Feder, A., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel, Technion, Israel Institute of Technology, Haifa, Israel
Burger, J., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Gao, S., Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, United States
Lewinsohn, E., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Katzir, N., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Schaffer, A.A., Plant Science Institutes, ARO, The Volcani Center, Bet Dagan, Israel
Meir, A., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Davidovich-Rikanat, R., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Portnoy, V., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel
Gal-On, A., Plant Protection Institutes, ARO, The Volcani Center, Bet Dagan, Israel
Fei, Z., Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, United States
Kashi, Y., Technion, Israel Institute of Technology, Haifa, Israel
Tadmor, Y., Cucurbit Section, Newe Ya‘ar Research Center, Agricultural Research Organization (ARO), Ramat Yishay, Israel

The flavonoids are phenylpropanoid-derived metabolites that are ubiquitous in plants, playing many roles in growth and development. Recently, we observed that fruit rinds of yellow casaba muskmelons (Cucumis melo ‘Inodorous Group’) accumulate naringenin chalcone, a yellow flavonoid pigment. With RNA-sequencing analysis of bulked segregants representing the tails of a population segregating for naringenin chalcone accumulation followed by fine mapping and genetic transformation, we identified a Kelch domain-containing F-box protein coding (CmKFB) gene that, when expressed, negatively regulates naringenin chalcone accumulation. Additional metabolite analysis indicated that downstream flavonoids are accumulated together with naringenin chalcone, whereas CmKFB expression diverts the biochemical flux toward coumarins and general phenylpropanoids. These results show that CmKFB functions as a posttranscriptional regulator that diverts flavonoid metabolic flux. © 2015 American Society of Plant Biologists. All rights Reserved.