Application of fast technology for analysis (FTA) for sampling and recovery of deoxyribonucleic acid (DNA) for molecular characterization of cowpea breeding lines for Striga resistance

Article purchasedStriga gesnerioides (Willd) Vatke is a significant constraint to cowpea production in the dry savannas of sub-Saharan Africa. Yield losses caused by S. gesnerioides in these regions are estimated in millions of tons annually and the prevalence of Striga soil infestation is steadily increasing. Conventional breeding efforts have developed some cowpea lines with Striga resistance as well as other important agronomic traits but it is time-consuming and difficult to pyramid favorable traits. The use of marker-assisted selection (MAS) makes it easier to select plant traits and reduce the time needed to develop new varieties. The potential of Fast Technology for Analysis (FTA) as an effective technology for sampling and retrieval of DNA from plant tissue and their subsequent molecular analysis was assessed in the laboratory. DNA was successfully recovered from the leaf tissues of cowpea pressed into the FTA® Classic card and the DNA obtained from the FTA papers was found to be suitable for molecular analysis by PCR-based techniques. The marker efficiency of Sequence Characterized Amplified Region (SCAR) marker MahSe2 and C42B was 93% in detecting SG3 resistance. This study demonstrated that the application of MAS using FTA technology has the potential to put the breeding process on a fast track and increase the efficiency of breeding activities

Inheritance of resistance to Cercospora leaf spot disease of cowpea [Vigna unguiculata (L.) Walp]

Open Access ArticleCercospora leaf spot (CLS) caused by Pseudocercospora cruenta (Sacc.) is an important disease affecting cowpea production in Nigeria. Understanding the genetic nature of CLS is an important step in developing an effective breeding strategy. This study investigated the inheritance of CLS disease in cowpea under natural epiphytotic field condition involving two CLS resistant parents (IT99K-573-1-1, IT99K216-24) and a CLS susceptible parent (UAM09-1055-6). The parental lines, F1, BC1P1, BC1P2, F2 and F3 generations were used to study the genetic nature and to detect SSR markers closely linked with the CLS resistance gene(s) using bulked segregant analysis (BSA). The result showed that F1 populations involving UAM09-1055-6 × IT99K-573-1-1 and UAM09-1055-6 × IT99K-216-24 were resistant to CLS in the 2 crosses suggesting the presence of gene dominance in the control of the disease. The observed segregating ratio of F2 populations fits the Mendalian ratio 3:1. The plants reaction to the disease in the backcross progeny test involving the resistant parent were all uniformly resistant, whereas those involving the susceptible parent segregated into ratio 1:1. The F3 generations, which segregated into ratio 1:2:1 further confirmed that resistance was controlled by a single dominant gene in the crosses studied. Heritability estimates varied from 81 to 97%. BSA showed that SSR marker code named RB24 of lima bean and validated on F2 population discriminated between resistance and susceptibility to CLS. Hence RB24 could be a useful marker for marker-assisted selection in CLS resistance breeding in cowpea

Breeding cowpea for resistance to striga gesnerioides in the Nigerian dry savannas using marker-assisted selection

Published online:10 April 2017Historically, conventional breeding has been the primary strategy used to develop a number of Striga-resistant varieties currently grown in the Sahel of Western Africa. In this study, we have successfully developed and applied a marker-assisted selection strategy that employs a single backcross programme to introgress Striga resistance into farmer preferred varieties of cowpea for the Nigeria savannas. In this strategy, we have introduced the Striga resistance gene from the donor parent IT97K-499-35 into an elite farmer preferred cowpea cultivar ‘Borno Brown’. The selected 47 BC1F2 populations confirmed the recombinants with desirable progeny having Striga resistance gene(s). The 28 lines selected in the BC1F2:4 generation with large seed size, brown seed coat colour and carrying marker alleles were evaluated in the field for resistance to Striga resistance. This led to the selection of a number of desirable improved lines that were immune to Striga having local genetic background with higher yield than those of their parents and standard varieties

Molecular characterization of cowpea breeding lines for Striga resistance using SCAR markers

