The root-hairless barley mutant brb used as model for assessment of role of root hairs in iron accumulation

Main components of Strategy II mechanism for Fe uptake are secretion of chelating compounds, phytosiderophores, and specific uptake of Fe(III)-phytosiderophores complex. Since the amount of phytosiderophores secreted correlates positively with plant ability to cope with Fe shortage, a role of root hairs in enhancing root capability to store phytosiderophores under Fe stress might be envisaged. In this study the root-hairless mutant of barley ( Hordeum vulgare L.) brb ( bald root barley) and the wild-type genotype (cv. Pallas) were compared with respect to their capacity to respond to Fe shortage in nutrient solution. Plants were grown with Fe III-EDTA at 0, 0.02 and 0.08 mM, in order to reproduce severe or moderate Fe deficiency, and adequate Fe nutritional status, respectively. Analysis was performed after 11 and 14 days considering leaf Fe content, phytosiderophores release and accumulation in root tips, and 59Fe uptake. Biomass accumulation and chlorophyll content were not reduced in mutant plants as compared to wild-type ones; leaf Fe content was similar in both genotypes after 14 days of growth. Accumulation and release of phytosiderophores showed a similar trend in both genotypes when subjected to Fe limitation. Furthermore, no significant difference between the two genotypes was observed when 59Fe uptake was measured. Results seem to support the idea that the presence of root hairs and their increased production in response to low-Fe availability, while causing major modifications of root geometry, did not necessarily lead neither to an effect on growth nor on Fe uptake and accumulation in barley plants. ► Root hairs do not affect growth rate of NS-grown barley plants. ► Root hairs do not affect PS release and accumulation in root tips in barley plants. ► Root hairs do not affect 59Fe uptake in NS-grown barley plants. ► Nutrient stores in seeds affect the time-course of the response to Fe shortage.