genetic enhancement of beta-carotene in storage roots of cassava varieties in africa
DESCRIPTION
Screening cassava germplasm for ß-carotene,Evaluation of ß-carotene-rich genotypes: agronomic characteristics,Introduction of germplasm from within and outside SSA,Gene introgression for the improvement of ß-carotene levels..TRANSCRIPT
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
GENETIC ENHANCEMENT OF BETA-CAROTENE IN
STORAGE ROOTS OF CASSAVA VARIETIES IN AFRICA:
WHERE DO WE STAND?
A.G.O. Dixon, G.N. Ssemakula, B. Maziya-Dixon
and J.M. Ngeve
International Institute of Tropical Agriculture, PMB 5320 Ibadan, Nigeria.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Outline Of Presentation
Screening cassava germplasm for β-carotene
Evaluation of β-carotene-rich genotypes: agronomic
characteristics
Introduction of germplasm from within and outside SSA
Gene introgression for the improvement of β-carotene levels
Deployment of β-carotene-rich germplasm to NARS in SSA
Assessment of effect of processing on β-carotene retention in
cassava foods and profiling of cassava carotenoids.
Participatory on-farm trials and variety release
Opportunities and challenges and the way Forward
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
The Cassava Germplasm Development-
Africa Component of H+
Initiated at IITA in 2003
Global objective
Develop cassava varieties with high ß-carotene,
levels in the roots packaged in preferred
agronomic backgrounds, and make these
varieties available to farmers in SSA
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Strategic objectives
- Increase micro-nutrient (pVAC, Fe, Zn) content in cassava
- Increase protein content in cassava
- Reduce hydrocyanic acid content in cassava
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Tactical objectives
- Characterize cassava products for pVAC, Fe and Zn
- Characterize cassava products for protein quality
and quantity
- Characterize cassava products for levels of HCN
- Develop source populations for selection for these
traits
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Screening traits of interest in
cassava germplasm
Development of sampling method: which portion of
the root? What maturity?
Longitudinal, distal, central, and proximal portions of
cassava roots
Sampling at 6, 9, and 12 MAP
Correlation between values from different portions
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
β-carotene 6 & 9 MAP df =24 T value = -7.96 p <.0001
β-carotene 6 & 12 MAP df =24 T value = -7.34 p <.0001
β-carotene 9 & 12 MAP df =24 T value = 2.53 p = .0182
Sampling at 12 MAP adopted
Visual rating for carotenoid concentration vs actual concentration
Mean micronutrient
concentrations 6, 9, &12 MAP
β-carotene (μg/g) Fresh root weight
MAP 6 9 12
Mean 0.33 3.08 2.09
SE 0.25 0.88 0.65
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Year Total
No.
families
Total
No.
plants
Screening method Deep
yellow
selected
Light
yellow
selected
Min
TC
Max
TC
2004/05 476 16,832 Color chart 24 379 - 10.1
μg/g †
2005/06 982* 19,644 Color chart,
spectrophotometric
895 1386 2.8
μg/g
11.9
μg/g
2006/07 490 8743 Color chart,
spectrophotometric
667 158 1.23
μg/g
14.81
μg/g
2007/08 638 28,865 Color chart,
spectrophotometric
1548 >500 1.56 13.27
* Comprised of 133 families from CIAT, 59 from Brazil, and 790 local crosses from IITA Ibadan ;
†Obtained from 2005 clonal evaluation; Screening done at different stages of the breeding prog.
Carotenoids (fresh wt basis)
from screening cassava in 4 yrs
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Selection stage
2009/10
Range of pVAC in
storage roots
Clonal Evaluations 0.2 – 10.4
Advanced Yield Trials 4.7 – 11.1
Uniform Yield Trials (UYT) 0.58 – 9.5
Levels of pVAC in different stages of selection in 2009
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Levels of pVAC in genotypes advanced from
seedling nursery to clonal evaluation in 2009
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Levels of pVAC in genotypes selected and
evaluated in advanced/UYT trials in 2009
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
G x E: carotenoid concentration FW basis)
AMMI:
High G –TC
G x E – highly
sig for TC
Carotenoid
concentration is
a stable trait
Single location
selection reliable
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Resistance to pests &
diseases
Stem yield & architecture
Root number &
size/weight
Root quality
Stability - across locations
Seedling nursery
Clonal Evaluation
Preliminary Trial
Advanced Yield Trial
Uniform Yield Trials
OFAR Trials
Agronomic superiority for
acceptability
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05/1601 1.0 2.0 36.5 38.9 9.4
05/1600 3.2 2.5 34.5 29.0 6.5
05/1570 1.0 2.0 33.3 41.9 2.4
05/0327 1.0 4.5 28.4 37.8 6.2
05/1862 1.2 2.5 27.1 39.3 4.5
05/0311 1.0 2.5 25.7 40.9 5.5
