Formação do aerênquima em raízes de milho Saracura BRS 4154 submetidas ao alagamento

Abstract

The maize cultivar ‘Saracura’ BRS-4154 was developed by the National Maize and Sorghum Research Center. Thus, the work was carried out with the purpose of analyzing the role of ethylene and hydrogen peroxide (H2O2) in the aerenchyma formation to different genetic selection cycles of ‘Saracura’ on four flooding times. For thus, plants of cycles C1, C5, C11 and C18, and sensitive variety BR 1 07 were flooded for 7 days with roots collected to 0 (control (no flooding)), 1, 3, 5 and 7 days. The gene expression of the enzymes ACC synthase (ACS), ACC oxidase (ACO), superoxide dismutase (SOD) and ascorbate peroxidase (APX); the determination of ethylene production and H2O2; the enzymatic activity of ACO, cellulase and polygalacturonase (PG); and the root anatomy were performed. There wasn’t expression to ACS and ACO. ACO activity and ethylene production were increased while SOD expression was higher at C1 and APX was higher at C18, with reduction in the last day. H2O2 content was similar between treatments. The cellulase activity was higher at C1 and C18 and it increased with time; the PG activity was slightly modified. The proportion of aerenchyma varied between cycles, depending on the formation rate and it increased during flooding. The total area of the cortex and the endoderm thickness increased with time and in the final cycles. The exoderm reduced in plants under long flooding; there was no variation of the epidermis. It was observed intercellular spaces formation in the meristem and change in the differentiation of endoderm in the root apex. The flooding time and genetic selection cycle influenced the aerenchyma formation mechanisms. The ethylene and H2O2 may be related to induction of tissue.