The Soil Nutrient Environment Determines the Strategy by Which Bacillus velezensis HN03 Suppresses Fusarium wilt in Banana Plants

Abstract

Biological control agents (BCAs) are considered as one of the most important strategies for controlling Fusarium wilt, and bioorganic fertilizer, in particular, has been extensively investigated. However, little is known regarding how a biocontrol microorganism affects the suppression mechanisms when combined with different amendments. In this study, a pot experiment was performed using banana plants to investigate the different mechanisms by which the biocontrol bacterium Bacillus velezensis HN03 (isolated from our laboratory) and amendments suppress Fusarium wilt. The incidence of banana wilt was decreased under HN03 and was reduced further when HN03 was combined with compost, particularly wormcast. In the suppression of Fusarium wilt, HN03 was found to influence the soil environment in various ways. HN03 increased the peroxidase level, which improves plant defense, and was highest when combined with wormcast, being 69 times higher than when combined with cow dung compost. The high accumulation of Mg and P in the “HN03 + wormcast” and Zn and Mn in the “HN03 + cow dung” treatments was negatively correlated with disease incidence. Furthermore, HN03 re-established the microbial community destroyed by the pathogen and further increased the level of suppression in the wormcast. HN03 also enhanced the functional traits of the soil, including defensive mechanism-related traits, and these traits were further enhanced by the combination of HN03 + wormcast.

Control of Banana Wilt Disease Caused by Fusarium oxysporum Schlecht f.sp. cubense (E. F. Smith) Using Crab Shell Powder and Chitosan

“…From an ecological point of view, biological control agents are often influenced by environmental factors, including the availability of nutrients and other microbes in the ecosystem. The combination of Bacillus velezensis HNO 3 with worm compost or cow dung has been shown to increase the suppression of Fusarium wilt in banana plants due to the high accumulation of several elements, such as Mg, P, Zn and Mn (Wu, Shan, Li, Li, & Wu, 2020). The other indirect mechanism may also be involved in suppressing this disease due to the addition of some mineral elements contained in CSP, including Ca, P, Zn, and K as reviewed by Orr & Nelson (2018).…”

Magnesium may be a key nutrient mechanism related to Fusarium wilt resistance: a new banana cultivar (Zhongjiao No. 9)

“…Previous studies have suggested that some nutrient elements in banana plants and their associated soils can reduce the severity of plant diseases by increasing disease tolerance and resistance against plant pathogens ( Dordas, 2008 ; Siddiqui et al, 2015 ; Wu et al, 2020 ). There were positive correlations observed between the contents of Zn, Mn, Mg, and P in banana and the suppression of wilt disease severity ( Wu et al, 2020 ). In present study, the nutrient uptake ratio of N:P:K:Ca:Mg:S were 1:0.13:3.86:0.68:0.40:0.07 (Zhongjiao No.…”

“…Banana Fusarium wilt is caused by vascular wilt pathogens, which satisfy their nutritional requirements by efficiently acquiring the scarce nutrients available in the xylem sap, by enzymatic digestion of host cell walls, by invading neighboring cells, or by inducing nutrient leakage from surrounding tissues ( Divon et al, 2005 ; Möbius & Hertweck, 2009 ; Klosterman et al, 2011 ; Yadeta & Thomma, 2013 ). High Mg accumulations could enhance plant suppression to Foc4 ( Wu et al, 2020 ). Therefore, the absorption and accumulation of Mg may be a key mechanism related to nutrient element modulation.…”

“…Additionally, previous studies have demonstrated that some nutrient elements in banana plants and their associated soils can reduce the severity of plant diseases by increasing disease tolerance and resistance against plant pathogens ( Dordas, 2008 ; Siddiqui et al, 2015 ; Wu et al, 2020 ). Other studies have demonstrated that the manipulation of soil nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) levels may reduce the incidence of Fusarium disease by direct toxic effects or by affecting the cell wall composition, lignin biosynthesis, phenol biosynthesis, photosynthesis, and several other functions ( Yergeau et al, 2006 ; Dordas, 2008 ; Hassan & Abo-Elyousr, 2013 ; Wu et al, 2020 ). However, few studies have focused on the nutrient budgets of the Fusarium wilt-resistant cultivar described above, and particularly, the key nutrient mechanism related to Fusarium wilt-resistant remains uncertain.…”

“…Nonetheless, uninformed fertilization may not meet the nutrient demands of banana plants that are necessary for growth and can easily cause pollution. Additionally, previous studies have demonstrated that some nutrient elements in banana plants and their associated soils can reduce the severity of plant diseases by increasing disease tolerance and resistance against plant pathogens (Dordas, 2008;Siddiqui et al, 2015;Wu et al, 2020). Other studies have demonstrated that the manipulation of soil nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) levels may reduce the incidence of Fusarium disease by direct toxic effects or by affecting the cell wall composition, lignin biosynthesis, phenol biosynthesis, photosynthesis, and several other functions (Yergeau et al, 2006;Dordas, 2008;Hassan & Abo-Elyousr, 2013;Wu et al, 2020).…”