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The former Coffea subgenus is a species complex showing qualitative gene flow and reproductive barriers between species. Such qualitative gene flow allowed its evolution over time, particularly during the successive forest expansion-regression cycles in relation with glaciation periods. The present paper reviews the main botanical, geographical and genetic characteristics of the Coffea genus and then focuses on the former Coffea subgenus. Its broad distribution in Africa, Madagascar and Mascarene Islands is related to the high diversity of ecological situations. The importance of sympatry and parapatry cases and their role on gene flow possibilities between species is then underlined in the paper. Such gene flow is nevertheless partially limited by reproductive barriers: flowering date, frequency of hybrid F1 emergence, as well as the vigor and fertility of such hybrids. When hybridization occurs, distortion of segregation and disruptive selection would allow qualitative flow of non-adaptative genes, thus limiting the effect of genetic drift in small populations. The last part of the paper defines the notion of metaspecies in the case of the former Coffea by extension of the concept of metapopulation to species. The evolution over time of a metaspecies is finally discussed in relation with sympatry situations, gene flow possibilities and forest fragmentation.

Coffea canephora Pierre ex Frohener is a perennial plant originated from Africa. Two main groups, Guinean and Congolese, have already been identified within this species. They correspond to main refugia in western and central Africa. In this paper we present the analysis of a region that has not yet been studied, Uganda. Two wild, one feral (once cultivated but abandoned for many years), and two cultivated populations of C. canephora from Uganda were evaluated using 24 microsatellite markers. Basic diversity, dissimilarity and genetic distances between individuals, genetic differentiation between populations, and structure within populations were analysed. Expected heterozygosity was high for wild compartments (0.48 to 0.54) and for cultivated and feral ones (0.57 to 0.59), with the number of private alleles ranging from 12 for cultivated genotypes to 37 for a wild compartment. The Ugandan samples show significant population structuring. We compared the Ugandan populations with a representative sample of known genetic diversity groups within the species using 18 markers. Coffea canephora of Ugandan origin was found to be genetically different from previously identified diversity groups, implying that it forms another diversity group within the species. Given its large distribution and extremely recent domestication, C. canephora can be used to understand the effect of refugia colonization on genetic diversity.

Coffee wilt disease (CWD) caused by Fusarium xylarioides, considered to be a soil-inhabiting fungus, is endemic in several African countries, affecting commercially important coffee species and causing serious economic losses. Coffee wilt disease development in naturally infected Coffea canephora fields at the Coffee Research Institute in Uganda was assessed from April 2001 to March 2006 to generate information about temporal and spatial spread of the disease. Maps of diseased trees were also generated from the data. Semi-variance analysis was performed on the data to show the spatio-temporal structure of disease. Host influence on the spatio-temporal structure was deduced from the distribution pattern of diseased and healthy trees and analysis of variance. Results show that the temporal disease epidemic progress was slow. The disease was found to spread from initial infections to healthy neighbouring trees, resulting in an aggregated pattern. An infected tree could infect up to three healthy trees away, in any direction. Disease foci formed and expanded with time, coalescing but punctuated in spots planted with resistant hosts. There were varying levels of susceptibility among host genotypes, affecting the rates and levels of epidemic development. The implications of the findings to the control of CWD are discussed.

Arabica coffees (60 % of current world coffee production) are generally sold at considerably better prices than robustas on account of superior beverage quality. However, costs of production are much higher, mainly due to more stringent demands for soil and climatic conditions, crop management, primary processing and control of several pests and diseases including the potentially very destructive coffee leaf rust (CLR) and berry disease (CBD). Breeding for disease resistance in combination with vigour, productivity and quality started in the early 1920s in India, but especially in the second half of the 20th century comprehensive breeding programmes have been implemented in several other coffee producing countries. Many of the resulting CLR- and CBD + CLR-resistant cultivars (true-breeding lines and F1 hybrids) meet the required standards of profitable and sustainable crop production. Challenges of more recent date include limited access to additional genetic resources of Coffea arabica, breakdown of host resistance to CLR, aggravating insect pest problems and the increasingly negative impact of climate change on arabica coffee production worldwide. This review discusses prospects of breeding and disseminating next generation (hybrid) cultivars of arabica coffee for sustainable coffee production under changing conditions of diseases, pests and climate. International networking on coffee breeding will facilitate sharing of resources (financial, genetic) and scientific information, application of genomics-assisted selection technologies, and pre-breeding for specific characters. Breeding and multiplication of new cultivars well adapted to the local environment will continue to be carried out at national or regional levels. A tree crop like arabica coffee does not lend itself to centralized variety development and dissemination on a global scale.

International audience; A microsatellite-based high-density linkage map for oil palm (Elaeis guinensis Jacq.) was constructed from a cross between two heterozygous parents, a tenera palm from the La Me population (LM2T) and a dura palm from the Deli population (DA10D). A set of 390 simple sequence repeat (SSR) markers was developed in oil palm from microsatellite-enriched libraries and evaluated for polymorphism along with 21 coconut SSRs. A dense and genome-wide microsatellite framework as well as saturating amplified fragments length polymorphisms (AFLPs) allowed the construction of a linkage map consisting of 255 microsatellites, 688 AFLPs and the locus of the Sh gene, which controls the presence or absence of a shell in the oil palm fruit. An AFLP marker E-Agg/M-CAA132 was mapped at 4.7 cM from the Sh locus. The 944 genetic markers were distributed on 16 linkage groups (LGs) and covered 1,743 cM. Our linkage map is the first in oil palm to have 16 independent linkage groups corresponding to the plant's 16 homologous chromosome pairs. It is also the only high-density linkage map with as many microsatellite markers in an Arecaceae species and represents an important step towards quantitative trait loci analysis and physical mapping in the E. guineensis species.

Summary The success of a new variety of Arabica coffee (Coffea arabica L.) depends to an important extent on its liquor and bean qualities. Selection for these traits is however constrained by the prevalence of large genotype-by-environment (G×E) interactions in conjunction with the low genetic variability characteristic of this species. The aim of this study was to assess the extent to which key bean and liquor traits are affected by the environments and could be combined in order to improve the efficiency of selection for coffee quality in a narrow genetic basis set of hybrids obtained from a set of related lines and collectively representing the Ruiru 11 cultivar. Twenty-one full-sib families representative of this hybrid cultivar grown in Kenya in five sites exhibiting strong edaphic and climatic differences were used for the study. Rainfall amounts during various phases of berry development were used to explain the differences observed in the discriminating abilities of the locations for bean and liquor traits. The results showed that these families were best differentiated for bean sizes in the site where moisture supply was optimal throughout berry expansion and filling stages, whereas discrimination on the basis of liquor traits were best observed in the site where moderate moisture stress occurred during bean filling stage. The overall precision in prediction of family values was low for liquor qualities; but a much more efficient selection for large bold beans, optimally based on the AA grade was shown to be possible. Selection indices for family selection were computed to realize a trade-off between genetic gains in bean size and liquor flavour.

