Biocontrol Characteristics of Bacillus Species in Suppressing Stem Rot of Grafted Cactus Caused by Bipolaris cactivora

Abstract

One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4) selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

Plant Growth Promotion and Biocontrol of Leaf Blight Caused by Nigrospora sphaerica on Passion Fruit by Endophytic Bacillus subtilis Strain GUCC4

“…In other words, our strain showed similar and comparable performance to both the commercial fungicide and the biofungicide. This was different with other B. subtilis strains showing significantly lower efficiency compared with synthetic fungicides against the same pathogen on the same hosts [ 75 , 76 , 77 ]. Therefore, B. subtilis GUCC4, in addition to its significant effects in promoting passion fruit seedling growth, has the potential to be further applied for the management of passion fruit leaf blight.…”

Suppression of Bipolaris Leaf Blotch and Improvement of Wheat Growth by Plant Growth Promoting Rhizobacteria Bacilli

“…Several studies have shown that B. subtilis and B. amyloliquefaciens significantly inhibited the germination and appressoria formation of Bipolaris conidia. For example, B. subtilis and B. amyloliquefaciens significantly inhibited the conidial germination of Bipolaris cactivora (Bae et al, 2013). Similarly, the culture filtrate of B. amyloliquefaciens strain XZ34-1 notably inhibited the spore germination of B. sorokiniana (Yi et al, 2021).…”

A comprehensive review on soft rot disease management in ginger (Zingiber officinale) for enhancing its pharmaceutical and industrial values

“… Pythium myriotylum [ 160 ] Rhizobium japonicum Fusarium solani [ 161 , 162 ] Pseudomonas fluorescens Pythium ultimum [ 163 ] Bacillus mycoides Pythium aphanidermatum [ 164 ] Bacillus subtilis Pythium ultimum, Fusarium solani [ 165 ] Alcaligenes sp . Bacillus cereus Bacillus thuringiensis Pythium myriotylum [ 166 ] Bacillus vietnamensis Pythium myriotylum [ 166 ] Bacillus BH072 B. amyloliquefaciens Q-12 B. amyloliquefaciens NK10.B Bacillus BH072 B. amyloliquefaciens Q-12 B. amyloliquefaciens NK10.B [ 83 ] Bacillus strains EU07, QST713 and FZB24 Fusarium oxysporum [ 80 ] Bacillus amyloliquefaciens B. cactivora [ 82 ] Bacillus sp. Pythium myriotylum.…”

“…It has been demonstrated that the antifungal abilities of the Bacillus amyloliquefaciens strain can suppress Bipolaris stem rotting brought upon by B. cactivora [ 82 ]. A unique bacteria called BH072 B. amyloliquefaciens , which was derived from nectar, demonstrated potent fungicidal action against many fungi in one investigation [ 83 ].…”