Plant Hormones and Plant Defense Response Against Pathogens

Biotic stresses are responsible for 20 to 40% losses of global agricultural productivity. Higher plants interact continuously with virus, fungi and bacteria, some of which lead to plant response firstly in the cell wall and cuticle acting as a physical barrier. However, successful resistance comes from a rapid switch on of the plant’s innate immune system, which involves the phytohormones salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), main players in signal transduction. Strategies have been developed by pathogens to manipulate plant hormonal pathways and modify the immune signaling for their own resistance enhancement in the host. Nitric oxide (NO) participates in this challenging signaling pathway shared with reactive oxygen species during plant-pathogen interaction, playing a decisive role from both adversaries. The complex crosstalk between pathogen and plant will be discussed considering the main categories of pathogens and the genetic constitution of the host. Moreover, the phytohormones signaling and their network regulation along with the involvement of NO and reactive oxygen intermediates will be revised according the recent efforts in plant biotechnology. Now, a primary challenge is to identify and characterize the host genes underlying the proteins targeted by effector molecules and to design targets for future genome editing approaches. Among the New Breeding Techniques (NBT), the application of CRISPR/Cas9 editing has become an effective tool for future reinforcement of disease resistance in crops.