Eleven mating designs, 6 top-crosses and 5 North Carolina II, were used to estimate narrow sense, broad sense and within-cross heritability of Coffea canephora yield in Cote d'Ivoire. The objective was to predict achievable genetic gains according to different breeding strategies. Narrow sense, broad sense, family and within-cross heritabilities were 0.32, 0.43, 0.83 and 0.22, on average respectively. The percentage of additivity was high (81% on average). A degree of variation was nevertheless observed for estimates over trials. This was found to be mainly due to parent sampling in each trial. By theoretical computation, the minimum number of parents required to obtain optimum precision was found to be around 30. Predicted genetic gains for yield through clonal selection at a selection level of 1% ranged from 7 to 28% over the best hybrid in each trial, suggesting thus clones still interesting for breeders. The consequences for coffee breeding are discussed.

Two complementary segregating plant populations of Coffea canephora were produced from the same clone. One population (DH) comprised 92 doubled haploids derived from female gametes, while the other population (TC) was a test cross consisting of 44 individuals derived from male gametes. Based on the DH population, a genetic linkage map comprising 160 loci was constructed. Eleven linkage groups that putatively correspond to the 11 gametic chromosomes of C. canephora were identified. The mapped loci included more than 40 specific sequence-tagged site markers, either single-copy RFLP probes or microsatellites, that could serve as standard landmarks in coffee-genome analyses. Furthermore, comparisons for segregation distortion and recombination frequency between the two populations were performed. Although segregation distortions were observed in both populations, the frequency of loci exhibiting a very pronounced degree of distortion was especially high in the DH population. This observation is consistent with the hypothesis of strong zygotic selection among the DH population. The recombination frequencies in both populations were found to be almost indistinguishable. These results offer evidence in favour of the lack of significant sex differences in recombination in C. canephora.Key words: coffee, mapping, sex differences, segregation distortion, recombination frequency.

Genetic diversity was studied using RAPD markers among119 coffee (Coffea arabica L.) individuals representing 88 accessions derived from spontaneous and subspontaneous trees in Ethiopia, the primary centre of species diversity, six cultivars grown locally in Ethiopia, and two accessions derived from the genetic populations Typica and Bourbon, spread in the 18th century, which gave rise to the most currently grown cultivars. Twenty-nine polymorphic fragments were used to calculate a similarity index and construct dendrograms. The Ethiopian material was separated from the Typica- and Bourbon-derived accessions and classified in four groups: one with most of the collected material from southwestern Ethiopia and three from southern and southeastern Ethiopia. Almost all detected diversity was found in the southwestern group while the southern and southeastern groups presented only 59% of identified markers. The genetic distances were low between the southwestern group and the southern and southeastern groups, and between the southwestern group and the Typica- and Bourbon-derived accessions. The cultivated coffee derived from the genetic populations Typica and Bourbon appeared little differentiated from wild coffee growing in the southwest. The results supported the hypothesis that southwestern Ethiopian coffee trees could have been introduced recently in the south and southeast. A separate analysis of the 80accessions classified in the southwestern group allowed identifying particular spontaneous- and subspontaneous-derived accessions and redundancies in the collected material from southwestern Ethiopia. RAPD markers did not detect any within-collection polymorphism except for two trees that were identified as off-types in the CATIE field genebank.

The taxonomy of the genus Manihot is still uncertain and the genetic origin of cassava (M. esculenta Crantz) continues to be controversial. We studied the degree of genetic relatedness between cassava and two naturally occurring species (M. flabellifolia and M. peruviana) which are probably involved in the evolution of cassava, using RAPD and AFLP molecular markers. Thirty-three clonal accessions of cassava of known genetic diversity and 15 accessions of the wild species M. flabellifolia and M. peruviana were analyzed using 92 polymorphic RAPD bands and 73 polymorphic AFLP bands. The genetic markers were unable to differentiate the two wild species, which confirms their botanical similarity. Half of the total number of amplified bands were monomorphic in all of the genotypes evaluated. The mean genetic similarity (Jaccard) between cassava and the species M. flabellifolia/M. peruviana was 0.59. A grouping analysis (neighbor-joining method) with RAPD markers of cultivated cassava, M. flabellifolia/M. peruviana and the other wild species located the genotypes of cassava and M. flabellifolia/M. peruviana at one extremity and the three Mexican species (M. aesculifolia, M. michaelis and M. chlorostica) at the other. An intermediate position between these groups was occupied by two wild species (M. glaziovii and M. reptans) native to central and northeastern Brazil. These results are consistent with the hypothesis that the species M. flabellifolia and M. peruviana gave rise to the cultivated species.A taxonomia do gênero Manihot em grande parte não está resolvida e a origem genética da mandioca (M. esculenta Crantz) continua controvertida. Na tentativa de contribuir para elucidar sua história evolutiva, as relações de proximidade genética da mandioca com duas espécies selvagens que provavelmente participaram da sua história evolutiva, M. flabellifolia e M. peruviana, foram estudadas através de dois tipos de marcadores moleculares, os RAPDs e os AFLPs. Para tanto, foram empregados 33 acessos clonais de mandioca de reconhecida diversidade genética e 15 acessos das espécies selvagens M. flabellifolia e M. peruviana das regiões central e norte do Brasil, importantes centros de ocorrência natural destas espécies. Noventa e duas bandas polimórficas RAPD e 73 AFLP foram utilizadas para análise dos resultados. Ambos marcadores foram incapazes de diferenciar as duas espécies selvagens utilizadas, confirmando a grande semelhança botânica entre elas. Em relação à mandioca cultivada, os resultados revelaram grande proximidade genética entre estas e as espécies selvagens. Metade do total de bandas amplificadas apresentaram-se monomórficas entre todos os genótipos avaliados. O valor médio de similaridade genética (Jaccard) entre a mandioca e as espécies M. flabellifolia/M. peruviana é de 0.59. As relações de proximidade genética entre a mandioca e M. flabellifolia/M. peruviana foram confirmadas quando outras cinco espécies selvagens foram também incorporadas em relação ao polimorfismo gerado pelos RAPDs. A análise de agrupamento (neighbor-joining) realizada com genótipos de mandioca, de M. flabellifolia/M. peruviana e das demais espécies selvagens reuniu numa extremidade os genótipos de mandioca e M. flabellifolia/M. peruviana e na outra extremidade três espécies mexicanas (M. aesculifolia, M. michaelis e M. chlorostica). Entre estes dois grupos se posicionaram outras duas espécies selvagens cuja ocorrência natural é na região central e no nordeste brasileiro (M. glaziovii e M. reptans). Embora não conclusivos, os resultados apresentados são coerentes com a hipótese de que as espécies M. flabellifolia e M. peruviana poderiam ter originado a espécie cultivada. No entanto, outras espécies pouco estudadas (M. procumbens, M. fruticulosa, M. pentaphylla e M. pruinosa) foram recentemente citadas como geneticamente muito próximas da mandioca. Assim, um estudo abordando maior número de espécies e com marcadores mais apropriados, a exemplo dos microsatélites, merece ser feito.