Earlier title: Journal of Agricultural Science and Technology, ISSN 1939-1250 (DAVID PUBLISHING)S. gesnerioides (Willd) Vatke is a major biological constraint to cowpea production in the dry savanna of sub-Saharan Africa. Yield losses caused by S. gesnerioides in these regions are estimated in millions of tons annually, and prevalence of Striga soil infestation is steadily increasing. The availability of molecular markers tightly linked to S. gesnerioides resistance genes opens up the possibility of applying Marker-Assisted Selection (MAS) to cowpea and would fast track the process of developing resistance varieties to the parasite. In the present study, we report the use of Fast Technology for Analysis (FTA) also known as PlantSaver Cards (Whatman® FTA), developed by Flinder Technology associate to retrieve DNA from plant tissue for molecular analysis. A total of 100 F2 individual plants derived from two crosses were validated for SG3 resistance using two different SCAR markers (MahSe2 and C42B) linked to Striga race 3 (SG3) and 5 (SG5) resistance in other segregating populations. Genomic DNA was successfully recovered from leaf tissues of cowpea pressed onto FTA classic card and the DNA obtained from the FTA papers was found to be suitable for molecular analysis by PCR-based techniques. The marker efficiency of SCAR MahSe2 and C42B in detecting SG3 resistance was 98.5% and 93% respectively. This result revealed the utility of SCAR markers in cowpea breeding programme. Therefore, the application of MAS using FTA technology has the potential to increase efficiency of selection and for molecular characterization of cowpea lines for Striga resistance

New sources of aphids [Aphis craccivora (Koch)] resistance in cowpea germplasm using phenotypic and molecular marker approaches

Published online: 15 July 2017This study sought to identify new sources of resistance to cowpea aphids (CPA) using molecular and phenotypic approaches and the inheritance pattern. Sixty cowpea genotypes were phenotyped for resistance to CPA using insect proof cages and further confirmed using markers linked to aphid resistance. Result revealed that among the cowpea genotypes, TVu 2897 and TVNu 1158 supported lowest number of aphids and plant damage scores. The seedlings of these genotypes also had high level of survival rates and were completely healthy with normal growth. This indicates that these genotypes are resistant to aphid attacks. However, the resistance in TVNu 1158 did not seem strong compared to the genotype TVU 2897 that was confirmed to be resistant to multiple aphid biotypes. The mechanism of resistance in TVu 2897 and TVNu 1158 were expressed as a hypersensitive response at the site of infestation on the leaves. The other genotypes especially Aloka local and keffi local supported the highest number of aphids, damage score and low level of survival rate, suggesting that they are susceptible to aphid attack. The cowpea genotype IT84S-224-6 previously reported to be resistant to aphids supported high number of aphids and was marked by stunted growth and high mortality rate. Molecular and phenotypic screening revealed that TVu-2876 has a strong resistance to cowpea aphid and should be a good source of resistance gene that can be used in breeding to develop new aphid resistant cowpea cultivars. Although, the results of phenotypic tests and molecular marker detection agreed in most cases, molecular markers detection was found more reliable in identifying genotypes for resistance to CPA. The segregation in F2 and BC1 populations derived from the cross between TVNu 2876 and Keffi local indicated that resistance to cowpea aphids in TVu-2876 is controlled by a single dominant gene. Allelism test revealed that resistance gene in TVNu 2876 is non-allelic with the gene that confers resistance in SARC 1-57-2 and TVNu 1158

Identification of new sources of resistance to Striga gesnerioides in cowpea Vigna unguiculata accessions

The parasitic weed, Striga gesnerioides, is a major threat to cowpea productivity throughout the savannas of West and Central Africa. The identification of sources of S. gesnerioides resistance and their incorporation into breeding programs would be a beneficial strategy to combat the devastation caused by the parasite in cowpea fields. In this study we examined one hundred and ninety-four (194) accessions, four commercial varieties and two controls collected from a mini core collection of cowpea held at the International Institute of Tropical Agriculture genebank for resistance to S. gesnerioides race 3 (SG3), the most prevalent race in Nigeria, using phenotypic screening and molecular marker analysis. Our studies identified two cowpea accessions, Tvu-1272 and Tvu-16514, that are resistant to S. gesnerioides SG3. Resistance in these lines is associated with the molecular marker SSR1, known to segregate with the gene conferring resistance to SG3 in the cultivar B301. Phenotypically, resistance in Tvu-1272 and Tvu-16514 is expressed as a hypersensitive response at the site of infection on the roots. Allelism tests indicated that the gene that conferring SG3 resistance in Tvu-1272 is independent of that conferring resistance in B301. Tvu-1272 and Tvu-16514 will provide additional new sources of resistance to Striga and races prevalent in Nigeria

Registration of ‘UAM14‑122‑17‑7 and UAM14‑123‑18‑3’ cowpea cultivars with high‑yield, resistance to Striga, and large seed size with brown colour

