Investigating the Elements of Plant Defense Mechanisms Within Plant Immune Responses Against Pathogens

Biotic stress can increase or reduce a plant's susceptibility to specific pathogens. A wide range of plant pathogens, i.e., viruses, bacteria, and fungi causing diseases, modulate different elements of plant defense mechanisms responses that influence disease and the physiological state of host plants. Nevertheless, plant hosts are not static and defenseless. Plants have developed active and dynamic complex defense mechanisms to protect themselves against different pathogenic stressors. Plants' defense mechanisms consist of multi-elements and can be determined by pre-formed, natural barriers or inducible defense responses directly activated upon detection of a pathogen. The inducible response is defined as ‘basal resistance’ or ‘innate immunity’ and is regulated by signal transduction and transcriptional networks. Moreover, plant responses to pathogens are finely tuned and complex at the immune receptor, cellular, proteome, epigenetic, and transcriptome levels. We can tell that a sophisticated molecular ‘arms race’ is taking place in the biological co-evolution of plant-pathogen interactions especially in developing novel elements involved in this interaction. Therefore, a comprehensive understanding of the broad spectrum and underlying elements of defense mechanisms in the interactions between plants and their pathogenic enemies will improve plant resistance to pathogens.

This Research Topic explores current knowledge with novel research insights and trends regarding the structural, molecular, and physiological aspects of plant defense mechanisms during interactions with pathogens. We welcome studies that take interdisciplinary approaches to decode the vast complexity of these defense mechanisms underlying resistance responses. We believe that host plants depend on a multilayered defense response system to mitigate pathogen infection. Therefore, understanding how pathogens change adaptive mechanisms to infection in plant hosts and how plants develop diverse resistance mechanisms to beat back pathogens will provide crucial scientific support for better prevention and control of plant diseases.

In recent years, significant developments have been made in the biology of interactions between plants and different pathogen groups. These developments have been made at the genetic, transcriptomic, proteomic, and metabolomic levels. However, the interaction between the pathogen and the plant is still not entirely understood. Therefore, this Research Topic aims to greatly expand our understanding of the molecular elements of the defense mechanisms of plants against pathogens. We would like to bring together the latest advances in response mechanisms in plants, including plant signaling (also hormones), resistant genes, and plant secondary metabolites during ongoing plant-pathogen interactions. The latest findings related to cloning and function analysis of key stress genes are invited. In addition, works describing the effect of exogenous compounds on boosting the activation and function of defense mechanisms against various pathogens are also welcomed.

This Research Topic focuses on deciphering cellular and molecular mechanisms associated with plant defense responses against pathogens. We welcome reviews and original research papers that advance knowledge and understanding of the following aspects:

• Molecular interactions between plants and pathogens like bacteria, fungi, viruses, oomycetes, and nematodes

• Plant pathogenesis mechanisms

• Plant physiology of pathogen interactions

• Plant immune responses to pathogens at the molecular and cellular level

• Evasion and/or suppression of plant defense responses by pathogens