Expressão de três isoformas de galactinol sintase em plantas de Coffea arabica L. submetidas a estresses abióticos

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

25/02/2009

RESUMO

Raffinose family oligosaccharides (RFOs) play multiple roles in plants, mainly in response to environmental stresses such as drought, salinity and extreme temperatures. Galactinol synthase (GolS) is the enzyme that catalyzes the first step of the biosynthesis of oligosaccharides of RFOs and plays an important regulatory role in the partition of carbon between sucrose and RFOs. The aim of this study was to evaluate the transcriptional activity of the gene GolS in coffee under varying conditions of abiotic stress and quantify oligosaccharides belonging to the family of the RFO. Searches were conducted within the database of the Coffee Genome Project for the identification and characterization of isoforms of GolS. The three isoforms CaGolS1, CaGolS2 and CaGolS3 have coding regions ranging from 334 to 344 amino acids. All isoforms have the same domain of glycosyltransferase 8, which is a characteristic of the family of RFOs, including GolS. By examining the transcriptional profile of CaGolS1 isoform, it was observed a basal expression of this gene in normal conditions of irrigation, with a prominent increase in transcription in plants submitted to moderate and severe water deficits and at the recovery period. The expression of CaGolS2 isoform was clearly detectable only in conditions of severe stress. The CaGolS3 isoform also showed a pronounced increase of transcripts in leaves when plant was submitted to severe water stress. There were signs of hybridization in periods of moderate stress and recovery, but at lower levels, not being detected expression in plants with normal conditions of water supply. CaGolS1 was constitutively expressed in leaves during the whole period of salt stress, while CaGolS2 isoform was expressed only under conditions of stress. Transcription was detected in CaGolS3 in levels lower than the previous isoforms in this type of stress. During heat stress, CaGolS1 isoform presented increased transcriptional activity on the third day and decreased on the fifth day of stress. The expression of CaGolS2 was not detected or observed very subtly in leaves of Coffea arabica cv. IAPAR-59. The presence of transcripts of CaGolS3 was detected only during the third day of stress. Using data from gene expression, it was observed that the three isoforms of CaGolS1, 2 and 3 showed differences in transcriptional pattern in leaves of C. arabica during the submission of different abiotic stresses. Based on the measurements, it was possible to confirm that raffinose and sthachyose must be acting in osmoprotection of C. arabica during abiotic stresses.

ASSUNTO(S)

café - aspectos genéticos genética vegetal enzimas - regulação oligossacarideos coffe genetic aspects plant genetics

ACESSO AO ARTIGO

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