Abstract: The objective of this research is to investigate the effects of acetosalicylic acid (ASA) on cell growth, fucoxanthin accumulation and expression levels of genes related to the biosynthesis of fucoxanthin in the model diatom Phaeodactylum tricornutum. Growth rate, fucoxanthin content and gene expression were detected by spectrophotometer, high performance liquid chromatography (HPLC) and real-time PCR respectively. The results indicated that fucoxanthin content were closely associated with the concentrations of ASA. ASA at a certain concentration suppressed proliferation of algae cells. With the concentration of ASA iuncreased, the content of fucxanthin was first increased and then declined. Notably, the content of fucoxanthin in Phaeodactylum tricornutum treated with 10 mg·L^-1 ASA was the highest (1.78 g·kg^-1DW), which was 1.9 times as much as that in control groups. The expression of genes (including PSY, PSD, ZDS, CRTISO, LCYB and ZEP) that encoding pivotal enzymes associated with the fucoxanthin biosynthesis were increased following ASA treatment. In particularly, the transcripts of detected genes were significantly up-regulated under 10 mg·L^-1 ASA treatment when compared with the control (P<0.01). Principal component analysis (PCA) indicated these six genes were positively correlated with fucoxanthin accumulation, therein ZEP exhibited the highest contribution. In general, proper concentrations of ASA induced the expression of genes responsible for fucoxanthin biosynthesis and increased the production of fucoxanthin. The present study provides a theoretic basis for molecular mechanism of fucoxanthin biosynthesis in Phaeodactylum tricornutum.

Key words: acetosalicylic acid, Phaeodactylum tricornutum, fucoxanthin, gene expression, principal component analysis

摘要： 为了研究不同浓度乙酰水杨酸(ASA)对三角褐指藻(Phaeodactylum tricornutum Bohlin)细胞生长、岩藻黄质积累及岩藻黄质生物合成相关基因的表达水平的影响,通过分光光度计、高效液相色谱(HPLC)以及荧光定量PCR测定不同浓度ASA处理后的三角褐指藻的各项指标。结果表明,三角褐指藻的生长和岩藻黄质积累与ASA浓度密切相关。一定浓度的ASA抑制了三角褐指藻的细胞数量;岩藻黄质含量也随着ASA浓度的升高呈现先上升后下降的趋势,当ASA浓度为10 mg·L^-1时,岩藻黄质含量最高,达1.78 g·kg^-1 DW,为对照组的1.9倍。在不同浓度ASA诱导下,与岩藻黄质生物合成途径有关的PSY、PDS、ZDS、CRTISO、LCYB和ZEP基因表达均上调,当ASA浓度为10 mg·L^-1时,相关基因的表达量极显著高于对照组(P<0.01)。主成分分析(PCA)结果表明,PSY、PDS、ZDS、CRTISO、LCYB和ZEP基因与岩藻黄质积累具有相关性,其中,ZEP基因对岩藻黄质生物合成贡献率最高。综上,适当浓度的ASA不仅提高了岩藻黄质合成途径中相关基因的表达水平,而且促进了岩藻黄质的积累。本研究结果为进一步深入研究三角褐指藻中岩藻黄质合成的分子机制奠定了理论基础。

关键词: 乙酰水杨酸, 三角褐指藻, 岩藻黄质, 基因表达, 主成分分析