Screening of Rhizobacterial Indigenous as Biocontrol Agents Against Bacterial Wilt on Chili Using In Planta Technique

Abstract

Bacterial wilt caused by Ralstonia solanacearum is one of the severe diseases on chili. Until now this disease is difficult to control, while these bacteria attack the xylem vessel and are unreachable by any bactericide. One group of important biocontrol agents are the plant growth-promoting rhizobacteria (PGPR). The PGPR have also the ability to increase growth and yield of plants. The aim of this research was to obtain rhizobacterial isolates, which have the ability to control bacterial wilt on chili and to increase growth and yield. Source of ​of rhizobacterial isolates were from healthy chili rhizosphere at endemic area of bacterial wilt diseases in two district (Agam and Solok) West Sumatera Province, Indonesia. Screening method based on in planta selection of root-colonizing bacterial isolates. This approach focuses on indirect mechanisms (systemic induced resistance). This technique has the possibility to find new, easy, and cheap biocontrol organisms. We have isolated 42 rhizobacteria from healthy chili’s rhizosphere. Only 17 rhizobacterial isolates could increase seedling growth of chili compared to control plants; the rest of isolates reduced growth of chili seedlings. There were no bacterial wilt symptom on 13 rhizobacterial isolate introduced chilies and lower infection (33.3%) on two rhizobacterial isolate introduced chilies, compared with control plants (100% wilt and die). We have obtained also two rhizobacterial isolates which could control bacterial wilt diseases and increase growth of chili. They were RZ.2.1.AG1 identified as Bacillus cereus strain INACH001 and RZ.1.3.AP1 as Bacillus subtilis strain BSn5.