“Hormonal crosstalking in the control of apical dominance in pea (Pisum sativum L.)”

The aim of my research is the study of the involvement of three plant growth regulators (Auxin, Gibberellins and Strigolactones) in the regulation of apical dominance in pea and how they interact to control lateral bud growth. Strigolactones (SL) are carotenoid-derived terpenoid lactones. Recently SL, or a derivative thereof, have been identified as the long distance branching inhibitor signal in plants. The synthetic SL GR24 may restore apical dominance by rescuing the bushy phenotype of mutant plants that are defective in SL biosynthesis. The effectiveness of this chemical has been tested on pea plants with normal SL biosynthesis and signaling, following disruption of apical dominance by decapitation of the stem. The hypothesized crosstalking between SL and gibberellins (GAs) was investigated by comparing the response to GR24 of plants with different levels of bioactive GAs. GR24 was applied to the axillary buds of decapitated climbing and dwarf plants, the latters being defective in GA biosynthesis. The results suggest that the level of bioactive GAs might modulate the response of decapitated pea plants to GR24, by antagonizing the action of the SL. Furthermore, decapitation of pea plants and treatment of the axillary buds with GR24 deeply influence GA metabolism in the buds and highlight the possibility that root-derived GAs may contribute to enhance bud outgrowth.