Breeding for black pod disease resistance cocoa in Ghana

By

Abu M. Dadzie and GeorgeA.Ameyaw

Outline of Presentation

Cocoa production and some challenges

affecting it.

Cocoa introduction

Black pod disease of cocoa

Germplasm and hybridization

Developed Hybrids

Use of MAS in cocoa breeding

Achievments

Introduction

• West Africa produces 70% of the world’s cocoa

• About 2,000,000 small holder farms in West Africa contributes

the entire production

• Ghana –produces 14% of the entire beans in the world

• Western region of Ghana produces 55% of total cocoa beans

from Ghana

Map of Ghana and Cocoa Districts

Challenges associated with cocoa cultivation

• Low yields: between 250 - 350kg/ha with unimproved

materials whiles improved materials gives between 500 –

1500 kg/ha

• Small-scale farmers (1-6 ha): unstable low income

• Cocoa Swollen Shoot Virus Disease

• Black pod caused by Phytophthora palmivora and

megakarya

• In megakarya endemic areas: 80 - 100% losses are

recorded

Early cocoa introductions / Planting materials

• Amelonado cocoa types which produce small pods with good

flavour was introduced from Fernando – po (Equatorial

Guinea) where it was cultivated to Ghana by Tetteh

Quarshie in 1878.

• This introduction succumbed to both Black pod and CSSVD.

Infected pods Healthy pods

Infected pods Heap of disease pods from P. megakarya endemic area

How can we address the black pod menace ?

• Develop improved cocoa varieties for farmers

• Application of good agronomic practices such as :

• Regular removal and burying of infected pods

• Good shade management

• Adhering to recommended plant spacing

• Regular pruning of chupons etc

How can we achieve our goal?

• Through:

– Training of research personnel

– Access to well characterized germplasm

– Merging conventional and molecular breeding

techniques and tools

– Application of Suitable technological Package

• Improved seed garden output

• Use of improved seeds by farmers

Further introductions made into the gene bank with

black pod resistance attribute

• Upper and Lower Amazon materials (Foresteros)

• Trinitarios (Foresterios x Criollos)

Germplasm

• Sources:

Ex-situ collections

– Amazon collections

– Local collections

• Characteristics:

– Resistance to pests

and diseases

– High yield

– Bean quality

– Tree architecture

Variation in germplasm collections

Hybridization (crossing) of various germplasm materials

to raise progenies with specific traits such as

Disease resistance, Moderate vigor, Large bean size, Reduced gestation etc.

X

Local Trinitario Upper Amazon

Comencement of Breeding by utilizing Germplasm materials

Established trials to address Black pod disease

• Progeny trials (Upper Amazon) Gestation Prd

x Amazon ( 2 – 4yrs)

x Trinitarios ( 3 – 4yrs)

x Amelonado (6 – 8yrs)

• Clonal trials (local Trinitarios and international clones)

• Combining ability trials ( varied males x females).

Early hybrids developed

• Series i

• Series ii

• Series iii

• Series iv

• Series v

• Series vi

General Purpose

Specific Purpose

iv – cssvd, v- black pod and vi- drought issues, some hybrids

were released in 1986 and are performing very well in

farmers’ farms

Variety development may last longer than 20yrs therefore the need to

employ molecular markers or marker assisted selection in breeding

Further breeding work done to improve resistance

Include:

Introduction of marker assisted selection (MAS) technique

where two main maker types are considered to hasten

breeding time. The markers are mainly used for,

• For (genetic finger printing) identification of planting materials

• For mapping or Identification of genes associated with black

pod resistance or other trait..

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3 WRKY-10 0.0 cir111 0.3 cir232 1.3 cir119 2.1 shrs37 5.2 shrs12 7.4 shrs11 7.6 cir148 13.5 shrs22 18.2 cir10 21.5 Tce030 26.1 cir196 cir123 26.8

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cir170 40.7 shrs19 47.7 cir245 48.8 cir69 WRKY-11 49.1

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10

Pod Number

Trunk Circumference

Pod Number & Wet Bean Weight

Witches’ Broom

Resistance

Pod Weight

Frosty Pod Resistance & Wet Bean Weight

Bean Length

Jorquette Height

Frosty Pod

Resistance

Bean Length, Seed Weight,Ovule Number, & Trunk Circumference

Black Pod

Bean Weight, Bean Thickness,

Pod Weight & Pod Length

~40 identified QTLs in cacao

Identifying favourable alleles using SSRs

Allele size calls

SNP Markers used for similar purpose

Certifed parents have been identified and are being used in

further breeding trials or recommended for Seed Production Unit

for multiplication and supply of improved planting materials to

farmers.

Presently new potential male and female parents have been

identified and will be released to the SPU to increase the

number of existing parents or replace some parents

At the institute some potential parents for black pod disease

resistance have been identified and crossed to most promising

genotype tolerant to CSSVD to raise population for further

molecular studies. It is expected that new hybrids that combine

both Black pod and CSSVD tolerance traits will made available

soon

Achievements

About 10 female clones and four good male clones have been

supplied to various seed gardens across Ghana for multiplication

and distribution to farmers based on the need of the community

Parents supplied to various seed gardens may vary depending

on the need of the community farmers.

Thank you