Abstract
In plants, carotenoids define fruit pigmentation and are involved in the processes of photo-oxidative stress defense and phytohormone production; a key enzyme responsible for carotene synthesis in fruit is phytoene synthase 1 (PSY1). Tomatoes (Solanum section Lycopersicon) comprise cultivated (Solanum lycopersicum) as well as wild species with different fruit color and are a good model to study carotenogenesis in fleshy fruit. In this study, we identified homologous PSY1 genes in five Solanum section Lycopersicon species, including domesticated red-fruited S. lycopersicum and wild yellow-fruited S. cheesmaniae and green-fruited S. chilense, S. habrochaites and S. pennellii. PSY1 homologs had a highly conserved structure, including key motifs in the active and catalytic sites, suggesting that PSY1 enzymatic function is similar in green-fruited wild tomato species and preserved in red-fruited S. lycopersicum. PSY1 mRNA expression directly correlated with carotenoid content in ripe fruit of the analyzed tomato species, indicating differential transcriptional regulation. Analysis of the PSY1 promoter and 5′-UTR sequence revealed over 30 regulatory elements involved in response to light, abiotic stresses, plant hormones, and parasites, suggesting that the regulation of PSY1 expression may affect the processes of fruit senescence, seed maturation and dormancy, and pathogen resistance. The revealed differences between green-fruited and red-fruited Solanum species in the structure of the PSY1 promoter/5′-UTR, such as the acquisition of ethylene-responsive element by S. lycopersicum, could reflect the effects of domestication on the transcriptional mechanisms regulating PSY1 expression, including induction of carotenogenesis during fruit ripening, which would contribute to red coloration in mature fruit.
Highlights
Tomato (Solanum lycopersicum L.) fruit represents a fleshy berry, which during ripening, changes the color from green to red or yellow, orange, pink, brown, or purple, primarily because of chlorophyll degradation and intensification of carotenoid synthesis and accumulation [1,2].S. lycopersicum belongs to the Solanum section Lycopersicon, which includes 12 related wild tomato species with different evolutionary ages
The open reading frame (ORF) was 1239-bp long and contained six exons; the length and number of exons, and, the cDNA size did not vary among the analyzed species and were the same as reported for S. lycopersicum phytoene synthase 1 (PSY1) [12] and other Solanum PSY1 genes available in the NCBI database
The results indicated that the fruit of wild tomatoes ripe fruit and leaf of GF species S. habrochaites (LA2144), S. pennellii (LA0716) and S. chilense (LA1963), lacked lycopene and contained 10–20 times less of total carotenoids than those of S. lycopersicum; YF S. cheesmaniae (LA0421) and RF S. lycopersicum
Summary
Tomato (Solanum lycopersicum L.) fruit represents a fleshy berry, which during ripening, changes the color from green to red (most common) or yellow, orange, pink, brown, or purple, primarily because of chlorophyll degradation and intensification of carotenoid synthesis and accumulation [1,2].S. lycopersicum belongs to the Solanum section Lycopersicon, which includes 12 related wild tomato species with different evolutionary ages. Tomato (Solanum lycopersicum L.) fruit represents a fleshy berry, which during ripening, changes the color from green to red (most common) or yellow, orange, pink, brown, or purple, primarily because of chlorophyll degradation and intensification of carotenoid synthesis and accumulation [1,2]. Most wild tomatoes produce green or dark-green fruit, with the exception of three species, which have yellow All tomato species have flower petals of bright yellow-orange color due to the accumulation of carotenoids neoxanthin, violaxanthin, and lutein [5]. Carotenoids color flower organs and fruit to attract insects and animals for pollination and seed dispersion but are involved in photosynthesis, photo-oxidative stress defense, and phytohormone production during plant vegetative growth [6,7,8,9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
