Identification of aphid and cowpea aphid-borne mosaic virus disease resistance sources for introgression into farmer preferred cowpea varieties in Malawi

Lilongwe University of Agriculture and Natural Resources (LUANAR)

The LUANAR Cowpea Breeding Team, 2023. Left to right: Ms Mwatitha Bowa, Mr Alex Saizi, Mr Collins Liyaya, Mr John Kafwambira, Mr Idrissah Kaisi, Mr Jameson Khombe, Dr Michael Chipeta (PI).

PROJECT OVERVIEW

Background

Cowpea is an important legume crop in Malawi especially among smallholder farmers in terms of food, nutrition and income generation. Most farmers use landraces which tend to be low yielding and susceptible to pests and diseases. Key biotic stresses are insect pests (aphids) and diseases (cowpea aphid borne mosaic virus disease CABMV) which can cause severe loses to production.

The LUANAR one-year pilot project aims to identify sources of resistance to cowpea aphid and CABMV disease and test available molecular markers to breed resistance to these important constraints to productivity in locally preferred cowpea varieties using marker-assisted selection.

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Evaluation of cowpea germplasm for aphid and CABMV resistance in the field (Feb 2023).

Objectives

To evaluate a collection of cowpea germplasm with known sources of resistance to aphids and CABMV to identify resistance sources in Malawi. These lines will be screened in the field at Chitala research station which is one of the hot spots for CABMV in the country.
To evaluate a collection of cowpea germplasm with known sources of resistance to aphids and CABMV in the screen-house using artificial infestation (for aphids) and artificial inoculation (for CABMV).
To screen the cowpeas showing resistance to aphids with two molecular markers linked to aphid resistance in cowpea, to determine whether they can be used in a marker assisted breeding programme in Malawi (i.e. they are linked to aphid resistance in the donor material and they differentiate between donor and recurrent parents).

Progress to date

Field screening of cowpea germplasm for aphid resistance was completed.
Screen-house screening of cowpea germplasm for aphid resistance:

The rearing of aphid was done in an insect proof net using a known susceptible check (TVX3236).
Fifty test genotypes and TVX3236 as a control were planted in an insect proof net.
Two weeks after planting (after the plants had just developed the first trifoliate leaves), the plants were infested with aphids (at least five per plant).
Data collection is in progress.

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Preparation of the field trial at Chitala Research Station (i); aphid plant infested by aphids (ii); cowpea aphid borne mosaic virus disease symptoms observed in the field (iii); screening for aphid resistance in the screenhouse (iv).

PROJECT TEAM MEMBERS

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Dr Michael Chipeta

Principal Investigator, Lilongwe University of Agriculture and Natural Resources (LUANAR).

Senior Lecturer and Plant Breeder at LUANAR. He holds a PhD in Plant Breeding from the University of Kwazulu-Natal, South Africa. The title of his thesis was 'Identification and Development of Cassava Brown Streak Disease Resistant and Early Storage Root Bulking Varieties in Malawi'.

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