Despite their many benefits, productivity of legumes in sub-Saharan Africa (SSA) is generally lower than world averages due to:Biotic stresses (diseases, pests, weeds), Abiotic stresses (heat, frost, drought, and salinity) and Edaphic factors (associated with soil nutrient. deficits). Reference sets developed for assorted legumes and traits of agronomic importance identified for further crop improvement.

1. Feb
2017
Advances in Legume Breeding for Better Livelihoods
of Smallholder Farmers in sub-Saharan Africa
Chris O Ojiewo1
, Asnake Fikre1
, Haile Desmae2
, Babu N Motagi3
, Ousmane Boukar4
, Clare Mukankusi-Mugisha5
, Emmanuel Monyo6
, Rajeev K Varshney7
1
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Ethiopia, 2
Mali, 3
Nigeria, 6
Kenya, 7
India; Addis Ababa, Ethiopia;
4
International Institute of Tropical Agriculture (IITA), Kano Station, Kano, Nigeria; 5
International Center for Tropical Agriculture (CIAT), Kampala, Uganda
About ICRISAT: www.icrisat.org
ICRISAT’s scientific information: http://EXPLOREit.icrisat.org
*Correspondence: c.ojiewo@cgiar.org
Benefits of legumes
• Intensify cropping systems as double, catch, relay
and intercrops;
• Provide ‘free’ nitrogen to soils through
atmospheric nitrogen fixation;
• Act as break crops for disease and pest cycles;
• Increase and diversify smallholder farmers’
incomes;
• Increase household diet quality with plant proteins
and micronutrients.
The Problem
Despite their many benefits, productivity of
legumes in sub-Saharan Africa (SSA) is generally
lower than world averages (Figure 1) due to:
• Biotic stresses (diseases, pests, weeds)
• Abiotic stresses (heat, frost, drought, and salinity)
• Edaphic factors (associated with soil nutrient
deficits)
Reference sets developed for assorted legumes and traits of agronomic importance identified for
further crop improvement.
Selected Legumes Important traits identified in reference collections Reference
Chickpea Drought, salinity, high temperature and herbicide
tolerance, Fusarium wilt, Ascochyta blight and Botrytis
gray mold and pod borer resistance
Upadhyaya et al. 2008
Groundnut Early-maturing groundnut (90 days) with high pod yield,
large variability in pod/seed characteristics, oil content and
oil quality (oleic/linoleic ratio), and grain Fe and Zn content;
tolerance to drought, salinity and low temperature;
resistance to root-knot nematode, and early/late leaf spot
Gowda et al. 2013
Pigeonpea Early flowering, high number of pods, high 100-seed
weight and high seed yield/plant
Upadhyaya et al. 2011
Cowpea Striga resistance, agronomic traits Mahalakshmi et al. 2006
Use of genome resources for trait discovery.
Selected Legumes Genome sequencing progress Reference
Chickpea ~738-Mb draft whole genome - 28,269 genes; disease
resistance and agronomic traits
Varshney et al. 2013
Groundnut Sub genome size ~2.7 Gb; disease resistance, enhanced pod
and oil yield, tolerance to drought and heat, better oil quality.
Chen et al. 2016
Bertioli et al. 2016
Pigeonpea Draft pigeonpea genome sequence - 48,680 genes;
drought tolerance agronomic traits
Varshney et al. 2012
Cowpea Genome size ~620 Mbp; 298,848 cowpea genespace
sequences (GSS) used to develop a database consisting of
GSS annotation and comparative genomics knowledge base,
GSS enzyme and metabolic pathway knowledge base, and
GSS simple sequence repeats (SSRs)
Chen et al. 2007
Common Bean Sequenced genome size ~74 Mbp; two independent
domestication events confirmed
Schmutz et al. 2010
Pre-breeding as a source of desired traits.
Selected Legumes Desired traits from evaluation of wild relatives and exotic landraces Reference
Chickpea Resistance/tolerance to Phytophthora root rot, cyst nematode
(Heterodera ciceri), root-lesion nematode (Pratylenchus spp.),
pod borer (Helicoverpa armigera), Ascochyta blight, Botrytis
gray mold and low temperatures
Gaur et al. 2010
Groundnut Resistance to disease and insect pests Sharma et al. 2013
Pigeonpea Cytoplasmic male sterility (CMS) systems Saxena et al. 2015
Cowpea Resistance to insect pests Fatokun 2002
Lentil Anthracnose and wilt resistance; drought tolerance Fiala et al. 2009
Deploying markers in breeding programs for developing improved lines in a cost- and
time-effective manner.
Selected
Legumes Phenotypic and molecular markers available for forward breeding Reference
Chickpea Nine QTL clusters containing QTLs for several drought tolerance traits
identified.
Two novel QTLs explain 10.4–18.8% of phenotypic variation for
resistance to race 1 of Fusarium wilt caused by Fusarium oxysporum
f. sp. ciceris and 6 QTLs explaining up to 31.9 % of phenotypic variation
for resistance to Ascochyta blight caused by Ascochyta rabiei
Varshney et al. 2014
Sabbavarapu et al. 2013
Groundnut Rust QTL (QTLrust01), contributing 6.90–55.20% variation identified.
