Abiotic Stress Tolerance Genes Characterized in Brown Seaweed

Saccharina japonica is an important commercial brown seaweed. Its main product, alginate, is used in food, textile and by the cosmetic and pharmaceutical industries. GDP-mannose dehydrogenase (GMD) is the key enzyme involved in the synthesis of alginate. However, little is known about GMD in S. japonica. Scientists from the Chinese Academy of Sciences, led by Pengyan Zhang, performed comparative biochemical analysis of two GMD genes in S. japonica.

The two GMD genes from S. japonica (Sjgmd1, Sjgmd2) were cloned and characterized. The proteins encoded by these two genes had optimum temperatures of 30°C (SjGMD1) and 20°C (SjGMD2), and the optimum pH values were 8.0 (SjGMD1) and 8.25 (SjGMD2), respectively. The metal iron Zn²⁺ was also found as a potent inhibitor of SjGMD1 and SjGMD2. PCR analysis showed that heat and desiccation treatments resulted in a significant increase in Sjgmd1 and Sjgmd2 transcript, suggesting that the SjGMDs are directly involved in the acclimatization of S. japonica to abiotic stresses.

The work identified two novel genes encoding GMD in S. japonica and revealed the function of GMD in the stress adaptability of S. japonica. The data obtained enriched our understanding of the alginate synthesis in S. japonica, and may promote further research on functional differences between GMD genes.

For more information on the study, read the full article on BMC Plant Biology.