Plant Chemical Defenses against Insect Herbivores-Using the Wild Tobacco as a Model

The Nicotiana genus, commonly known as tobacco, holds significant importance as a crucial economic crop. Confronted with an abundance of herbivorous insects that pose a substantial threat to yield, tobacco has developed a diverse and sophisticated array of mechanisms, establishing itself as a model of plant ecological defense. This review provides a concise overview of the current understanding of tobacco's defense strategies against herbivores. Direct defenses, exemplified by its well-known tactic of secreting the alkaloid nicotine, serve as a potent toxin against a broad spectrum of herbivorous pests. Moreover, in response to herbivore attacks, tobacco enhances the discharge of volatile compounds, harnessing an indirect strategy that attracts the predators of the herbivores. The delicate balance between defense and growth leads to the initiation of most defense strategies only after a herbivore attack. Among plant hormones, notably jasmonic acid (JA), play central roles in coordinating these defense processes. JA signaling interacts with other plant hormone signaling pathways to facilitate the extensive transcriptional and metabolic adjustments in plants following herbivore assault. By shedding light on these ecological defense strategies, this review emphasizes not only tobacco's remarkable adaptability in its natural habitat but also offers insights beneficial for enhancing the resilience of current crops.