Polimorfismos em genes da oxidase alternativa (AOX) de ecótipos de Arabidopsis thaliana e Oryza sativa associados à altitude e à pluviosidade

Abstract

Alternative oxidase (AOX) is an essential enzyme to maintain redox homeostasis and supplying carbon for mitochondrial metabolism in stressed and developing plant. Here, we investigate the connection between AOX SNPs and the geographic conditions of origin of the ecotypes (climate, altitude and precipitation) using a genomic dataset from Arabidopsis and rice, 1190 and 90 ecotypes, respectively, in order to find potential markers of AOX stresses. The parameters defined to detect non-synonymous SNPs were that they belong to the mature AOX protein, occur in at least 30% of the population and cause class changes in the affected AA. Under these conditions, were detected the AA changes in AOX1c [A161E&G165R (35.6%), W186R (90.6%), R242S (77.5%)], in AOX1d [D274H (35.8%)] and in AOX2 [S76F (91.1%)] from Arabidopsis and in AOX1c [A232T (66.6%), G239R (73.3%), A232T&G239R (66.6%)] from rice, compared to AOX references from Columbia-0 and Japonica, respectively. Among these AA changes, all revealed a connection with high rainfall, or high altitude, or both. Comparative 3D modeling demonstrated that, generally, all polymorphic AOX had structural differences in relation to the references. Molecular docking revealed lower binding affinity values for interactions between AOX and the substrate ubiquinol in all structures compared to the reference (except the Os_AOX1c_G239R structure), indicating that most polymorphic structures have better affinity of enzyme-substrate binding. Overall, the data suggest that most of the AA alterations, related to the geographic conditions analyzed here, confer a better enzyme-substrate interaction, indicating a positive selection of a more efficient AOX induced by environmental conditions.