Antibacterial Potential of Bacillus amyloliquefaciens GJ1 against Citrus Huanglongbing

Abstract

Citrus huanglongbing (HLB) is a destructive disease caused by Candidatus Liberibacter species and is a serious global concern for the citrus industry. To date, there is no established strategy for control of this disease. Previously, Bacillus amyloliquefaciens GJ1 was screened as the biocontrol agent against HLB. In this study, two-year-old citrus infected by Ca. L. asiaticus were treated with B. amyloliquefaciens GJ1 solution via root irrigation. In these plants, after seven irrigation treatments, the results indicated that the photosynthetic parameters, chlorophyll content, resistance-associated enzyme content and the expression of defense-related genes were significantly higher than for the plants treated with the same volume water. The content of starch and soluble sugar were significantly lower, compared to the control treatment. The parallel reaction monitoring (PRM) results revealed that treatment with B. amyloliquefaciens GJ1 solution, the expression levels of 3 proteins with photosynthetic function were upregulated in citrus leaves. The accumulation of reactive oxygen species (ROS) in citrus leaves treated with B. amyloliquefaciens GJ1 flag22 was significantly higher than untreated plants and induced the defense-related gene expression in citrus. Finally, surfactin was identified from the fermentation broth of B. amyloliquefaciens GJ1 by high-performance liquid chromatography. These results indicate that B. amyloliquefaciens GJ1 may improve the immunity of citrus by increasing the photosynthesis and enhancing the expression of the resistance-related genes.

Bioprospecting Microbiome for Soil and Plant Health Management Amidst Huanglongbing Threat in Citrus: A Review

“…The ROS accumulation was also observed significantly higher in treated citrus leaves as compared to untreated leaves, up-regulating the defense-related genes. These results disclosed that B. amyloliquefaciens could be an effective antagonist against HLB ( Nan et al, 2021 ).…”

“…In a recent study, the role of Bacillus amyloliquefaciens (strain GJ1) in protecting citrus against HLB was unfolded ( Nan et al, 2021 ). It is now a known fact that citrus with infected HLB possesses blocked phloem with excess accumulation of starch and sugar in the leaves ( Tang et al, 2018 ), damaging the chloroplast functions and affecting the transport of photosynthetic products.…”

Comunidades epifíticas em citros associadas ao huanglongbing em áreas com e sem aplicação de biofertilizante

“…Essa mesma espécie também pode estar relacionada com o aumento de HLB (Zhang et al, 2013). Nan et al (2021) observaram alterações fisiológicas benéficas em plantas infectadas por Ca. L. asiaticus após a inoculação de Bacillus amyloliquefaciens GJ1, um isolado bacteriano previamente obtido de plantas com HLB.…”

An Overview of the Mechanisms Against “Candidatus Liberibacter asiaticus”: Virulence Targets, Citrus Defenses, and Microbiome

“…Currently, many strategies have been developed for HLB mitigation, including application of antimicrobials ( Zhang et al, 2011a , 2012 , 2014 , 2021 ; Hu and Wang, 2016 ; Hu et al, 2018 ; Yang et al, 2018 ), thermotherapy ( Hoffman et al, 2013 ; Fan et al, 2016 ; Yang et al, 2016b ; Doud et al, 2017 ; Ghatrehsamani et al, 2019 ; Vincent et al, 2019 ), macro-and micronutrients ( Spann and Schumann, 2009 ; Gottwald et al, 2012 ; Rouse et al, 2017 ; Mattos-Jr et al, 2020 ; Dong et al, 2021 ; Zhou et al, 2021 ), plant defense inducers ( Canales et al, 2016 ; Li et al, 2016 , 2019 , 2021a ; Hu et al, 2018 ; Wang, 2021 ), control of the insect vector ( Grafton-Cardwell et al, 2013 ; Boina and Bloomquist, 2015 ; Cocuzza et al, 2017 ; Pierre et al, 2021 ), biocontrol ( Trivedi et al, 2011 ; Hopkins and Wall, 2021 ; Nan et al, 2021 ; Poveda et al, 2021 ), and eradication of HLB symptomatic citrus trees ( Bassanezi et al, 2013 ; Yuan et al, 2020 ). However, these strategies have shown limited success in field applications and effective HLB management remains a challenge.…”