ABSTRACT
ABSTRACT Bacteria are one of the major causal agents of the plant diseases that create great economic losses in agriculture. An effective biocontrol of bacterial pathogens is essential to reduce the environmental risks posed by chemical control agents. A biocontrol agent for the control of plant diseases should colonize the rhizosphere and reduce the population or activity of the pathogens, but should not leave behind any toxic residues. The natural activities of microorganisms in soil or rhizospheres may contribute to the biocontrol of pathogens and improve the supply of nutrients, thereby enabling plants to maintain their health and tness and produce higher yields. The various processes of arbuscular mycorrhizal fungal (AMF) symbiosis, which can also alleviate the negative effects of plant pathogens, are the preferred
13.1 Introduction ..........................................................................................................................256 13.2 Plant Pathogenic Bacteria ..................................................................................................... 257 13.3 Arbuscular Mycorrhizal Fungi and Plant Pathogenic Bacteria ............................................ 257 13.4 Steps Involved in Bioprotection of AMF against Plant Pathogens ....................................... 258 13.5 Mechanisms Involved in the AMF-Mediated Biocontrol of Plant Pathogenic Bacteria ...... 258
13.5.1 Improvement of Plant Nutrition ................................................................................ 259 13.5.1.1 Tolerance to Pathogen ................................................................................ 259
13.5.2 Damage Compensation ............................................................................................. 259 13.5.3 Competition for Host Photosynthates ....................................................................... 259 13.5.4 Competition for Infection/Colonization Sites ...........................................................260 13.5.5 Anatomical and Morphological Changes in the Root System ..................................260 13.5.6 Microbial Changes in the Mycorrhizosphere ........................................................... 261 13.5.7 Activation of Plant Defense Mechanisms ................................................................. 261 13.5.8 Changes in Chemical Constituents ........................................................................... 262
13.5.8.1 Systemic and Induced Resistance .............................................................. 262 13.5.8.2 Phytoalexins and Phytoanticipins .............................................................. 262 13.5.8.3 Role of AMF in Phytohormones Production and Induced
Resistance in Plants ................................................................................... 262 13.5.8.4 Root Exudates ............................................................................................ 263
13.6 Effect of AMF in Stimulating Benecial Microorganisms That Are Antagonistic to Bacterial Plant Pathogens ................................................................................................. 263
13.7 In Vitro Studies on AMF and AMF-Associated Bacteria ....................................................264 13.8 Limitations ............................................................................................................................265 13.9 Conclusion and Future Considerations .................................................................................265 References ......................................................................................................................................266
