Microbial diseases of nursery and field-cultivated Saccharina japonica (Phaeophyta) in China

Saccharina japonica is an economically important alga worldwide as a source of of alginate, mannitol and iodine etc. China contributes 60 % of S. japonica production volume and 90 % of its alginate globally. Like the land crops, S. japonica is also plagued by diseases initi- ated by causative bacteria, fungi or viruses. In this article, we review investigations over the last 50 years on microbial diseases in nursery and fi eld-cultivated S. japonica in China, including the etilology of two different sources of diseases occurring in S. japonica cultivation, the prev- alence of causative alginic acid-decomposing bacteria and the recent progress in the under- standing of innate immunity mechanisms of S. japonica. Meanwhile, we highlight the questions for future research and advocate that researchers from different disciplines apply traditional technologies and newly emerging ones to elucidate the S. japonica microbial diseases. The full understanding of interactions between S. japonica, causative bacteria and environmental fac- tors will help to develop management strategies for preventing and mitigating the disease out- breaks in S. japonica aquaculture in the long term.