title: A transient assay system for the assessment of cell-autonomous gene function in dehydration-stressed barley.
abstract: Drought is a serious, worldwide problem for crop production and also affects yields of barley and wheat, together with other stressors such as frost, viral diseases, or fungal pathogens. Although a number of candidate genes have been identified by transcriptome approaches in recent years, only very few have been tested in functional assays for a beneficial effect on drought tolerance. Here, a transient assay system in microprojectile-bombarded barley leaves is described that allows the functional testing of dehydration stress-related candidate genes by RNA interference (RNAi) or overexpression. Cellular stress or damage in dedydrated leaves is reported by a reduced accumulation of slowly maturing, native red-fluorescing protein DsRed that is known to be sensitive to denaturing conditions. After a dehydration-stress period of 4 d during which the relative fresh weight of leaves was kept at 60-66% of initial fresh weight, a reproducible reduction of normalized DsRed fluorescence was observed. In order to obtain proof of concept, a number of barley mRNAs homologous to drought response genes were selected and targeted by transient induced gene silencing (TIGS). TIGS of four tested genes resulted in a significantly stronger decrease of normalized DsRed fluorescence in dehydration-stressed leaves, whereas they had no effect in fully turgescent control leaves. These genes encode barley drought-responsive factor HvDRF1 (DREB2-like), dehydrin 6, late embryogenesis-abundant protein HVA1, and the vacuolar sodium/proton antiporter HvHNX1. The four targeted transcripts were also found to accumulate rapidly in dehydration-stressed barley leaf segments. The results suggest a value of the TIGS system for functional pre-screening of larger numbers of drought or dehydration stress-related candidate genes in barley.
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Marzin
authors.forename: Robert
authors.initials: R
authors.lastname: Mihaly
authors.forename: Janos
authors.initials: J
authors.lastname: Pauk
authors.forename: Patrick
authors.initials: P
authors.lastname: Schweizer
mesh_terms: D004190:Disasters; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D001467:Hordeum / Q000235:genetics / Q000502:physiology*; D008163:Luminescent Measurements / Q000379:methods*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods*; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D010940:Plant Proteins; C413663:fluorescent protein 583; D014867:Water; D049452:Green Fluorescent Proteins