This work focuses on the genetic diversity of American cassava through RAPD molecular markers. The 126 genotypes studied were distributed on four geographical levels ranging from local to continental. Samples included ethnocultivars from the Santa Isabel community in the Brazilian Amazon, local cultivars collected in the State of São Paulo, native accessions from very diverse Brazilian regions, and representative accessions from the Centro Internacional de Agricultura Tropical (CIAT) core collection. Eighty-eight polymorphic bands were analyzed. Results revealed the weak genetic structure of the cassava analyzed. The pattern formed by the first two axes of the principal coordinates analysis (PCoA) revealed an overlapping of the São Paulo State genotype, the Brazilian group and the core collection accessions. The Santa Isabel ethnocultures formed a separate group. The weak genetic structure of cassava can be explained by the common practice of exchanging botanical material among small producers as well as by recombinations among genotypes. When the genotypes were analyzed using climatic data, the sample sites were found to be structured according to temperature and precipitation. RAPD markers proved very useful in the genetic diversity study, resulting in important implications for cassava germ plasm collections and genetic breeding.Este trabalho enfoca a diversidade genética de mandiocas americanas através de marcadores moleculares do tipo RAPD. Os 126 genótipos estudados estão distribuídos em quatro escalas geográficas, indo do local ao continental, ou seja, etnocultivares de uma comunidade chamada Santa Isabel, na Amazônia brasileira, cultivares locais coletados no Estado de São Paulo, um grupo representado por acessos oriundos das mais diversas regiões brasileiras e acessos representantes da "core collection" do CIAT. Oitenta e oito bandas RAPD polimórficas foram retidas para as análises. A estrutura genética das mandiocas deste estudo revelou-se fraca. O plano formado pelos dois primeiros eixos da análise de coordenadas principais (PCoA) revelou sobreposição dos genótipos do Estado de São Paulo, do grupo Brasil e dos acessos da "core collection". Por outro lado, os etnocultivares de Santa Isabel mostraram-se estruturados num grupo a parte com relação aos demais genótipos. Além disso, os etnocultivares de Santa Isabel apresentaram importante diversidade genética em relação aos genótipo dos outros três grupos. A fraca estrutura genética das mandiocas cassava pode ser explicada pelas trocas de material botânico entre pequenos produtores, prática normalmente empregada, assim como recombinação entre genótipos, visto que a mistura de diferentes cultivares em uma mesma parcela de cultura é também uma prática usada por pequenos produtores. Entretanto, quando os genótipos foram analisados em função de dados climáticos das localidades de origem dos mesmos, pudemos evidenciar uma estruturação em função da temperatura e da precipitação destes locais. Os marcadores RAPD mostraram-se informativos para o estudo da diversidade genética de mandiocas, oferecendo indicações importantes para a coleta de germoplasma de mandioca, assim como para o seu melhoramento genético. Com relação à importante diversidade genética encontrada na comunidade de Santa Isabel, outros estudos, através de outros marcadores e com genótipos de outras localidades, precisariam ser realizados para se tirarem conclusões mais diretas a respeito desta variabilidade.

In coffee trees, chlorogenic acids (CGA) mainly includes three classes: the caffeoylquinic acids (CQA), the dicaffeoylquinic acids (diCQA) and the ferulylquinic acids (FQA), each class containing three isomers). An interspecific cross between Coffea pseudozanguebariae (PSE) With low CGA content and C. liberica var dewevrei (DEW) high CGA content was investigated for chlorogenic acid (CGA) contents in F1 and back-cross hybrids. The aim was to analyse CGA inheritance and relationships between CGA classes and isomers. Results constitute a model for the genetic improvement of C. canephora using interspecific crosses with PSE. CGA inheritance: 1. The importance of environmental effects (years + interactions) varies from 22% (5-CQA) to 65% (3,4-diCQA). 2. Additivity is found for 5-CQA, 3,4-diCQA and 4,5-diCQA isomers. 3. Additivity is verified, but after data transformation, for 3-CQA, 3,5-diCQA, and 5-FQA. Relationship between CGA isomers: 1. Relationships between CGA isomers are curvilinear or curvilinea. 2. The shape of the relation explains the use of transformation for additivity test. 3. The presence and the importance of the relation agree with our current knowledge on CGA pathways.

The aim of this study was to develop a cultivar identification tool based on molecular analysis and a statistical approach. From the PIC parameter we defined the D parameter, which evaluates the efficiency of a primer for the purpose of identification of varieties; i.e. the probability that two randomly chosen individuals have different patterns. D can be used to compare different types of markers even if only the allelic frequencies are known. We used this parameter to develop an algorithm for selecting the optimal combination of primers necessary to identify a set of varieties. The optimal combination of primers determined for a small elite group of varieties applied on a larger set induces a risk of confusion involving 1 of the elite varieties. We estimated the risk of confusion using the D value of each primer of the combination. We applied this methodology on a set of 224 varieties of Vitis vinifera screened with 21 RAPD primers and two microsatellite loci. The discriminating power of the primers did not only depend on the number of patterns it generates but also on the frequencies of the different patterns. A combination of 8 primers (6 RAPD and two microsatellite) was found to be optimum for the discrimination of these 224 varieties. A subset of 38 elite varieties was also investigated. The determined optimal combination of 4 primers (3 RAPD and one microsatellite) applied on the 224 varieties gave 9 risks of confusion involving 1 of the elite varieties. Confusion can happen between varieties with the same origin as well as between varieties of very diverse geographical origins.

Coffee species originating from Africa, in particular the two major cultivated species #C. arabica$ and #C. canephora$, usually contain caffeine in their beans, whereas almost all Malagasy coffee species are caffeine-free. However, one wild coffee species #C. pseudozanguebariae$, collected near the coast in south Kenya, is also caffeine-free. Beans of this species contain a specific heteroside diterpene (hereinafter referred to simply as heteroside) and give a bitter coffee beverage. We have investigated the inheritance of the caffeine and heteropside contents of the first and second generations of an interspecific cross between #C. pseudozanguebariae$ and #C. liberica$ var #dewevei$, for which the caffeine content is about 1% dmb (dry matter basis). The caffeine content of F1 hybrids (0.2% dmb) was lower than the parental average (0.47% dmb). Caffeine and heteroside contents appeared to be under polygenic control with a strong genetic effect. Nevertheless, one major gene with two alleles seemed to be involved in the control of both compounds. Absence of caffeine was apparently controlled by one recessive gene. Heteroside content seemed to be controlled by one co-dominant gene, heterozygotes being intermediate between the two different groups of homozygotes. (Résumé d'auteur)

SUMMARY Drought strongly affects cereal yield in several regions of the world. Plant growth and plant water status in response to soil water deficit play an important role in tolerance to drought and in yield stability. In order to investigate the relationship between plant growth and water relations, 187 barley (Hordeum vulgare L.) recombinant inbred lines from a cross between two Mediterranean varieties, Tadmor and Er/Apm, were studied in a growth chamber for RWC , number of leaves on the main tiller (NL), number of tillers (NT) and total shoot fresh and dry biomass (TSFM and TSDM). Measurements were made at the beginning of tillering on well watered plants and at a soil moisture content of 14 % of field capacity. A negative phenotypic correlation between RWC and growth parameters was obtained in both treatments. Under water stress, a negative genetic correlation was also found between the same characters. QTLs involved in RWC, NL and TSFM variation were positioned on a RFLP-RAPD genetic map. Different DNA regions involved in constitutive and water stress responses were detected. In the stress treatment, one region on chromosome 1 was involved in RWC and NL variation giving a genetic basis to the phenotypic correlations found. Separated map positions were also found for RWC and NL. Epistatic interactions between several QTLs and between QTLs and other markers were detected only in the water stress treatment, suggesting that some chromosomal regions might be involved in the regulation of the expression of the traits under water stress. This work suggested that even if some parameters are strongly correlated, finding QTLs for only one trait is not sufficient to detect all the candidate regions which might be involved in the control of the correlated traits. The results of localization and co-localization of QTLs are physiologically interpreted.

