IDENTIFICATION OF NEW PLANT GROWTH INHIBITORS

BLAZQUEZ, MIGUEL; GABRIEL GOLA; CERDAN, PABLO DIEGO; JAVIER RAMIREZ; ANTONIETTI, MARIANA SOFÍA; ALABADÍ, DAVID; MAXIMILIANO SANCHEZ-LAMAS

Congreso; XII Reunión de Biología Vegetal; 2017

We have isolated compounds that inhibit germination during a chemical screening. These compounds comprised sulfonamides that inhibited germination in the presence of gibberellic acid. We observed a synergistic interaction with Abscisic acid (ABA) to inhibit germination; addition of fluoridone (an inhibitor of carotenoid and ABA biosynthesis) restored germination, suggesting that these compounds could be acting in the ABA pathway. Seedlings overexpressing enzymes involved in ABA catabolism were less sensitive to these compounds. However, ABA levels were lower in seeds exposed to these compounds and PYR/PYL (ABA receptor) deficient plants were also sensitive to the compounds, ruling out that they could act as agonists of ABA. We performed an RNAseq assay to try to understand the mode of action of these compounds. A significant subset of genes was activated by both ABA and the compounds, suggesting a mechanistic connection. However, this interaction was restricted to a specific subset of genes, including UV response genes, ruling out a general effect of these compounds in the ABA signaling or metabolic pathways that could explain their effects. Further analysis at the seedling stage indicated that these compounds inhibit plant growth, probably affecting cell division. The inhibitory action occurs both in dark and light conditions, but weak light protects seedlings from compound effects, whereas high light produces plant death. This is consistent with the similar transcriptome profiles of seedlings treated with these sulfonamides compared to seedlings treated with the herbicide norfluorazon. Now we expect to identify the potential targets through a genetic screening.