Climate change is one of the major threats to biodiversity globally. Understanding the effects of global change on economically important plants is particularly important for identifying spatial patterns and enhances our ability to predict responses to future environments. We examined if predicted changes in precipitation patterns, resulting from global change, were associated with the accumulation of potentially beneficial mutations of genes that code for proteins from one of the most widely planted eucalyptus timber and pulp species, Eucalyptus grandis. Specifically, we examined gene regions of tonoplast intrinsic aquaporin proteins (TIPs) that are responsible for facilitating the transport of water molecules across cell membranes. Aquaporins play major roles in plant adaptations under stress conditions. Forty plants were grown in a glasshouse under ‘wet’ and well-fertilized conditions. After one month, an ‘extreme watering treatment’ was imposed on 20 plants. The ‘extreme’ treatment received double the watering (2 L), half as often as the 20 control plants. Leaf tissue was collected and DNA was extracted using the DNeasy Plant Mini Kit. Amplicons were sequenced by MacrogenUSA. Contigs were aligned and consensus sequence was generated using Geneious software. Full sequences were identified to be TIP1 using the nBLAST algorithm.
Results/Conclusions
Nucleotide variants were found across both the control and the treated samples. However, a pairwise alignment revealed 38 polymorphisms that code for the same polypeptide in all but one of the individuals. This one individual from the extreme treatment was found to have two SNPs that produced a glutamine amino acid residue in place of leucine at position 128 of the polypeptide product. The manner in which this amino acid change alters TIP1 protein function is still to be determined but presence of a protein variant in this highly conserved gene demonstrates that flood-stress can influence the evolution of a gene. These preliminary results suggest genes coding for tonoplast intrinsic aquaporin proteins may not be susceptible to mutations from extreme precipitation patterns. Additionally, we are currently expanding this research to include more TIP gene regions as well as other genes involved with growth that may respond to environmental stress.