GM2009, GM1536, GM2301 and GM2079 new markers for QTLrust01
reported.
Khedikar et al. 2010
Sujay et al. 2012
Cowpea E-ACT/M-CAA524, 61R and 61M2 gene markers available for use in
introgression of Striga resistance into susceptible cowpea lines.
Five QTLs representing 9% of the cowpea genome identified to explain
11.5–18.1 % of the phenotypic variation for heat tolerance and tagged
with 48 transcript-derived SNP markers
Ouedraogo et al. 2012
Lucas et al. 2013
Common
Bean
Potyviral resistance associated with the homozygotic presence of a
mutated eIF4E allele.
A random amplified polymorphic DNA (RAPD) molecular marker
(OPH181200C) linked in resistance to race 73 of Colletotrichum
lindemuthianum causing anthracnose in beans was identified.
Three QTL regions responsible for angular leaf spot (ALS) resistance
Naderpour et al. 2010
Young et al. 1998
Keller et al. 2015
• Released 177 improved varieties of 6 legumes (groundnut, cowpea, chickpea, common bean,
pigeonpea, soybean) in SSA and India between 2007-2016 under Tropical Legumes Projects (TLII/
TLIII; Figure 2)
• Produced 601,284 tons of various seed classes (Breeders, basic, certified and QDS).
• 2.245 million ha potentially planted with this amount of seed
• With farm size of 0.2ha/farmer about 11,225,365 households reached
• Some of these variety releases and their adoption are included in the CGIAR DIIVA (Diffusion and
Impact of Improved Varieties in Africa) project (Figure 3) while others are more recent.
Conclusions and Prospects for Legume Breeding in SSA
• Integrating genomics-assisted breeding approaches and rapid generation advancement to
reduce time required for cultivar development
• Improving targeting, speed, scale, efficiency, quality (control, precision, and accuracy)
• Developing formal product profiles for key varieties, prioritizing traits and rationalizing resource
allocation
• Increased throughput (more crosses, larger populations, more plots at more sites and more
generations per year)
• Use of modern high-throughput phenotyping and genotyping protocols and platforms
• Increased mechanization and automation (plot threshers, seed cleaners and seed counters)
• Broadening genetic base by greater use of genetic diversity, either natural or artificial
• Improved experimental and statistical designs and methods, precision and accuracy of data
handling (e.g. electronic data capture and barcoding)
• Tracking pipeline metrics (#crosses, #lines/cross, #lines/evaluation, yield trials) and trends (CV%,
genetic progress and genetic gains) of the breeding program
• Dissemination models that are rapid and that support rapid varietal replacement.
Figure 2. TLIII operates in 8 focus geographies and 4 crops down from 15 countries
and 6 crops in TLII.
Figure 3. Variety release and adoption as summarized
by the CGIAR DIIVA (Diffusion and Impact of Improved
Varieties in Africa) project data on selected crops in
Sub-Saharan Africa (http://www.asti.cgiar.org/diiva).
Figure 1. Global and SSA comparative figures on yield increase
of selected legumes over the years.
Priority challenges and traits for genetic improvement of selected legumes in sub-Saharan Africa.
Crop Constraints
Biotic Abiotic Others
Groundnut Rosette, rust, early leaf spot,
late leaf spot, aphids
Drought Aflatoxin, oil content
and quality
Common
bean
Anthracnose, common bacterial
blight, angular leaf spot, bean common
mosaic (necrotic) virus (BCM(N)V),
bean stem maggots, bruchids
Heat, drought, low
phosphorus (P) and
nitrogen (N) tolerance
Symbiotic nitrogen
fixation, cooking time and
canning quality
Chickpea Botrytis gray mold, Ascochyta blight,
Fusarium wilt, dry root rot, pod borer
Drought, heat, cold Large-seeded, cooking
time and quality
Pigeonpea Fusarium wilt, and sterility mosaic
disease, pod borer
Terminal drought,
waterlogging
Grain quality and hybrids
for different niches
Soybean Rust, Cercospora leaf spot, bacterial
pustule, and mosaic viruses
Drought, low P tolerance Processing quality,
symbiotic nitrogen fixation
Cowpea Aphids, thrips, bacterial blight,
Striga, alectra, and mosaic viruses
Drought, low P tolerance, Pod quality, dual purpose
The Solution
• Genetic resources (reference sets, pre-breeding, Multi-parent Advanced Generation Inter-cross
(MAGIC) and intraspecific mapping populations)
• Genomic resources (comprehensive genetic maps, whole genome sequences, QTLs and trait-
specific markers)
• Integrated breeding approaches (high-throughput genotyping and phenotyping platforms, MAS
in pedigree breeding schemes, MABC and MARS)
• Improved varieties released and disseminated together
• Innovative seed and associated technology dissemination systems.
Results
• Policy issues (less emphasis on legumes compared to staples).