
Genetic improvement of cowpea for resistance to Striga and Alectra vogelii in Nigeria

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A field of the Striga resistant cowpea variety FUAMPEA 2, released in 2016.
PROJECT OVERVIEW
Background
In previous phase of the KT funded cowpea improvement projects at FUAM, two Striga resistant cowpea varieties were developed and released: FUAMPEA 1 and FUAMPEA 2. The project also identified breeding lines resistant to the parasitic weed Alectra vogelii, Fusarium wilt and aphids. The current project aims to consolidate on the progress made and complete the introgression of Fusarium wilt and aphid resistances into FUAMPEA 1 and FUAMPEA 2 using marker assisted selection. A further target trait for improvement is seed size, as large seeded varieties are prized by farmers and consumers.
Objectives
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Identify molecular markers for resistance to Alectra, aphids and Fusarium wilt.
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Introgress the aphid resistance gene into UAM elite varieties using marker-assisted backcrossing.
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Introgress Fusarium wilt resistance into UAM elite varieties using marker-assisted backcrossing.

FUAMPEA 1, the Striga resistant cowpea variety released by FUAM in 2016.

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Professor Omoigui in the KT lab in FUAM, 2013 (i); Ms Deborah Ayeni (former technician in the lab) in the screen house in 2016 (ii); FUAMPEA 1 seeds (iii); FUAMPEA 2 seeds (iv); example of selection of large seeded improved varieties (v).
PROJECT TEAM MEMBERS



Professor Lucky Omoigui
Principal Investigator, Federal University of Agriculture, Makurdi, and Seed Systems Specialist at the International Institute for Tropical Agriculture (IITA).
Professor Omoigui has led the KT-funded cowpea breeding programme in FUAM since its inception in 2010.
Mr Macsamuel Ugbaa
Co-PI & PhD Student
Mr Ugbaa, a current KT PhD scholar, became a Co-PI of the FUAM KT cowpea improvement programme in January 2020.
Mr Godspower Ekeruo
Co-PI & PhD Student
Mr Ekeru became a Co-PI of the FUAM KT cowpea improvement programme in January 2020.

Ms Judith Ezugwu Ogechi
Lab Manager

Mr Nathaniel Iworndu
Screenhouse Labourer

Mr Simon Mnzughul
Research Technician

Ms Catherine Danmaigona
Former MSs Student, graduated 2017.

Mr Abiodun Ekundayo
Field Assistant
STUDENT PROJECTS
Identification and validation of molecular markers for Alectra vogelii resistance in cowpea (Vigna unguiculata (L.) Walp)
Mr Macsamuel Ugbaa
PhD in Plant Breeding and Genetics, Federal University of Agriculture Makurdi (FUAM), Nigeria, 2016-2021.
Supervisor: Professor Lucky Umoigui, FUAM, Professor L. L. Bello, FUAM.
Background
Alectra vogelii (also called yellow witch weed or cowpea witch weed) is an annual parasitic weed of legume crops in semi-arid areas of West Africa. Its most important host is cowpea, and is responsible for significant loses to production.
Project objectives
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To assemble germplasm and evaluate for reaction to Alectra.
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To carry out allelism test to identify sources of genetic resistance other than B301 (an Alectra resistant cowpea variety).
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To generate segregating and mapping populations derived from B301 and Yamisra (susceptible to Alectra).
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To phenotype segregating and mapping populations for reaction to Alectra vogelii using the pot culture technique inoculated with Alectra seeds.
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To identify and validate molecular markers for Alectra resistance.

Mr Ugbaa working at the FUAM cowpea improvement molecular lab.
Progress to date
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Elite, local and landracesowpea germplasm screened for their reaction to Alectra using pot culture technique.
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F2 population comprising 352 lines derived from B301 and Yamisra and phenotyped for reaction to Alectra.
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32 allele-specific molecular markers were used to screen the DNA of B301 and Yasmira for polymorphisms.
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Bulk Segregant Analysis (BSA) performed on 10 homozygous Alectra resistant F2 lines, and 10 homozygous susceptible F2 lines.