Resistance to Coffee Berry Disease (CBD) in Arabica coffee is controlled by at least three genes which are present in the varieties Hibrido de Timor (T gene), Catimor (T gene), Rume Sudan (R and k genes) and K7 (k gene). Hibrido de Timor, Catimor and Rume Sudan are genetically distant from most of the commercial cultivars, and the utilisation of molecular markers would greatly improve the efficiency of breeding programmes concerned with CBD resistance. The objectives of the present work were therefore: (1) to identify random amplified polymorphic DNA (RAPD) markers associated with CBD resistance and (2) to identify markers which could be used to select against the genetic background of the resistance donors. Identification of RAPD markers was carried out in three steps. The first step involved the comparison of the RAPD profiles between the susceptible cultivars and the resistant donors. This was followed by comparison of the RAPD profiles between resistant and susceptible types of each donor variety. The final step involved assay of the resistance markers in the first and the second backcrosses between these donors and the recurrent parent. High genetic variability was demonstrated in Catimor, and to some extent in Rume Sudan. Three RAPD markers were shown to be closely associated to the T gene. Attempts to identify markers associated with the R and k genes were less rewarding. The implications of the current observations in relation to breeding for CBD resistance in Arabica coffee are discussed.

Knowledge on heritability is essential for selecting varieties resistant against coffee wilt disease caused by Fusarium xylarioides, which is currently devastating coffee in East and Central Africa. Variability of the resistance against coffee wilt disease in Coffea canephora and its inheritance were investigated in three experiments corresponding to a clonal trial involving 20 clones, a 10- parent partial diallel progeny, and a half-sib progeny test. There were significant quantitative genetic variations among the clones and progenies, suggesting polygenic control of the resistance. Around 50-65 % tree mortality was the optimal disease level for calculating heritability and genetic gains. General and specific combining abilities calculated within the optimal disease range for partial diallel analysis were significant. Broad-sense heritability for the same analysis and same disease range was moderate (0.329), and corresponding narrow-sense heritability was low (0.112). Broad-sense heritability from clones in the field at the same disease range was also moderate (0.333). Narrow-sense heritability from regression of half-sib progeny means onto parent means in the field and screen house was 0.183 and 0.369, respectively. Selecting tolerant clones for improvement against the disease is possible, and genetic gains are possible by using tolerant parents in breeding programs.

There are few estimates of genetic variability within and among populations of the nine annual Cicer species and for the wild species this information is based on few accessions. The present study was undertaken to examine genetic variation within and between annual Cicer species. One hundred and thirty-nine accessions of nine annual Cicer species were used for electrophoretic analysis at ICARDA. High levels of polymorphism in all eight wild annual Cicer species was found. This is in contrast to earlier research which had shown high polymorphism only in C. reticulatum. Cicer reticulatum had the highest proportion of polymorphic loci. However, for the cultigen, among 14 loci assayed, only two were polymorphic, ADH and PGD2. The nine species formed four phylogenetic groups based on the neighbor-joining method. The first group comprised C. arietinum, C. Reticulatum and C. echinospermum, the second C. bijugum, C. judaicum and C. pinnatifidum, the third C. chorassanicum and C. yamashitae; and the fourth group consisted of one species, C. cuneatum. The phylogenetic tree developed from the neighbor-joining technique illustrated that C. reticulatum is the probable progenitor of C. arietinum and that C. echinospermum split off from a common ancestor at an earlier stage in the evolutionary history of Cicer. Genetic diversity data showed that the greatest diversity was within C. reticulatum and the lowest with the cultigen, C. arientinum. With the exception of C. reticulatum, genetic diversity increased with genetic distance from the cultigen. Little geographic variation in genetic diversity was found.

Afin d'étudier leur aptitude à la combinaison, cinquante-cinq haploïde-doublées (HD) de #Coffea canephora$ ont été croisés avec soit des génotypes hétérozygotes soit des génotypes HD. Trois essais agronomiques ont été établis. Une vigueur hybride marquée est observée pour tous les caractères analysés dont la production. Des différences importantes sont mises en évidence entre HD produits à partir d'un même clone reflétant le haut niveau d'hétérozygotie des clones. L'analyse d'un plan factoriel de croisement indique que la variance génétique est essentiellement due aux effets additifs pour la production ainsi que pour la hauteur des arbres et la forme des feuilles. L'aptitude générale à la combinaison apparaît aussi prédominante pour le diamètre au collet et la résistance à la rouille bien que des effets d'interaction soient détectés. Des combinaisons hybrides ont une productivité semblable à celle de variétés clones témoins. Les implications de ces résultats pour l'amélioration génétique de #Coffea canephora$ sont discutées. Particulièrement, le développement de variété hybride F1 est envisagé. (Résumé d'auteur)

Cassava (Manihot esculenta Crantz) cDNA clones were used to detect restriction fragment length polymorphisms in a collection of Manihot germplasm maintained as in vitro plants at ORSTOM, Montpellier. The collection consisted of mostly African cultivars of M. esculenta, together with a few M. glaziovii Mueller von Argau and M. caerulescens Pohl, and some interspecific hybrids between M. esculenta and M. glaziovii. The clones revealed significant levels of polymorphism both within and between the species; sufficient to construct dendrograms indicating the genetic diversity within the collection.

Genetic parameters were estimated in trials planted in connection with a reciprocal recurrent selection programme applied to Coffea canephora in Cote d'Ivoire. Narrow sense heritability values, estimated from a breakdown of the analysis of variance, were high for architectural characters (0.22 to 0.78) and medium for tree vigour (0.13 to 0.40) and for bean weight (0.15 to 0.28). Calculated heritability values for the first two harvests were high (h2>0.7), but much lower for the following harvests (less than 0.2). Heritability estimates by parent-offspring regressions gave variable results, though they were often similar to those obtained by variance analysis, especially for bean weight. Phenotypic and genetic correlations between tree vigour traits and productivity were high. Bean weight was not correlated with vigour or production. Canopy diameter of 4 year-old trees was closely correlated with cumulated productivity from 2 to 5 years in the absence of development competition between trees, but the correlation was low if trees were in competition with each other. The consequences of the results for the choice of characters to be selected among intergroup hybrids or the parents of both populations are discussed.

