Análises do proteoma de raízes de cana-de-açúcar e da expressão de uma peroxidase apoplástica responsiva à micorriza arbuscular / Analysis of the sugarcane roots proteome and expression of an arbuscular mycorrhizaresponsive apoplastic peroxidase

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Arbuscular mycorrhizae (AM) are symbiotic associations between fungi of the phylum Glomeromycota and most of the plant species. Even though the molecular mechanisms controlling the colonization process and AM development are largely unknown, proteins with differential accumulation in AM may have important regulatory roles. The aim of this work was to detect, by bi-dimensional electrophoresis (2D-PAGE) and mass spectrometry, proteins with differential accumulation in the intercellular fluid (IF), plasma membrane or radicular tissue of sugarcane colonized by Glomus clarum Micropropagated sugarcane plantlets were inoculated with G. clarum and growth under low or high P conditions, 20 or 200 mg P kg-1 substrate, respectively. Mycorrhizal and non-mycorrhizal roots, eight weeks after inoculation, were used to extract proteins from the IF, plasma membrane and root tissue (total soluble proteins). Protein separation and analyses were performed using 2D-PAGE and mass spectrometry. The total soluble and plasma membrane protein profiles did not reveled symbiosis-related proteins. However, three proteins from the IF, a putative aspartic hydrolase, a putative histidine kinase and a putative peroxidase showed induced accumulation in mycorrhizal roots. Peroxidase activities in roots and apoplastic fluid were determined, and shown to be higher in mycorrhizal roots at low P than in non-mycorrhizal control roots. Based on the partial amino acid sequence of this peroxidase, a partial cDNA sequence of its gene (POX1) was cloned from PCR-amplified cDNA from sugarcane roots. The POX1 sequence showed 90% and 91% identity to maize (NCBI) and sugarcane (TIGR) peroxidase, respectively. Expression analyses of POX1 were perfomed using quantitative PCR of reverse transcripts from mycorrhizal and non-mycorrhizal roots at low and high P conditions. The steady state level of POX1 transcripts in mycorrhizal roots at low P condition was 6.8-fold higher than in mycorrhizal roots at high P conditions. In mycorrhizal roots at high P conditions the steady state level of POX1 transcripts was 3.9-fold lower than in nonmycorrhizal control roots. These data suggest that the metabolism of reactive oxygen species may be an important factor controlling the development of AM. Studies with plants altered in POX1 expression are, however, required to elucidate the essentiality of this peroxidase in AM.

ASSUNTO(S)

cana-de-açúcar células micorriza apoplast peroxidase arbuscular mycorrhiza proteome sugarcane proteínas peroxidase

ACESSO AO ARTIGO

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