Fire as a Potent Mutagenic Agent Among Plants

Abstract

Many of the earth's species-rich floras are fire-prone and current research is showing a key role for fire in their evolution and diversification. However the mechanisms by which fire might direct evolution at the cellular level are unknown. Mutagenesis is the foundation on which speciation is based and our literature survey shows that burning biomass may be a major source of potent mutagens in the form of heat, combustion products and recycled metals and radionuclides. Even mild heat may cause dysfunctional cell division and induce diploid gametes and genome duplication that are considered one of the cornerstones of speciation among flowering plants. Plant cell walls that undergo pyrolysis yield particulates and gases with strong mutagenic properties, among which polycyclic aromatic hydrocarbons, such as benzo[a]pyrene, are notable. Plants concentrate essential, nonmetabolic, and radioactive metal/metalloid ions from the soil and air; they are fractionated even further on combustion and may also have mutagenic effects on the chromosomes of stored seeds and regenerating plants. Morphological consequences may be profound, even mimicking traits present among other species in the lineage, and hold promise that fire-related mutagenesis may provide the missing mechanistic explanation for the close historical association between wildfire and speciation among seed plants.