Two breeding populations have been identified with Coffea canephora, based on geographical and genetic differences: the Guinean group from West Africa and the Congolese group from central Africa. A reciprocal recurrent selection programme based on these groups was initiated in Cote d'Ivoire in 1984. Genotypes of both groups available in field collections are either of cultivated or wild origin. Genotypic and phenotypic variability was evaluated within and between the groups for the following characteristics: isozyme patterns, architecture, drought tolerance and vigour, technological and organoleptic traits, pest and disease resistance. Variation between and within groups was found to be large. Based on isozyme analysis and phenotypic observations, two subgroups were identified within the Congolese group. Phenotypic values of parents and testers used in the first cycle of reciprocal recurrent selection are presented. Results of two intergroup hybrid trials indicate high yield and vigour for these hybrids compared to intragroup hybrids, justifying the reciprocal selection approach. Furthermore, the variation observed indicates that recurrent selection would allow progress for selection traits for both populations and intergroup hybrids.

Randomly amplified polymorphic DNA (RAPD) markers combined with the Simple Matching index for calculating the distance matrix were used to determine the genetic diversity of African cassava clones. A preliminary study of three Manihot species using 20 primers clearly showed that RAPD markers were relevant for analyzing their genetic diversity. DNAs from 19 cultivars of Manihot esculenta Crantz (cassava) were amplified using 8 primers. Cultivars were well discriminated and coherently distributed, comparing to previous results from isozymes and RFLP studies. Genetic diversity analysis, characterization of collections and study of introgression are the domains that RAPD markers can contribute to the improvement of cassava.

Des microboutures de caféiers (#Coffea arabica$ L. et #Coffea canephora$ Pierre) ont été conservées #in vitro$ pendant 0-20 semaines à différentes températures (12, 17, 22 et 27°C). La survie est généralement élevée, sauf pour #C. canephora$ conservée à 12°C. Après une augmentation transitoire de la concentration en glucose et fructose au début de la période de stockage, le niveau de sucre reste stable. Pendant les premières semaines de conservation, la quantité de proline est multipliée par deux pour les deux espèces, à 12°C. Une chute de la concentration en proline est observée chez #C. canephora$ à la fin de la période de conservation à 12°C. Alors que chez #C. arabica$, aucune modification n'est notée dans la concentration en malonedialdéhyde (MDA), son niveau augmente dans les boutures de #C. canephora$ stockées à 12°C. Cette augmentation est réversible après 10 jours à 27°C, au début de la période de stockage, mais elle devient irréversible après 20 semaines de conservation. La production d'éthylène démarre après transfert à 27°C dès deux semaines de conservation pour #C. canephora$, mais après 12 semaines seulement pour #C. arabica$. Cette synthèse diminue à la fin de la période de stockage chez les boutures de #C. canephora$ stockées à 12°C. Les résultats indiquent que parmi les quatre composés utilisés, le MDA apparaît comme le meilleur indicateur de la sensibilité au froid chez les deux espèces de caféier étudiées. (Résumé d'auteur)

A quantitative trait locus (QTL) analysis designed for a multi-parent population was carried out and tested in oil palm (Elaeis guineensis Jacq.), which is a diploid cross-fertilising perennial species. A new extension of the MCQTL package was especially designed for crosses between heterozygous parents. The algorithm, which is now available for any allogamous species, was used to perform and compare two types of QTL search for small size families, within-family analysis and across-family analysis, using data from a 2 × 2 complete factorial mating experiment involving four parents from three selected gene pools. A consensus genetic map of the factorial design was produced using 251 microsatellite loci, the locus of the Sh major gene controlling fruit shell presence, and an AFLP marker of that gene. A set of 76 QTLs involved in 24 quantitative phenotypic traits was identified. A comparison of the QTL detection results showed that the across-family analysis proved to be efficient due to the interconnected families, but the family size issue is just partially solved. The identification of QTL markers for small progeny numbers and for marker-assisted selection strategies is discussed. Electronic supplementary material The online version of this article (doi:10.1007/s00122-010-1284-y) contains supplementary material, which is available to authorized users.

The effects of reduced sucrose concentrations and low temperature on a collection of coffee microcuttings have been examined. Sucrose concentrations of 0.5 g l-1 and 20 g l-1 and temperatures of 20°C and 27°C were compared in three accessions: the Arabusta (interspecific hybrid) and Coffea arabica L. cv. ‘Caturra amarillo’ and cv. ‘Mokka de Tahiti’. After six months, low sucrose concentrations reduced microcutting growth, rooting and survival rate. At 20°C, microcutting growth was also reduced, but leaf loss and survival rate were promoted. The genotypic differences at six months were minor. After one year without subculture, survival rate was influenced by sucrose concentration and by genotype. These two species can be cold-stored six months at 20°C on a medium containing at least 20 g l-1 sucrose.

Theobroma cacao pollen fertilization capability was studied after 0, 50, 100, 200, 500 and 1000 Gy gamma-irradiation. For all irradiation doses, no alteration of pollen grain viability and in vitro germination was observed. In situ, for all doses, pollen tubes penetrated into the styles and reached the ovules 20 hours after pollination. In vitro observations of the pollen grain nuclei after 20 hours incubation showed that pollen irradiation causes inhibition of the division of the generative nucleus. Fruit survival rate 30 days after pollination decreased as irradiation doses increased from 0 to 100 Gy, and over 100 Gy no fruit set was obtained. The possibility of using irradiated pollen as a method for obtaining haploid cacao plantlets is discussed.

International audience; Coffee is one of the main products on the international markets, in association with oil, corn, sugar, and paper pulp. The history of coffee-tree cultivation is incompletely documented, both regarding its domestication in Africa, and its assisted dispersal throughout the world. This review focuses on the coffee mutant, Coffea arabica ‘Laurina’ (Chevalier A in Encyclopedie Biologique. Vol 28, 1947), also named ‘Bourbon pointu’. This plant is generally acknowledged to have been selected in the island of ‘Bourbon’ (La Réunion) from a field at the beginning of the 19th century. Compared with the common ‘Bourbon’ variety, ‘Bourbon pointu’ trees are dwarf, with a characteristic Christmas-tree shape and the beans have an excellent cup quality. Although cited many times in literature, the origin of this variety is ambiguous and is largely discussed even today with increasing confusion, particularly in books and local newsletters. This article provides a thorough historical and bibliographical review of coffee cultivation in La Réunion, which leads to an understanding of the bottleneck responsible for the low genetic diversity of the ‘Bourbon’-type modern varieties. Complemented by a review of the scientific studies conducted on this subject, confirmation of the veracity of the various historical accounts becomes possible, and appropriate conclusions on the origin of the ‘Bourbon pointu’ are derived. Although historical texts provide important information and represent priceless resources that give direction to scientific research, it is clear that this same research makes it possible, in turn, to clarify and to interpret historical texts.

