Xanthomonas bacteriophages: a review of their biology and biocontrol applications in agriculture

Abstract

Phytopathogenic bacteria are economically important because they affect crop yields and threaten the livelihoods of farmers worldwide. The genus Xanthomonas is particularly significant because it is associated with some plant diseases that cause tremendous loss in yields of globally essential crops. Current management practices are ineffective, unsustainable and harmful to natural ecosystems. Bacteriophage (phage) biocontrol for plant disease management has been of particular interest from the early nineteenth century to date. Xanthomonas phage research for plant disease management continues to demonstrate promising results under laboratory and field conditions. AgriPhage has developed phage products for the control of Xanthomonas campestris pv. vesicatoria and Xanthomonas citri subsp. citri. These are causative agents for tomato, pepper spot and speck disease as well as citrus canker disease.Phage-mediated biocontrol is becoming a viable option because phages occur naturally and are safe for disease control and management. Thorough knowledge of biological characteristics of Xanthomonas phages is vital for developing effective biocontrol products. This review covers Xanthomonas phage research highlighting aspects of their ecology, biology and biocontrol applications.

Isolation of Novel Xanthomonas Phages Infecting the Plant Pathogens X. translucens and X. campestris

“…Our results suggest that our phages are suitable candidates for an application in planta and, thereby, will add up to the many phage biocontrol trials performed against a broad spectrum of different plant pathogenic bacteria in the recent years [4][5][6]61]. A comprehensive overview over the current phage isolates for Xanthomonas species is given by Nakayinga et al (2021) [6].…”

“…Only the large terminase shares sequence identity for five of the seven phages (dark purple arrow, Figure 4). Therefore, we selected all available genomic sequences for phages infecting Xanthomonas reviewed by Nakayinga et al (2021) [6] and from literature [24]. The set was further expanded by unique entries of VirusHost DB [50], as well as by our phages and their closest relatives according to NCBI nucleotide blast, resulting in a total of 97 genomes.…”

“…However, due to their high specificity, phages were replaced by broad-range antibiotics and cheaper copper treatments in the beginning of the last century. Nowadays, the massive spread of antibiotic-resistant bacteria has fostered a global surge in the reinvestigation of phage biology and phage-based biocontrol as an alternative to antibiotic treatments [ 3 , 4 , 5 , 6 ].…”

Deploying Viruses against Phytobacteria: Potential Use of Phage Cocktails as a Multifaceted Approach to Combat Resistant Bacterial Plant Pathogens

“…Lytic phages interact with the host through completely different mechanisms than antibiotics, having extraordinary effectiveness against both antimicrobial resistant (AMR) and non-AMR bacterial infections [195]. For example, lytic phages can interact with SAR inducers to integrate into the host for successful management of tomato bacterial spot and Xanthomonas leaf blight of onion [50,52]. Lytic phages have prime importance in agriphage cocktail formulations for sustainable disease management to enhance crop production.…”

“…As copper application is regarded as a primary approach to control phytopathogens, it is a huge concern in microbial disease management. Recently, copper-based plant protection compounds have been banned or limited in several countries, and innovative control strategies, including the recruitment of bacteriophages as potential sustainable antimicrobial agents, have been established [47][48][49][50][51][52].…”