Effect of Pantanal Fire Events on the Secondary Metabolism of Plants

Abstract We investigated the effects of fire on the secondary metabolites of Rhamnidium elaeocarpum in the Pantanal region. We analyzed the total phenol and tannin content of individuals from four different sampling groups and used LC-MS metabolomics techniques to observe the metabolites present in the samples and the thermogravimetric behavior of the species. Our findings suggest that recent fires did not significantly affect the species' phenolic metabolism, except for specimens affected by the 2020 megafire, which exhibited a decline in compounds due to leaching. The data suggests that recent fire incidents did not impact the phenolic metabolism of the species, and the high levels indicate that the species has a biochemical tolerance to the stress caused by seasonal fires. Metabolomic profiles showed intense biosynthesis of proanthocyanidin oligomers, which protect against oxidative stress and post-fire environmental disturbances. The results of the thermogravimetric behavior showed the species' thermotolerance and intrinsic relationship with secondary compounds. Overall, our study advanced our understanding of the impact of fire on woody species' metabolism. However, distinguishing whether chemical traits are an adaptive feature or a response to surrounding environmental factors presents a challenge.