The allelopathy and underlying mechanism of Skeletonema costatum on Karenia mikimotoi integrating transcriptomics profiling

The roles of allelopathy for succession of marine phytoplankton communities remain controversial, especially for the development of blooms. Physiological parameters measurement (Fv/Fm value, MDA content, SOD activity, Na+/K+, Ca2+/ Mg2+-ATPase activity, cell size, chlorophyll content, apoptosis and cell cycle) and whole transcriptome profiling analysis were used to investigate allelopathy effect of Skeletonema costatum on Karenia mikimotoi. Filtrate and extracts from S. costatum culture inhibited the growth of K. mikimotoi. Allelopathic effects were dose-dependent for filtrate culture and extract culture. K. mikimotoi scavenged excessive ROS and adapted to the stress fastly and easily, so oxidative damage was not the main cause of the growth inhibition. Allelochemicals of S. costatum were found to influence the structure and function of cell membrane of K. mikimotoi by damaging membrane structure till to cell necrosis, which caused high mortality. Coupled with the sensitivity of algal cells to environmental stress and restricted cell cycle, allelopathy was suggested to be deeply detrimental to the development of competition algal population.

Automated summary

The allelopathic effects of Skeletonema costatum on Karenia mikimotoi were found to inhibit the growth of K. mikimotoi, with the degree of inhibition dependent on the dosage. K. mikimotoi was able to adapt quickly to stress and scavenge excessive ROS, with oxidative damage not being the main cause of growth inhibition. The allelopathy of S. costatum influenced the cell membrane structure of K. mikimotoi, leading to cell necrosis and high mortality, suggesting a detrimental impact on the development of competitive algal populations.