RESUMO
Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from Arabidopsis thaliana T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Cisteína/metabolismo , Dioxigenases/metabolismo , Redes e Vias Metabólicas , Sulfurtransferases/metabolismo , Aminoácidos/metabolismo , Arabidopsis/embriologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Cisteína/análogos & derivados , Dioxigenases/genética , Metabolismo Energético , Glutationa/metabolismo , Mitocôndrias/metabolismo , Mutagênese Insercional , Ácido Pirúvico/metabolismo , Sementes/embriologia , Sementes/enzimologia , Sementes/genética , Compostos de Sulfidrila/metabolismo , Enxofre/metabolismo , Sulfurtransferases/genética , Tiossulfatos/metabolismoRESUMO
The TCP-type transcription factors BRANCHED1 and BRANCHED2 shape plant architecture by suppressing bud outgrowth, with BRANCHED2 only playing a minor role in Arabidopsis. Here, we investigated the function of orthologs of these genes in the model tree Populus. We used CRISPR/Cas9 to generate loss-of-function mutants of previously identified Populus BRANCHED1-1 and BRANCHED2-1 candidate genes. BRANCHED1-1 mutants exhibited strongly enhanced bud outgrowth. BRANCHED2-1 mutants had an extreme bud outgrowth phenotype and possessed two ectopic leaves at each node. While BRANCHED1 function is conserved in poplar, BRANCHED2, in contrast to its Arabidopsis counterpart, plays an even more critical role in bud outgrowth regulation. In addition, we identified a new, not yet reported association of this gene to leaf development.