Mitigation of Emergent Bacterial Pathogens Using Pseudomonas syringae pv. actinidiae as a Case Study—From Orchard to Gene and Everything in Between

Abstract

Globalization propelled human migration and commercial exchanges at the global level, but woefully led to the introduction of non-indigenous organisms into several agroecological systems. These include pathogenic bacteria with devastating consequences for numerous crops of agronomical importance for food production worldwide. In the last decade, research efforts have focused on these noxious organisms, aiming to understand their evolutionary processes, degree of pathogenicity, and mitigation strategies, which have allowed stakeholders and policymakers to develop evidence-based regulatory norms to improve management practices and minimize production losses. One of these cases is the bacterium Pseudomonas syringae pv. actinidiae (Psa), the causal agent of the kiwifruit bacterial canker, which has been causing drastic production losses and added costs related to orchard management in the kiwifruit industry. Although Psa is presently considered a pandemic pathogen and far from being eradicated, the implementation of strict regulatory norms and the efforts employed by the scientific community allowed the mitigation, to some extent, of its negative impacts through an integrated pest management approach. This included implementing directive guidelines, modifying cultural practices, and searching for sources of plant resistance. However, bacterial pathogens often have high spatial and temporal variability, with new strains constantly arising through mutation, recombination, and gene flow, posing constant pressure to agroecosystems. This review aims to critically appraise the efforts developed to mitigate bacterial pathogens of agronomical impact, from orchard management to genome analysis, using Psa as a case study, which could allow a prompter response against emerging pathogens in agroecosystems worldwide.

Scientific and technological advances in the development of sustainable disease management tools: a case study on kiwifruit bacterial canker

“…In the last two decades the scientific community and commercial sector have made a good progress in developing and bringing to the market more environmentally friendly alternatives to the use of copper and antibiotics. The gradual substitution of susceptible Actinidia cultivars with Psa-tolerant ones (plant breeding programs) ( Wang et al., 2020 ), and the application of plant elicitors for triggering plant defenses against the Psa ( Beatrice et al., 2017 ), are supporting a slow recovery of the kiwifruit sector ( Nunes da Silva et al., 2022b ). More recently, the development of eco-friendly KBC control methods has been focused on screening and testing a myriad of emerging molecules, compounds, and Microbial Biological Control Agents (MBCAs) with potential to reduce in planta Psa load, motility and spread capacity, resulting from their bacteriostatic, bactericidal and competition activity.…”

Prevention of Stomatal Entry as a Strategy for Plant Disease Control against Foliar Pathogenic Pseudomonas Species

“…One of these cases is the kiwifruit canker outbreak, caused by P. syringae pv. actinidiae ( Psa ) (PG1b) [ 7 ]. In particular, Psa biovar 3 ( Psa 3) caused devastating damage and spread rapidly to kiwifruit production areas worldwide [ 8 ].…”

Occurrence of copper‐resistant Pseudomonas syringae pv. actinidiae strains in kiwifruit orchards of Central Italy

“…The control of kiwifruit bacterial canker is not easy due to the lack of systemicity that characterizes most of the compounds usually sprayed to the plant canopy. The copper‐based compounds are the most utilized products to limit the leaf colonization of Psa (Cameron & Sarojini, 2014; Nunes da Silva et al, 2022; Tyson et al, 2017) even though they do not assure a complete efficacy to impede to the pathogen the reaching of the internal plant tissue (Lamichhane et al, 2018). Other compounds, such as acibenzolar‐S‐methyl, chitosan and some biocontrol agents, are also used in an integrated approach control strategy (Daranas et al, 2019; Reglinski et al, 2013; Scortichini, 2014; Wickasono et al, 2018).…”