Bacterial endophytes as potential biocontrol agents of vascular wilt diseases – Review and future prospects

• Bacterial endophytes have various possible disease suppression mechanisms.
• We present a number of case studies of bacterial endophytes antagonistic to wilts.
• The challenges encountered are discussed.
• Several strategies that can optimize the endophytic research are presented.

Vascular wilts are devastating plant diseases that can affect both annual crops as well as woody perennials, hence inducing major food losses and damaging valuable natural ecosystems. Because of ecological and economical reasons, the management of vascular wilt diseases by conventional chemical methods is raising concerns. More environmentally friendly alternatives such as the use of microbial antagonists to control phytopathogens are now of growing interest. The fact that bacterial endophytes are able to colonize an ecological niche similar to that of vascular wilt pathogens favors them as potential biocontrol agents against wilt diseases. Several possible disease suppression mechanisms of beneficial bacteria were proposed, among them induction of systemic resistance, growth promotion, competition, etc. However, there are still numerous challenges for the development and exploitation of bacterial endophytes such as the inherent characteristics of the endophyte itself or the environmental conditions. The optimization and improvement of the strategies employed in the endophytic research from early stages can help finding effective and competent biocontrol bacterial endophytes. Additionally, the use of genomic technologies and interdisciplinary research approaches in investigating the biocontrol potential of specific bacterial endophytes can deepen our knowledge of their mode of action and its regulatory backgrounds which may lead to more predictable and consistent beneficial effects from these microorganisms.