Are Barley Dwarfing Genes Important in Tolerance to Abiotic Stress?
DELLA proteins are a highly conserved group of growth inhibitors, mutants of which were integral to the semi-dwarf, high yielding wheat lines of the Green Revolution. In addition to reducing plant growth, the gain of function (GoF) mutants in which DELLA protein is stabilised were shown to confer resistance to salt stress in the model species Arabidopsis. In order to determine whether these findings could be translated from Arabidopsis to monocot crop species, GoF and loss of function (LoF) mutants of the barley DELLA orthologue, Sln1, were characterised and growth and development assessed. By subjecting DELLA wild-type and mutant barley plants to abiotic stress conditions (salt stress and heat shock) it was established that the increased survival conferred by stabilised DELLA that was reported in Arabidopsis was also applicable to barley, and that survival of the LoF barley mutants was decreased. Further evidence for the importance of stabilised DELLA was obtained when additional mutants in the GA signalling pathway (gse1a,j,n; Gse1, GA receptor mutants) in which DELLA protein is predicted to accumulate, also showed increased tolerance to abiotic stress. These data suggest DELLA protein function is conserved between monocot (cereal) and dicot plants. Attempts to produce transgenic barley plants in which Sln1 was silenced were inconclusive, likely underlining the essential nature of the gene in growth, development and regeneration. The studies provide a basis for further work to investigate the mechanisms underlying DELLA function in cereals.
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