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RNA Silencing and Disease Resistance

Head of Group: Professor Sir David Baulcombe

david baulcombeWe research various types of disease resistance in plants but we have a particular interest in one of them - RNA silencing - that has significance beyond infection. RNA silencing controls the level of gene expression at various stages of the plant life cycle. Some of these effects are epigenetic – they persist through cell division or even from one plant generation to the next. Our approach involves cell and molecular biology but the aim is always to understand plants at the whole organism or population level.

Recent research highlight:

Optimising Disease Resistance

NB-LRR (nucleotide-binding leucine-rich repeat) proteins can be viewed as the plant equivalent of antibodies. These proteins, as a class, mediate resistance to a huge range of viruses, bacteria, fungi and invertebrates but individual NB-LRRs are specific to one or a few pests and pathogens. They serve as a switch in which molecular recognition of the pathogen triggers a transition from inactive to active (defense) signalling states. The newly published work used random mutagenesis (artificial evolution) to identify mutations that broaden the recognition specificity of an NB-LRR. In previous work the lab have shown that mutations can affect either the recognition or the signalling function of an NB-LRRs and, in a recent paper we illustrate how artificial evolution proceeding in small sequential steps can be used to optimise a new resistance phenotype. These findings could be used to inform design of NB-LRRs for use in agriculture.

Current projects include:

3d model etc
From top: 3D model of protein domain required for disease resistance; Hybrid tomato (Zamir (2001) Nature Reviews Genetics 2: 983-989); The alga Chlamydomonas reinhardtii used as a model for RNA silencing studies.
Artificial evolution of disease resistance

We select mutant forms of disease resistance proteins that confer broader spectrum disease resistance than the progenitor wild type. This approach will influence breeding and biotechnological approaches to disease resistance in crops.

 Understanding hybrid plants

One of the mysteries in biology involves hybrids. How can progeny be larger, more vigorous or more productive than the parents as they often are in both plants and animals? Our recent work indicates that RNA silencing and epigenetics play a role and we are using tomato as a model with the aim of making plant breeding a more effective process.

Epigenetic modification of crops

We are developing methods that will improve heritable characters of crops without changing their DNA sequence. The approach involves using RNA to target epigenetic modifications to the crop plant chromosomes.

RNA silencing in model organisms

Our favourite model organisms for the dissection of RNA silencing include Arabidopsis thaliana, tomato and Chlamydomonas  reinhardtii.

effects of rna
From left: Effects of RNA silencing - A. Molnar and C. Melnyk; 3D model of Argonaute protein required for RNA silencing - B.Chung