Phytohormones (also named as plant hormones) are chemicals produced by plants in order to modulate various aspects of plant development, stress responses and defence.


Recent studies revealed that fungi can also produce phytohormones or phytohormone-mimiking molecules, while it remains poorly understood about the details in the role and regulatory mechanism of such fungal produced phytohormonal molecules in plant-fungus interactions. The rice-blast fungus Magnaporthe oryzae imposes a great threat to global food security. Intensive investigation has been conducted to elucidate M. oryzae pathogenicity and rice (Oryza sativa L.) defense mechanism against blast disease, in order to provide theoretical basis and/or identify potential target(s) for developing novel disease control strategies, as well as for breeding of resistance varieties. Phytohormones have been demonstrated to play conserved and divergent roles in fine-tuning the balance of ricegrowth and immunity towards M. oryzae. Meanwhile, M. oryzae evolved elaborate strategy to manipulate the rice phytohormones metabolism, or even directly produce and secrete phytohormones, during their invasion process. In this review, we discuss the chemical communication in term of phytohormones in M. oryzae-rice pathosystem.






Figure 1: Schematic summary of inter-kingdom communication between M. oryzae and rice using phytohormonesM. oryzae produces (and like secretes) auxin, CKs and ABA during its infection on rice. Both auxin and ABA could promote rice growth while suppress its defense agains blast-disease. M. oryzae may use CKs for nutrient translocation, but meanwhile CKs signaling in rice may trigger defense response. M. oryzae is able to suppress rice JA biosynthesis and simultaneously convert JA to 12-OH JA, to interfere with rice defense response mediated by JA-signaling pathway.