Improving <i>Brassica Juncea</i> (L.) Defences against Herbivory Through Phosphate-solubilizing Bacteria

Phosphate solubilising bacteria (PSB) are safe alternatives to synthetic fertilisers due to their ability to mobilise bound phosphorus reserves. To evaluate the possibility of using PSB, not only to improve plant growth but also to provide fortification against herbivores, we studied morphological responses (trichome density, leaf thickness and biomass) in PSB-supplemented Brassica juncea, post damage by Spodoptera litura. Furthermore, the preference and performance of late-arriving herbivores on these plants were determined. A systemic increase of both adaxial and abaxial trichome density was observed in PSB-supplemented plants, especially in the newly emerging leaf. However, herbivory negatively affected the biomass of these plants. Moreover, the late-arriving herbivore showed reduced preference for the PSB-supplemented plants and showed a decline in consumption index and efficiency of conversion of ingested and digested food. Our study, therefore suggests that PSB supplementation shows a priming effect through elevated morphological responses which in turn deters herbivory on these plants.