Comparative transcriptome analysis unveils mechanisms underlying the promoting effect of potassium iodide on astaxanthin accumulation in Haematococcus pluvialis under high light stress
Comparative transcriptome analysis unveils mechanisms underlying the promoting effect of potassium iodide on astaxanthin accumulation in Haematococcus pluvialis under high light stress
复制标题
比较转录组分析揭示了强光胁迫下碘化钾促进雨生红球藻虾青素积累的机制
DOI：
10.1016/j.aquaculture.2020.735279
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发表时间：
2020-08-30
期刊：
影响因子：
4.5
通讯作者：
Xu, Nianjun
中科院分区：
文献类型：
--
作者：
Cui, Dandan;Hu, Chaoyang;Xu, Nianjun
雨生红球藻产生的虾青素是一种经济价值很高的类酮类胡萝卜素，对人类健康有益。在强光胁迫下，虾青素可在雨生红藻细胞中积累高达3%。在强光(HK)条件下，加入1 mM的碘化钾(KI)，可获得比单独强光(HL)高26%~35%的虾青素。与HL在第5天和第10天全部转化为富含虾青素的不活动细胞相比，HK中约有30%-35%的细胞保留了鞭毛，这些鞭毛活动，但没有增厚的次生细胞壁。值得注意的是，这些富含虾青素的运动细胞比含有虾青素的非运动细胞含有更多的虾青素。与HL相比，香港的最大光化学效率(Fv/Fm)较高，而实际光化学效率(Fv‘/Fm’)较低。HK组和HL组细胞转录差异显著，尤其是在第5天和第10天，这与HK和HL细胞的上述形态差异是一致的。KI通过上调虾青素生物合成基因的转录水平，同时下调竞争虾青素生物合成前体的其他途径中涉及的基因的转录水平，促进了虾青素的积累。转录数据还显示，HK细胞和HL细胞在与细胞壁生物合成(57)、鞭毛生物合成和细胞运动(620)、ROS稳态(42)和转录因子(42)相关的基因上发生了显著变化。根据形态和转录数据，讨论了KI在强光下促进雨生螺旋藻细胞生长的可能机制。综上所述，本研究提供了一种增加雨生红藻虾青素积累的新方法，其成果拓展了目前对强光胁迫下雨生红藻的生存策略和虾青素积累的认识。
Astaxanthin produced by Haematococcus pluvialis is an economically valuable ketocarotenoid pigment that benefits the health of human being. Astaxanthin can be accumulated in H. pluvialis cells up to 3% under high light stress. In this study, by adding 1 mM potassium iodide (KI) into the culture media of H. pluvialis cells under high light condition (HK), 26%-35% more astaxanthin than that of high light alone (HL) was obtained. As compared with HL that all cells turned into astaxanthin-rich non-motile ones at day 5 and day 10, about 30%-35% cells in HK remained flagella, which were motile without thickened secondary cell wall. Notably, these astaxanthin-rich motile cells contained more astaxanthin than astaxanthin-containing non-motile cells. The maximal photochemical efficiency (Fv/Fm) was higher in HK while the actual photochemical efficiency (Fv'/ Fm') was lower in HK as compared with those in HL. Transcriptomes of cells in HK and HL groups were significantly different, especially at day 5 and day 10, which were consistent with above-mentioned morphological differences between HK and HL cells. KI promoted astaxanthin accumulation by up-regulating the transcription levels of astaxanthin biosynthetic genes and by simultaneously down-regulating the transcription levels of genes involved in other pathways that compete for precursors of astaxanthin biosynthesis. Transcriptomic data also revealed significant changes between HK and HL cells in genes involved in cell wall biosynthesis (57), flagella biosynthesis and cell movement (620), ROS homeostasis (42), and transcriptional factors (42). The possible mechanisms underlying KI's promoting role in H. pluvialis cells under high light were discussed based on morphological and transcriptomic data. In summary, this study provides a new method to increase astaxanthin accumulation in H. pluvialis, and its output expands current understanding of survival strategies and astaxanthin accumulation of H. pluvialis under high light stress.