The pentose catabolic pathway of the rice-blast fungus Magnaporthe oryzae involves a novel pentose reductase restricted to few fungal species.

A gene (MoPRD1), related to xylose reductases, was identified in Magnaporthe oryzae. Recombinant MoPRD1 displays its highest specific reductase activity toward L-arabinose and D-xylose. Km and Vmax values using L-arabinose and D-xylose are similar. MoPRD1 was highly overexpressed 2-8h after transfer of mycelium to D-xylose or L-arabinose, compared to D-glucose. Therefore, we conclude that MoPDR1 is a novel pentose reductase, which combines the activities and expression patterns of fungal L-arabinose and D-xylose reductases. Phylogenetic analysis shows that PRD1 defines a novel family of pentose reductases related to fungal D-xylose reductases, but distinct from fungal L-arabinose reductases. The presence of PRD1, L-arabinose and D-xylose reductases encoding genes in a given species is variable and likely related to their life style.