Exogenous Application of Polycationic Nanobactericide on Tomato Plants Reduces the Candidatus Liberibacter Solanacearum Infection.

Adela Nazareth García-Sánchez,José Luis Hernández-Flores,Ramiro Guerrero-Santos,Ariel Álvarez-Morales,José Humberto Valenzuela-Soto,Carlos Guerrero-Sanchez,Roberto Yáñez-Macias

doi:10.3390/plants10102096

Adela Nazareth García-Sánchez, José Luis Hernández-Flores + Show 5 more

Open Access

https://doi.org/10.3390/plants10102096

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Abstract

Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and transmitted by the tomato psyllid Bactericera cockerelli. A polymeric water-dispersible nanobactericide (PNB) was evaluated against CaLso as a different alternative. PNB is a well-defined polycationic diblock copolymer designed to permeate into the vascular system of plants. Its assessment under greenhouse conditions was carried out with tomato plants previously infected with CaLso. Using a concentration as low as 1.0 mg L−1, a small but significant reduction in the bacterial load was observed by real-time qPCR. Thus, to achieve an ecologically friendly dosage and set an optimum treatment protocol, we performed experiments to determine the effective concentration of PNB to reduce ~65% of the initial bacterial load. In a first bioassay, a 40- or 70-fold increase was used to reach that objective. At this concentration level, other bioassays were explored to determine the effect as a function of time. Surprisingly, a real reduction in the symptoms was observed after three weeks, and there was a significant decrease in the bacterial load level (~98%) compared to the untreated control plants. During this period, flowering and formation of tomato fruits were observed in plants treated with PNB.

Highlights

Tomato (Solanum lycopersicum L.) is a herbaceous plant of the genus Solanum and the Solanaceae family, with more than 3000 species, including many plants of agricultural importance [1]
Because Candidatus Liberibacter solanacearum (CaLso) is phloem-limited, it represents a challenge for the design of practical control strategies
We reported the antibacterial activity of a polymeric nanobactericide (PNB) in tomato plants against CaLso

Summary

Introduction

Tomato (Solanum lycopersicum L.) is a herbaceous plant of the genus Solanum and the Solanaceae family, with more than 3000 species, including many plants of agricultural importance [1]. According to FAO, globally, the average tomato consumption reached 20.1 kg per capita in 2013 from an all-time low of 7.77 kg registered in 1963. This crop stands as one of the riskiest for growers. It is known that there are more than 60 pathogens, including fungi, viruses, nematodes, and bacteria, which cause diseases and generate significant economic losses all around the globe [3]. Such conditions have a higher incidence and impact when growers operate in open fields. Phytophagous insects and pathogen infections are severe, mainly when “good practices” are not rigorously followed [5]

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