Effects of Bacillus velezensis zk1 on the physiology and metabolism of peaches

Abstract

Bacillus velezensis zk1 is the dominant bacterium that causing rot in peaches. However, the mechanisms through that this bacterium causes rot have not been elucidated. Here, we explored the mechanisms of peach decay caused by B. velezensis zk1. The invasion of B. velezensis zk1 in peaches resulted in an increase in glucose and arabinose contents in fruit tissues. Moreover, the relative conductivity of the fruit reached 84% after 4 days of culture with bacterial invasion. With the destruction of cells, the malondialdehyde content increased, whereas the vitamin C, dialdehyde, flavonoid and total phenol contents decreased. Polyphenol oxidase, superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and ammonia lyase activities also decreased. Overall, these findings demonstrated that B. velezensis zk1 infection damaged peach chloroplasts, mitochondria, respiratory chain activity and related free radical scavenging enzyme systems, thereby disrupting the normal physiological metabolism of peaches and causing rot.

Biocontrol Ability of the Bacillus amyloliquefaciens Group, B. amyloliquefaciens, B. velezensis, B. nakamurai, and B. siamensis, for the Management of Fungal Postharvest Diseases: A Review

“…50,51 Although most studies have indicated that B. amyloliquefaciens species do not show any kind of pathogenicity in postharvest fruits, Zeng et al reported that B. velezensis zk1 was the dominant bacterium causing rot in peach fruit. 52 This is an important feature that must be examined to confirm that B. amyloliquefaciens species cannot cause any kind of disease symptoms on postharvest fruit and can have real applications in postharvest preservation. Unfortunately, the pathogenic properties of B. amyloliquefaciens species are not studied in the screenings.…”

“…It must be noted that some strains were studied for the control of postharvest diseases in different hosts. For example, B. amyloliquefaciens CPA-8 was studied for the control of fungal pathogens in apples, cherries, nectarines, peaches, and flat peaches. − Commercial B. amyloliquefaciens QST713 has been used for the control of fungal diseases in cucumbers, grapes, mangoes, and tomatoes, , while B. amyloliquefaciens D747 was used in grapes, strawberries, and tomatoes. , Although most studies have indicated that B. amyloliquefaciens species do not show any kind of pathogenicity in postharvest fruits, Zeng et al reported that B. velezensis zk1 was the dominant bacterium causing rot in peach fruit . This is an important feature that must be examined to confirm that B. amyloliquefaciens species cannot cause any kind of disease symptoms on postharvest fruit and can have real applications in postharvest preservation.…”