Plant–phytopathogen interactions: bacterial responses to environmental and plant stimuli

Abstract

Summary Plant pathogenic bacteria attack numerous agricultural crops, causing devastating effects on plant productivity and yield. They survive in diverse environments, both in plants, as pathogens, and also outside their hosts as saprophytes. Hence, they are confronted with numerous changing environmental parameters. During infection, plant pathogens have to deal with stressful conditions, such as acidic, oxidative and osmotic stresses; anaerobiosis; plant defenses; and contact with antimicrobial compounds. These adverse conditions can reduce bacterial survival and compromise disease initiation and propagation. Successful bacterial plant pathogens must detect potential hosts and also coordinate their possibly conflicting programs for survival and virulence. Consequently, these bacteria have a strong and finely tuned capacity for sensing and responding to environmental and plant stimuli. This review summarizes our current knowledge of the signals and genetic circuits that affect survival and virulence factor expression in three important and well‐studied plant pathogenic bacteria with wide host ranges and the capacity for long‐term environmental survival. These are: Ralstonia solanacerarum, a vascular pathogen that causes wilt disease; Agrobacterium tumefaciens, a biotrophic tumorigenic pathogen responsible for crown gall disease and Dickeya, a brute force apoplastic pathogen responsible for soft‐rot disease.

The impact of type VI secretion system, bacteriocins and antibiotics on competition amongst Soft-RotEnterobacteriaceae: Regulation of carbapenem biosynthesis by iron and the transcriptional regulator Fur

“…It is important to note that because of the difficulty associated with identification and quantification of antibiotics and bacteriocins produced by bacteria in planta , most studies, including the current study, make inferences based on in vitro detection of these compounds and extrapolations/inferences are made to in planta conditions based on the assay conditions which mimic plant apoplast (minimal media and anaerobic conditions) (65). Against this background it is possible that Pcb 1692 does not produce carbapenem in planta but is able to produce bacteriocins.…”

“…In support of this hypothesis, recent studies have shown that bacterial SOS can be triggered directly or indirectly by different factors such as nutrient starvation, iron deficiency, chromate stress, acidic and alkaline stress, oxidative stress and β-lactam antibiotics (10, 66-69). All the above scenarios can be encountered by Pcb in planta , for example, one of the first stresses encountered by Pcb , SREs and other endophytes in potato tubers is acidic pH, which SREs must neutralize to be able to produce PCWDEs (65, 70, 71). Similarly, intake of excess iron can lead to oxidative burst in bacteria through Fenton reaction (72).…”

Formulation, Characterizations and Antibacterial Activity of some Nanoemulsions Incorporating Monoterpenes

“…It like many phytopathogenic bacteria produce multiple extracellular plant cell wall degrading enzymes. Some of these enzymes have been implicated as virulence factors contributing to the pathogen ability to invade and colonize host tissues causing the wilt disease (Liu et al,2005;Leonard et al, 2017).…”

Dickeya dianthicola emerged from a potato culture area exhibiting a wide diversity of pectinolytic pathogens in northern Morocco

“…by pectinolytic pathogens are soft rot and blackleg, respectively. These pathogens produce a large set of extracellular enzymes that break down the plant cell wall, resulting in plant tissue decay and maceration [3]. These pathogens cause important losses to the production of potato tubers for food market, and all along the certification steps of tuber seeds.…”