Systemic biocontrol of fusarium wilt in tomato (Solanum lycopersicum L.) using Bacillus endophytes

Abstract

Tomato (Solanum lycopersicum L.) is one of the most important vegetables consumed globally for its culinary and medicinal significance. However, fusarium wilt, caused by Fusarium oxysporum Schlechtendal, is a recalcitrant limitation to tomato production. This is due to the evasive pathogenesis and systemic proliferation of F. oxysporum. Therefore, this study attempts to develop a stable, effective, passive-systemic control measure against fusarium wilt in tomato. Tomato seeds were bioprimed with 108 CFU/mL of antifungal endophytes (Bacillus amyloliquefaciens Sa08 and Bacillus subtilis Og04). Biocontrol experiment was set up as a factorial experiment arranged in completely randomized design involving two tomato varieties (Alausa and Ibadan-local), endophytes and carbendazim. Endophyte colonization pattern, in vivo fusarium-biocontrol potential, and residual wilt control efficacy were determined. Both antifungal Bacillus species exhibited a systemic colonization pattern in treated tomato. Highest tissue colonization (13.25 ×102 CFU/g) was expressed by Bacillus subtilis Og04 in the root of Ibadan-local tomato variety. Bacillus endophytes also conferred systemic protection against fusarium wilt and improved yield properties in treated plants. Bacillus amyloliquefaciens Sa08 increased fruit production in infected Alausa tomato from 0% to 79%, while Bacillus subtilis Og04 retained 86.40% of its wilt control efficacy six months after seed treatment in Ibadanlocal variety. Seed treatment with Bacillus endophytes will limit the laborious application process associated with previously recommended biocontrol materials against fusarium wilt. Based on their residual biocontrol potentials, the Bacillus species should be evaluated under field conditions, as a seed pre-treatment strategy, to reduce the need for scientific expertise by farmers and other end-users.