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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #319560

Research Project: Genetic Improvement of Cacao Through Genomics-Assisted Breeding

Location: Subtropical Horticulture Research

Title: Molecular Characterization of Resistant Accessions of Cocoa (Theobroma cocoa L.) to Phytophthora Pod Rot Selected on-Farm in Côte-d’Ivoire.

Author
item Pokou, Desire - Centre National De Recherche Agronomique (NCAR)
item Motomayer, Carlos - Mars, Inc
item Tondo, Cecile
item Tahi, Mathias - Centre National De Recherche Agronomique (NCAR)
item Schnell, Raymond - M & M Mars Company - United States

Submitted to: International Journal of Agriculture and Biosciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2014
Publication Date: 10/30/2014
Citation: Pokou, D., Motomayer, C., Tondo, C.L., Tahi, M., Schnell, R. 2014. Molecular Characterization of Resistant Accessions of Cocoa (Theobroma cocoa L.) to Phytophthora Pod Rot Selected on-Farm in Côte-d’Ivoire. International Journal of Agriculture and Biosciences. 3(5):36-240.

Interpretive Summary: Cacao is an important agricultural product of Ivory Coast and Ivory Coast ranks first in the world, in export of cacao. Black pod is the most widespread disease of cacao, with losses to this disease ranging globally from 15% to 80% of farm production. Due to the economic importance of cacao, resistance to Black pod is becoming an increasingly important criterion for selection of new cacao varieties in Ivory Coast. Some new cacao cultivars, selected within the past ten years by CNRA in cooperation with farmers, have shown resistance to Black pod using the detached pod test. Results of genetic diversity analysis and Structure analysis, using 12 microsatellites primers, are presented for these resistant plants. Control clones from breeders collections were used, based on their membership to the recently established genetic groups of cacao. All farmers' accessions presented high heterozygosity value, and most were hybrids between the Amelonado and Upper amazon groups. Neighbor joining analysis performed, with 500 bootstraps, revealed 6 genetic groups which clustered closely with the 5 control groups of Amelonado, Maranon, Contamana, Iquitos and Nanay. One group remained unknown based on the controls used. Clones from the Scavina group, known to be resistant to Black pod at the CNRA Research station, are quite different to the resistant accessions from farmers' fields. It is recommended that these promising plants in farmers' fields be further exploited in breeding programs to obtain new hybrid or clonal cacao varieties with low incidence of Black pod.

Technical Abstract: Cocoa is (Theobroma cacao L.) is a significant agricultural commodity in Côted’Ivoire which ranks 1st in the world cocoa export. Phytophthora pod rot (Ppr)also call Black pod is the most widespread disease of cocoa. Lost due to this disease depends on the species of the pathogen and vary globally from 15% et 80% of the farm production. Due to the impact of cocoa on the economy, resistance to Phytophthora Pod rot (Ppr) is becoming increasingly important criterion of selection for new cocoa varieties in Côte-d’Ivoire. In this decade,the CNRA has selected new cocoa cultivars with involvement of farmers. Some of these cultivars have shown resistance scoring using detached pod test. Based on 12 microsatellites primers, the results of the genetic diversity and structure of these resistance plant materials are presented. Control clones from breeders collections were used basedon their relationship to the recent genetic structure of cocoa. All the farmers’ accessions presented high heterozygosity value. Most of farmers’ accessions were hybrids between amelonado and upper amazons groups. The neighbour joining analysis performed after 500 bootstrapping revealed 6 genetic groups respectively close to the 5 control groups of amelonado, maranon, contamana, Iquitos and Nanay. Control clones from the scavina group especially, those known be resistant to Pprat the CNRA Research station are quite different to the resistance accessions on the farmers’ field. One group remained unknown based on the controls used. It is recommended that the genetic structure identified through these promising plants in farmers’ fields be further exploited in breeding to obtain new hybrid or clonal cocoa varieties with low incidence of Ppr.