Antagonistic and growth-promoting potential of Stenotrophomonas sp., an endophytic bacteria from ginger rhizomes against soft rot pathogen Pythium myriotylum

Abstract

Ginger (Zingiber officinale Rosc.) is a major spice crop, and its cultivation is seriously constrained by soft rot disease caused primarily by Pythium aphanidermatum and P. myriotylum. In the present study, bacterial endophytes were isolated from healthy ginger rhizomes and screened for antagonistic activity against P. myriotylum together with plant growth-promoting traits. Four isolates showed promising disease-suppressive potential and expressed traits such as indole-3-acetic acid production, siderophore secretion, and phosphate solubilisation, confirming their dual role in growth promotion and pathogen inhibition. Among these, Stenotrophomonas sp. gained particular significance as this study represents the first report of its occurrence as an endophyte in ginger with detectable antagonistic activity. This novel finding broadens the understanding of the endophytic community associated with ginger and highlights its potential as a sustainable and eco-friendly alternative for the management of soft rot disease.