Presentation at the November 2012 dialogue workshop of the Biosciences for Farming in Africa media fellowship programme in Arusha, Tanzania. Please see www.b4fa.org for more information

1. Application of marker assisted
selection: A strategy to improve
cassava production in Tanzania
Esther Andrew Masumba
Root/Tuber Research Program
Tanzania

2. Importance of Cassava
Cassava is among the primary
staples in some areas within
Tanzania.
Ranks second after maize
It is among the leading food
security crops in Tanzania
It strives well in marginal soils
and drought prone climates
Hence, liable to positively cope
with the current climate change
effects
Cassava plant

3. Utilization of Cassava
Domestic consumption
Tubers:
Fresh
Flour making (Ugali)
Cooked/boiled
Crisps
Leaves: As vegetable

4. Utilization cont.
Cassava cake
Industrial raw material:
Food industries
Confectioneries (cakes, biscuits, etc)
Bakeries (breads)
Cassava biscuits
Weaning food for babies
e.g. Power foods (agro processing
company)
Bread

5. Utilization
cont.
Starch production
Ethanol production
e.g. 280 L (222kgs) of 96% pure ethanol
from 1 ton of cassava roots with 30%
starch

6. Animal feed
Cassava chips
Silage

7. Main cassava
cropping
zones in
Tanzania
High production
Moderate production
Low production

8. National cassava production statistics
Location (zones)
Production
(%)
Production
(tones)
Eastern & Southern
48.8
2,684,000
Lake
23.7
1,303,500
Southern Highlands
Western
Central
Others
TOTAL
13.7
7.9
5.0
0.9
100
753,500
434,500
276,100
49,510
5,451,600

9. Constraints in cassava production
Average yield in the farmers fields ~ 10.5 tones per
hectare.
Far below the crop potential production potential of
up to 90 tones per hectare.
The decline is contributed by:
o Low yielding ability inheritable to the varieties
o Poor agronomic practices
o Varieties susceptibility to existing pests and
diseases (Major)

10. Important diseases
1. Cassava mosaic disease (CMD)
Symptoms:
o
Distortion of leaf shape
o
Reduction in leaflet size
o
General stunting
Yield reduction of up to
95 percent
o

11. 2. Cassava brown streak disease
(CBSD)
Leaf symptoms
Stem symptoms
Root symptoms

12. Causal agents and spread of both CMD and
CBSD
Causal agent:
Viruses
Spread:
Whitefly (Bemisia tabaci)

13. Control of CMD and CBSD
Phytosanitation
Selection of healthy planting materials
Up rooting of diseased plants
Use of tolerant/resistant varieties
Developed through conventional breeding
Marker assisted selection

14. EFFORTS DONE BY ROOT/TUBER
RESEARCH PROGRAM IN TANZANIA
Molecular Marker-Assisted and Farmer Participatory
Improvement of Cassava Germplasm for Farmer/Market
Preferred Traits in Tanzania Project
Phase 1: 2003 – 2006 (Rockefeller foundation funded)
Phase 2: 2007 – 2009 (Alliance for Green Revolution in Africa funded)

15. Objectives
Improve local germplasm for cassava mosaic
resistance using improved genotypes from CIAT
Impalement Molecular Marker-Assisted (MAS) for
Cassava Mosaic Disease to increase cost-effectiveness
Train NARS breeders in Molecular breeding methods
Involve end users and trade intermediaries in uptake

16. Identification of markers associated with
CMD resistance (CIAT)
Tagging of CMD resistance gene CMD2
R
Dist
cM
Marker
Name
rGY115
Molecular markers (SSR) that
explain > 90% of phenotypic
variance for CMD resistance,
identified
7.9
rGY9
15.6
rGY1
16.1
CMD2
rSSRY28
11.3
Ai19
RME1, RME2, NS158 and NS169

17. MAS Scheme to Improve Tanzanian Cassava Germplasm
Introduce CMD
resistant varieties
from CIAT ≈ 90 (Year1)
Controlled crossing
(next slide)
(Year 2)
Seedling trial
(60,000 seedlings)
(Year 3)
Single row trial
≈ 10,000 genotypes
(Year 4)
Local varieties with
CBSD tolerance
(selected by farmers)
≈ 60 (Year 1)
MAS
(Year 3)
Farmer participatory trial
≈ 600 genotypes
(Year 5)

18. Development of resistant varieties
Female flower: Adaptable and
Tolerance to CBSD (Local variety)
Male flower: With a molecular marker associated with
CMD resistance (from CIAT, Colombia)
X
F1 s
Fruits and seeds
(Segregating population)

19. Typical cassava conventional breeding scheme
Year
Activity
1
4
Collection , evaluation and selection of
parents
Crosses among elite clones planned,
nurseries planted and pollinations made
F1: Evaluation of seedlings from
botanical seeds. Strong selection for
CMD and CBSD in Africa
Clonal evaluation trial (CET)
5
Preliminary yield trial (PYT)
6
Advanced yield trial (AYT)
2
3
7-9 Regional trials (RT)
Number
Plants per genotype
Up to 100,000
100,000a;
50,0000b;
50,00 c
20,000–30,000a,b
700 c
100 a; 300 b; 80 c
25 a; 100 b; 20–25
c
5-30 a, b, c
1
6–8
(1 rep, 1 location)
20–60
(3 reps, 1 location)
100–500
(3 reps, 2–3 location)
500-4 000
(3 reps, 3–4 locations)

20. Enhanced development, evaluation and official release
of four CMD/CBSD resistant cassava varieties
S/N
Variety
1.
Pwani
Pedigree
Female
Male
parent
parent
Namikonga AR 42-4
2.
Mkumba
Namikonga
AR 42-4
3.
Dodoma
Kiroba
AR 3x-1
4.
Makutupora AR 11-12
Namikonga

21. Recommended agro ecologies for the dissemination of
the new varieties
S/no Clone (Variety)
Target zone
Agro ecology
1.
Pwani (B2C20-65)
Eastern and
southern
Lowland warm sub
humid
2.
Mkumba (3C20-10)
Southern
Lowland warm sub
humid
3.
Makutupora (2C80-42)
Central
Mid to high altitude
warm semi arid
4.
Dodoma (BC231-2)
Central
Mid to high altitude
warm semi arid

22. Characteristics of the varieties
S/no.
Variety
Maturity
age
Yield
Root taste
potential
1.
Pwani
11 - 12
50.8
Sweet
2.
Mkumba
9 -10
23.3
Sweet
3.
Makutupora
9 - 10
30.3
Bitter
4.
Dodoma
9 - 10
36.1
Sweet

23. Thank you

24. FUTURE PLANS
Multiplication and dissemination of the officially
released varieties to the farming communities