Harry Klee holds the Dickman Chair for Plant Improvement at the University of Florida (UF) in Gainesville. Dr Klee’s research interests center around the biochemistry and genetics that underlie flavor in tomato and other fruit, and he has pioneered the use of transgenic plants to boost hormone function.
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How farmers and scientists are engineering your food
Prof Harry Klee of Florida University's horticultural sciences department is working to understand the chemical and genetic make-up of fruit and vegetable flavours - focusing on the tomato. "The tomato has been a long-term model system for fruit development. It has a short generation time, great genetic resources and [is] the most economically important fruit crop worldwide.
Curious about the sense of smell and loss after COVID-19? UF can help
The Gainesville Sun online
Others, like flavor and scent projects with citrus, strawberries and tomatoes, done by Yu Wang, Linda Bartoshuk and Harry Klee, search for new compounds that help enhance sweetness or reduce bitterness, he said. Their findings could be harnessed to help reduce the amount of sugars added to juices, make children's medicine easier to swallow and up the appeal of healthy but less popular foods.
Gardening Q&A: 2 improved varieties of tomato will be sold under Proven Winners brand
The Virginian Pilot online
The tomatoes are Garden Treasure and Garden Gem, developed at the University of Florida’s horticulture department by Harry Klee. Klee is Eminent Scholar, Dickman Chair for Tomato Improvement. His areas of research are biochemistry and genetics of flavor, and tomato fruit development. His lab is working to understand the chemical and genetic makeup of the flavors in fruits and vegetables, and then to develop varieties for the home garden that have heirloom taste coupled with improved performance.
Help Wanted from Tomato Taste Testers Around the World
Growing Produce online
“We have always encouraged feedback from these gardeners, and the enthusiasm they have shown encouraged us to formalize the process” Klee says. “Although UF/IFAS has supported the distribution of our seeds for roughly five years, this is the first time that we have established a formal program to collect data from individuals throughout the world, involving them directly in selection of new garden tomato varieties.”
The Great Tomato Debate: Should You Refrigerate or Not For Best Taste?
Discover Magazine online
“If you take the literature as a whole, the story is much more complicated than you shouldn’t or should refrigerate tomatoes,” says Harry Klee, a molecular biologist at the University of Florida in Gainesville. Klee was the lead researcher for a different study, published in 2016 in PNAS, about the impact of refrigeration on tomato taste. His team’s conclusion: Don’t refrigerate, like the packaging reads on NatureSweet Cherubs — "It's too cold in there!"
Bringing back a tastier tomato
CBS News tv
Biologist Harry Klee, of the University of Florida in Gainesville, has been researching tomatoes and their disappearing flavor for more than two decades. Horticulturalists are working to pack more flavor into the fruit that’s grown flavorless over the years. “All we’ve done between now and then was to add water to this fruit and make it bigger and bigger,” he told CBS News correspondent David Begnaud.
High-Throughput Chlorophyll and Carotenoid Profiling Reveals Positive Associations with Sugar and Apocarotenoid Volatile Content in Fruits of Tomato Varieties in Modern and Wild AccessionsMetabolites
Yusuke Aono, Yonathan Asikin, Ning Wang, Denise Tieman, Harry Klee, Miyako Kusano
2021 Flavor and nutritional quality has been negatively impacted during the course of domestication and improvement of the cultivated tomato (Solanum lycopersicum). Recent emphasis on consumers has emphasized breeding strategies that focus on flavor-associated chemicals, including sugars, acids, and aroma compounds. Carotenoids indirectly affect flavor as precursors of aroma compounds, while chlorophylls contribute to sugar production through photosynthesis. However, the relationships between these pigments and flavor content are still unclear. In this study, we developed a simple and high-throughput method to quantify chlorophylls and carotenoids. This method was applied to over one hundred tomato varieties, including S. lycopersicum and its wild relatives (S. l. var. cerasiforme and S. pimpinellifolium), for quantification of these pigments in fruits. The results obtained by integrating data of the pigments, soluble solids, sugars, and aroma compounds indicate that (i) chlorophyll-abundant varieties have relatively higher sugar accumulations and (ii) prolycopene is associated with an abundance of linear carotenoid-derived aroma compounds in one of the orange-fruited varieties, “Dixie Golden Giant”. Our results suggest the importance of these pigments not only as components of fruit color but also as factors influencing flavor traits, such as sugars and aroma.
Domestication of Crop Metabolomes: Desired and Unintended ConsequencesTrends in Plant Science
Saleh Alseekh, Federico Scossa, Weiwei Wen, Jie Luo, Jianbing Yan, Romina Beleggia, Harry J Klee, Sanwen Huang, Roberto Papa, Alisdair R Fernie
2021 The majority of the crops and vegetables of today were domesticated from their wild progenitors within the past 12 000 years. Considerable research effort has been expended on characterizing the genes undergoing positive and negative selection during the processes of crop domestication and improvement. Many studies have also documented how the contents of a handful of metabolites have been altered during human selection, but we are only beginning to unravel the true extent of the metabolic consequences of breeding. We highlight how crop metabolomes have been wittingly or unwittingly shaped by the processes of domestication, and highlight how we can identify new targets for metabolite engineering for the purpose of de novo domestication of crop wild relatives.