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An Alectra infested cowpea field in Northern Nigeria (i); A detached Alectra plant (ii); a successful cross between B301 (a cowpea variety resistant to Alectra) and Yasmira (an Alectra susceptible variety; iii); scoring plants in the screen house for their reaction to Alectra (iv).
Genetics of aphid resistance in cowpea [Vigna unguiculata (L.) Walp] using molecular and conventional breeding tools
Mr Godspower Ekeruo
MSc in Plant Breeding and Genetics, Federal University of Agriculture Makurdi (FUAM), Nigeria.
Supervisor: Dr Lucky Omoigui, FUAM, Prof. L. L. Bello
Background
Aphid (Aphis craccivora Koch) is an important insect pest for cowpea in Nigeria that can result in significant loses to production.
Project objectives
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To identify cowpea genotypes with good sources of genetic resistance to aphid.
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To elucidate inheritance pattern of aphids resistance in cowpea.
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To identify molecular markers linked to the aphid's resistance gene to facilitate application of MAS in breeding programmes.
Achievements
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Screening for reaction to aphids identified resistant and susceptible cowpea varieties.
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TVu2876 (an aphid resistant variety) and Aloka local (a variety susceptible to aphids) were selected to generate F1 and segregating populations: resistance to cowpea aphids in TVu-2876 was found to be controlled by a major single dominant gene.
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Two SSR markers, CP-171/172 and KAD-61, were identified to be associated with the aphid resistance gene.
Mr Ekeruo is introgressing the aphid resistance gene from TVu2876 into FUAMPEA 1 and FUAMPEA 2 for his PhD degree.

Mr Ekeruo loading a gel in the lab, 2017.

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An aphid infested cowpea plant (i); Mr Ekeruo infesting plants with aphids to test for resistance (ii); the reaction of aphid resistant and susceptible cowpea varieties after the screen (iii); the FUAM aphid screen house (iv).
Genetics of Fusarium wilt (Fusarium oxysporum f. sp trachiephilum) resistance in cowpea (Vigna unguiculata (L.) Walp) using conventional and molecular approaches
Ms Catherine Danmaigona Clement
MSc in Plant Breeding and Genetics, Department of Plant Breeding and Seed Science, Federal University of Agriculture Makurdi (FUAM), Nigeria, awarded 2017.
Supervisors: Professor Lucky Omoigui, FUAM, Professor Prof. L. L. Bello, FUAM.
Background
Nigeria is the largest producer and consumer of cowpea in the world but production is greatly constrained by several biotic and abiotic factors. Fusarium wilt caused by Fusarium oxysporum f. sp tracheiphilum (Fot) is a serious disease of cowpea in Nigeria posing a major threat to cowpea production. Host resistance offers an effective and preferred solution for managing this disease in cowpea.