International audience; Coffea canephora Pierre breeding in Cote d'Ivoire is based on indirect reciprocal recurrent selection (RRSi) using the Congolese and Guinean populations. In practice, the genotypes of each population (78 Congolese genotypes and 100 Guinean genotypes) are tested with several testers from the reciprocal population: two Guinean and three Congolese testers. These testers are heterozygous as C. canephora is a strictly outcrossing species. After a first cycle of RRSi, we judged the efficiency of these testers for yield, susceptibility to coffee leaf rust (SCLR) and hundred bean weight (HBW). All the testers discriminated the tested genotypes highly significantly (P < 0.01), even though differences were found in the degrees of discrimination. For yield and SCLR, no interaction between tested genotypes and testers was observed and correlations between test values obtained from different testers were significant or highly significant. Furthermore, test values of tested genotypes could be used to predict the yield and SCLR of between-population (BP) hybrids. Prediction was always more accurate with the best tester than with the mean of several testers. As opposed to yield and SCLR, HBW showed significant interactions between tested genotypes and testers and HBW of hybrids could not be predicted from the test value of the genotypes. We conclude that only one reciprocal tester can be used in the next cycles of RRSi applied to C. canephora. This will allow either a reduced cost of selection or increased selection intensity.

The performance of F1 hybrid plants derived from crosses between traditional varieties of Coffea arabica of Latin America with a "wild" collection of Sudan - Ethiopian origin were studied for yield, fertility and bean weight. Sudan Ethiopian material possesses resistance to certain diseases, and possibly, better beverage quality. The objective of this breeding programme is to widen the very narrow genetic base of Central American coffee, even while increasing quality and productivity. The hybrid plants were obtained from two factorial crosses made and evaluated in two locations. They were compared in the two field trials using the six maternal lines as controls. Observations were taken on vegetative characters, annual and cumulated yield, dry weight of 100 beans, extent of early abortion as measured by the fraction of 'peaberries' and post-zygotic ovule fertility as measured by the fraction of mature no-floating berries in water (FF). The F1 hybrid population were compared to the populations of maternal lines for the aforementioned variables. An index-based selection was done in the hybrid populations employing three traits, yield, 100-bean weight and the post-zygotic fertility ( FF). The performance of the selected hybrids was then compared to those of the best parental 'control' lines in each trial. The hybrid populations yielded 22 - 47% more than the maternal lines, but hybrids showed significantly more sterility than the parental control lines. Selection in the hybrid populations using the three selected traits led to significant genetic gain for yield and dry weight of 100 beans, and insignificant gain for fertility ( FF). When selected on the basis of fertility alone, increase in yield and 100-bean weight were not obtained within the hybrid populations. By applying selection on yield and 100-bean weight, the selected hybrids produced 11 - 47% higher yields than the best line along with significantly higher or identical 100-bean weight and performed identically for fertility. The yield performance of hybrids between the Latin American material and the "wild" Sudan - Ethiopian material calls for further selection effort for improving beverage quality.

Male fertility of interspecific hybrids was analysed in one F1 and two backcrossed progenies originating from a cross between Coffea canephora and Coffea heterocalyx. Male fertility was tested using pollen stainability with acetic carmine. The results showed a marked decline in fertility at the F1 level, and fertility was almost fully restored after two backcrosses. The computed broad-sense heritability represented 47% of the variance. Quantitative trait loci (QTLs) locations and effects on pollen viability were estimated using an amplified fragment length polymorphism (AFLP) genetic linkage map constructed in the segregating BC1 population. Three significant QTLs (LOD>3 and p < 0.001 by ANOVA) were detected for pollen viability, two of which were responsible for the bimodal distribution of pollen viability in the segregating population. One QTL was involved in fertility variations among fertile BC1 plants. Fertility inheritance is discussed in relation with previously demonstrated chromosomal sterility in Coffea hybrids and the effect of detected QTLs. The potential use of genetic markers to overcome sterility in interspecific hybrids is also discussed.

Self-compatibility segregation was assessed in two successive backcross progenies originating from an interspecific cross between Coffea canephora (self-incompatible) and Coffea heterocalyx (self-compatible). After self- and cross-pollination, pollen tube behaviour in styles was observed under ultraviolet fluorescence microscopy and fruit-set was determined at harvesting time. Segregation ratios in the two progenies were consistent with monofactorial control of self-compatibility. Self-compatible plants exhibited higher fruit-set than self-incompatible ones in open-pollination conditions. Segregation of AFLP markers was scored in the first backcross progeny. By molecular linkage analysis, the S locus could be mapped to a short linkage group.

The sucrose content of coffee beans is an important component of the coffee flavour: the higher the sucrose content in green beans, the more intense coffee cup flavour. Beans of the formerly cultivated Coffea liberica dewevrei (DEW) have lower levels of sucrose (5.37% dmb) than beans of the wild species Coffea pseudozanguebariae (PSE) (7.57% dmb). In the present study, the genetic inheritance of sucrose accumulation in green beans is analysed in an interspecific cross including F1 and backcross hybrids between these two species. Main results concerning genetic inheritance: 1. Between-tree variation exists within species. 2. There is no between-year variation, but an interaction "between-year x tree". 3. Additivity is emphasised for sucrose content in F1 and BCDEW hybrids. 4. Discrepancy to additivity in BCPSE hybrids is due to a segregation distortion eliminating hybrids with sucrose content >5.2% dmb. Conclusions: Our results clearly indicate that, using an interspecific cross with PSE, we can expect an improve-ment of the sucrose content in C. canephora beans. The intraspe-cific variability of C. pseudozangue-bariae and the genetic additivity allow to select genotypes as parent for breeding. As an example, the PSE genotype having 9.25% dmb of sucrose is of special interest. The large within-BCDEW variance, coupled with additivity, strongly suggests that the choice of parents for the next generation BC2 should be efficient.

An interspecific partial genetic linkage map of #Coffea$ sp. based on 62 backcross hybrids is presented. F1 hybrids were generated by a cross between the wild #C. pseudozanguebariae$ and the anciently cultivated #C. liberica$ var. #dewevrei$ (DEW) ; progeny were then derived from a backcross between F1 hybrid and DEW. The map construction consisted of a two-step strategy using 5.5 and 3.1 LOD scores revealed by simulation file. The map consisted of 181 loci : 167 amplified fragment length polymorphism (AFLP) and 13 radom fragment length polymorphism (RFLP) loci. The markers were assembled into 14 linkage groups, each with 4-31 markers covering 1,144 cM. Segregation distorsion was observed for 30% of all loci, in particular 3:1 and 1:3 ratios equally favouring each of the two parents. The existence of such ratios suggests genetic conversions events. This map also represents an initial step towards the detection of quantitative trait loci. (Résumé d'auteur)

Restriction fragment length polymorphism (RFLP) markers were used in combination with genomic in situ hybridisation (GISH) to investigate the origin of the allotetraploid species Coffea arabica (2n = 44). By comparing the RFLP patterns of potential diploid progenitor species with those of C. arabica, the sources of the two sets of chromosomes, or genomes, combined in C. arabica were identified. The genome organisation of C. arabica was confirmed by GISH using simultaneously labelled total genomic DNA from the two putative genome donor species as probes. These results clearly suggest that C. arabica is an amphidiploid formed by hybridisation between C. eugenioides and C. canephora, or ecotypes related to these diploid species. Our results also indicate low divergence between the two constituent genomes of C. arabica and those of its progenitor species, suggesting that the speciation of C. arabica took place relatively recently. Precise localisation in Central Africa of the site of the speciation of C. arabica, based on the present distribution of the coffee species, appears difficult, since the constitution and extent of tropical forest has varied considerably during the late Quaternary period.

