PAN AFRICAN GRAIN LEGUME & WORLD COWPEA CONFERENCE, 2016.

IMPROVING THE FIELD RESISTANCE OF COWPEA GENOTYPES TO COWPEA APHID

GLORIA TETTEH KUBI1; FRANCIS KUSI3; AARON ASARE2; MARY BOTCHEY1

1 DEPT. OF ENTOMOLOGY & WILDLIFE, UNIVERSITY OF CAPE COAST, GHANA; 2 DEPT OF MOLECULAR BIO & BIOTECH, UCC; 3CSIR,SARI-GHANA

LEGUME INNOVATION LAB 2016 AWARDEE

glory193@gmail.com

Outline of Presentation • Introduction

– Background to study – Objective

• Materials and methods – Study sites – Aphids screening methods – Breeding of cowpea lines

• Results • Summary • Future works

3/9/2016 2

Introduction

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• UN global population projects = Over 9 billion by 2050 • Africa expected to account for more than half of this growth (source:www.unpopulation.org)

www.flickr.com/photos/laurenmanning/2979574719

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FOOD PRODUCTION INCREASE

Deteriorating soils; Climate changes; Reduced agricultural

lands; Pest invasions, etc.

Problem

Identify and improve plant

genotypes better adapted to

the new environment

Maintain quality

www.foodanddrinkguides.co.uk/blog/2013/10/29/feeding-the-9-billion/

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Nutrient cycling, feed, food, easily adaptable to marginal soils, potential high yields

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Chemical application is a common practice in commercial cowpea farms;

Commercial cowpea production is not

possible without pesticides (Jackai et al., 1985; Kyamanywa, 1996);

Peasant farmers (mostly women) are unable

to purchase expensive chemicals and thus suffer heavy on-farm yield loss

Expensive

Ecologically unsafe

Harmful to humans

Cultivation of resistant genotypes

Environmentally friendly

Cost effective

Food security Poverty alleviation

Source: Author

Background to Study

• Previous work conducted by Dr. Aaron T. Asare from UCC identified advanced Striga resistant cowpea lines,

• 7 promising lines were selected for aphids resistant screening, – Aim of improving the field resistance of these lines

– Also identify other potential sources of the aphids resistance gene.

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Objective

To improve Striga gesnerioides

resistant genotypes by

introgression of the aphid-

resistant gene as identified in

SARC 1-57-2 (Kusi et al, 2010)

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Source: Author

Plant materials

• 7 advanced Striga resistant lines

– UC96-11, UC96-32, UC96-241, UC96-460,

UC96-471, UC96-478 & UC96-513

• Aphids resistant donor/check

– SARC 1-57-2

• Aphids susceptible check

– Apagbaala

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Methods

• 9 parental lines were planted in pots to constitute a CRD with 3 replications

• 3-4 days after emergence, each seedling was inoculated with 5 adult aphids (Kusi et al., 2010)

• Population build up was allowed until susceptible check died

• Seedlings were then grouped as resistant or susceptible

• Leaf sample from each parental line was taken using the FTA plant card

• DNA samples will be run

with the SSR marker (CPF171F/172R) which has been found to have association with the resistant SARC 1-57-2

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2 methods employed for screening; Phenotypic and Genotypic tests

Phenotyping Genotyping

Methods Cont’

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UC96-471(r) x SARC 1-57-2 (R) UC96-241 (R) x SARC 1-57-2 (R)

F1

F2

Crossed

Selfed

Crossed

Selfed

F2

Screen for aphids resistance segregation ratios

Results

• Parental genotypes were

grouped as resistant or

susceptible using SARC 1-

57-2 & Apagbaala as

resistant and susceptible

checks respectively

– UC96-241 (resistant, R)

– UC96-471 (susceptible, r)

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PHENOTYPING OF PARENTAL LINES

SARC 1-57-2

UC96-471

UC96-241

Apagbaala

Results Cont’

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SUSCEPTIBLE CHECK

UC96-471

SUSCEPTIBLE PARENT

Apagbaala

Vs.

Results Cont’

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RESISTANT CHECK

SARC 1-57-2 UC96-241

RESISTANT PARENT Vs.

Results Cont’

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F2 Screening of Susceptible (UC96-471) x Resistant (SARC 1-57-2) population

Total = 312

Resistant = 226

Susceptible = 86

Results

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Chi-square test for goodness of fit

Results fits into the expected 3R:1S ratio of a monogenic inheritance

Category Observed expected Chi-Sq alive 226 234 0.273504 dead 86 78 0.820513 total 312 312 1.09402

P-value = 0.296

Summary

• 7 Striga resistant lines were screened for aphids resistance

– 2 lines UC96-241(resistant) & 471 (susceptible) were

selected for further studies

• Both lines crossed with SARC 1-57-2

• Cross between SARC & 471 advanced to F2 and screened for

segregation ratios

– Fits into single dominance inheritance (3:1)

• Progeny of SARC & 241 are being studied to determine

whether the gene controlling resistance occupy the same loci.

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F2 resistant seedlings are being advanced,

Identify source of resistance for UC96-241,

Determine the heritability of the aphid-resistance gene,

Genotyping of the F2 lines,

Gene pyramiding &

Developing varieties that combine the Striga & aphids

resistance.

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THANK YOU