05/0099 1.0 2.0 25.1 38.9 5.8
05/1654 1.0 3.0 23.0 34.9 6.9
05/0476 1.0 3.0 19.7 40.3 4.0
05/1652 1.0 2.5 19.5 31.3 8.3
Agronomic characteristics and pest reactions
of promising micronutrient-rich clones
Clone CMD CGM Yield DM Carotene
(t/ha) (%) (µg/g)
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
G x E : fresh root yield
E effect highest for yield
G x E*** for yield
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
G x E : DM content
G effect highest for DM
G x E*** for DM
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Source Form Quantity
Tanzania Landarace 18
Malawi Landarace 14
Zambia Landarace 11
Latin America ,
Thailand
Landarace ,
improved clones
44
CIAT Seed populations 207 families
(4754 seeds)
Brazil (thru CIAT) Seed populations 59 families
(8074 seeds)
Acquisition of β-carotene-rich and
African adapted germplasm
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Introgression of genes to enhance carotene
levels in IITA germplasm
Season Families Seeds
2003/04 499 >16000
2004/05 790 19,644
2005/06 490 14,000
2006/07 859 33,548
2007/08 725 54,295
2008/09 166 9006
Total 3529 146,493
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Virus-free certified tissue culture plantlets
Deployment of germplasm
Country Seed families No. of seeds
Guinea 71 >10,100
Congo DR 30 >10,000
Uganda 64 >10,100
Kenya 23 >23,000
Malawi 24 >24,000
Angola 23 >23,000
Mozambique 23 >23,000
Sierra Leone 23 >46,000
Ghana 17 >18,100
HS seed families
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Colchicine induced
polyploidy >20 YR Clones
4x versus 2x counterparts
Effect of polyploidization on
carotene content
(carotene 4x>carotene2x)
Tetraploid x diploid crosses
for more productive triploids
Polyploid breeding for enhanced
carotene content
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
• Tetraploids had significantly higher concentrations of total carotene than diploids
• Mean dry matter content of tetraploids was significantly lower than of diploids
• Clone X ploidy level interaction was significant
• Some tetraploid clones had higher dry matter content over the mean
Comparative analysis for total carotene and dry matter
content of 20 artificially induced Tetraploids (4x)
vs their diploid counterparts (2x)
TC DM %
Parameter 2X 4X Mean 2X 4X Mean
Mean 4.7 5.4 5.03 36.78 33 35.5
SE 0.6 0.7 0.59 0.9 0.7 0.75
Min 0.4 0.7 0.57 27.19 28 29.67
Max 8.4 10 9.18 42.49 38 42.44
Pr>F (Ploidy level) *** ***
Pr>F (Clone) *** ***
Pr>F (Clone*Ploidy level) *** ***
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Mutation breeding – (with IAEA)
TMS lines 01/1371, 98/0002 irradiated with gamma rays
Mutants cloned and total carotene (TC) determined
Worth of mutation breeding in enhancing nutrient concentration
Effect of irradiation with gamma rays/fast neutron on β-carotene
concentration
30, 600 seeds irradiated (100 families), nursery ~ 2, 797 seedlings harvested,
cloned and selfed
Parameter TC
Mean 6.09
SE 0.12
Min 3.55
Max 9.74
N 112
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Crop Pot Plate Mouth Intestine
Nutrient loss during processing: an
inevitable and unfortunate reality
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
0
10
20
30
40
50
60
70
80
90
100
Boil Raw fufu Cooked fufu Gari chips
Processed product
% n
utri
ent r
eten
tion
Total carotene
β-carotene
Iron
Zinc
Highest nutrient retention in boiled roots
True micronutrient retention (%) of cassava products prepared from
fresh storage roots of three elite yellow-fleshed cassava clones
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
True micronutrient retention (%) of gari prepared
from 24 elite yellow-fleshed cassava clones
Micronutrient retention is genotype dependent
Genetic variation for micronutrient retention can be exploited via breeding
0
5
10
15
20
25
30
35
40
45
50
01/111
5
01/122
4
01/123
5
01/127
3
01/127
7
01/133
1
01/133
5
01/136
8
01/137
1
01/141
2
01/141
3
01/144
2
01/161
0
01/164
6
01/164
9
01/166
2
01/166
3
90/015
54
94/000
6
94/033
0
95/037
9
98/213
2
Total carotenoids in fresh roots (µg/g)
Total carotenoids in Gari (µg/g)
% True total carotenoids retention*
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Carotenoids profile of 22 yellow-fleshed cassava genotypes
90% of carotenoids in cassava is β-carotene
> 50% of carotenoids in cassava is Trans- β-
carotene
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Carotenoids species in yellow-fleshed cassava
clones evaluated at 5 locations in Nigeria, 2005/06
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Shift in nutrient levels with conventional
breeding and selection for nutritional quality
Micro-nutrient Baseline 2003/2004 2004/2005 2005/2006 2006/2007 2007/2008 2008/2009
Total carotene 0.4 μg/g 4.8 μg/g 10.1μg/g 11.9 μg/g 14.8μg/g 13.3 μg/g 10.4 μg/g
