Evaluation of the genes CYP 85 A 2 , BZR1, and CAD1 in the attenuation of cadmium in seedlings of the species Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby (PARICÁ) under different concentrations of 24- epibrassinolide

The Amazonian species paricá ( Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby ) accumulates cadmium (Cd) primarily in the roots, but the lack of understanding of gene modulation in response to this metal and the phytohormonal mechanisms complicates its relevance in the rehabilitation of degraded areas. Therefore, the present study aims to examine the expression of the CYP ₈₅ A ₂ and BZR1 genes, precursors of 24-EBL, in the production of chelating proteins by the CAD1 gene in seedlings of the Paricá species, under various concentrations of CdCl ₂ and 24-EBL. The experiment was conducted in a growth room at the Laboratory of Studies on Biodiversity of Higher Plants (EBPS) at the Federal Rural University of Amazon (UFRA), Belém-Pará Campus, following a completely randomized experimental design (CRD), in a 4x3 factorial scheme, totaling 60 experimental units with 4 treatments of CdCl ₂ (0, 50, 100, and 150 µM) and 3 doses of 24-epibrassinolide (0, 20, and 40 nM). The data were subjected to analysis of variance (ANOVA) (p < 0.05), and the differences between treatments were analyzed using Tukey's test (p < 0.05). The biometric variables indicated a significant reduction in root length due to the harmful effect of CdCl ₂ . Additionally, losses in Chl a , Chl b , and Chl a+b were observed due to the entry of Cd ²⁺ into the leaf tissues. Despite this, the CYP ₈₅ A ₂ , BZR1 , and CAD1 genes showed greater expression in the aerial part with varying doses of 24-EBL, while CAR and ACN were affected by increased CdCl ₂ , indicating a genetic adjustment in the upper parts of the plants to cope with Cd toxicity and maintain biological functions.