Progress 01/01/03 to 08/31/09
Outputs
OUTPUTS: We identified multiple genes involved in synthesis of tomato flavor volatile compounds. These compounds contribute to overall flavor acceptability. We also identified multiple quantitative trait loci (QTL) that alter the volatile composition of tomato fruits. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Fruit and vegetable breeders PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The genes and QTL that we identified are the basis for a systematic approach to understanding and ultimately modifying tomato fruit flavor quality. We have mapped on the tomato genome multiple loci encoding activities that control volatile output. We also initiated experiments with consumer preference panels to determine how levels of the various volatile compounds influence peoples' perceptions of tomato flavor. Together with collaborators at Cornell University, we have established a database on flavor and nutrition quality in a range of tomatoes with the goal of discovery of the most important genes affecting flavor and nutritional quality.
Publications
- Mathieu S, Dal Cin V, Fei Z, Li H, Bliss P, Taylor MG, Klee HJ, Tieman DM. 2008. Flavor compounds in tomato fruits: identification of loci and potential pathways affecting volatile composition. J. Exp. Bot. 60: 325-337.
- Dal Cin V, Kevany B, Fei Z, Klee HJ. 2009. Identification of Solanum habrochaites loci that quantitatively influence tomato fruit ripening-associated ethylene emissions. Theor. Appl. Genet. 119: 1183-1192.
- Tieman D, Loucas H, Kim J-Y, Clark D, Klee H. 2007. Tomato phenylacetaldehyde reductases catalyze the last step in the synthesis of the aroma volatile 2-phenylethanol. Phytochem. 68: 2660-2669.
- Vogel JT, Tan B-C, McCarty DR, Klee HJ. 2008. The carotenoid cleavage dioxygenase 1 enzyme has broad substrate specificity, cleaving multiple carotenoids at two different bond positions. J. Biol. Chem. 283: 11364-113736.
- Joung J-G, Corbett AM, Moore Fellman S, Tieman DM, Klee HJ, Giovannoni JJ, Fei Z. 2009. Plant MetGenMAP: an integrative analysis system for plant systems biology. Plant Physiol. 151: 1758-1768.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: We have identified several genes encoding enzymes involved in tomato flavor volatile synthesis (described in publications). We have also identified approximately 30 new quantitative trait loci that affect synthesis of important flavor volatiles. This work has been written up and submitted for publication. PARTICIPANTS: Results of the project have been disseminated to multiple tomato breeding companies. One student, Michelle Zeigler, has graduated with a PhD. The subject of her dissrtation was related directly to this project. Several undergraduate interns, including two minority students, were supported to work on this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The identification of loci affecting flavor and genetic markers linked to those loci permits breeders to develop varieties with improved flavor quality. Such markers have been disseminated to several tomato breeding companies directly.
Publications
- Tieman D, Loucas H, Kim J-Y, Clark D, Klee H. 2007. Tomato phenylacetaldehyde reductases catalyze the last step in the synthesis of the aroma volatile 2-phenylethanol. Phytochemistry 68:2660
- Vogel JT, Tan B-C, McCarty DR, Klee HJ. 2008. The carotenoid cleavage dioxygenase 1 enzyme has broad substrate specificity, cleaving multiple carotenoids at two different bond positions. J. Biol. Chem. 283: 11364
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Progress 10/01/05 to 09/30/06
Outputs
In the past year we have made significant progress on characterization of the pathway that involves synthesis of the tomato flavor volatile 2-phenylethanol from phenylalanine. We have created transgenic plants that over-express either of two aromatic amino acid decarboxylases (AADCs). These plants have substantially more 2-phenylethanol, indicating that these enzymes encode the rate limiting step to synthesis of the end product. This work has been published in the Proceedings of the National Academy of Sciences. We have also identified a second gene that encodes phenylacetaldehyde reductase, the last step in the pathway. We have finished mapping approximately 35 quantitative trait loci (QTLs) that affect synthesis of flavor-related volatiles in tomato. This work has been published (see publications). We have begun a program to fine-map these loci to regions small enough to identify the genes responsible for two of these traits. We have also identified transgenic plants
that either over- or under-express the gene responsible for conversion of salicylic acid to methylsalicylate. This compound, also known as oil of wintergreen, is another contributor to tomato flavor. We have also received official permission to conduct taste panels with these transgenic lines to see if people can detect differences and preferences.
Impacts
With the identification of several genes that are involved in synthesis of different flavor volatiles, we are in a position to 1) manipulate synthesis of these compounds to alter tomato flavor and 2) provide molecular markers for assisting breeders in tomato flavor improvement. These genes will also in some cases be valuable tools for enhancing the scent of various ornamentals, most notably rose.