Crop/weed gene flow is often of great concern for a better understanding of germplasm diversity. This paper provides an overview of the levels and partition of genetic diversity assessed between wild and cultivated populations of Medicago sativa L. in Spain for both molecular markers and agromorphological traits. We report that most wild populations preserve a great agronomic and morphological originality despite their occasional parapatry with cultivated forms and the occurrence of crop/weed gene flow in many locations. However, populations that display either a continuous range of intermediate plants between the typical wild and cultivated forms, or a mosaic of individuals that can be assigned to each gene pool respectively, were also identified. Providing that reproductive isolation is not strict, we hypothesise that contrasted selective pressure between wild and cultivated populations mainly accounted for the maintenance of their phenotypic integrity., L’existence d’un flux génique entre des populations cultivées et sauvages joue souvent un rôle prépondérant dans l’évolution de la diversité génétique de ces dernières. Nous présentons ici une vue générale des niveaux, et de l’organisation de la diversité génétique mesurée sur la base de marqueurs neutres et de caractères agromorphologiques dans des populations sauvages et cultivées de luzerne (M. sativa L.)en Espagne. La plupart des populations sauvages maintiennent une claire originalité agronomique et morphologique bien qu’elles soient parapatriques de populations cultivées et qu’elles fassent parfois l’objet d’introgressions régulières de leur part. Néanmoins notre étude a permis de mettre en évidence un ensemble de populations sauvages moins typiques, présentant un continuum de formes intermédiaires ou une mosaïque d’individus caractéristiques de chaque forme. Notre étude suggère que l’isolement reproducteur entre populations sauvages et cultivées n’est pas total et qu’il est vraisemblable que de fortes pressions de sélection engendrées par le milieu jouent un rôle déterminant dans le maintien de l’intégrité phénotypique des formes sauvages.

RAPD markers were used to investigate the genetic diversity of 31 Brazilian cassava clones. The results were compared with the genetic diversity revealed by botanical descriptors. Both sets of variates revealed identical relationships among the cultivars. Multivariate analysis of genetic similarities placed genotypes destinated for consumption "in nature" in one group, and cultivars useful for flour production in another. Brazil’s abundance of landraces presents a broad dispersion and is consequently an important resource of genetic variability. The botanical descriptors were not able to differentiate thirteen pairs of cultivars compared two-by-two, while only one was not differentiated by RAPD markers. These results showed the power of RAPD markers over botanical descriptors in studying genetic diversity, identifying duplicates, as well as validating, or improving a core collection. The latter is particularly important in this vegetatively propagated crop. Marcadores moleculares do tipo RAPD foram utilizados para estudar a diversidade genética de 31 clones de mandiocas brasileiras. Os resultados foram comparados com a diversidade genética fornecida por descritores botânicos. As relações de parentesco obtidas foram semelhantes para os dois tipos de marcadores utilizados. A análise multivariada baseada nos índices de similaridade genética entre os cultivares deste estudo permitiu o grupamento de genótipos mais indicados para o consumo "in natura", assim como daqueles genótipos destinados à produção de farinha num outro grupo. A maioria das raças locais, procedentes de várias regiões do país, apresentaram ampla dispersão, revelando serem uma importante fonte de variabilidade genética para a espécie. Os descritores botânicos foram incapazes de diferenciar treze pares de cultivares comparados dois-a-dois, enquanto que, através dos marcadores RAPD, apenas um par não foi possível diferenciar. Os resultados deste estudo mostram o poder da técnica RAPD em relação aos descritores botânicos para estudos de diversidade genética de mandiocas, assim como para a identificação de duplicatas e para a formação de "core collections", que são particularmente importantes nesta espécie de propagação vegetativa.

ThetrnL–trnF intergenic spacer of cpDNA has been sequenced from 38 tree samples representing 23Coffeataxa and the related genusPsilanthus.These sequences were used for phylogenetic reconstruction using parsimony analyses. The results suggest a radial mode of speciation and a recent origin in Africa for the genusCoffea.Phylogenetic relationships inferred from the cpDNA analysis suggest several major clades, which present a strong geographical correspondence (i.e., west Africa, central Africa, east Africa, and Madagascar). The overall results agree well with the phylogeny previously inferred from nuclear genome data. However, several inconsistencies are observed among taxa endemic to west Africa, suggesting the occurrence of introgressive hybridization. Evidence is also obtained for the genetic origin of the allotetraploid speciesC. arabica.

F1 hybrids were obtained between two coffee species with the same chromosome number (2n=22) but with different nuclear DNA contents [#C. pseudozanguebariae$ (PSE) 2C=1.13 pg and #C. liberia$ var "dewevrei" (DEW) 2C=1.42 pg]. G2 hybrids were obtained by open-pollination of the F1 hybrids. Genomic in situ hybridisation (GISH) and flow cytometry were used on six F1 hybrids and seven G2 hybrids to determine their parenteral chromosomic contribution and their nuclear DNA content (qDNA), respectively. GISH efficiently identified chromosomes from both species. F1 hybrids had a qDNA intermediate between that of the parental species and contained the expected 11 chromosomes from each species. There was a linear relationship between the number of PSE chromosomes and the nuclear DNA content, which indicates that flow cytometry can be used to give a rough estimate of the parental chromosomic contribution in G2 hybrids. (Résumé d'auteur)

International audience; Osmotic adjustment (OA) was previously demonstrated to be an important adaptive mechanism of drought tolerance in cereals. In order to determine which genomic regions are involved in OA variation, 187 barley (Hordeum vulgare L.) recombinant inbred lines (RILs) derived from a cross between Tadmor (drought tolerant) and Er/Apm (susceptible) were studied in a growth chamber for their OA capacity (through correlated traits and by calculation), at an early growth stage and under two water treatments (soil moisture of 14% and 100% of field capacity). The continuous distribution of the traits and their broad-sense line heritabilities, ranging from 0.04 to 0.44, indicated that OA and related traits should have a polygenic nature. A subset of 167 RILs were also genotyped using 78 RFLP, 32 RAPD and three morphological markers and a linkage map was constructed. Despite strong environmental effects acting on the traits, interval mapping and single-marker ANOVA allowed the detection of three QTLs for relative water content (RWC), four QTLs for osmotic potential (ψπ), two QTLs of osmotic potential at full turgor (ψπ100) and one QTL for osmotic adjustment at a soil moisture of 14% field capacity. For the irrigated treatment, only two QTLs were detected: one for RWC and one for ψπ100. Two chromosomal regions were involved in several OA-related trait variations and could be considered as regions controlling OA; these were present on chromosome 1 (7H) and chromosome 6 (6H), whereas other regions were specific for one trait. No major QTL was found. However, the genomic region involved in OA-related traits on chromosome 1 (7H) in barley seemed to be conserved for OA variation among cereals. Epistatic effects, with or without additive effects, acted on the traits.

