Garden Soaps - intimacy, deceit and betrayal in the plant world.

Many plants produce natural soaps (called saponins, or technically, plant glycosides) that have anti-fungal and anti-bacterial activity and so help defend the plant against disease attach. Saponins can be present in high concentrations (up to 10% of dry weight) in healthy plants. Microbes that can successfully invade saponin-containing plants produce enzymes that break down the saponins into less toxic chemicals, thus allowing them to breach the plant's first line of defence...read entire handout.

Pests and Pathogens.

Plants are food for a wide range of animals - including many we recognise as garden or agricultural pests, but they are also food (in the general sense of a supply of raw materials and energy) for pathogens such as bacteria, fungi and viruses. Consequently, plants have evolved many defence strategies to protenct themselves against grazing animals, pests and pathogens... read entire handout.

Silencing the Opposition.

Plant viruses are extremely simple but sophisticated pathogens. They consist of an outer protective coat of protein and an innter component of genetic material (either DNA or RNA). The latter carries the few genes that viruses need to be effective disease agents. Viruses are transferred from plant to plant by stealth, commonly by a pest feeding on an uninfected plant shortly after it has fed on an infected plant. Typically viruses are transported by feeding insects, although some viruses are transmitted by nematode worms or fungi... read entire handout.