pan african grain legume & world cowpea...
TRANSCRIPT
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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
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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
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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
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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
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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
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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
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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
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Results Cont’
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SUSCEPTIBLE CHECK
UC96-471
SUSCEPTIBLE PARENT
Apagbaala
Vs.
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Results Cont’
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RESISTANT CHECK
SARC 1-57-2 UC96-241
RESISTANT PARENT Vs.
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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
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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
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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