Disease Assessment of Brassinosteroid (BR)-Insensitive 1 (BRI1) Mutant Lines of Barley Under Irish Agronomic Conditions and Phenotyping of BRI1 Wheat Tilling Lines

Brassinosteroid (BR) hormones are known to be involved in many aspects of plant growth and development. The characterisation of BRI1 (brassinosteroid-insensitive1), a brassinosteroid (BR) membrane receptor, as a central player in the brassinosteroid signalling cascade has been assessed using various bri1 mutant lines. Recently, barley Uzu lines carrying the BRI1 mutation have shown enhanced disease resistance potential against a range of fungal pathogens compared to parental barley cultivars. As part of the WheatEnhance project, we are assessing the disease resistance enhanced due to mutations in BRI1 in barley lines viz., Akashinriki Uzu and Bowman Uzu compared to their parental lines Akashinriki and Bowman under Irish agronomic conditions. There was severe powdery mildew infestation observed in all the four varieties perhaps due to moist climatic conditions; however no Fusarium head blight occurred possibly due to early maturity of the Uzu lines. Considering barley as a model for more complex genomes such as that in wheat, it was hypothesised that the presence of the BRI1 mutation would improve the capacity of wheat to resist agronomically important fungal diseases. Previously, a mutagenized wheat TILLING population (provided by John Innes Centre, n = 2,016) of the spring wheat cultivar Cadenza was screened for the presence/absence of mutations in the BRI1 kinase domain and 18 TILLING lines were selected as potential carriers of a BRI1 mutation (Thapa G. et al., unpublished). These wheat lines were verified by KASP^TM genotyping assay and to date we have performed two successive back crossings and a third round of back crossing (BC3) with the parental type Cadenza is underway. Alongside this, phenotypic analysis of BC2 lines has also been conducted with initial results confirming the presence of leaf curl and differences of plant height relative to the parental type as true indicators of BRI1 mutation carrier lines.

This research project is supported by DAFM Research Stimulus fund grant (R13591).