RESUMEN
Genetic screens are powerful tools for biological research and are one of the reasons for the success of the thale cress Arabidopsis thaliana as a research model. Here, we describe the whole-genome sequencing of 871 Arabidopsis lines from the Homozygous EMS Mutant (HEM) collection as a novel resource for forward and reverse genetics. With an average 576 high-confidence mutations per HEM line, over three independent mutations altering protein sequences are found on average per gene in the collection. Pilot reverse genetics experiments on reproductive, developmental, immune and physiological traits confirmed the efficacy of the tool for identifying both null, knockdown and gain-of-function alleles. The possibility of conducting subtle repeated phenotyping and the immediate availability of the mutations will empower forward genetic approaches. The sequence resource is searchable with the ATHEM web interface (https://lipm-browsers.toulouse.inra.fr/pub/ATHEM/), and the biological material is distributed by the Versailles Arabidopsis Stock Center.
RESUMEN
Hydathodes are small organs found on the leaf margins of vascular plants which release excess xylem sap through a process called guttation. While previous studies have hinted at additional functions of hydathode in metabolite transport or auxin metabolism, experimental support is limited. We conducted comprehensive transcriptomic, metabolomic and physiological analyses of mature Arabidopsis hydathodes. This study identified 1460 genes differentially expressed in hydathodes compared to leaf blades, indicating higher expression of most genes associated with auxin metabolism, metabolite transport, stress response, DNA, RNA or microRNA processes, plant cell wall dynamics and wax metabolism. Notably, we observed differential expression of genes encoding auxin-related transcriptional regulators, biosynthetic processes, transport and vacuolar storage supported by the measured accumulation of free and conjugated auxin in hydathodes. We also showed that 78% of the total content of 52 xylem metabolites was removed from guttation fluid at hydathodes. We demonstrate that NRT2.1 and PHT1;4 transporters capture nitrate and inorganic phosphate in guttation fluid, respectively, thus limiting the loss of nutrients during this process. Our transcriptomic and metabolomic analyses unveil an organ with its specific physiological and biological identity.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos , Hojas de la Planta , Xilema , Arabidopsis/metabolismo , Arabidopsis/genética , Ácidos Indolacéticos/metabolismo , Xilema/metabolismo , Xilema/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Transcriptoma , Transporte Biológico , Fosfatos/metabolismo , Nitratos/metabolismo , Nutrientes/metabolismoRESUMEN
Xanthomonas campestris pv. campestris is a group of phytopathogenic bacteria causing black rot disease on Brassicaceae crops. Here, we report on draft genome sequences of 17 strains representing eight of nine known races of this pathogen, including the pathotype strain CFBP 6865.
RESUMEN
Bellenot et al. introduce hydathodes, an oft-overlooked plant organ that acts as a pressure valve to expel excess guttation sap at the leaf margin, typically visible at dawn.