Magali Dufour

Genetics of coffee quality

Coffee quality, in the present context of overproduction worldwide, has to be considered as a main selection criterion for coffee improvement. After a definition of quality, and an overview of the non genetic factors affecting its variation, this review focuses on the genetic factors involved in the control of coffee quality variation. Regarding the complexity of this trait, the different types of quality are first presented. Then, the great variation within and between coffee species is underlined, mainly for biochemical compounds related to quality (caffeine, sugars, chlorogenic acids, lipids). The ways for breeding quality traits for cultivated species, Coffea arabica and Coffea canephora are discussed, with specific challenges for each species. For C. arabica, maintaining a good quality in F 1 intraspecific hybrids, introgressed lines from Timor hybrid, and grafted varieties are the main challenges. For C. canephora, the improvement is mainly based on intraspecific and interspecific hybrids, using the whole genetic variability available within this species. An improvement is obtained for bean size, with significant genetic gains in current breeding programmes. The content in biochemical compounds related to cup quality is another way to improve Robusta quality. Finally, ongoing programmes towards the understanding of the molecular determinism of coffee quality, particularly using coffee ESTs, are presented.

Stable resistance against the leaf miner #Leucoptera coffeella# expressed by genetically transformed #Coffea canephora# in a pluriannual field experiment in French Guiana

SummaryA pluriannual field trial of transgenic clones of Coffea canephora (the Robusta coffee tree) transformed for resistance to the lepidopteran coffee leaf miner Leucoptera coffeella was installed in French Guiana. Fifty-eight transformed clones produced by transformation of the C. canephora clone 126 were planted. They were harbouring the pEF1α constitutive promoter of Arabidopsis thaliana controlling either the Bacillus thuringiensis native gene for the cry1Ac insecticidal protein (eight clones) or a synthetic cry1Ac gene (53 clones). The vectors for the transformation were a strain of the bacterium Agrobacterium tumefaciens and one of Agrobacterium rhizogenes. The transformed clones were generally independent, presenting different integration patterns of the genetic construct. Four randomly distributed groups of five plants per transformed clone were planted along with 60 untransformed control trees. Over a 4-year period after plantation six releases of L. coffeella were performed. Mines on the leaves are the marks of larvae development and were counted on plants. A majority of the independent transformed clones harbouring the synthetic gene and transformed by the strain of A. tumefaciens displayed constantly much less mines than the control, therefore expressing a stable resistance. The need for complementary research is presented.

An initial assessment of linkage disequilibrium (LD) in coffee trees: LD patterns in groups of Coffea canephora Pierre using microsatellite analysis.

BackgroundA reciprocal recurrent selection program has been under way for the Coffea canephora coffee tree for approximately thirty years in the Ivory Coast. Association genetics would help to speed up this program by more rapidly selecting zones of interest in the genome. However, prior to any such studies, the linkage disequilibrium (LD) needs to be assessed between the markers on the genome. These data are essential for guiding association studies.ResultsThis article describes the first results of an LD assessment in a coffee tree species. Guinean and Congolese breeding populations of C. canephora have been used for this work, with the goal of identifying ways of using these populations in association genetics. We identified changes in the LD along the genome within the different C. canephora diversity groups. In the different diversity groups studied, the LD was variable. Some diversity groups displayed disequilibria over long distances (up to 25 cM), whereas others had disequilibria not exceeding 1 cM. We also discovered a fine structure within the Guinean group.ConclusionsGiven these results, association studies can be used within the species C. canephora. The coffee recurrent selection scheme being implemented in the Ivory Coast can thus be optimized. Lastly, our results could be used to improve C. arabica because one of its parents is closely related to C. canephora.

Coffee (Coffea Sp.) Genetic Transformation for Insect Resistance

Coffee, as a woody species, has a long biological cycle and it takes between four and five years from seed to seed. Therefore, classical breeding programmes generally spread over 20 to 30 years. Unconventional breeding techniques would be of utmost importance for quick genetic progress. One of these techniques is genetic transformation. Using this process, it could be possible to insert selected traits in coffee without changing the whole genome. Genetic transformation is basically the introduction of foreign DNA into plant cells. Two main techniques are used for plant transformation: i) direct transformation, through biolistics (McCabe et al., 1988), DNA uptake (Zhang and Wu, 1988), or protoplast electroporation (Fromm et al., 1985), and, ii) indirect transformation using viruses or Agrobacterium sp (Bevan et al., 1983).

Coffea SPP. Genetic Transformation

Coffee is an extremely important agricultural crop with more than 7 millions tonnes of green beans produced every year on about 11 millions hectares. In terms of economic importance on the international markets, it is second only to oil and contributes to more than US

Construction and characterization of a Coffea canephora BAC library to study the organization of sucrose biosynthesis genes

9,000 million.