A sinthetic steroid as a novel ABA-independent drought response inductor

LAILA TOUM; ESTEBAN MARIANO PARDO; J. GONZÁLEZ-OLMEDO; FAUSTO COLL-MANCHADO; LUCÍA PÉREZ BORROTO; ATILIO CASTAGNARO; YAMILET COLL-GARCÍA

Habana

Congreso; V Simposio de Bioquímica y Biología Molecular del 33 Congreso Latinoamericano de Química; 2018

Sociedad Cubana de Química

Water deficit is the greatest abiotic stress in worldwide agriculture, therefore reasearch aimed at reducing its effect, constituted a priority. Among them is the application of synthetic compounds like DI-31, a spirostanic brassinosteroid analog with greater persistence in the field. During the investigation, DI-31 (2.23uM) was analyzed as a regulator of the response to water and osmotic stress, by evaluating parameters such as oxidative burst, reduction of lipoperoxidation products, antioxidant activity of superoxide dismutase(SOD),catalase (CAT), ascorbate peroxidase (APX) and phenol peroxidase (POX) enzymes in Arabidopsis thaliana wild type and ABA-mutant plants, besides the relative expression by qRTPCR of abscisic acid (ABA)-related responsive genes. The oxidant burst induced by the DI-31 was registered 6 hours after the application of the compound, reaching the highest levels after 48 hours,time at which the antixidant enzyme SOD showed the greatest increases with concomitant decreaseof lipid peroxidation products. At the same time, DI-31 significantly decreased the activity of APX and POX peroxidases in both WT and ABA-hypersensitive pp2ca mutant plants subjected to stress, unlike all the control plantstreated with the compound and the ABA-insensitive SnRK2 mutant under stress. These peroxidases are regulated by ABA-dependent transcriptional factors, so their decrease in both WT and pp2ca plants, such as the increase in the SnRK2 mutant could be associated with an antagonist interaction between brassinosteroid and ABA stress-response transcriptional regulation.Also the gene expression patterns in DI-31 treated WT showed similar trends, by an increase in the expression of ABA-independent P5CS gene and the significant repression of RAB18, RD22 AND RD29A ABA-responsive genes.These results suggest that DI-31 may masks ABA effects in stress response, although acts as an effective antioxidant activity regulator in A.thaliana. However, it is possible to consider that most of its action will be developed as ABA-independent water stress responsive-inductor.