茉莉酸甲酯对雨生红球藻虾青素含量和dxs基因表达的影响

The effects of methyl jasmonate(MeJA)on the astaxanthin production and dxs gene expression of Haematococcus pluvialis

雨生红球藻是一种能产生重要次生代谢产物———虾青素的单细胞绿藻,茉莉酸甲酯(MeJA)等诱导因子可促进植物次生代谢产物的积累。以雨生红球藻为研究对象,研究了不同浓度MeJA对雨生红球藻细胞生长、虾青素含量和dxs基因表达的影响。结果表明,MeJA在抑制雨生红球藻细胞生长和总虾青素产量的积累的同时,却能促进雨生红球藻单位细胞虾青素的合成能力。当MeJA浓度为800μmol/L时,单位细胞虾青素合成能力可达1.75×10-9mg,相比对照组(1.42×10-9 mg)增加23.24%。RT-PCR分析结果表明,dxs基因的表达受MeJA的诱导,800μmol/L MeJA处理条件下,dxs基因的表达水平最高。相关分析结果表明,MeJA作用下的雨生红球藻虾青素含量和dxs基因表达量呈正相关,推断dxs基因可能是雨生红球藻虾青素合成的一个关键酶基因,这为进一步通过代谢工程策略提高雨生红球藻虾青素含量提供了一个靶点,也为虾青素规模化生产和探讨虾青素积累的分子机理提供参考。

Haematococcus pluvialis,a unicellular green alga,is one of the potent biological sources for valuable secondary metabolite astaxanthin production.Methyl jasmonate（MeJA）,a naturally-occurring plant cellular signal molecular,was found to induce secondary metabolites production.In this paper,the effects of MeJA on the cell growth,astaxanthin production and dxs gene expression of Haematococcus pluvialis were investigated in detail,which provides a theoretical foundation for cosmically manufacturing astaxanthin.The results showed that,the addition of different concentrations of MeJA restrained the cell growth of H.pluvialis and decreased total astaxanthin production also.Addition of MeJA could promote unit cell astaxanthin accumulation,and with the increased MeJA concentrations,the unit cell astaxanthin content showed the trendency that was first increased and then decreased.The optimum addition concentration of MeJA for astaxanthin production was 800 μmol/L.The highest yield of the unit cell astaxanthin content in H.pluvialis was 1.75×10-9 mg,which increased by 23.24% compared with 1.42×10-9 mg without MeJA.This study provides a simple means to increase astaxanthin production.RT-PCR analysis showed that dxs gene expression was induced by MeJA.With the treatment of 800 μmol/L MeJA,dxs gene expression levels were the highest.The correlation analysis results showed that,the astaxanthin content of H.pluvialis and the amount of dxs gene expression were in positive correlation,thus it can be seen that the dxs gene expression level can reflect the astaxanthin production of H.pluvialis,and dxs gene was a key enzyme gene of astaxanthin synthesis of H.pluvialis.