Modern commercial tomato varieties are substantially less flavorful than heirloom varieties. To understand and ultimately correct this deficiency, we quantified flavor-associated chemicals in 398 modern, heirloom, and wild accessions. A subset of these accessions was evaluated in consumer panels, identifying the chemicals that made the most important contributions to flavor and consumer liking. We found that modern commercial varieties contain significantly lower amounts of many of these important flavor chemicals than older varieties. Whole-genome sequencing and a genome-wide association study permitted identification of genetic loci that affect most of the target flavor chemicals, including sugars, acids, and volatiles. Together, these results provide an understanding of the flavor deficiencies in modern commercial varieties and the information necessary for the recovery of good flavor through molecular breeding.

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In an attempt to physically protect greenhouse tomato plants from the powdery mildew fungus Oidium neolycopersici, we developed a new electrostatic spore precipitator in which a copper wire conductor is linked to an electrostatic generator and covered with a transparent acrylic cylinder (insulator). The conductor was negatively charged by the generator, and the electrostatic field created by the conductor was used to dielectrically polarize the insulator cylinder. The dielectrically polarized cylinder also produced an electrostatic force without a spark discharge. This force was directly proportional to the potential applied to the conductor and was used to attract conidia of the pathogen. The efficacy of this spore precipitator in protecting hydroponically cultured tomato plants from powdery mildew was evaluated in the greenhouse. The hydroponic culture troughs were covered with a cubic frame installed with the spore precipitator, and the disease progress on precipitator-guarded and unguarded seedlings was traced after the conidia were disseminated mechanically from inoculum on tomato plants. Seedlings in the guarded troughs remained uninfected during the entire experiment, in spite of rapid spread of the disease to all leaves of the unguarded seedlings.

Auxin transport network, which is important in the integration of plant developmental signals, depends on differential expression of the auxin efflux carrier PIN gene family. We cloned three tomato PIN (referred as SlPIN) cDNAs and examined their expression patterns in fruit and other organs. The expression of SlPIN1 and SlPIN2 was highest in very young fruit immediately after anthesis, whereas the expression of SlPIN3 was low at this same stage of fruit development. SlPIN2::GUS was expressed in ovules at anthesis and in young developing seeds at 4 days after anthesis, while SlPIN1::GUS was expressed in whole fruit. The DR5::GUS auxin-responsive reporter gene was expressed in the fruit and peduncle at anthesis and was higher in the peduncle 4 days after anthesis. These studies suggest that auxin is likely transported from young seeds by SlPIN1 and SlPIN2 and accumulated in peduncles where SlPIN gene expression is low in tomato. The possible role of SlPINs in fruit set was discussed.

An ozone-generative electrostatic spore precipitator was developed to protect nursery-stage seedlings of tomato from both airborne conidia of powdery mildew ( Oidium neolycopersici ) and root-infecting pathogen propagules of bacterial wilt ( Ralstonia solanacearum ) and fusarium crown and root rot ( Fusarium oxysporum f.sp. radicis-lycopersici ). The device was a cylindrical electrostatic spore precipitator (S2 cylinder) in which a positively charged straight conductor wire insulated with a transparent acrylic cylinder originated from a spore-precipitation cylinder (S1 cylinder) designed to physically control airborne conidia of tomato powdery mildew in greenhouses. The S2 cylinder consisted of two sites for conidial attraction and ozone production. The site for ozone production was located at the end of the cylinder, where an earthed copper conductor ring (as a cathode) was attached to the edge of the cylinder, responding to the anodal tip of a positively charged central conductor wire. Distinct types of discharge (corona, corona-streamer, streamer and arc discharge) occurred between the two electrodes and were dependant on the voltages applied to the wire and the distances between the electrodes. The highest ozone production was observed through streamer discharge. The remaining portion of the S2 cylinder, which was dielectrically polarized by a positively charged wire, created a non-uniform electric field outside the cylinder to attract conidia that came into the generated field. Hydroponic culture troughs to raise tomato seedlings in a nursery greenhouse were paralleled with S2 cylinders. The aim was to control rhizosphere pathogens R. solanacearum and F. oxysporum f.sp. radicis-lycopersici and to prevent them entering the hydroponic system during cultivation, while at the same time trapping O. neolycopersici conidia in the spaces between the cylinders. The results indicated that susceptible tomato plants in culture troughs attached to the S2 cylinders remained uninfected by both rhizosphere and aerial pathogens throughout the experimental period (2 and 3 weeks, respectively). This suggests that the present system will enable the dual control of both these pathogens in hydroponic systems in greenhouses.Keywords : fusarium crown and root rot of tomato, ozone production, physical control of pathogens, polarized dielectric insulator, tomato bacterial wilt, tomato powdery mildew IntroductionWhile a greenhouse environment is excellent for growing tomatoes, it is even better for propagating disease-causing organisms. Because of the higher temperature, higher relative humidity and lush green foliage, diseases are constant threats once they enter a greenhouse. Management of disease at the seedling nursery stage is important to prevent the establishment of diseases that may affect cropping. In greenhouses, powdery mildew of tomato ( Oidium neolycopersici ) has frequently been detected on hypocotyls, cotyledons and first leaves of nursery-stage seedlings, as well as on well-developed plants in the propagation stage (M...