Sweetpotato Regional Breeding for East and Central Africa

R. Mwanga, S. Tumwegamire, Sammy Agili, W. Gruneberg, J. Low, G. Ssemakula, E. Tsegaye, P. Ndolo, L. Karanja, E. Lukonge

R. Amour, J. Ndirigwe

Outline

Recent sweetpotato breeding

activities in E. & Central Africa

Example of sweetpotato breeding

cycle, Uganda

East and Central Africa

support platform breeding activities

Accelerated breeding

Sweetpotato Breeding Activities

Previously Supported by HarvestPlus

HP Meeting 2003, CIAT, Cali, Colombia

Introduced 40 OFSP In Vitro Clones to SSA

plus seed

Target total 10 countries from West, South and

Central Africa.

OFSP Clones Released/Grown in Sub-Saharan Africa

*

**

Uganda

(Namulonge, Serere)

*

*

*

*

Zanzibar

*

*

Gurue

Kibaha

Angoni

Umbelezi

Hombolo

Bukoba

Mandoto**Mimosa

*

Kenya

(Kakamega)

*Rwanda (Rubona, Kibundo)

Madagascar

TZ

SA

GH

MO

**

Regional GxE OFSP 15 Trial Sites, 2006/2007

Breeding programs

introduced and

produced seed

(open pollinated

and specific

crosses) for

screening, selection

and exchange

Exchange of Sweetpotato Seed

6 Released in 1999 2 Released in 2004

5 Released in 2007 NASPOT 11 Released in 2010

Twenty Varieties Released by the Sweetpotato Breeding

Program in Uganda, 1995-2010 (Mwanga et 2009, 2010)

Local, Introduced &

Improved Germplasm & Breeding lines

Crossing Block (Polycross)

Clonal Evaluation (Yr 2)

2,000 Clones (No Reps)

Seedling Nursery (Yr 1)

100,000 Seedlings

Preliminary Yield Trial (Yr 3)

100 Clones (Replicated)

Intermediate

Yield Trial (Yr 4)

50 Clones (Replicated)

Advanced / Multi-Location

Trials (Yrs 5,6) 25 Clones

Replicated

On-farm Trials (Yr 7) 5

Clones (Replicated

Variety Release (Yr 8)

Sweetpotato

Breeding

Scheme

Uganda

Sweetpotato Weevil Damage

Losses can reach 100%

during dry periods

To date no durable resistance

Sweetpotato virus

disease (SPVD) can cause up 98% yield loss

(Gibson et al. 1998)

SP chlorotic stunt virus SP feathery mottle virus

Sweetpotato Support Platform (SSP) Breeding

Activities• Population (P)

improvement by SSP –

long term (SASHA)-

use distinct

populations to lead to

major improvements

(heterosis) in e.g. yield,

disease resistance

•Variety (V)

improvement by

sweetpotato National

programs – short term

(AGRA or other

support)

Population improvement

SASHA Project

Accelerated Breeding

Multiply new breeding lines in

screenhouses, glasshouses,

irrigated fields

Accelerated Breeding

•Use more sites at

earlier stages in the

breeding cycle to

substitute for fewer

sites over seasons

Kachwekano

Namulonge

Serere

Ngetta

Trial Sites in

Uganda

Confirming Resistance to Viruses

Complex and tedious

Identify Gene/Marker and Verify

Marker

Sequence

Compare to

known sequences

Specific

Primers

(rkn1f, rkn1r))

Confirm

QTL

Testing in other

Progeny or

clones

Use marker for

selecting resistant

clones (MAS)

pCIP84

14602 bp

kanamycin (R)

nptII

Cry7Aa1

Cry3Ca1

T-BORDER (R)

pVS1 Sta

T BORDER (L)

pBR322 bom site

POLY A SITE

gSPOA1 promoter

nos P

B-amyl

pBR322 ori

pVS1-REP

TATA box

T35S

3' beta-amy

3' gSPOA1

Introduce Weevil Resistance

Genes into Sweetpotato Using

Biotechnology

END