Montpellier Scientific Community



Coconut lethal yellowing diseases and citrus greening (JMCGA)

Director: Michel Dollet
Research area
The Coconut lethal yellowing diseases and citrus greening unit (JMCGA) works on the molecular characterization of the phytoplasma (mollicutes) and Phytomonas (trypanosomes) associated with several yellowing syndromes of coconut (CLYs) and searches for tolerant or resistant coconut varieties. Its operations concern phytoplasmas syndromes in Ghana, Mozambique, Cuba and Jamaica, with DNA extraction, amplification of gene sequences of the ribosomal operon, cloning, sequencing and comparative analysis of the sequences and the search for other usable genes. In Ghana and in Mexico entomologists are looking for the vector of the local lethal yellowing. In parallel, it is continuing research on the spread of the disease in Ghana. Research on Phytomonas concerns the diversity, variability, phylogeny and taxonomy of these poorly known parasites, some of them associated with lethal yellowing of coconut and oil palm in Latin America and the Caribbean. Studies on their molecular karyotype should represent an essential primary step towards sequencing the genome of these parasites. Citrus Greening or Huanglongbing (HLB) is caused by another phloem- restricted organism: an alpha-proteobacterium, transmitted by a psyllid. The main work concerns the study of the relationships between the bacterium and its vector
Research highlights
Because of the history of most of the scientists working in this RU (some of them were members of the Research Institute for Oil crops -IRHO - and then members of the coconut research programme of CIRAD), the unit is among the principal leaders as far as coconut genetics or coconut diseases are concerned. They were the first to identify the phytoplasmas in the case of CLY in Togo and in Cameroon and took part in the characterization of the diversity and variability -using molecular markers- in the phytoplasmas associated with CLY in Cuba, Jamaica, Dominican Republic, Ghana and Mozambique. In Ghana, in association with the Oil Palm Research Institute, they developed two new coconut hybrids, one of them being the high hope for the future of the coconut in the country. The RU has the only cryobank in the world of in vitro cultured trypanosomatids associated with wilts of coconut and oil palm. The total of its plant trypanosomatids collection represents 77 isolates from 12 countries (LAC, Europe, Africa and India). The RU, using isoenzymes and several molecular markers (rDNAs, SL RNA gene, mini-circles...), identified between 8 and 10 different groups, one of them -group "H" composed only of phloem-restricted trypanosomatids of palms. We obtained the first molecular karyotype of these organisms in 2007.
Staff profile
 
Total permanent staff Total Scientists Scientists with "HDR" [1] Post-doc fellows PhD
9
7
1
1
-
[1]French university degree for confirmed thesis supervisor
    
         
Research teams
Research is conducted along the following main axes:
  • Pathogen diversity and variability (phytoplasmas and trypanosomatids of coconut diseases)
  • Studies on pathogen transmission (HLB and lethal yellowing)
  • Research on control strategies (mainly coconut genetics)
  • Epidemiology (coconut diseases in Ghana)
Platforms and other tools
The RU shares the same laboratory with the RU "Control of exotic and emerging animal diseases". This laboratory is fully equipped for molecular biology research with PCR and RT PCR machines, in vitro culture with laminar flow hoods, -80°C freezers, cryobanks, laboratory for bacterial transformation etc.
Most important international partnerships
  • Centro de Investigaciones Científicas de Yucatan, (CICY), Mexico
  • Oil Palm Research Institute, (OPRI) Ghana
  • Coconut Industry Board, (CIB), Jamaica
  • Centre National de Recherche Agronomique, Ivory Coast
  • Department of Immunology & Molecular Genetics (University of California), and Department of
  • Plant Sciences (University of Arizona), USA
  • Instituto de Biotecnología, University of Granada, Spain
  • Laboratoire de parasitologie et mycologie du CHU de Montpellier, UMR 5093 (CNRS- Univ.)
Facts and figures
Publications in international ranking journals
2007: 5
2006: 5
2005: 1
Representative publications
Marin C., Alberge B., Dollet M., Pages M. and Bastien P. (2007)- The first complete chromosomal organisation of a protozoan plant parasite (Phytomonas spp.) Genomics. 91:88-93

Marín C., Fabre S., Sánchez-Moreno M., Dollet M. (2007) - Herpetomonas spp. isolated from tomato fruits (Lycopersicon esculentum) in southern Spain. Experimental Parasitology 116: 88-90

Baudouin L., Lebrun P., Konan J.L., Ritter E., Berger A., Billotte N. (2006) - QTL analysis of fruit components in the progeny of a Rennell Island Tall coconut (Cocos nucifera L.) individual. Theoretical and applied genetics. vol.112, (2): p. 258-268.

Myrie W., Paulraj L., Dollet M., Wray D., Been B.O., McLauglin W. (2006.) - First Report of Lethal Yellowing Disease of Coconut Palms Caused by Phytoplasma on Nevis Island. Plant Disease. vol.90, (6): p. 834.

Podlipaev, S. A., Sturm, N., Fiala, I., Fernandes, O., Westenberger, S.J., Dollet, M., Campbell, D., Lukes, J. (2004) - Genetic diversity of insect trypanosomatids assessed from the Splice Leader RNA and 5S r RNA genes and intergenic regions. The Journal of Eukaryotic Microbiology. 51, (3):283-290.