em dois pontos dos dosséis: acima e abaixo, por meio de um light ceptometer. A taxa de emissão e de expansão foliar foi calculada ao final do ciclo das culturas. A duração da área foliar e o coeficiente de extinção foram calculados antes e após o florescimento. Não se observaram diferenças no desenvolvimento dos biótipos de E. heterophylla quanto à taxa de aparição de folhas, taxa de expansão foliar, DAF ou k. Entre as culturas, o feijão apresentou menor taxa de emissão foliar (0,591 por dia) comparado à soja (0,933 por dia). Dentre as plantas daninhas, D. tortuosum apresentou a maior taxa de emissão foliar (0,699 por dia). A taxa de expansão foliar observada pela soja foi superior a todas as demais espécies avaliadas (6,77 cm².dia-1). Todas as espécies apresentaram maior valor para DAF após o florescimento, em comparação com a fase vegetativa. A soja apresentou maior valor de k (antes e após o florescimento 0,52 e 0,93, respectivamente) frente às demais espécies, demonstrando maior potencial de interceptação da radiação solar.<br>The objective of this study was to compare the emission rate and expansion of the leaves, duration of the leaf area (DLA) and the extinction coefficient (k) for the crops soybean and of the bean, and for the weeds Euphorbia heterophylla sensitive and Euphorbia heterophylla resistant to the herbicides inhibiting of the ALS enzyme, Bidens pilosa and Desmodium tortuosum. The experiment was developed in the field, in soil classified as Red-Yellow Claysoil, in the period of october of 2000 to march of 2001. Each plantspecies consisted of a treatment. The treatments were arranged in a randomized complete block design with four replications. The mensurations of the photosynthetically active radiation (PAR) were accomplished in two points of the plants: above and bellow the canopy, by means of a light ceptometer. The emission rate and the expansion of leaves was calculated at the end of the cycle of the crops. The DLA and k were calculated before and after the plant flowering. It was not observed differences in the development of the biotypes of E. heterophylla with relation to the rate of appearance of leaves, expansion rate, DLA or k. Among the cultures, the bean presented smaller leaf emission rate (0.591 / day) compared to the soybean (0.933 / day). Among the weeds, the largest leaf emission rate was with D. tortuosum (0.699 / day). The leaf expansion rate observed by the soybean was superior to all the other species (6.77 cm².dia-1). All plant species presented larger value for DLA after the flowering compared before flowering. The soybean presented larger value of k (before and after the flowering 0.52 and 0.93, respectively) compared to the other species, demonstrating high potential of interception of solar radiation