A focus on high-lycopene tomato cultivars: horticultural performance and functional quality

Abstract

Both transgenic and conventional breeding methods have been used to increase levels and diversify the profile of antioxidants in ripe tomato fruit. The high-pigment (hp) tomato mutants exemplify this approach, representing useful genetic resources to be introgressed into elite cultivars (high-lycopene cultivars) to simultaneously enhance the levels of different classes of antioxidants. Although several studies have been recently published on high-lycopene cultivars, information on their horticultural performance, processing attributes and functional quality is still scarce. In spite of the high content of lycopene, flavonoids and ascorbic acid, high-lycopene tomato cultivars are claimed to have poor horticultural performance, which limits their commercial acceptance. Therefore, the aim of this study was to review their agronomic and horticultural performance briefly as well as to review the functional quality of some recently developed high-lycopene tomato cultivars. Experiments conducted in the Mediterranean region showed that all the assayed high-lycopene tomato cultivars ('HLY02', 'HLY13', 'HLY18', 'Kalvert' and 'Lyco 2', including the latest developed lines 'HLT-F61' and 'HLT-F62') were vigorous, with an excellent dark-green foliage cover and characterized by dark-green immature fruits without morphological aberrations. Tomato yield ranged from 110 to 152 t ha-1, exceeding in some trials the yield of the elite industrial tomato cultivars ('Perfectpeel', 'Rio Grande' and 'Donald'). The average fruit weight ranged from 70 to 93 g, and soluble solids content was higher than 6 °Brix in some cases, associated with desirable titratable acidity values (0.381 for 'HLY18'). Regarding the phytochemical profiles, experiments under different geographical and environmental conditions confirmed that all tested high-lycopene cultivars were characterized by enhanced synthesis and accumulation of carotenoids, mainly lycopene and β-carotene (more than 280 and 20 mg kg-1 fw, respectively), as well as of other valuable health-promoting molecules such as phenolics, flavonoids and vitamins. Thus, the central role of high-lycopene tomato cultivars in enhancing fruit pigmentation and functional quality, summarized in this report, justifies extended efforts and breeding programs to decrease some initial adverse pleiotropic effects on their horticultural performance.