Dehghanpour FarashahS (2023) Defense responses by nitric oxide in plant-pathogen interaction. Plant Pathology Science 12(2):130-142.
The control of diseases in agriculture often relies on pesticides and chemical fertilizers, which negatively affect the rhizosphere natural microflora and ecosystem balance. Today, researchers are looking to replace these chemicals with other environment friendly agents to improve agricultural production and control plant pathogens. Research on the interaction of nitric oxide (NO) with plant pathogens has shown that NO is a key messenger in the response of plants to biotic and abiotic stresses. Due to the role of NO in the regulation of plant defense genes, especially through programmed cell death, it has attracted the attention of many plant pathologists. Although NO plays an important role in the hypersensitive reaction in response to various biotic and abiotic stresses, it has been found that NO also plays a role in regulating the expression of genes related to non-specific resistance. In this review, the role of nitric oxide in plant-pathogens interaction has been investigated.
Humic acid (HA) is the most important and widely used biostimulants in agriculture. As a powerful, multifaceted tool in increasing soil health and plant resistance, HA has significant effects for sustainable agriculture and plant disease management. This safe organic compound controls diseases through direct and indirect mechanisms. In the indirect dimension, HA creates an unfavorable environment for the development of pathogens by improving the physical structure of the soil by increasing porosity and ventilation, enhancing the cation exchange capacity and chemical fertility of the soil, as well as stimulating the population of beneficial soil microorganisms. In addition, HA strengthens the plant by stimulating the development of the root system, facilitating the absorption of water and nutrients, and especially by activating the mechanisms of inducing systemic resistance in the plant, leading to the production and accumulation of defensive metabolites increasing the activity of defensive enzymes, and the proteins associated with pathogenesis. This article provides a summary of the effectiveness of HA as a plant stimulant on plant pathogens and the prospects for its use to reduce the use of chemical pesticides or even replace them in controlling plant diseases. A good understanding of the function of biostimulants, including humic acid, will help farmers and agricultural scientists in their better use.
