Coordinated transcriptional regulation of the carotenoid biosynthesis pathway genes contributes to fruit lycopene content in high-lycopene tomato breeding cultivars
James Duduit, MS Final Seminar
Under the direction of Drs. Wusheng Liu (Chair), Penelope Perkins-Veazie, Thomas Ranney
Friday, June 26, 2020, at 1:00 PM
Join Zoom Meeting:  https://ncsu.zoom.us/j/92084491394
Meeting ID: 920 8449 1394

Abstract
Lycopene content in tomato fruit is largely under genetic control and varies greatly among genotypes. Little is known about the molecular mechanisms regulating fruit lycopene content in high-lycopene tomato breeding cultivars. In the present study, 42 representative high-lycopene tomato breeding cultivars with different genetic backgrounds were collected worldwide. High-performance liquid chromatography (HPLC) analysis was used to quantify fruit carotenoid (lycopene, phytofluene, and beta-carotene) contents at four fruit developmental stages (i.e., breaker, orange, pink, and ripe) of each cultivar. Real-time RT-PCR was used to quantify the relative expression levels of all the 25 pathway genes individually at the breaker and ripe stages. In these cultivars, we found i) a general trend of strong expression of upstream genes prior to lycopene biosynthesis and weak expression of most downstream genes at both stages; ii) significant higher expression in 7 upstream genes and 8 downstream genes at the breaker or both stages than in the negative control cultivar Moneymaker; and iii) significant higher phytofluene, lycopene, and beta-carotene contents during fruit ripening than in Moneymaker. Thus, coordinated transcriptional regulation of the pathway genes contributed to a significantly higher metabolic flux flow into the pathway in these cultivars than in Moneymaker, leading to higher fruit lycopene content. This was the first systematic investigation of the role of the complete carotenoid biosynthesis pathway genes in fruit lycopene content in high-lycopene cultivars, which will enable tomato breeding and gene editing for improved fruit lycopene content.