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2-Plants: Brazil invests in cocoa genom reserach



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TITLE:  A) Brazil hopes cocoa genome will beat witch's broom
        B) The use of molecular biology techniques in search for varieties
           resistant to witches' broom disease in cocoa 
SOURCE: A) Reuters, by Jeremy Smith
        B) Common Fund for Commodities, The Netherlands
           http://www.common-fund.org/projects.htm
DATE:   A) November 7, 2000
        B) November 2000

------------------ archive: http://www.gene.ch/genet.html ------------------


A) Brazil hopes cocoa genome will beat witch's broom

ITABUNA, Brazil - Brazil hopes to use genome mapping to find a solution to 
the witch's broom fungus that has hit cocoa output over the past decade. 
Cocoa output in Brazil's northern state of Bahia, the key growing region of 
the Americas, has dropped sharply since the disease was first discovered in 
1989 - eliminating Brazil's status as a major world producer. "We have 
mapped some of the cocoa genome with markers and know that in some specific 
parts of it, there are a couple of genes which we can use...which are very 
associated with resistance to witch's broom," said Raul Rene Valle, head of 
the Agriculture Ministry's Cocoa Research Centre (Cepec). "But the (key) 
gene is there somewhere and we need to find it and put it in our plants. At 
least for witch's broom, we hope to have found it in two to three years," 
he said, speaking at Cepec's headquarters in Itabuna, heart of the cocoa 
region.

Cepec researchers are using biochemical and molecular markers to map the 
genome of cocoa and also that of the crinipellis perniciosa fungus causing 
witch's broom, tagging what may prove to be useful genes in their search to 
separate disease-resistant yet compatible types. The fungus attacks the 
living tissue of cocoa trees, particularly the pods, and petrifies the pulp 
inside. Its spores are mainly transmitted by small eddies of wind under the 
forest canopy - the traditional growing location in Bahia - even though 
this is normally a virtually windless area. The colourful name refers to 
the usual appearance of the tree's leaves after it has been infected with 
the fungus, as they tend to droop from the branches in a limp brown mass 
and resemble the broom which a witch is supposed to ride.

Cepec's research project involves analysing fungus samples from 20 
different localities in Bahia and a further 10 from other producing regions 
in Brazil. "They are testing different levels of aggressivity of the fungus 
in the samples, by region. There are genetic differences in the strains 
found in south and central Bahia," said Valle. "It's going to take time and 
money, but we have the expertise," he told Reuters. The $3.5 million 
programme is jointly funded by the Brazilian government and the 
International Cocoa Organization (ICCO) via the U.N.-linked Common Fund for 
Commodities in Amsterdam.

Sequencing a genome - the entire collection of genetic material - is only a 
very early step in unravelling the code underlying all of biology and has 
been compared with receiving several copies of a coded message that are all 
mixed up. These bits must be assembled and analysed, and even then it will 
probably still take years before the Cepec team knows where all the genes 
are located and the role of each one. Before witch's broom reared its head, 
Brazil ranked among the world's leading cocoa producers and saw output peak 
in Bahia - where some 90 percent of the country's crop was grown at that 
time - at just under 400,000 tonnes in 1985/86. But Bahia's yields tumbled 
by some 60 percent from 1990 to 1994 and Brazil now produces less than half 
that amount.

                               ****


B) The use of molecular biology techniques in search for varieties 
resistant to witches’ broom disease in cocoa 

Sponsoring ICB: International Cocoa Organisation 
Project Executing Agency: Comissao Executiva do Plano da Lavoura Cacaueira 
(CEPLAC) 

Project Cost                    USD 3,196,936 
Common Fund Grant               USD   816,197 
Counterpart Contribution
 CEPLAC                         USD 1,180,639 
Co-financing
 IOOC                           USD   422,100
 ISCMA                          USD   378,000
 UENF                           USD   400,000 

This research and development project aims at developing and releasing new 
cocoa plant varieties which are more uniform, more tolerant to disease 
(particularly to Witches’ Broom), and more productive. The loss 
attributable to Witches’ Broom in areas where it is endemic ranges from 30% 
to 70%. Biological control and the use of fungicides have been found to be 
inefficient in terms of cost/yield ratios and long-term control of the 
disease can be best achieved by use of resistant cocoa varieties. The 
project will develop the use of molecular markers to speed up the breeding 
procedures. Since 80% of the world’s cocoa is produced by smallholders, 
they stand to gain most from the project. The South American and Caribbean 
countries affected by Witches Broom disease will be the direct 
beneficiaries. Other cocoa producing countries will have access to the 
results of this project by participating in its training programmes and 
through workshops that will be held as part of the dissemination programme. 

The project includes the following activities: 
- construction of genetic linkage maps for cocoa; 
- identification and characterisation of molecular markers associated with 
  resistance to Witches’ Broom; 
- identification of QTL related to agronomic traits; 
- use of recurrent selection to form improved populations; 
- backcrossing of cocoa; this is a technique that was rarely used in cocoa 
  because of the long generation time; however, the use of molecular
  markers helps make it more efficient; 
- germplasm evaluation. 

After completion of the first two stages of the project, an independent 
comprehensive terminal evaluation  report on the results will be prepared. 
The findings will be discussed in a workshop to evaluate the  project's 
achievements against its predetermined objective. The implementation of 
project activities is expected to begin in 1999. 



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