The pathogenic bacterium penetrated through the interior of the seaweed by decomposing the epidermic cell walls.There were more pathogens in the pith than those in the cortex.

• 两种发病藻体病理变化基本一致，细菌通过分解表皮细胞壁后侵入藻体内部，表皮和皮层细胞内细菌数量较少，髓部较多。