Uniform ripening Encodes a Golden 2-like Transcription Factor Regulating Tomato Fruit Chloroplast Development

[EN] Modern tomato (Solanum lycopersicum) varieties are bred for uniform ripening (u) light green fruit phenotypes to facilitate harvests of evenly ripened fruit. U encodes a Golden 2-like (GLK) transcription factor, SlGLK2, which determines chlorophyll accumulation and distribution in developing fruit. In tomato, two GLKs-SlGLK1 and SlGLK2-are expressed in leaves, but only SlGLK2 is expressed in fruit. Expressing GLKs increased the chlorophyll content of fruit, whereas SlGLK2 suppression recapitulated the u mutant phenotype. GLK overexpression enhanced fruit photosynthesis gene expression and chloroplast development, leading to elevated carbohydrates and carotenoids in ripe fruit. SlGLK2 influences photosynthesis in developing fruit, contributing to mature fruit characteristics and suggesting that selection of u inadvertently compromised ripe fruit quality in exchange for desirable production traits.Minimum Information About a Microarray Experiment (MIAME)-compliant microarray data are available at http://ted.bti.cornell.edu. and at http://www.ebi.ac.uk/arrayexpress/(accession E-MEXP-3652). F. Carrari and A. Fernie provided S. pennellii SlGLK2, and J. Maloof provided S. habrochaites SlGLK2 sequences. The U. S. Department of Agriculture (USDA)/National Institute of Food and Agriculture Solanaceae Coordinated Agricultural Project provided potato data. We are grateful to the Tomato Genome Consortium and the SOL Genomics Network for prepublication access to the tomato genome sequence. The S. pennellii introgression lines were provided by the C. M. Rick Tomato Genetics Resource Center; the S. pimpinellifolium populations were provided by the Instituto de Hortofruticultura Subtropical y Mediterranea "La Mayora," Consejo Superior de Investigaciones Cientificas; and both populations are available by request from the sources. The AtGLK-expressing lines were provided by Mendel Biotechnology and Seminis/Monsanto Vegetable Seeds. SlGLK2, the corresponding lines, and the F2 10-1 IL x M82 population lines and seeds are available from J. J. G. without restriction. Seminis/Monsanto will make available, upon request, and under a material transfer agreement indicating they are to be used for noncommercial purposes, the following lines: LexA:AtGLK1:p35S:LexA-Gal4; LexA:AtGLK1:pLTP:LexA-Gal4; LexA:AtGLK1:pRbcS:LexA-Gal4; LexA:AtGLK1:pPDS:LexA-Gal4; LexA:AtGLK2:p35S:LexA-Gal4; LexA:AtGLK2:pLTP:LexA-Gal4; LexA:AtGLK2:pRbcS:LexA-Gal4; LexA:AtGLK2:pPDS:LexA-Gal4; plus the T63 control line. Other biological materials are available by request from A. L. T. P. or J.J.G. A. L. T. P., T. H., K.L.-C., R.F.-B., and A. B. B. have filed a provisional U. S. patent application UC #2011-841, "Introduction of wild species GLK genes for improved ripe tomato fruit quality," through the University of California. A. L. T. P. and A. B. B. have filed the U. S. patent application #2010/0154078, " Transcription factors that enhance traits in plant organs," through Mendel Biotechnology. Assistance from B. Blanco-Ulate, S. Phothiset, S. Reyes, A. Abraham, L. Gilani, and G. Arellano is gratefully acknowledged. J. Langdale provided helpful advice regarding GLK phylogeny and nomenclature. G. Adamson and P. Kysar, Electron Microscopy (EM) Laboratory, University of California Davis Medical Center did the EM work. University of California Discovery and partners funded the pepper analysis and the initial investigations of the Arabidopsis GLKs. The Vietnam Education Foundation supported C.N. Fundacion Genoma Espana ESPSOL Project provided partial funding to A.G. USDA-Agricultural Research Service, USDA-National Research Initiative (2007-02773), and NSF (Plant Genome Program IOS-0923312) provided support to J.J.G.Powell, AL.; Nguyen, CV.; Hill, T.; Cheng, KL.; Figueroa-Balderas, R.; Aktas, H.; Ashrafi, H.... (2012). Uniform ripening Encodes a Golden 2-like Transcription Factor Regulating Tomato Fruit Chloroplast Development. Science. 336:1711-1715. doi:10.1126/science.1222218S1711171533