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The interplay between GA (Gibberellin) and Age (miR156 node) pathways controlling tomato flowering

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Geraldo Felipe Ferreira e Silva
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba.
Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
Defense date:
Examining board members:
Fabio Tebaldi Silveira Nogueira; Marcelo Carnier Dornelas; Luciano Freschi; Maria Magdalena Rossi; Victor Alexandre Vitorello
Advisor: Fabio Tebaldi Silveira Nogueira

The flowering process is a major developmental event during the plant life cicle. The meristem identity switches from vegetative to reproductive, triggering substantial genetic modifications that affect the whole plant body. Arabidopsis thaliana is a major model for flowering with five different pathways controlling this process. These pathways are redundant, making complex the complete elimination of phase change in this species. One of the pathways is termed AGE since it is regulated by the time of development. The miR156 and its direct target SBP (SQUAMOSA PROMOTER BINDING PROTEIN-like) are the main regulators of the AGE pathway. A second pathway is controlled by the phytohormone gibberellin (GA), which acts in opposite ways when comparing Arabidopsis thaliana and tomato. In tomato, unlike Arabidopsis, the cross between mutants with altered contents of GA and transgenic plants overexpressing the miR156 (156OE; SILVA et al, 2014) showed synergistic effect in delayed flowering time. Treatments of GA3 in plants 156OE lead to similar effects visualized on the crosses above related to meristem transition. Among the crosses between GA mutants and 156OE plants, one double mutant could completely abolish the phase change in tomato. An extra offer of the florigen (SINGLE FLOWER TRUSS or SFT) by grafting experiments was unable to restore the flowering process in this double mutant. It suggests, pathways associated to GA and AGE regulate common downstream targets, which could be independent of SFT regulation. Moreover, the transcriptional regulation, and possible the post-transcriptionally regulation of some SBP targets by different pathways associated to GA, suggest a complex network between GA and AGE during the flowering in tomato. The combined action of GA and AGE pathways can complete impaired the flowering in tomato, this interaction is opposed to the model Arabidopsis thaliana. The negative effect of GA over the time of flowering is presented in wood plants, suggesting the scientific discoveries in tomato could be expanded to these species, which experiments are slow and laborious (AU)

FAPESP's process: 13/16949-0 - Plant architecture regulation of tomato by the pathway miR156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL)
Grantee:Geraldo Felipe Ferreira e Silva
Support Opportunities: Scholarships in Brazil - Doctorate