Bacterial spot and early blight biocontrol by epiphytic bacteria in tomato plants

Abstract

-The objective of this work was to evaluate in vitro and in vivo biocontrol of bacterial spot (Xanthomonas vesicatoria) and early blight (Alternaria solani) by the epiphytic bacteria Paenibacillus macerans and Bacillus pumilus. Tomato plants were previously sprayed with epiphytic bacteria, benzalkonium chloride and PBS buffer and, after four days, they were inoculated with A. solani and X. vesicatoria. To determine the phytopathogenic bacteria population, leaflet samples were collected from each treatment every 24 hours, for seven days, and plated on semi-selective medium. The effect of epiphytic bacteria over phytopathogens was performed by the antibiosis test and antagonistic activity measured by inhibition zone diameter. The epiphytic and benzalkonium chloride drastically reduced the severity of early blight and bacterial spot in comparison to the control (PBS). In detached leaflets, the epiphytic bacteria reduced in 70% the number of phytopathogenic bacteria cells in the phylloplane. The antibiosis test showed that the epiphytic bacteria efficiently inhibit the phytopathogens growth. In all the bioassays, the epiphytic bacteria protect tomato plants against the phytopathogens.Index terms: Alternaria solani, Bacillus pumilus, Paenibacillus macerans, Xanthomonas vesicatoria, biological control, epiphytic bacteria. Biocontrole da mancha-bacteriana e da pinta-preta por bactérias epifíticas em tomateiro Resumo -O objetivo deste trabalho foi avaliar o biocontrole in vitro e in vivo dos fitopatógenos manchabacteriana (Xanthomonas vesicatoria) e pinta-preta (Alternaria solani) pelas bactérias epifíticasPaenibacillus macerans e Bacillus pumilus. Plantas de tomate foram previamente pulverizadas com as bactérias epifíticas, cloreto de benzalcônio e tampão PBS e, após quatro dias, receberam inoculação com A. solani e X. vesicatoria. A fim de determinar a população da bactéria fitopatogênica, amostras de folíolos foram coletadas de cada tratamento em intervalos de 24 horas, durante sete dias, e inoculadas em meio semisseletivo. O efeito das bactérias epifíticas sobre os fitopatógenos foi realizado pelo teste de antibiose e atividade antagônica avaliada pelo diâmetro da zona de inibição. As bactérias epifíticas e o cloreto de benzalcônico reduziram drasticamente a severidade da pinta-preta e da mancha-bacteriana, comparado com o controle (PBS). Em folíolos destacados, as bactérias epifíticas reduziram em até 70% o número de células da bactéria fitopatogênica no filoplano. As bactérias epifíticas inibem eficientemente o crescimento dos fitopatógenos em meio de cultura. Em todos os bioensaios, as bactérias epifíticas protegem as plantas de tomate contra os fitopatógenos.Termos para indexação: Alternaria solani, Bacillus pumilus, Paenibacillus macerans, Xanthomonas vesicatoria, controle biológico, bactéria epifítica.

Foliar spraying with bacterial biocontrol agents for the control of common bacterial blight of bean

“…Regarding antibiosis, if constitutively produced, BBAs would have been in leaves longer, allowing a greater accumulation of compounds toxic to the pathogen. The DFs93, DFs513, and DFs769 bacteria are producers of effective antimicrobial compounds against Xap (Silva et al, 2008), which is an indication of antibiosis, reported in several studies as a mechanism responsible for the biocontrol of plant pathogens (Lanna-Filho et al, 2010;Kumsingkaew & Akarapisan, 2014). For induced systemic resistance (ISR) to act as a mechanism, the presence of BBAs is required in advance to antagonize the pathogen.…”

Biological Control of Tomato Bacterial Wilt, Kimchi Cabbage Soft Rot, and Red Pepper Bacterial Leaf Spot Using Paenibacillus elgii JCK-5075

“…The fermentation broth of P. elgii JCK-5075, at a 5-fold dilution, displayed a control value of 67%, which was not significantly different to that of oxolinic acid. P. macerans was reported to control leaf spot disease on tomato, having a biocontrol efficacy of higher than 50% ( Lanna Filho et al, 2010 ). None of the plants treated with the 5-fold dilutions of the fermentation broth of the P. elgii JCK-5075, showed any phytotoxic symptoms ( Sarwar et al, 2018 ).…”

Pyoverdine use for the control of passion fruit bacterial blight

“…First, the 29RR isolate was cultured in test tubes with King's B medium for 48 hours at 27°C (King et al, 1954). Three treatments (T) were performed: T1, King's B medium; T2, King's B medium supplemented with 2 μmol L -1 Fe 2+ ; and T3, King's B medium surface cultured with 1 mL of the 29RR bacterial culture.…”

“…The number of CFUs cm -2 of leaf was calculated after a 72-hour incubation at 27°C. Leaf samples were collected for seven consecutive days after the inoculation of Xap-SP (adapted from the study by Lanna Filho et al, 2010). Regression analyses were performed using SigmaPlot v.12 (Madden et al, 2007).…”

“…29RR, which was used in a previous study to control passion fruit bacterial blight. This antagonist strain produces pyoverdine that inhibits the Xap-SP growth by restricting iron availability in the culture medium, instead of restricting it by antibiosis (Halfeld-Vieira et al, 2015).First, the 29RR isolate was cultured in test tubes with King's B medium for 48 hours at 27°C (King et al, 1954). Three treatments (T) were performed: T1, King's B medium; T2, King's B medium supplemented with 2 μmol L -1 Fe 2+ ; and T3, King's B medium surface cultured with 1 mL of the 29RR bacterial culture.…”