Diversity studies in the interaction between the anthracnose fungus Colletotrichum gloeosporioides and its host plant Stylosanthes spp. in Mexico

Pests and diseases are important constraints to production in both traditional and modern agricultural systems. It is widely accepted that crop diversity, mainly through use of resistance and tolerance genes, is an important asset in reducing the risk of crop losses related to pests and diseases. However, little is known about the effect of the natural pathogen diversity on the occurrence and severity of phytopathological infestations. This publication summarizes the results of the multidisciplinary project ‘Genetic diversity studies in the interaction between the anthracnose fungus Colletotrichum gloeosporioides and its host plant Stylosanthes spp.’ The legume Stylosanthes is an important forage crop worldwide and Colletotrichum gloeosporioides is its most important pathogen. This project was a multidisciplinary bi-national effort centred in Mexico, a centre of origin of the host plant, which focused on characterizing both the host plant and the pathogen using different characterization techniques, from macro-morphological through molecular. As anthracnosis is reducing Stylosanthes yields from Africa to Australia, an increased knowledge and understanding of the co-existence of crop and pathogen diversity will benefit stakeholders outside the study area as well. A team of international researchers undertook a coordinated effort to increase the inclusion of information on host and pathogen diversity in areas where the crop and its pathogen are native. The Unité de Phytopathologie de l’Université catholique de Louvain, Louvain-la-Neuve, Belgium (UCL) focused on the characterization of C. gloeosporioides and other Colletotrichum species associated with wild Stylosanthes species in Mexico, while Stylosanthes diversity and taxonomy were studied by the Laboratorio de Recursos Naturales, Unidad de Biología, Tecnología y Prototipos, Facultad de Estudios Superiores Iztacala de la Universidad Nacional Autónoma de México (UNAM) at the morphological level and by the Laboratory of Gene Technology, Katholieke Universiteit Leuven, Belgium (KUL) that studied the material at the molecular level. The Mexican partner, UNAM, was responsible for the collection of materials, both host plant and pathogen, while the Belgian partners, UCL and KUL, carried out the molecular analysis. This study is a clear example of how a collaborative, multidisciplinary effort, including the exchange of plant material, allows for the optimal use of existing synergies between different research centres, leading to a better understanding of a complex theme such as host-pathogen diversity. This will permit a better use of the crop’s genetic diversity, and the corresponding resistance genes available, as well as the application of better screening methods for pest or disease resistance, based on a more extensive pathogen diversity. Bioversity International, formerly known as IPGRI, and its Regional Office for the Americas in Cali, Colombia is honoured that it was allowed to coordinate this project

Genetic relationships among isolates of Colletotrichum gloeosporioides from Stylosanthes spp. in Africa and Australia using RAPD and ribosomal DNA markers

Thirty-three isolates of Colletotrichum gloeosporioides from various Stylosanthes species collected in Africa and Australia and associated with restricted (type A), extensive (type B) or nontypical anthracnose lesions (type C) were first compared by random amplified polymorphic DNA (RAPD) analysis. A phylogenetic tree was constructed based on 118 reproducible polymorphic bands generated with 16 random primers, using the upgma method. Twenty-nine isolates were grouped in two main clusters, corresponding to types A and B, within which polymorphic subgroups were partially related to geographical origin. Strong similarities were observed among isolates of distant origin. Four isolates presented profiles completely different from the A and B types and were grouped in two additional clusters. To assess the phylogenetic relationship among isolates of various types and origins at the species level, the Internal Transcribed Spacer region (ITS 1) of the ribosomal DNA was sequenced. Type A isolates and a restricted number of type B isolates selected in the RAPD clusters showed an homology of 99.4-100%. When compared with published sequence data, the isolates that were clustered separately in the phylogenetic tree, had the exact sequence of a C. gloeosporioides strain associated with the rotting of coffee berries, or of C. kahawae, the causal agent of coffee berry disease

Diversity studies in the interaction between the anthracnose fungus Colletotrichum gloeosporioides and its host plant Stylosanthes spp. in Mexico

Pests and diseases are important constraints to production in both traditional and modern agricultural systems. It is widely accepted that crop diversity, mainly through use of resistance and tolerance genes, is an important asset in reducing the risk of crop losses related to pests and diseases. However, little is known about the effect of the natural pathogen diversity on the occurrence and severity of phytopathological infestations. This publication summarizes the results of the multidisciplinary project ‘Genetic diversity studies in the interaction between the anthracnose fungus Colletotrichum gloeosporioides and its host plant Stylosanthes spp.’ The legume Stylosanthes is an important forage crop worldwide and Colletotrichum gloeosporioides is its most important pathogen. This project was a multidisciplinary bi-national effort centred in Mexico, a centre of origin of the host plant, which focused on characterizing both the host plant and the pathogen using different characterization techniques, from macro-morphological through molecular. As anthracnosis is reducing Stylosanthes yields from Africa to Australia, an increased knowledge and understanding of the co-existence of crop and pathogen diversity will benefit stakeholders outside the study area as well. A team of international researchers undertook a coordinated effort to increase the inclusion of information on host and pathogen diversity in areas where the crop and its pathogen are native. The Unité de Phytopathologie de l’Université catholique de Louvain, Louvain-la-Neuve, Belgium (UCL) focused on the characterization of C. gloeosporioides and other Colletotrichum species associated with wild Stylosanthes species in Mexico, while Stylosanthes diversity and taxonomy were studied by the Laboratorio de Recursos Naturales, Unidad de Biología, Tecnología y Prototipos, Facultad de Estudios Superiores Iztacala de la Universidad Nacional Autónoma de México (UNAM) at the morphological level and by the Laboratory of Gene Technology, Katholieke Universiteit Leuven, Belgium (KUL) that studied the material at the molecular level. The Mexican partner, UNAM, was responsible for the collection of materials, both host plant and pathogen, while the Belgian partners, UCL and KUL, carried out the molecular analysis. This study is a clear example of how a collaborative, multidisciplinary effort, including the exchange of plant material, allows for the optimal use of existing synergies between different research centres, leading to a better understanding of a complex theme such as host-pathogen diversity. This will permit a better use of the crop’s genetic diversity, and the corresponding resistance genes available, as well as the application of better screening methods for pest or disease resistance, based on a more extensive pathogen diversity

Conceptual design of processes for structured products

Applied Science

Phylogenetic analysis of Stylosanthes (Fabaceae) based on the internal transcribed spacer region (ITS) of nuclear ribosomal DNA

Phylogenetic relationships in Stylosanthes are inferred by DNA sequence analysis of the ITS region (ITS1–5.8S–ITS2) of the nuclear ribosomal DNA in 119 specimens, representing 36 species of Stylosanthes and 7 species of the outgroup genera Arachis and Chapmannia. In all examined specimens of any particular diploid and (allo)polyploid species, only a single ITS sequence type was observed. This allowed us to identify a parental genome donor for some of the polyploids. In several diploid and polyploid species, different specimens contained a different ITS sequence. Some of these sequence types were present in more than one species. Parsimony analysis yielded several well-supported clades that agree largely with analyses of the chloroplast trnL intron and partially with the current sectional classification. Discordances between the nuclear and cpDNA analyses are explained by a process of allopolyploidization with inheritance of the cpDNA of one parent and fixation of the ITS sequences of the other. S. viscosa has been an important genome donor in this process of speciation by allopolyploidy.status: publishe