ABSTRACT
ABSTRACT Conventional control methods for plant pathogenic bacteria include avoidant, exclusive, eradicative, protective, resistant, and therapeutic applications. Sustainable agriculture has become a norm for modern agriculture. As environmental and ecological issues continue to impact agriculture, all technologies developed for crop production must be economically feasible, ecologically sound, environmentally safe, and socially acceptable. Non-chemical methods for control of crop diseases, such as pathogen-free seeds, disease resistance, crop rotation, plant extracts, organic amendments, and biological control are considered to be less harmful than synthetic chemical pesticides and, therefore, offer great potential for application in conventional agriculture, organic farming, and/or soilless culture. Inoculations with plant-growth-promoting rhizobacteria (PGPR) were effective in controlling bacterial and multiple diseases caused by different pathogens. A number of chemical elicitors of SAR and ISR may be produced upon inoculation by PGPR strains, including salicylic acid, siderophores, lipopolysaccharides, 2,3-butanediol, and other volatile substances. Mycorrhizal fungi can limit subsequent infections by some bacterial pathogens. The use of bacteriophages as an effective phage therapy strategy faces signicant challenges for controlling plant diseases in the phyllosphere. A new approach to protect plants against bacterial diseases is based on a type of interference with the communication system known as quorum sensing (QS), which is used by several phytopathogenic bacteria to regulate expression of virulence genes according to population density. Traditional bactericides used too frequently and in excessive amounts on plants to manage these disease cause serious damage to agricultural and natural ecosystems. Therefore, there is a need to curtail pesticide use and reduce the environmental impacts of pesticides. In this connection, recognition of the importance of spices and their derivatives (extracts, essential oils, decoctions, hydrosols) in crop protection is increasing under the concept of integrated pest and disease management. A new generation of chemical compounds is being produced by either chemical synthesis or biotechnological processes. This new strategy includes the use of bioactive products, called plant activators, that induce
19.1 Introduction .......................................................................................................................... 352 19.2 Biological Control ................................................................................................................. 352
19.2.1 Plant Growth-Promoting Rhizobacteria (PGPR) ..................................................... 353 19.2.2 Mycorrhizal Activity ................................................................................................ 355 19.2.3 Bacteriophages .......................................................................................................... 355 19.2.4 Quorum Sensing (QS) ............................................................................................... 356 19.2.5 Using Essential Oil and Extracts of Medicinal and Aromatic Plants ...................... 357
19.3 Chemical Control of Plant Pathogenic Bacteria ................................................................... 357 19.4 Management of Plant Diseases Using Genetic Engineering ................................................ 359 19.5 Integration of Control Methods ............................................................................................ 361 19.6 Conclusion ............................................................................................................................ 362 References ...................................................................................................................................... 363
SAR in plants to many pathogens, including bacteria. R genes encode putative receptors that respond to the products of Avr genes expressed by the pathogen during infection, which are used in conventional resistance breeding programs. Transgenic plants have increased resistance to many plant pathogenic bacteria. Antimicrobial peptides have received attention as candidates for plant protection products. There is no single method of satisfactory control for plant diseases, especially those caused by bacteria. An integrative approach in accordance with the dynamics of agro-ecosystem management is not only the best strategy; it is the key to success in the control of crop diseases and the achievement of sustainable crop production.