Publications
- Tieman D, Zeigler M, Schmelz E, Taylor M, Bliss P, Kirst M, Klee H. 2006. Identification of loci affecting flavor volatile emissions in tomato fruits. J. Exp. Bot. 57: 887-896.
- Goff SA, Klee HJ. 2006. Plant Volatile Compounds: Sensory Cues for Health and Nutritional Value? Science. 311: 815-819.
- Tieman D, Taylor M, Schauer N, Fernie AR, Hanson AD, Klee HJ. 2006. Aromatic amino acid decarboxylases participate in the synthesis of the flavor and aroma volatiles 2-phenylethanol and 2-phenylacetaldehyde in tomato fruits. Proc. Nat. Acad. Sci. USA. 103:8287-8292.
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Progress 10/01/04 to 09/30/05
Outputs
In the past year we unambiguously identified genes that encode the first step in synthesis of the important flavor volatiles, 2-phenylethanol and phenylacetaldehyde. This pathway is initiated by action of a family of aromatic amino acid decarboxylases. Transgenic tomato plants with altered levels of these volatiles were identified. We also completed mapping of 31 loci in tomato that quantitatively affect volatile emissions from fruits.
Impacts
The identification of the loci affecting fruit volatile emissions will assist breeding programs targeting improved flavor quality. The genes associated with these traits, as they are identified will also be important tools for genetic manipulation of fruit flavor quality.
Publications
- Tieman D, Zeigler M, Schmelz E, Taylor M, Bliss P, Kirst M, Klee H. 2006. Identification of loci affecting flavor volatile emissions in tomato fruits. J. Exp. Bot. In press.
- Auldridge M, Block A, Vogel J, Dabney-Smith C, Mila I, Bouzayen M, Magallanes-Lundback M, DellaPenna D, McCarty D, Klee H. 2006. Characterization of three members of the Arabidopsis Carotenoid Cleavage Dioxygenase family demonstrates the divergent roles of this multifunctional enzyme family. Plant J. In Press
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Progress 10/01/03 to 09/30/04
Outputs
In the last year we have integrated biochemical data for multiple seasons relating to flavor volatiles in tomato. We have done a similar analysis for acids as well. As a consequence, we have identified 16 genetic loci that affect accumulation of various acids and volatiles. We have also produced transgenic plants that are altered in expression of candidate genes that we believe may be involved in synthesis of the important volatiles, pehnylethanol and phenylacetaldehyde. Finally, we have identified genes that clearly do control synthesis of the carotenoid-derived volatiles beta-ionone and geranylacetone. We have produced transgenic tomato plants that are reduced in synthesis of these compounds by approximately 50%.
Impacts
Now that germplam with reproducibly altered composition has been identified, we expect to clone genes controlling the synthesis of some of these chemicals in teh coming year. This will lead to molecular markers useful for traditional breeding as well as tools for genetically modifying available lines with poor flavor.
Publications
- Booker J, Auldridge M, Wills, S, McCarty D, Klee H, Leyser O. 2004. MAX3/CCD7 is a carotenoid cleavage dioxygenase required for synthesis of a novel plant signaling molecule. Current Biol. 14: 1232-1238.
- Simkin A, Schwartz S, Auldridge M, Taylor M, Klee H. 2004. The tomato CCD1 (CAROTENOID CLEAVAGE DIOXGENASE 1) genes contribute to the formation of the flavor volatiles ?-ionone, pseudoionone and geranylacetone. Plant J, in press.
- Simkin A, Underwood B, Auldridge M, Loucas H, Shibuya K, Schmelz E, Clark D, Klee H. 2004. Circadian regulation of the PhCCD1 carotenoid dioxygenase controls emission of ?-ionone, a fragrance volatile of petunia flowers. Plant Physiol. 136: 3504-3514.
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Progress 10/01/02 to 10/01/03
Outputs
During the reporting period, we screened a large set of tomato germplasm for variations in flavor-related chemistry. The majority of effort was focused on recombinant inbred lines derived from a cross between L. pennellii and L. esculentum. We also initiated screens on a new set of germplasm derived from a cross between L. hirsutum and L. esculentum. We identified a subset of the screened materials that were reproducibly altered in flavor volatiles as well as in acids composition. The differences have shown up at least twice across multiple seasons and locations of testing. The next step is to screen for expression of a large set of genes in these various selected lines. The most progress on gene expression has been in relation to teh pathway for synthesis of the volatile, 2-phenylethanol. Here we have proven both in vitro and in vivo that we have cloned the gene encoding teh enzyme that is the last of three steps in synthesis.
Impacts
Now that germplam with reproducibly altered composition has been identified, we expect to clone genes controlling the synthesis of some of these chemicals in teh coming year. This will lead to molecular markers useful for traditional breeding as well as tools for genetically modifying available lines with poor flavor.
Publications
- No publications reported this period
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