‘UAM14-122-17-7 and UAM14-123-18-3’ (Reg. no. NGVU-22-39 and NGVU-22-40, respectively) are medium maturity group, high-yielding, Striga-resistance, large brown seeded cowpea [Vigna unguiculata (L) Walp.] cultivars developed and released in 2022 by the Cowpea Breeding Program of the University of Agriculture, Makurdi. The two cultivars UAM14-122-17-7 and UAM14-123-18-3 were developed by crossbreeding with marker-assisted selection (MAS) from a three-way cross between BOSADP, IT99K-573-1-1 and YAMISRA ‘(BOSADP × IT99K-573-1-1) × YAMISRA’. The parents, BOSADP and YAMISRA, are photosensitive local landraces popularly grown in northeast Nigeria because of their large seed size and suitability for intercropping. BOSADP has brown seed coat colour, while YAMISRA has white seed coat colour with black hilum; both are highly susceptible to Striga gesnerioides. The other parent, IT99K-573-1-1’ is an improved cultivar bred at the International Institute of Tropical Agriculture (IITA). It was derived from an F5 selection from the cross IT93K-596-9-12 × IT86D-880. Thus, IT99K-573-1-1 has a wide genetic background that carries the B301 (Striga resistance) gene. It is a semi-erect medium maturing cultivar with medium seed size, and highly resistant to Striga. Before release, UAM14-122-17-7 and UAM14-123-18-3 were tested in multi- environments and on-farm trials in the Guinea savannas of Nigeria from 2018 to 2021 for yield and other agronomic traits. On average, UAM14-122-17-7 recorded a grain yield of 1671 kg ha−1, while UAM14-123-18-3 recorded a grain yield of 1511 kg ha−1, which is higher than the mean of all the local checks (SAMPEA 19, Borno Brown and IT99K-573-1-1), about 80% for UAM14-122-17-7 and 95% for UAM14-123-18-3. UAM14-122-17-7 and UAM14-123-18-3 are medium maturing (80–85 days), with seed sizes ranging from 26 to 28 g/100 and 27–30 g/100, respectively. These two cultivars, therefore, have larger seed sizes with brown seed coat texture compared with the previously released cultivars. Their seed protein content ranged from 22 to 25% above that of the parental cultivars, BOSADP and YAMISRA. The two cultivars showed absolute resistance to Striga gesnerioides race 3 (SG3) prevalent in Nigeria and good adaptation for intercropping with cereals. The two cultivars were approved for release and registered in the Nigeria Variety Catalogue of the Plant Varieties in 2022 based on their superior performance in on-station, field and multi-locational trials and the massive demand for high-yielding Striga-resistant cowpea cultivars with brown seed coat colour and large seed by farmers. The National Variety Release Committee formally released the two cultivars UAM14-122-17-7 and UAM14-123-18-3 in 2022. It gave it the national code name FUAMPEA 3 and FUAMPEA 4, respectively, for cultivation in Nigeria (NCGRB 2023). The availability of these cultivars to farmers would increase cowpea production and productivhity under variable cropping systems

The parasitic plant genome project: New tools for understanding the biology of <em>Orobanche</em> and <em>Striga</em>.

The Parasitic Plant Genome Project has sequenced transcripts from three parasitic species and a nonparasitic relative in the Orobanchaceae with the goal of understanding genetic changes associated with parasitism. The species studied span the trophic spectrum from free-living nonparasite to obligate holoparasite. Parasitic species used were Triphysaria versicolor, a photosynthetically competent species that opportunistically parasitizes roots of neighboring plants; Striga hermonthica, a hemiparasite that has an obligate need for a host; and Orobanche aegyptiaca, a holoparasite with absolute nutritional dependence on a host. Lindenbergia philippensis represents the closest nonparasite sister group to the parasitic Orobanchaceae and was included for comparative purposes. Tissues for transcriptome sequencing from each plant were gathered to identify expressed genes for key life stages from seed conditioning through anthesis. Two of the species studied, S. hermonthica and O. aegyptiaca, are economically important weeds and the data generated by this project are expected to aid in research and control of these species and their relatives. The sequences generated through this project will provide an abundant resource of molecular markers for understanding population dynamics, as well as provide insight into the biology of parasitism and advance progress toward understanding parasite virulence and host resistance mechanisms. In addition, the sequences provide important information on target sites for herbicide action or other novel control strategies such as trans-specific gene silencing