CIRAD is tackling the complete sequencing of the banana genome

11/09/2009 - Article

Scientists from CIRAD and Génoscope in Evry are going to work on deciphering the 600 megabases of the banana genome over 2 years. The complete sequencing of the giant plant will make varietal improvement more effective, with particular focus on better resistance to diseases.

Producers and scientists had given up hope. Then, the news broke a few months ago: the complete banana genome-sequencing project starts in 2009. It will be conducted by CIRAD and Génoscope in Evry and financed by the Agence nationale de la recherche in France.

A considerable help to varietal improvement

The banana, which is the guarantor of both food and economic security for many populations, is constantly under threat from parasites. The main diseases, including Panama disease (fusariosis), black leaf streak or sigatoka (cercosporiosis), or the disease caused by ‘Banana Bunchy Top Virus’, represent major constraints for production. In addition, obtaining interesting new varieties using conventional crossing is limited by the low fertility of cultivated bananas. Therefore, the choice of parents and their improvement are key steps, which require thorough knowledge of genetic resources and a good understanding of the transmission of characteristics of agronomic interest. Thus, genome frequencing will be of considerable help for identifying interesting genetic characteristics for banana varietal improvement. It will also contribute to a better understanding of the evolution of the genome over time and to the evolution of the genomes of monocotyledons, more widely.

In order to conduct the project successfully, scientists are using different tools and resources, particularly those developed by CIRAD, with support from the Generation Challenge Programme (GCP) and the Global Musa Genomics Consortium (GMGC): banks of large DNA fragments (BAC banks), molecular markers and genetic maps.

The complete sequence totally accessible in the next 2 years

The sequencing will be conducted using a genotype created by CIRAD. This genotype is a double haploid: there are two identical copies of each of the 11 chromosomes, which will simplify the assembly of the sequence. The mass sequencing will be conducted at Génoscope in Evry, in the Paris region, as well as the first prediction of the position of genes. To achieve this, CIRAD will obtain the DNA extracted from this genotype, the BAC banks and ARN, the coding part of the genome. The structure of 300 genes will also be characterised manually, as precisely as possible. This data will be used as the basis of software programmes for predicting the position of genes. Lastly, CIRAD scientists will construct a dense genetic map of the sequenced clone, with two markers per megabase, i.e. 1200 markers. This map will be made with the anchorable markers (SSR, DArT) on the sequence and will facilitate the work of assembling the sequence of the whole genome.

In the next 2 years, the complete sequence will be totally and freely accessible on Internet. It will also be available on a biocomputing platform southgreen.cirad.fr proposed by CIRAD.