Plant–Pathogen Interactions: Broad Mite (Polyphagotarsonemus latus)-Induced Proteomic Changes in Chili Pepper Plant (Capsicum frutescens)

Plant-pathogen interactions are key biological events that shape ecological dynamics, food production, agriculture and economy. In this context, Capsicum frutescens is an economically and culturally significant chili pepper plant grown widely across the globe as an essential ingredient of hot sauces, chili concentrates, oleoresin flavors, and also in traditional medicines. An important pathogen that limits chili cultivation causing low yield and economic loss is the broad mite, Polyphagotarsonemus latus. Broad mite-infested chili plants have stunted growth and leaves appear coppery and dark, which show symptoms of leaf curl and more importantly the smaller fruits unfit for consumption. The molecular mechanisms of how broad mite affect chili remain poorly understood. In this study, we report a tandem mass tag (TMT)-labeled mass spectrometry-based quantitative proteomic analysis of leaves and apical meristems of healthy and infected chili pepper plants. In total, we identified 5799 proteins, of which 1677 proteins were found to be differentially regulated in infested plants. Related signaling pathways of the differentially expressed proteins were examined using bioinformatics tools. Predominantly, we identified pathways associated with jasmonic acid synthesis, mitogen-activated protein kinase, and plant defense and hormone signal transduction. We also observed upregulation of several enzymes of the phenylpropanoid and carotenoid biosynthetic pathways. This study provides the first in-depth proteomic analysis that correlates broad mite infestation in chili and dysregulation of various pathways that take part in plant defense. In the future, data can be extrapolated for innovation in pest management methods whose ecological footprints are better understood.