OAES horticulture researchers are looking at what happens when
plant bacterial spot attacks bell peppers. They wanted to look
close-at the cellular level-to see what defense mechanisms go
into action when a pathogen threatens.
They knew that one early change is in the pH of the solution
inside the cell. When a resistant plant comes under attack, cell
pH becomes significantly more acidic, while the environment between
cells becomes more alkaline. Associated with that is a selective
breaking down of the pectic material that binds plant components
together.
Earlier work showed that plants under stress give off a substantial amount of methanol, the source of which is from the pectin. Methanol is released naturally as the plant matures, but the presence of stress or an invading pathogen greatly increases the process. The overall significance is that once the methanol is released, the pectin is susceptible to breakdown by the plant's own enzymes. The researchers wanted to see if it is the initial breakdown of these materials that trigger the production of defense mechanisms against pathogens. Once researchers have some answers with bell peppers, they plan to see if the mechanisms are at work in other plants as well.