title: Engineering melon plants with improved fruit shelf life using the TILLING approach.
abstract: BACKGROUND
  Fruit ripening and softening are key traits that have an effect on food supply, fruit nutritional value and consequently, human health. Since ethylene induces ripening of climacteric fruit, it is one of the main targets to control fruit over ripening that leads to fruit softening and deterioration. The characterization of the ethylene pathway in Arabidopsis and tomato identified key genes that control fruit ripening.
  
  
  RESULTS
  To engineer melon fruit with improved shelf-life, we conducted a translational research experiment. We set up a TILLING platform in a monoecious and climacteric melon line, cloned genes that control ethylene production and screened for induced mutations that lead to fruits with enhanced shelf life. Two missense mutations, L124F and G194D, of the ethylene biosynthetic enzyme, ACC oxidase 1, were identified and the mutant plants were characterized with respect to fruit maturation. The L124F mutation is a conservative mutation occurring away from the enzyme active site and thus was predicted to not affect ethylene production and thus fruit ripening. In contrast, G194D modification occurs in a highly conserved amino acid position predicted, by crystallographic analysis, to affect the enzymatic activity. Phenotypic analysis of the G194D mutant fruit showed complete delayed ripening and yellowing with improved shelf life and, as predicted, the L124F mutation did not have an effect.
  
  
  CONCLUSIONS
  We constructed a mutant collection of 4023 melon M2 families. Based on the TILLING of 11 genes, we calculated the overall mutation rate of one mutation every 573 kb and identified 8 alleles per tilled kilobase. We also identified a TILLING mutant with enhanced fruit shelf life. This work demonstrates the effectiveness of TILLING as a reverse genetics tool to improve crop species. As cucurbits are model species in different areas of plant biology, we anticipate that the developed tool will be widely exploited by the scientific community.
authors.affiliation: Unité de Recherche en Génomique Végétale, UMR1165 ERL8196 INRA-UEVE-CNRS, Evry, France.
authors.forename: Fatima
authors.initials: F
authors.lastname: Dahmani-Mardas
authors.forename: Christelle
authors.initials: C
authors.lastname: Troadec
authors.forename: Adnane
authors.initials: A
authors.lastname: Boualem
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lévêque
authors.forename: Abdullah A
authors.initials: AA
authors.lastname: Alsadon
authors.forename: Abdullah A
authors.initials: AA
authors.lastname: Aldoss
authors.forename: Catherine
authors.initials: C
authors.lastname: Dogimont
authors.forename: Abdelhafid
authors.initials: A
authors.lastname: Bendahmane
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000235:genetics; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray / Q000379:methods; D019662:Cucurbitaceae / Q000235:genetics* / Q000502:physiology*; D005030:Ethylenes / Q000737:chemistry; D005638:Fruit / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering / Q000379:methods; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010641:Phenotype; D011487:Protein Conformation; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D005030:Ethylenes; C036216:ethylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase