Carbonic anhydrase in maize plants submitted to different doses of zinc

Abstract

Carbonic anhydrase (EC 4.2.1.1) is an extremely important metalloenzyme in the metabolism of plants, animals, and microorganisms, taking part in photosynthesis, the metabolism of carbohydrates, proteins and lipids, and has zinc in the structure of its active site. Zinc is a micronutrient, but also a heavy metal, which can cause benefits or toxicity to plants, depending on the amount it is absorbed. The aim of this research was to evaluate the activity of carbonic anhydrase in maize plants (Zea mays L.) grown in a nutrient solution with different concentrations of zinc. The plants were grown in a greenhouse in washed sand contained in lysimeters with a capacity for 1,300 g of sand, which received a nutrient solution without Zn and individualized additions of increasing doses of Zn as ZnSO4.7H2O. The experiment was set up in a completely randomized experimental design with 6 treatments (0, 5, 10, 20, 40 and 80 mg Zn kg-1 of substrate), with 6 replicates. Carbonic anhydrase activity increased significantly with the dose of zinc, with the highest activity at a concentration of 10 mg kg-1 of substrate. The concentration of zinc in the plant increased significantly in the root and aerial part, reaching the maximum total value (root + shoot) at the highest dose of zinc applied to the substrate. The lowest dry mass production by the corn plant occurred at the highest dose of zinc (80 mg Zn kg-1 of substrate) as a response to possible phytotoxicity and there was no significant difference between the other treatments, indicating that the Zn present in the seed was sufficient for the initial phase of corn development. Carbonic anhydrase activity did not correlate significantly with Zn accumulated in the plant and with dry mass production.

DOI:https://doi.org/10.56238/sevened2023.006-114