Isolation of the aldose reductase gene (XvAld1) from the resurrection plant Xerophyta viscosa, and characterisation of the gene product and transgenic plants expressing the gene

Abstract

The Xerophyta viscosa aldose reductase cDNA (XvAld1) was isolated from a dehydration library. Gene transcripts that are upregulated during stress are normally involved in protection and/ or adaptation, leading to stress tolerance. The genomic organisation of XvAld1 was characterised using Southern blot analysis and DNA sequencing. The results revealed more than one copy of the gene with a complex banding pattern that was partially resolved by sequencing. The sequencing of PCRamplified genomic clones showed that the gene is organised into nine exons and eight introns spanning ~2.9 kb. The observed nucleotide differences between the sequenced clones could reflect polymorphisms between different copies of the gene. An 870-bp clone of the 5′ untranslated region, matching the 5′ leader sequence on the XvAld1 cDNA was analysed for cis-acting response elements. Many of the sequence motifs matched those for hormonal regulation, organ specific expression, dehydration, high or low temperature responses, light and phytochrome responsiveness, wounding, as well as G-box, CAAT and TATA-boxes.