July 4, 2012
Scientists Obtain Complete Melon Genome
redOrbit Staff & Wire Reports - Your Universe Online
Researchers in Spain report that they have obtained the melon genome. This is the first time that a Spanish initiative that unites private and state-run centers has gained the complete genome of a higher organism, a plant, which produces flowers and seeds. Also, it has been done by applying massive sequencing technologies.
Besides the complete melon genome, scientists have obtained the particular genomes of seven melon varieties.
The study is published in the magazine Proceedings of the National Academy of Sciences (PNAS).
The scientific project has been led by Pere PuigdomÃ¨nech, at the Spanish National Research Council (CSIC), and Jordi Garcia Mas, at the Institute for Research and Technology in Food and Agriculture (IRTA). Both scientists work at the Center for Research in Agricultural Genomics (CRAG), in Barcelona. Also, the team lead by Roderic GuigÃ³, at the Genomic Regulation Center has made a huge contribution to the project.
The Melonomics project was launched by the Spanish Genome Foundation. Nine research centers have been involved, having the support of five companies and of five Spanish self-governing communities.
Results have shown that the melon genome has 450 millions of base pairs and 27.427 genes. It is much bigger than the genome of its nearest "relative," the cucumber that has 360 million base pairs.
”This difference is due mainly to the amplification of transposable elements. We didn't find recent duplications within the genome, which are very common in plant species", highlights PuigdomÃ¨nech.
"We have identified 411 genes that can be related in disease resistance. They are few but, nonetheless, the melon has a high capacity of adjustment to different environments", explains the CSIC scientist. During the work, when comparing this genome with others that are near philogenetically, they have observed how changes occur to the genome of this species, which is known for its high variability.
Another point of interest is related to the ripening of the fruit, a process which determines fruit characteristics such as taste and flavor. Scientists have identified up to 89 genes related with some aspects of this process: 26 genes related to the carotenoid accumulation - which gives the color to the melon flesh - and 63 related to the sugar accumulation and the taste of melon. 21 genes out of the last 63 had never been described before.
"Knowing the genome and the genes related to the characteristics of value for agriculture will allow us to improve this species for obtaining more disease resistant varieties and with better organoleptic properties", points out the IRTA scientist Jordi Garcia Mas.
Melon belongs to the family of cucurbits that also includes species such as cucumbers, watermelons and squashes. Cucurbits have relatively small genomes. "These are species of high financial interest, especially in the Mediterranean, Asian and African countries. Diseases that affect them, such as the mosaic virus in the case of cucumber or fungi can cause high financial losses. Therefore, we hope the genome sequentiation will have an important impact on improving this crop", says Pere PuigdomÃ¨nech.
According to figures of 2009 from the Food and Agriculture Organizations (FAO) of the United Nations, the production of melon worldwide is 26 million tons every year. Spain is the fifth biggest producer in the world. About one third of the production is exported, which makes Spain the biggest exporter of melon.
The melon genome project has been led by CRAG, which is a consortium of different institutions and universities, where they have done the sequencing and assembling of the genome. The Center of Genomic Regulation has annotated the genome.
Also, the project has had teams working on it at different centers and universities: the Pompeu Fabra University (Barcelona), the CSIC's Centro de EdafologÃa y BiologÃa Aplicada del Segura of the CSIC (Murcia), the Centro Nacional de AnÃ¡lisis GenÃ³mico (Barcelona), the Universidad PolitÃ©cnica in Valencia and Wisconsin University (U.S.). Furthermore, the company Roche Diagnostics has facilitated technologies in order to help the genome assembling.