RESUMO
Rosettes of 25 Arabidopsis thaliana accessions and an Antwerp-1 (An-1) x Landsberg erecta (Ler) population of recombinant inbred lines (RILs) grown in optimal watering conditions (OWC) and water deficit conditions (WDC) were analysed for mineral concentrations to identify genetic loci involved in adaptation of mineral homeostasis to drought stress. Correlations between mineral concentrations were determined for accessions and a quantitative trait locus (QTL) analysis was performed for the RIL population. Plant growth and rosette mineral contents strongly decreased in WDC compared with OWC. Mineral concentrations also generally decreased, except for phosphorus (P), which remained constant, and potassium (K), which increased. Large variations in mineral concentrations were observed among accessions, mostly correlated with total rosette leaf area. Mineral concentration QTLs were identified in the RIL population, but only a few were common for both conditions. Clusters of mineral concentration QTLs often cosegregated with dry weight QTLs. Water deficit has a strong effect on rosette mineral status. This is genetically determined and seems largely a pleiotropic effect of the reduction in growth. The low number of common mineral concentration QTLs, shared among different RIL populations, tissues and conditions in Arabidopsis, suggests that breeding for robust, mineral biofortified crops will be complex.
Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Secas , Minerais/metabolismo , Locos de Características Quantitativas/genética , Biomassa , Mapeamento Cromossômico , Cruzamentos Genéticos , Epistasia Genética , Genótipo , Endogamia , Folhas de Planta/genética , Análise de Componente Principal , ÁguaRESUMO
The regulation of mineral accumulation in plants is genetically complex, with several genetic loci involved in the control of one mineral and loci affecting the accumulation of different minerals. To investigate the role of growth medium and organ type on the genetics of mineral accumulation, two existing (LerxKond, LerxAn-1) and one new (LerxEri-1) Arabidopsis thaliana Recombinant Inbred Line populations were raised on soil and hydroponics as substrates. Seeds, roots, and/or rosettes were sampled for the determination of their Ca, Fe, K, Mg, Mn, P or Zn concentrations. For seeds only, the concentration of phytate (IP6), a strong chelator of seed minerals, was determined. Correlations between minerals/IP6, populations, growth conditions, and organs were determined and mineral/IP6 concentration data were used to identify quantitative trait loci (QTLs) for these traits. A striking difference was found between QTLs identified for soil-grown versus hydroponics-grown populations and between QTLs identified for different plant organs. Three common QTLs were identified for several populations, growth conditions, and organs, one of which corresponded to the ERECTA locus, variation of which has a strong effect on plant morphology.
Assuntos
Arabidopsis/metabolismo , Minerais/metabolismo , Ácido Fítico/metabolismo , Estruturas Vegetais/metabolismo , Locos de Características Quantitativas , Arabidopsis/química , Arabidopsis/genética , Flores/química , Flores/genética , Flores/metabolismo , Jardinagem , Hidroponia , Minerais/análise , Ácido Fítico/análise , Raízes de Plantas/química , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Estruturas Vegetais/química , Estruturas Vegetais/genética , Sementes/química , Sementes/genética , Sementes/metabolismoRESUMO
Cadmium (Cd) is a widespread, naturally occurring element present in soil, rock, water, plants and animals. Cd is a non-essential element for plants and is toxic at higher concentrations. Transcript profiles of roots of Arabidopsis thaliana (Arabidopsis) and Thlaspi caerulescens plants exposed to Cd and zinc (Zn) are examined, with the main aim to determine the differences in gene expression between the Cd-tolerant Zn-hyperaccumulator T. caerulescens and the Cd-sensitive non-accumulator Arabidopsis. This comparative transcriptional analysis emphasized the role of genes involved in lignin, glutathione and sulphate metabolism. Furthermore the transcription factors MYB72 and bHLH100 were studied for their involvement in metal homeostasis, as they showed an altered expression after exposure to Cd. The Arabidopsis myb72 knockout mutant was more sensitive to excess Zn or iron (Fe) deficiency than wild type, while Arabidopsis transformants overexpressing bHLH100 showed increased tolerance to high Zn and nickel (Ni) compared to wild-type plants, confirming their role in metal homeostasis in Arabidopsis.