Stomatal and pollen dependant metabolic changes as a metric of stress tolerance and invasive potential of invasive plant – Lantana camara (L.) growing under abiotic stress like conditions

Abstract

Lantana camara (L.) from family Verbenaceae, is an ornamental, annual noxious invasive weed native to tropical America but now found in many other countries due to its fast growth and spread. It has the potential to diminish native plants and can survive under variety of adverse abiotic stresses. Plants growing under natural conditions at different temperatures were sampled and used for various metabolic analysis. Indices like Malondialdehyde (MDA), Membrane Injury Index (MII), Membrane Stability Index (MSI) and stomata measurements were performed on stomata and pollens under adverse conditions. For studying the reason behind high level of invasiveness of Lantana, in-tissue localisation of various secondary metabolites and antioxidant enzymes and reactive oxygen species (ROS) were investigated in stomata and pollens. The histochemical level of secondary metabolites (lignin, lipids, suberin, cellulose, hemicellulose, callose) were increased in stomata and pollens under adverse abiotic stress conditions as compared to control conditions. Similarly, in-tissue localisation of various antioxidants viz: Glutathione, Thioredoxin reductase, Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), Catalase, Superoxide Dismutase, Peroxidase, Monodehydroascorbate reductase increased substantially under cold and heat stress compared to control in stomata and pollens. Elevated levels under stressful conditions suggests the role of all these enzymes and secondary metabolites in plant stress tolerance against environmental abiotic stress conditions. Therefore, it can be implied from the results that invasive alien plants can protect themselves from certain stresses by accumulating ROS scavenging enzymes and other stress related metabolites.