RESUMO
Gene networks involved in inorganic phosphate (Pi) acquisition and homeostasis in woody perennial species able to form mycorrhizal symbioses are poorly known. Here, we describe the features of the 12 genes coding for Pi transporters of the Pht1 family in poplar (Populus trichocarpa). Individual Pht1 transporters play distinct roles in acquiring and translocating Pi in different tissues of mycorrhizal and nonmycorrhizal poplar during different growth conditions and developmental stages. Pi starvation triggered the up-regulation of most members of the Pht1 family, especially PtPT9 and PtPT11. PtPT9 and PtPT12 showed a striking up-regulation in ectomycorrhizas and endomycorrhizas, whereas PtPT1 and PtPT11 were strongly down-regulated. PtPT10 transcripts were highly abundant in arbuscular mycorrhiza (AM) roots only. PtPT8 and PtPT10 are phylogenetically associated to the AM-inducible Pht1 subfamily I. The analysis of promoter sequences revealed conserved motifs similar to other AM-inducible orthologs in PtPT10 only. To gain more insight into gene regulatory mechanisms governing the AM symbiosis in woody plant species, the activation of the poplar PtPT10 promoter was investigated and detected in AM of potato (Solanum tuberosum) roots. These results indicated that the regulation of AM-inducible Pi transporter genes is conserved between perennial woody and herbaceous plant species. Moreover, poplar has developed an alternative Pi uptake pathway distinct from AM plants, allowing ectomycorrhizal poplar to recruit PtPT9 and PtPT12 to cope with limiting Pi concentrations in forest soils.
Assuntos
Perfilação da Expressão Gênica , Família Multigênica/genética , Micorrizas/fisiologia , Proteínas de Transporte de Fosfato/química , Proteínas de Transporte de Fosfato/genética , Populus/genética , Populus/microbiologia , Contagem de Colônia Microbiana , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Genótipo , Glomeromycota/efeitos dos fármacos , Glomeromycota/crescimento & desenvolvimento , Glomeromycota/fisiologia , Glucuronidase/metabolismo , Anotação de Sequência Molecular , Micorrizas/efeitos dos fármacos , Proteínas de Transporte de Fosfato/metabolismo , Fosfatos/farmacologia , Filogenia , Plantas Geneticamente Modificadas , Populus/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Especificidade da EspécieRESUMO
Genome-wide analysis of fungal manganese transporters was undertaken, making use of whole genome sequences available in fungal databases. A repertoire of 281 putative manganese transporters was found in total across 26 fungal species representing 20 fungal orders. The process of gene duplication was apparently accompanied by gene loss events, and this resulted in a great variety of manganese transporters that can be observed in the genome of modern fungi. Eleven transporters belonging to gene families in which manganese transporters have been found were identified in the Phanerochaete chrysosporium genome. This whole set of transporters may cover the need of P. chrysosporium cells for manganese loading in and unloading out of the cytosol, thereby insuring manganese homeostasis. The tight control of intracellular Mn(2+) ion concentration is for instance of crucial importance for the control of lignin-degradative systems by saprotrophic fungi, and thereof the carbon cycle in forest ecosystems.