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Participatory on-farm evaluation and
release of yellow-fleshed cassava
Objectives
Assess performance of yellow-fleshed clones under
farmer managed conditions
pluses (+) and minuses (-) of the clones – farmers’
perspective
Farmer exposure to yellow genotypes
SE states: Abia, Imo, Anambra, Enugu, Ebonyi, Akwa
Ibom,& Cross River
SW states: Lagos, Ogun, Ondo, Ekiti, Oshun, & Oyo
Preferences
96/1089A, 01/1115, 01/1371, 01/1412,
01/1368, 98/2132, 30572, 01/1663,
01/1610, 01/1235, 01/1404
Selection criteria
Yield, processed product yield and
quality, tuber size, no need to fortify
gari with palm oil, color, recognition
Skeptical farmers- yellow cassava a
GMO?!Farmer carries a tuber of 01/1404; it
weighed more than 6 kg
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
98/2132 5.9 5.3 5.1 4.7 5.901/1368 5.4 5.2 5.0 4.8 5.794/0006 4.2 4.4 4.0 3.8 5.195/0379 4.7 4.6 4.0 4.6 5.096/1089A 4.3 4.8 4.3 4.7 4.901/1380 4.9 4.8 4.6 4.3 4.890/01554 4.5 4.4 4.1 4.3 4.801/1277 4.9 4.1 3.9 3.0 4.401/1649 4.7 3.9 3.9 3.7 4.401/1663 4.1 3.8 3.9 4.0 4.4
TME 1 1.3 2.1 2.6 2.0 1.630572 4.2 4.1 3.6 3.8 4.691/02324 5.3 5.2 4.7 4.7 5.7
Clone Color Texture Mealiness Starchiness Overall
acceptability
Scored on a
1-6 scale
where:
1=poor
6= very
good
Levels of acceptability of food from yellow
root cassava: Gari
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
1. Correlation of Total Carotene (TC) to Fresh root Yield
(FYLD) and dry mater content (DM) was negative and
significant for some trials.
2. Across all yellow root trials , the correlation remained
negative but was not significant
Trait Association
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Status of germplasm introduced to target
NARS (Nigeria and DR Congo)
Nigeria• Improved seed populations have been planted in seedling nurseries
• Improved genotypes with high pVAC are in various selection trials
• Three high pVAC genotypes are in pre-release trials
DR Congo• Improved seed populations have been planted in seedling nurseries
• Improved genotypes with high pVAC are in various selection trials
• Germplasm collection of high pVAC genotypes is maintained at
Mvuazi
• Hybridization of high pVAC parents is ongoing
• Product and market development and sensitization key to
release of new pVAC varieties before 2012.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Nigeria: TMS 96/1089A - First ever Official release of
yellow-flesh cassava variety
DR Congo: TMS 94/0330 and TMS 01/1661
Official Releases in Africa
Yellow cassava in Nigeria (Gari) and DR Congo (fufu, chikwangue,
fresh roots) have higher price premium than white or cream ones
Yellow Gari
White Gari
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Variety
Fresh
Yield
(t/ha)
Dry
matter
(%)
Starch
content
(%)
CMD CBSD Color
Total
carotene
content
(μg/g) FW
94/0330 27.8 40.5 21.5 1.3 1.0 Yellow 5.23
01/1661 39.6 28.8 14.0 1.0 1.0 Yellow 7.29
TME
41945.6 39.3 28.9 1.0 1.0 White
-
RAV
(check)14.0 31.3 20.3 3.0 1.0 White
-
Characteristics of YR varieties released in
DR Congo by INERA in June 2008.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Opportunities and challenges
Opportunities
High prospects of hitting the target level (15 μg/g) for
β-carotene
Some countries (Nigeria, DR Congo and Ghana) are
already exposed to and/or using yellow root cassava -
attitude may not be a major issue
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Some of the high carotenoid clones are weak, probably
because they resulted from selfing
Often high carotenoid clones have low DM and low yield
Plateauing of Total Carotene
Will have to develop early bulking varieties since carotene
is lost with age in the ground, ie > 9 months
Challenges
Opportunities and challenges;
lessons learnt
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Way forward
• Introduce diverse genotypes with higher levels of beta carotene (esp. mealy deep yellow/orange parents)
• Identify parents with high breeding values for deep yellow-fleshed roots, mealiness, high dry matter content, low CnPand resistance to CMD and CBSD for use in crossing blocks
• Develop source population for yellow-fleshed roots by crossing selected genotypes to locally adapted lines
• Multiply and distribute available beta-carotene and agronomically superior genotypes for selection under local environmental conditions
• Sensitize the population on the importance of consuming beta-carotene rich cassava varieties
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
• Investigating the underlying environmental and agronomic factors on pVAC trait expression
• Use of index selection for overcoming the negative association between pVAC and yield/DM
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Acknowledgements:
HarvestPlus and IITA, NRCRI and INERA
Thank You!