PAG-XIV  Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA


Workshop: Cucurbit

W80

The Melon Fruit: A Study Of Genes And Their Function

Nurit Katzir1 , Efraim Lewinsohn1 , Vitaly Portnoy1 , Yael Benyamini1 , Yoela Yariv1 , Mwafaq Ibdah1 , Zhangjun Fei3 , Nir Dai2 , Shahar Cohen2 , Yosef Burger1 , Yaakov Tadmor1 , Arthur Schaffer2 , Jim Giovannoni3

1  Agricultural Research Organization, Dept. of Genetics and Vegetable Crops, Newe Ya'ar Research Center, Ramat Yishay 30095, Israel
2  Agricultural Research Organization, Dept. of Genetics and Vegetable Crops, Bet Dagan, 50250, Israel
3  Boyce Thompson Institute for Plant Sciences & USDA-ARS, Cornell University, Ithaca, NY 14853, USA

A project aimed at the discovery and application of important genes controlling the metabolism of fruit quality components in melon (Cucumis melo L.) will be described. EST libraries of melon fruits were developed, representing the great variability of the species C. melo. These include subtracted and nonsubtracted, nonnormalized libraries. Altogether, 4800 ESTs from all these libraries were sequenced and a relational melon EST database was developed (http://melon.bti.cornell.edu/). The database also includes ca. 100 genes involved in major metabolic pathways (sugar, acid and carotenoids) cloned on the basis of homology to genes from other plant families. A microarray of over 3,000 unigenes is expected to be available to the public by the beginning of 2006.
The EST database has been mined to identify candidate genes affecting fruit ripening and fruit quality traits. Expression profiles of more than 200 genes were characterized by Northern blots and real-time PCR. Functional analyses of putative genes involved in aroma biosynthesis will be presented. Two novel sesquiterpene synthase genes have been isolated from melon varieties: CM-SS1 (‘Dulce’) and CM-SS2 (‘Noy Yizre’el’). Both genes have been overexpressed in E. coli and shown to code for proteins that are able to convert farnesyl diphosphate into (1) E,E, farnesene (CM-SS1) or (2) alpha & delta-cadinene and alpha-copaene (CM-SS2) . In addition, a CCD-like gene has also been isolated from melon. The gene has been functionally expressed in E. coli overproducing carotenoids. The gene product is able to catalyze the formation of volatile norisoprenoids from various carotenoid pigments.