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| Author(s): |
Scarlet Santos Monteiro
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2022-12-16 |
| Examining board members: |
Luciano Freschi;
Daniele Silva Pereira Rosado;
Ivan Sestari
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| Advisor: | Luciano Freschi |
| Abstract | |
Light modulates plant growth and development through photosensing mechanisms initiated by photoreceptors, among which phytochromes play a central role. Based on the previous identification of a photoinsensitive and constitutively active Tyr276His mutant allele of Arabidopsis thaliana phytochrome B (allele AtYHB), the present study aimed to investigate the impacts of constitutively active PHYB alleles in tomato (Solanum lycopersicum). Opposite to A. thaliana, the tomato genome harbors two PHYB genes (SlPHYB1 and SlPHYB2), which exhibit distinct expression profiles, suggesting functional diversification. Pioneering studies conducted in tomato have focused on investigating the impacts of SlPHYB1/B2 loss-of-function or silencing; however, the phenotypic alterations linked to the presence of constitutively active alleles of SlPHYB1 and SlPHYB2 (SlYHB1 and SlYHB2, respectively) during tomato vegetative and reproductive growth remains elusive. Therefore, here, the impacts of SlYHB1 or SlYHB2 overexpression on tomato physiology and the nutritional quality of its fruits were investigated.Transgenic plants overexpressing SlYHB1 or SlYHB2 displayed reduced shoot height, delayed axillary bud outgrowth, heavier leaves, overaccumulation of chlorophyll in different organs (i.e., leaves and green fruits), as well as delayed flowering transition, fruit ripening and age-induced leaf senescence. SlYHB1 or SlYHB2 overexpression also promoted the accumulation of antioxidant compounds, such as tocopherols, &beta-carotene and lutein, in the ripe fruits, a phenotype even more evident in response to SlYHB2 than SlYHB1. Fruit production was slightly reduced in SlYHB2-overexpressing lines, though red ripe SlYHB2 fruits exhibited increased total soluble solids. Therefore, the data obtained suggest that the overexpression of constitutively active SlPHYB1 or SlPHYB2 alleles results in similar phenotypical alterations during tomato vegetative development, whereas multiple pieces of evidence point to a possible functional diversification between these paralogs regarding tomato fruit production, ripening and nutritional quality. (AU) | |
| FAPESP's process: | 18/25774-2 - Overexpression of hyperactive mutant forms of phytochromes B1 and B2 as a means of manipulating tomato quality traits |
| Grantee: | Scarlet Santos Monteiro |
| Support Opportunities: | Scholarships in Brazil - Master |