Les relations phylogénétiques d'espèces de caféiers (#Coffea$ L.) ont été estimées à partir de la séquence de l'espaceur interne transcrit (ITS 2) de l'ADN ribosomique nucléaire. La région ITS 2 de 37 accessions représentant 26 taxons de #Coffea$ et 3 espèces de #Psilanthus$ a été déterminée par séquençage direct de fragments amplifiés par PCR. Le niveau de variation est suffisamment important pour rendre l'ITS 2 utile à la reconstruction phylogénétique. Cependant, un niveau inhabituel de variation intraspécifique est observé conduisant à certaines difficultés dans l'interprétation des divergences des séquences d'ADNr. Les séquences ont été analysées à la fois par des méthodes cladistique (parcimonie de Wagner) et phénétique (Neighbour-joining distance). Les taxons de caféiers apparaissent répartis entre plusieurs groupes majeurs qui présentent une forte correspondance géographique (i.e. Madagascar, Afrique de l'Est, Afrique Centrale et Afrique de l'Ouest). Cette organisation est bien supportée par les données cytogénétiques. Par contre, les résultats sont en contradiction avec la classification actuelle des caféiers en deux genres, #Coffea$ et #Psilanthus$. Par ailleurs, l'additivité des types parentaux d'ADNr n'est pas observée chez l'espèce allotétraploïde #C. arabica$. (Résumé d'auteur)

CpDNA variation among 52 tree samples belonging to 25 different taxa of #Coffea$ and two species of #Psilanthus$ was assessed by RFLP analysis on both the total chloroplast genome and the atpB-rbcL intergenic region. Twelve variable characters were distinguished allowing the identification of 12 different plastomes. The low sequence divergence observed might suggest that #Coffea$ is a young genus. The results were in contradiction with the present classification into two genera. Additionally, cpDNA inheritance was studied in interspecific hybrids between #C. arabica$ and #C. canephora$, and in an intraspecific progeny of #C. canephora$, using PCR-based markers. Both studies showed exclusively maternal inheritance of cpDNA. (Résumé d'auteur)

Des marqueurs RAPD (Random Amplified Polymorphic DNA) ont été utilisés avec succès pour analyser la diversité génétique parmi des accessions sauvages et cultivées de #Coffea arabica$. La base génétique étroite des cultivars est confirmée. En revanche, une relative large diversité est observée dans le matériel sauvage illustrant l'intérêt des prospections. Des résultats suggèrent une différenciation génétique Est-Ouest en Ethiopie qui constitue le centre primaire de diversification de #C. arabica$. L'important effet d'hétérosis observé chez des hybrides intergroupes pourrait être lié à cette différenciation génétique. La méthode RAPD apparaît performante pour l'étude de la variabilité génétique et la classification du germplasm de #C. arabica$. (Résumé d'auteur)

Des haploïde-doublés (HD) de #Coffea canephora$ ont été développés en utilisant les embryons haploïdes qui apparaissent spontanément en association avec la polyembryonie. Les fréquences de graines polyembryonées et d'embryons haploïdes varient en fonction du génotype parental. Cependant la production d'un grand nombre de HD semble possible à partir de tous les génotypes. Plus de 750 HD produits à partir de différents génotypes ont été cultivés au champ et évalués pour plusieurs caractères agronomiques. Environ la moitié des génotypes HD n'ont pas survécu, suggérant un fort et négatif effet de l'homozygotie. La dépression de consanguinité est particulièrement sévère pour la vigueur végétative et les aspects liés à la reproduction. Pour plusieurs caractères tels que la forme des feuilles, la résistance à la rouille et le poids de 100 graines, une variation génétique considérable a été observée entre et à l'intérieur des groupes de génotypes HD constitués par les HD produits à partir d'un même clone. Malgré leur faible vigueur et fertilité réduite, les haploïde-doublés de #Coffea canephora$ offrent de nouvelles possibilités pour les études génétiques et l'amélioration des caféiers. (Résumé d'auteur)

L'électrophorèse sur gel d'amidon a été utilisée pour évaluer le polymorphisme isoenzymatique chez deux espèces de manioc. Les extraits bruts ont été obtenus à partir de feuilles et de pollen. Dix enzymes ont été examinés pour leur polymorphisme dans une collection de germplasm de 365 cultivars plus 109 échantillons sauvages, la plupart d'Afrique. L'hérédité de ces allozymes a été examinée en utilisant treize descendances intra et interspécifiques. 17 locus polymorphes ont été trouvés pour les dix systèmes enzymatiques, avec 59 allèles. Tous les marqueurs ont montré une hérédité disomique et trois groupes de liaison ont été identifiés. (Résumé d'auteur)

L'intérêt des "RAPDs" (Ramdom Amplification of Polymorhic DNA sequence) comme marqueur génétique chez les caféiers a été évalué. Des oligonucléotides ont été utilisés comme amorces pour l'amplification de séquence d'ADN génomique par la réaction de polymérisation en chaîne (PCR). Différentes accessions comprenant les principales espèces de caféiers ont été analysées. Une variation intra-spécifique a été facilement détectée chez #Coffea canephora$ et #Coffea liberica$. Par contre, les amorces testées n'ont pas permis de mettre en évidence du polymorphisme entre les différentes accessions de #C. arabica$. Un important polymorphisme inter-spécifique a été observé. Des relations génétiques entre espèces de caféiers ont pu être déduite à partir des degrés de similarité des profils de produits d'amplification. Les marqueurs "RAPD" présentent une grande valeur pour la caractérisation, l'analyse et l'utilisation des ressources génétiques chez les caféiers. (Résumé d'auteur)

Isozyme diversity is described among a collection of 365 Manihot esculenta cultivars plus 109 accessions from wild relatives (M. glaziovii and spontaneous hybrids) from Africa. The study is based on 17 polymorphic loci. A natural hybrid swarm is detected between the two species. Although they were recently introduced, M. esculenta and M. glaziovii show high levels of polymorphism: heterozygosity estimates are 0.225 and 0.252 respectively. For the wild species, diversity is structured at the unilocus level, and the multilocus approach reveals a geographical pattern. The organization of the diversity is not so clear for the cultivated cassava, but a multilocus approach, based on both common and rare alleles, led us to identify different groups of clones with many intermediate genotypes between them. Elements of the secondary diversification process of Manihot in Ivory Coast are discussed.

We have studied the influence of low concentrations of 6-benzyladenine on growth limitation, in order to preserve coffee germplasm through a microcutting collection. Concentrations of 0 μM, 1.3 μM and 4.4 μM were compared in four species: Coffea congensis, C. canephora, C. liberica and C. racemosa. After six months, microcutting behaviour varied between the different treatments, and a species effect was observed. The slow growing species (C. liberica and C. congensis) needed 1.3 μM; the others coffee species (C. canephora and C. racemosa) exhibited moderate caulogenesis on 6-benzyladenine-free medium. Zero and low concentrations did not affect survival rates. In conclusion 1.3 μM seems most appropriate for conserving all four species.

While the international coffee trade is concerned with only two coffee species — Coffea arabica and C. canephora — botanists regard as coffee trees all tropical plants of the Rubiaceae family, which produce seed resembling coffee beans. During botanical explorations of the tropical regions, from the sixteenth century onwards, wild coffees also attracted the attention of explorers and botanists. Their specimens are found in the herbaria and the names of the most famous explorers have been commemorated in both specific and generic epithets. Hundreds of species have been described, but the taxonomic classification of the genus Coffea has become very complex and rather confused.