Application of marker assisted selection: A strategy to improve cassava production in Tanzania

Esther Andrew Masumba

Root/Tuber Research Program

Tanzania

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

Utilization of Cassava� Domestic consumption

� Tubers:

Fresh Cooked/boiled Crisps

Flour making (Ugali) Leaves: As vegetable

Utilization cont.

Industrial raw material:

� Food industries � Confectioneries (cakes, biscuits, etc)�Bakeries (breads)

�Weaning food for babiese.g. Power foods (agro processing company)

Cassava cake

Cassava biscuits

Bread

Utilizationcont.

�Starch production

�Ethanol productione.g. 280 L (222kgs) of 96% pure ethanol from 1 ton of cassava roots with 30% starch

Animal feed Silage

Cassava chips

High production Moderate production Low production

Main cassava cropping zones in Tanzania

National cassava production statistics

Location (zones) Production (%)

Production (tones)

Eastern & Southern 48.8 2,684,000

Lake 23.7 1,303,500

Southern Highlands 13.7 753,500

Western 7.9 434,500

Central 5.0 276,100

Others 0.9 49,510

TOTAL 100 5,451,600

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)

Important diseases

1. Cassava mosaic disease (CMD)

Symptoms:

o Distortion of leaf shape

o Reduction in leaflet size

o General stunting

o Yield reduction of up to 95 percent

2. Cassava brown streak disease (CBSD)

Leaf symptoms

Stem symptomsRoot symptoms

Causal agents and spread of both CMD and CBSD

Causal agent:Viruses

Spread:Whitefly (Bemisia tabaci)

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

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)

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

Identification of markers associated with CMD resistance (CIAT)

Tagging of CMD resistance gene -CMD2

� Molecular markers (SSR) that explain > 90% of phenotypic variance for CMD resistance, identified

� RME1, RME2, NS158 and NS169

Dist MarkercM Name

rGY1157.9

rGY9

15.6

rGY1

16.1

rSSRY28

11.3

Ai19

CMD2

R

MAS Scheme to Improve Tanzanian Cassava Germplasm

Seedling trial

(60,000 seedlings)

(Year 3)

Controlled crossing

(next slide)

(Year 2)

MAS

(Year 3)

Farmer participatory trial

≈ 600 genotypes

(Year 5)

Single row trial

≈ 10,000 genotypes

(Year 4)

Local varieties with

CBSD tolerance

(selected by farmers)

≈ 60 (Year 1)

Introduce CMD

resistant varieties

from CIAT ≈ 90 (Year1)

Development of resistant varieties

X

F1 sFruits and seeds

(Segregating population)

Female flower: Adaptable and

Tolerance to CBSD (Local variety)

Male flower: With a molecular marker associated with

CMD resistance (from CIAT, Colombia)

Typical cassava conventional breeding schemeYear Activity Number Plants per genotype

1 Collection , evaluation and selection of

parents

2 Crosses among elite clones planned, nurseries planted and pollinations made

Up to 100,000

3 F1: Evaluation of seedlings from

botanical seeds. Strong selection for CMD and CBSD in Africa

100,000a;

50,0000b;

50,00 c

1

4 Clonal evaluation trial (CET) 20,000–30,000a,b 700 c

6–8

(1 rep, 1 location)

5 Preliminary yield trial (PYT) 100 a; 300 b; 80 c 20–60

(3 reps, 1 location)

6 Advanced yield trial (AYT) 25 a; 100 b; 20–25 c

100–500

(3 reps, 2–3 location)

7-9 Regional trials (RT) 5-30 a, b, c 500-4 000

(3 reps, 3–4 locations)

Enhanced development, evaluation and official release of four CMD/CBSD resistant cassava varieties

S/N Variety Pedigree

Female parent

Male parent

1. Pwani Namikonga AR 42-4

2. Mkumba Namikonga AR 42-4

3. Dodoma Kiroba AR 3x-1

4. Makutupora AR 11-12 Namikonga

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

Characteristics of the varieties

S/no. Variety Maturity

age

Yield

potential

Root taste

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

Thank you

FUTURE PLANS

Multiplication and dissemination of the officially released varieties to the farming communities