Chemico-Biological Characterization of Torpedino Di Fondi® Tomato Fruits: A Comparison with San Marzano Cultivar at Two Ripeness Stages

Torpedino di Fondi (TF) is a hybrid tomato landrace developed in Sicily and recently introduced in the south Lazio area along with the classical San Marzano (SM) cultivar. The present study aimed at characterizing TF tomatoes at both pink and red ripening stages, and at comparing them with traditional SM tomatoes. A multidisciplinary approach consisting of morphological, chemical (FT-ICR MS, NMR, HPLC, and spectrophotometric methods), and biological (antioxidant and antifungal in vitro activity) analyses was applied. Morphological analysis confirmed the mini-San Marzano nature and the peculiar crunchy and solid consistency of TF fruits. Pink TF tomatoes displayed the highest content of hydrophilic antioxidants, like total polyphenols (0.192 mg/g), tannins (0.013 mg/g), flavonoids (0.204 mg/g), and chlorophylls a (0.344 mg/g) and b (0.161 mg/g), whereas red TF fruits were characterized by the highest levels of fructose (3000 mg/100 g), glucose (2000 mg/100 g), tryptophan (2.7 mg/100 g), phenylalanine (13 mg/100 g), alanine (25 mg/100 g), and total tri-unsaturated fatty acids (13% mol). Red SM fruits revealed the greatest content of lipophilic antioxidants, with 1234 mg/g of total carotenoids. In agreement with phenolics content, TF cultivar showed the greatest antioxidant activity. Lastly, red TF inhibited Candida species (albicans, glabrata and krusei) growth.

The Use of a Tomato Landrace as Rootstock Improves the Response of Commercial Tomato under Water Deficit Conditions

Grafting onto drought tolerant rootstocks has been proposed as a useful strategy to overcome future water scarcity periods. The ‘de Ramellet’ tomato is a drought tolerant landrace selected under semiarid Mediterranean summer conditions under rain-fed or low irrigation. In this manuscript, the responses of a commercial hybrid ‘de Ramellet’ genotype grafted onto a traditional ‘de Ramellet’ (RL) and a commercial Maxifort (Mx) tomato rootstocks under commercial greenhouse conditions are studied. Non-grafted (NON) and self-grafted (SELF) plants were used as controls. Two water regimes were established: well-watered (WW, covering plant water demands) and water deficit (WD, reducing 50% irrigation as compared to WW). The results confirm an improvement in agronomic performance of Mx as compared to NON, but also show a similar improving effect of RL. Grafting enhanced plant growth regardless of the rootstock under WW conditions. Similarly, water-use efficiency (assessed as leaf carbon isotope composition) increased in grafted plants under WD treatment as compared to NON. Despite the lack of significant differences, RL tended to promote higher fruit production and fruit number than Mx, irrespective of the water treatment, whereas RL was the single graft combination with higher fruit production than NON under WD. In conclusion, the results uncover the potential of drought-adapted landraces to be used as rootstocks in order to increase plant growth and fruit production under both well-watered and water deficit cultivation conditions.

Fruit-specific expression of crtB, HpBHY, CrBKT and SlLCYB triggers hyper-production of carotenoids in tomato fruit

Background Tomato is a major source of dietary carotenoids that play an important role in human health. The biosynthesis of carotenoids involved in a number of catalytic steps, among which the phytoene synthase (crtB) is the first committed enzyme for carotenoid biosynthesis, and the lycopene β-cyclase (LCYB) catalyzes the synthesis of β-carotene, β-carotene hydroxylase (BHY) or β-carotene ketolase (BKT) plays a vital role in synthesizing xanthophylls. Although there are some studies about improving the carotenoids of tomato fruit, it is still challenged to engineer tomato landraces with good traits for hyper-production of carotenoids, and the effects of vital carotenogenic genes working together remain unclear. The aim of this study is to improve the production of carotenoids in a tomato landrace by fruit-specific expression of four carotenogenic genes. Results A plant expression cassette containing the tomato E8 promotor to drive the four genes ( crtB , HpBHY , CrBKT , and SlLCYB ) in a polycistronic structure was constructed and introduced into a tomato landrace “ Huang Song ”. Three independent lines were confirmed to be putative transformants, which showed similar phenotypes to wild-type (WT) control excepting for the fruit colors. The transgenic fruit exhibited deep red color due to the accumulation of novel ketocarotenoids including astaxanthin, canthaxanthin, and ketolutein and much more lycopene. The contents of total carotenoids in transgenic fruit were up to 3.1~6.6 mg/g dry weight (DW), 20~44-fold of that in WT fruit which only accumulated low levels of lutein, lycopene and β-carotene. Furthermore, various generations of the transgenic plants (T0, T1, and T2) exhibited similar growing status and carotenoid profiles, indicating that the transformants were genetically stable. Moreover, most of the endogenous carotenogenic genes were up-regulated in transgenic fruits at mature stage, and more plastoglobules were found in chromoplast, suggested the causes of the enhanced accumulation of carotenoids and antioxidant activity in transgenic plants. Conclusions Fruit-specific expression of crtB , HpBHY , CrBKT and SlLCYB triggers hyper-production of carotenoids and the synthesis of ketocarotenoids in tomato fruit. This study provides insights into metabolic engineering of tomato for enhanced production of value-added carotenoids.

Exploiting Genetic and Genomic Resources to Enhance Heat-Tolerance in Tomatoes

High temperature is one of the most detrimental abiotic stresses in tomatoes. Many studies highlighted that even small increases in temperature can alter the plant reproductive system, causing a significant reduction in tomato yield. The aim of this study was to exploit the phenotypic and genomic variations of a tomato landrace collection grown at high temperatures. Fifteen genotypes were selected as the best performing in two experimental fields. The selection was based on six yield-related traits, including flower earliness, number of flowers per inflorescence, fruit set, number of fruit per plant, fruit weight and yield per plant. In order to identify markers targeting traits that could be highly influenced by adverse climate conditions, such as flowering and fruit setting, an association mapping approach was undertaken exploiting a tomato high-throughput genomic array. The phenotypic variability observed allowed us to identify a total of 15 common markers associated with the studied traits. In particular, the most relevant associations co-localized with genes involved in the floral structure development, such as the style2.1 gene, or with genes directly involved in the response to abiotic stresses. These promising candidate genes will be functionally validated and transferred to a cultivated tomato to improve its performance under high temperatures.

TUBE GRAFTING REDUCES INCIDENCE AND SEVERITY OF BACTERIAL WILT IN TWO TOMATO CULTIVARS IN ABEOKUTA, NIGERIA

Bacterial wilt, Ralstonia solanacearum, causes severe loss of tomato (Solanum lycopersicum L.) pro-duction in Nigeria. Tube grafting of two tomato cultivars (Beske and UC82-B) on bacterial wilt-resistant tomato landrace rootstock (Tomachiva) was conducted to reduce incidence of bacterial wilt and in-crease the yield in the two cultivars. The experiments were laid in Randomized Complete Block De-sign (RCBD). Percentage incidence and Percentage Severity Index (PSI) of grafted tomato were 0.00% each in the early planting season. Incidence (1.70%) and PSI (1.50%) of grafted tomato were observed in late planting season. Non-grafted tomato had higher significant values of 42.50% and 38.80% in incidence and percentage severity index in late planting season. Grafting on Tomachiva effectively reduced the incidence and severity of bacterial wilt in two cultivars of tomato in southwest Nigeria