Isolation of a drought-responsive alkaline α-galactosidase gene from New Zealand spinach

We isolated a cDNA clone encoding a New Zealand spinach (Tetragonia tetragonioides) alkaline α-galactosidase that we designated TtAGA1. The clone was found by monitoring an up-regulated transcripts accumulation with the differential display reverse transcription–polymerase chain reaction method during a treatment of New Zealand spinach shoots with drought. Deduced amino acid sequence suggests that the gene belongs to a family of plant-specific alkaline α-galactosidases. When detached shoots of New Zealand spinach were treated with abiotic stresses such as drought, administration of mannitol (150 mM), wounding, salinity (200 mM and 400 mM sodium chloride), dark, and cold (4°C), drought most enhanced the accumulation of the TtAGA1 transcripts. Treatments with mannitol, wounding, salinity, and dark increased the transcripts accumulation, but cold did not. It is supposed that the degradation of galactosyl saccharides may correlate with drought responses in New Zealand spinach growing in seashore areas.