Project description:RNA interference (RNAi) is a widely-used approach to generate virus-resistant transgenic crops. However, durability of RNAi-mediated resistance under extreme field conditions and side-effects of stable RNAi expression have not been thoroughly investigated. Here we performed field trials and molecular characterization of two RNAi-transgenic Solanum lycopersicum lines resistant to Tomato yellow leaf curl virus (TYLCV) disease, the major constraint for tomato cultivation in Cuba and worldwide. In order to determine potential impact of the hairpin RNA transgene expression on tomato genome expression and development, differences in the phenotypes and the transcriptome profiles between the transgenic and non-transgenic plants were examined. Transcriptome profiling revealed a common set of up- and down-regulated tomato genes, which correlated with slight developmental abnormalities in both transgenic lines.
Project description:Transcriptional changes triggered by the systemic infection of the tospovirus Tomato Spotted Wilt Virus (TSWV) in roots and shoots of tomato plants (Solanum lycopersicum) mycorrhized by Glomus mosseae
Project description:Tomato fruit ripening is under the control of ethylene as well as a group of ethylene-independent transcription factors, including NON-RIPENING (NOR) and RIPENING INHIBITOR (RIN). During ripening, the linear carotene lycopene accumulates at the expense of cyclic carotenoids. Fruit-specific overexpression of LYCOPENE β-CYCLASE (LCYb) under the control of the PHYTOENE DESATURASE (PDS) promoter resulted in increased levels of β-carotene and ABA and in decreased ethylene levels. Genes regulated by ABA, or involved in its synthesis and signaling, were overexpressed, while those associated with ethylene and cell wall remodeling were repressed. In agreement with the transcriptional data, LCYb-overexpressing fruits exhibited increased density of cell wall material containing linear, under-methylated pectins and displayed an array of additional ripening phenotypes, including delayed softening, increased turgor, enhanced shelf life and a thicker cuticle with a higher content of cutin monomers and triterpenoids. The levels of several primary metabolites and phenylpropanoids also changed in the transgenics, which could be attributed to delayed fruit ripening and to ABA respectively. Network correlation analysis suggests that ABA, acting through NOR and RIN, is responsible for many of the above phenotypes. These data reinforce suggestions that ABA plays an important role in tomato fruit ripening and provide clues that fruit b-carotene, acting as a precursor for ABA, actively participates in controlling the ripening process rather than merely being an output thereof. Overexpression of a LCYb gene from Arabidopsis under the control of the ripening-associated PDS promoter leads to ripe tomato fruits accumulating high β-carotene levels. Using several independent transgenic lines, we conducted a system-wide study of the effect of increased β-carotene levels on tomato fruit ripening and shelf life. Our data suggest that β-carotene, acting through ABA, is involved in a regulatory loop within the network controlling tomato fruit ripening.