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Genetic improvement of cowpea plant architecture for superior agronomic performance (PhD)

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Data collection at Kabwe Agricultural Research Station.

PROJECT OVERVIEW

Background

 

Cowpea (Vigna unguiculata) is an important source of nutritional and food security for many households in Zambia. Plant architecture of cowpea plays a major role in its adaptation to pest resistance and easy harvesting. For example, cowpea plants with long peduncle and erect pods have previously been associated with resistance to Pod Borer (Marica vitrata) while number of pods per peduncle is an important component of seed yield. Creating genetic variation for this yield component and understanding the genetic basis of that variation could support genetic enhancement of seed yield in cowpea.

 

A cowpea mutant germplasm known as Mutant Diversity Panel (MDP), comprised of 750 M5 mutants, exhibits diversity for a wide range of traits including those for plant architecture. MDP is also variable for yield component such as number of pods per peduncle. An understanding of the genetic basis of the plant architecture could support development of cowpea germplasm that is less susceptible to pest damage, easier to harvest and higher yielding. The MDP will be evaluated for peduncle length, pod orientation and number of pods per peduncle in multi-locational field trials to identify mutants with all the three traits or with two of the three mentioned traits.

 

When a mutant/line with a combination of the three traits or at least two of the mentioned traits is identified/or developed, it will be crossed with unrelated Zambian varieties. The F1 that will be developed will be selfed to F2 and then use single seed descent method to advance the F2’s to F4:5 families. The F4:5 population will then be phenotyped in multi locational field trials for peduncle length, pod orientation and number of pods per peduncle. The F4:5 RILs will also be genotyped with a SNP Chip. Thereafter QTL analysis will be conducted to identify QTL for peduncle length, pod orientation and number of pods per peduncle.

 

The project will develop and release cowpea varieties that have a plant architecture that supports easy harvesting of cowpea, and potentially reduced Maruca infestation and higher productivity. The mutant germplasm used here will be made available to other interested KT-funded cowpea projects as genetic resource for identification of valuable traits to support breeding objectives in their respective countries.

Objectives

 

  1. Characterise the Mutant Diversity Panel for plant architecture traits including peduncle length, pod orientation (angle) and number of pods per peduncle.

  2. Pyramid genes for long peduncle, erect pod orientation and higher pod number per peduncle in the same genetic background.

  3. Map quantitative trait loci for peduncle length, pod orientation and pod number per peduncle.

Progress to date

 

  1. Field trials were planted in 2023/2024 growing season in 4 different locations (GART, Mochipapa, Kabwe and UNZA).

  2. Severe drought led trials in GART and Mochipapa to fail.

  3. Kuwabo has performed characterisations of plant architecture in Kabwe. Following traits were recorded: peduncle length, pod orientation and number or pods per peduncle.

  4. Data analysis have so far identified mutant M110 with erect pod orientation to have the best peduncle length in relation to number of pods per peduncle.

  5. Mutants MM64, MM22, NM289 and NM642, with drooping pod orientation, to have a combination of long peduncle and higher number of pods per peduncle.

  6. Next steps will be to collect data from UNZA and fulfil objectives 2 and 3.

PROJECT TEAM MEMBERS

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Dr Kelvin Kamfwa

Principal Investigator, University of Zambia.

Dr Kamfwa has led the KT-funded bean improvement programme in Zambia since its inception in 2017. He holds a PhD in Plant Breeding, Genetics and Biotechnology from Michigan State University, USA, and an MSc in Crop Science from Makerere University, Uganda.

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Ms Swivia Hamabwe

Co-PI

​Ms Hamabwe obtained her MSc in Plant Physiology and Biochemistry from the University of Nairobi in 2020. Since 2017 she has been working as a Staff Development Fellow in the University of Zambia. She is also working as an assisting lecturer and Research Assistant in the Bean Breeding Program in the University of Zambia. Alongside these roles, Ms Hamabwe conducts her own research focusing on crop physiology and plant responses to environmental stress.

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Mr Kuwabo Kuwabo

KT PhD Scholar

PhD in Plant Breeding and Seed Systems, University of Zambia, 2024-2026

Supervisors: Dr Kelvin Kamfwa and Professor Paul Gepts (University of California, Davis).

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