Science, Technology and Engineering

Anderson Laboratory

Department of Biochemistry

Research - Plant Innate Immunity Proteins

Anderson lab 2011

Plants lack an adaptive immunity system of the sophistication found in higher organisms. Nevertheless they have developed complex strategies to minimise infection by microorganisms and damage by insect pests. We have been working on three groups of plant innate immunity proteins All are disulphide rich proteins and potent insecticidal or antifungal molecules. We have focused on structure, mechanism of action and ultimately on their commercial application in plant protection. Two of these groups of molecules were discovered in the flowers of solanaceous plants where they act to protect the reproductive structures and ensure seed set.

The first group are serine proteinase inhibitors that target trypsins and chymotrypsins, the major digestive proteinases in the gut of Lepidopteran larvae. The way larvae respond to and survive the ingestion of these proteinase inhibitors (PIs) has been investigated and this knowledge has been applied to enhance the resistance of transgenic plants to insect attack in the field.

Plant proteinase inhibitors & insect proteases

Floral defensins

Plant cyclotides

The second group of floral defence molecules are the defensins which are potent antifungal molecules. These defensins interact specifically with the cell wall of filamentous fungi, penetrate the plasma membrane and enter the cytoplasm of the hyphae where they induce cell death. They also have application in plant protection and have been used to enhance disease resistance in transgenic cotton in the field.

The cyclotides comprise the newest group of plant innate immunity proteins. These 29 amino acid cyclic peptides are common in the Rubiaceae and the Violaceae. Although new to plant science they are the most abundant cyclic proteins on earth. Their function has not been fully explored but the best characterised are potent insecticidal and nematacidal molecules. Our research focuses on their biosynthesis and mechanism of insecticidal activity.

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