Transcriptional and epigenetic analysis reveals that NAC transcription factors regulate fruit flavor ester biosynthesisThe Plant Journal
Xiangmei Cao, Chunyan Wei, Wenyi Duan, Ying Gao, Jianfei Kuang, Mingchun Liu, Kunsong Chen, Harry Klee, Bo Zhang
2021 Flavor-associated volatile chemicals make major contributions to consumers’ perception of fruits. Although great progress has been made in establishing the metabolic pathways associated with volatile synthesis, much less is known about the regulation of those pathways. Knowledge of how those pathways are regulated would greatly facilitate efforts to improve flavor. Volatile esters are major contributors to fruity flavor notes in many species, providing a good model to investigate the regulation of volatile synthesis pathways. Here we initiated a study of peach (Prunus persica L. Batsch) fruits, and identified that the alcohol acyltransferase PpAAT1 contributes to ester formation. We next identified the transcription factor (TF) PpNAC1 as an activator of PpAAT1 expression and ester production. These conclusions were based on in vivo and in vitro experiments and validated by correlation in a panel of 30 different peach cultivars. Based on homology between PpNAC1 and the tomato (Solanum lycopersicum) TF NONRIPENING (NOR), we identified a parallel regulatory pathway in tomato. Overexpression of PpNAC1 enhances ripening in a nor mutant and restores synthesis of volatile esters in tomato fruits. Furthermore, in the NOR-deficient mutant tomatoes generated by CRISPR/Cas9, lower transcript levels of SlAAT1 were detected. The apple (Malus domestica) homolog MdNAC5 also stimulates MdAAT1 expression via binding to this gene’s promoter. In addition to transcriptional control, epigenetic analysis showed that increased expression of NACs and AATs is associated with removal of the repressive mark H3K27me3 during fruit ripening. Our results support a conserved molecular mechanism in which NAC TFs activate ripening-related AAT expression, which in turn catalyzes volatile ester formation in multiple fruit species.
Sensory and chemical characteristics of tomato juice from fresh market cultivars with comparison to commercial tomato juiceFlavour and Fragrance Journal
Stephen J Koltun, Andrew J MacIntosh, Renee M Goodrich‐Schneider, Harry J Klee, Samuel F Hutton, Paul J Sarnoski
2021 Fatty acid-derived volatile organic compounds (FA-VOCs) make significant contributions to tomato (Solanum lycopersicum) fruit flavor and human preferences. Short-chain FA-VOCs (C5 and C6) are among the most abundant and important volatile compounds in tomato fruits. The precursors of these volatiles, linoleic acid (18:2) and linolenic acid (18:3), are derived from cleavage of glycerolipids. However, the initial step in synthesis of these FA-VOCs has not been established. A metabolite-based genome-wide association study combined with genetic mapping and functional analysis identified a gene encoding a novel class III lipase family member, Sl-LIP8, that is associated with accumulation of short-chain FA-VOCs in tomato fruit. In vitro assays indicated that Sl-LIP8 can cleave 18:2 and 18:3 acyl groups from glycerolipids. A CRISPR/Cas9 gene edited Sl-LIP8 mutant had much lower content of multiple fruit short-chain FA-VOCs, validating an important role for this enzyme in the pathway. Sl-LIP8 RNA abundance was correlated with FA-VOC content, consistent with transcriptional regulation of the first step in the pathway. Taken together, our work indicates that glycerolipid turnover by Sl-LIP8 is an important early step in the synthesis of multiple short-chain FA-VOCs.
Identification of a lipase gene with a role in tomato fruit short-chain fatty acid-derived flavor volatiles by genome-wide associationThe Plant Journal
Xiang Li, Denise Tieman, Zimeng Liu, Kunsong Chen, Harry J Klee
2020 Fatty acid-derived volatile organic compounds (FA-VOCs) make significant contributions to tomato (Solanum lycopersicum) fruit flavor and human preferences. Short-chain FA-VOCs (C5 and C6) are among the most abundant and important volatile compounds in tomato fruits. The precursors of these volatiles, linoleic acid (18:2) and linolenic acid (18:3), are derived from cleavage of glycerolipids. However, the initial step in synthesis of these FA-VOCs has not been established. A metabolite-based genome-wide association study combined with genetic mapping and functional analysis identified a gene encoding a novel class III lipase family member, Sl-LIP8, that is associated with accumulation of short-chain FA-VOCs in tomato fruit. In vitro assays indicated that Sl-LIP8 can cleave 18:2 and 18:3 acyl groups from glycerolipids. A CRISPR/Cas9 gene edited Sl-LIP8 mutant had much lower content of multiple fruit short-chain FA-VOCs, validating an important role for this enzyme in the pathway. Sl-LIP8 RNA abundance was correlated with FA-VOC content, consistent with transcriptional regulation of the first step in the pathway. Taken together, our work indicates that glycerolipid turnover by Sl-LIP8 is an important early step in the synthesis of multiple short-chain FA-VOCs.