Ms Catherine Dabmaigona in the molecular lab in FUAM, 2015.
Project objectives
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To identify potential genetic sources of resistance to cowpea Fusarium wilt.
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To elucidate the inheritance pattern of Fusarium wilt resistance in cowpea.
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To identify molecular markers closely linked to Fusarium wilt resistance in cowpea.
Achievements
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The reaction of 60 cowpea genotypes to Fusarium for resistance and susceptibility was characterized by two methods (the seed soak method and the root deep inoculation method).
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Three resistant varieties (TVu 134, TVu 410 and TVu 109-1) were identified as sources of resistance to Fusarium wilt in Nigeria.
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Three sets of F2 populations developed between resistant and susceptible parents were characterized for resistance against Fusarium wilt using genetic analysis. Fusarium wilt resistant gene in genotypes TVu 134, TVu 410 and TVu 109-1 is conditioned by a single dominant gene.
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A new molecular marker for Fusarium resistance, C13-16, was developed to facilitate breeding for resistance to Fusarium wilt in cowpea.
Ms Danmaigona is currently completing a PhD degree at the Agriculture & Life Sciences Texas A&M University, USA.
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Reddish brown vascular discolouration of cowpea stems and roots infected with Fusarium wilt (i). The pot screening method to characterise reaction to Fusarium wilt (ii-v). uCowpea seeds were surface sterilized and planted in pots with sterile soil; 1 week after planting the seedlings were uprooted washed and roots were trimmed using scissors (ii). The seedlings with trimmed roots were soaked in a spore suspension (iii). The seedlings were replanted in sterile soil, watered and fertilised (iv). After 9 weeks this screen distinguishes resistant and susceptible cowpea varieties to Fusarium wilt (v; arrow points to a susceptible variety).
PUBLICATIONS
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M.S. Ugbaa, L.O. Omoigui, B.S. Gowda and M.P. Timko. (2021). SSR markers associated with Alectra vogelii resistance gene in cowpea [Vigna unguiculata (L.) Walp]. World Researchers Association- Research Journal of Biotechnology 16: 94-101. doi: https://doi.org/10.25303/169rjbt94101
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Ugbaa, M., OMOIGUI, L. and BELLO, L., 2020. Phenotypic screening of cowpea (Vigna unguiculata) genotypes in response to parasitic weed Alectra vogelii. Asian Journal of Agriculture 4(1).
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Omoigui, L.O., Arrey, M.O., Danmaigona, C.C., Ekeruo, G. and Timko, M.P., 2019. Inheritance of resistance to Cercospora leaf spot disease of cowpea [Vigna unguiculata (L.) Walp]. Euphytica, 215: 1-12.
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Omoigui, L.O., Danmaigona, C.C., Kamara, A.Y., Ekefan, E.J. and Timko, M.P., 2018. Genetic analysis of Fusarium wilt resistance in cowpea (Vigna unguiculata Walp.). Plant Breeding, 137: 773-781.
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Omoigui, L.O., Ekeuro, G.C., Kamara, A.Y., Bello, L.L., Timko, M.P. and Ogunwolu, G.O., 2017. New sources of aphids [Aphis craccivora (Koch)] resistance in cowpea germplasm using phenotypic and molecular marker approaches. Euphytica 213: 1-15.
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Omoigui, L.O., Kamara, A.Y., Alunyo, G.I., Bello, L.L., Oluoch, M., Timko, M.P. and Boukar, O., 2017. Identification of new sources of resistance to Striga gesnerioides in cowpea Vigna unguiculata accessions. Genetic resources and crop evolution 64: 901-911.
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Omoigui, L.O., Ajeigbe, H.A., Akinwale, R.O., Timko, M.P., Oyekunle, M. and Bello, L.L., 2017. Performance of cowpea varieties under Striga gesnerioides (Willd.) Vatke infestation using biplot analysis. Euphytica, 213: 1-16.
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Omoigui, L.O., Kamara, A.Y., Moukoumbi, Y.D., Ogunkanmi, L.A. and Timko, M.P., 2017. Breeding cowpea for resistance to Striga gesnerioides in the Nigerian dry savannas using marker‐assisted selection. Plant Breeding 136: 393-399.
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Omoigui, L.O., Ishiyaku, M.F., Gowda, B.S., Kamara, A.Y. and Timko, M.P., 2015. Suitability and use of two molecular markers to track race-specific resistance Striga gesnerioides in cowpea (Vigna unguiculata (L.) Walp.). African Journal of Biotechnology 14: 2179-2190.
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M.S. Ugbaa, L.O. Omoigui, B.S. Gowda and M.P. Timko. (2021). SSR Markers Associated with Alectra vogelii Resistance Gene in Cowpea (Vigna unguiculata (L.) Walp). World Researchers Association - Research Journal of Biotechnology. 16(9): 94-101