Abstract：
The globally distributed harmful algal blooms (HAB) species, Heterosigma akashiwo, has been found to exhibit ichthyotoxicity. Previous studies have shown that H. akashiwo achieves a competitive edge during bloom occurrences by inhibiting the growth of a coexisting diatom, Skeletonema costatum, through allelopathy. However, the specific allelopathic mechanisms underlying the allelopathic effects of H. akashiwo on S. costatum remain unknown. To bridge this gap, our study utilized a combination of quantitative real-time PCR and metabolomics to examine the allelopathic processes of H. akashiwo on S. costatum. Our results demonstrate that the growth of S. costatum is hindered when co-cultured with H. akashiwo (initial cell concentration, 2 × 104 cell/mL). Gene expression investigation showed a substantial reduction in the mRNA levels of cytochrome b6, ribulose bisphosphate carboxylase large chain, and silicon transporter in S. costatum when grown in co-culture conditions. Furthermore, metabolic pathway analysis suggested that the allelopathic effects of H. akashiwo disrupted several vital metabolic pathways in S. costatum, including a reduction in purine and pyrimidine metabolism and an increase in fatty acid biosynthesis. Our investigation has revealed the intricate and substantial involvement of allelopathy in the formation of H. akashiwo blooms, demonstrating the complexity of the allelopathic interaction between H. akashiwo and S. costatum. These insights also contribute significantly to our understanding of the dynamics within HAB species.
摘要：
全球分布的有害藻华（HAB）物种，Heterosigmaakashiwo,已经发现表现出鱼鳞病毒性。先前的研究表明，H.akashiwo通过抑制共存硅藻的生长，在开花期间获得了竞争优势，Skeletonemacostatum,通过化感作用。然而,赤蜡对S.costatum的具体化感作用机制尚不清楚。为了弥合这个差距，本研究采用实时定量PCR和代谢组学相结合的方法,研究了赤石草对S.costatum的化感过程.我们的结果表明，与H.akashiwo共培养时，S.costatum的生长受到阻碍（初始细胞浓度，2×104细胞/mL)。基因表达调查显示细胞色素b6，核糖二磷酸羧化酶大链的mRNA水平显着降低，当在共培养条件下生长时，S.costatum中的硅转运蛋白。此外，代谢途径分析表明，赤石草的化感作用破坏了S.costatum的几个重要代谢途径，包括嘌呤和嘧啶代谢的减少和脂肪酸生物合成的增加。我们的调查揭示了化感作用在H.akashiwo花的形成中的复杂而实质性的参与，证明了akashiwo和S.costatum之间化感作用的复杂性。这些见解也大大有助于我们对HAB物种内部动力学的理解。
