Endophytic bacteria from Piper colubrinum suppress Phytophthora capsici infection in black pepper (Piper nigrum L.) and improve plant growth in the nursery

Foot rot caused by Phytophthora capsici is a threat for black pepper cultivation. No cultivated variety is resistant to the disease. Endophytic bacteria were obtained from the roots, stem and leaves of Piper colubrinum, a wild relative of black pepper, resistant to P. capsici. In vitro dual culture plate assay showed that seven among them were antagonistic against P. capsici. Lesion suppression assay on detached black pepper leaves showed that leaves treated with the isolate Bacillus velezensis PCSE10 caused 79.02% disease suppression. In greenhouse experiment the lowest disease index occurred in plants treated with Rhizobium radiobacter PCRE10 with 75.05% disease suppression. The endophytes improved growth of black pepper in the nursery when the cuttings were bacterized and planted. We report for the first time that the wild relative of black pepper, P. colubrinum is a good source of antagonistic bacteria against P. capsici causing foot rot disease of black pepper.