Brassinosteroid hormones regulate many aspects of plant growth and
development with the membrane receptor BRI1 as the central player in the
signaling cascade. A team of researchers led by Shahin S. Ali of the
University College of Dublin in Ireland are studying the semi-dwarf "uzu"
barley, which carries a mutation in BRI1 known for its positive contribution
to yield and lodging resistance.

The "uzu" barley exhibited enhanced resistance to a wide range of pathogens
due to a combination of pre-formed and inducible defense responses. Gene
expression studies revealed that the uzu barley has a repressed
brassinosteroid signaling. Reduction of BRI1 RNA levels compromised uzu's
disease resistance.

These suggest that the pathogen resistance of "uzu" may be due to the
possible role of BRI1 on a plant defense pathway or the indirect effect of
repressed brassinosteroid signaling.

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