甘草根系分泌物乳酸外源施用对GuSQS1和GubAS基因表达及甘草酸含量的影响

为探究甘草根系分泌物乳酸是否对其自身存在化感自毒作用,以蒸馏水水培甘草幼苗为对照组,实际分泌浓度(1×10^(-4)mol/L)乳酸溶液培养为处理组,通过实时荧光定量PCR技术,分析2种甘草酸生物合成关键酶基因GuSQS1,GubAS表达情况,并通过HPLC法检测甘草根中甘草酸的含量.结果表明,在甘草幼苗根中,GuSQS1,GubAS基因的表达量极显著高于叶中.GuSQS1基因在处理组甘草幼苗的根和叶中,6 h时达到最大值,而在对照组甘草幼苗的根和叶中,9 h时达到最大值.GubAS基因在处理组甘草幼苗的根中,6,48 h时达到表达量的2个高峰,叶中的6 h达最大表达量,而在对照组甘草幼苗的根中,9,24 h时出现2次表达量的高峰.从整个处理周期看,处理组这2个基因表达量显著低于对照组.在处理末期,处理组甘草幼苗根中甘草酸含量显著低于对照组.甘草根系分泌物乳酸对甘草自身具有较明显的化感自毒作用.

Enhancing ergosterol production in Pichia pastoris GS115 by overexpressing squalene synthase gene from Glycyrrhiza uralensis

The present study was designed to determine the effects of copy number variations(CNVs) of squalene synthase 1(SQS1) gene on the mevalonate(MVA) pathway.SQS1 gene from G.uralensis(Gu SQS1) was cloned and over-expressed in Pichia pastoris GS115.Six recombinant P.pastoris strains containing different copy number of Gu SQS1 were constructed.HPLC was used to assay the level of ergosterol in all transgenic P.pastoris strains containing Gu SQS1.HPLC analysis showed that the contents of ergosterol in all of the transgenic P.pastoris containing Gu SQS1 were higher than that in the negative control.And with the increase of copy number of Gu SQS1,the content of ergosterol showed an increasing-decreasing-increasing pattern.The contents of ergosterol in 10-copy-Gu SQS1 P.pastoris and 47-copy-Gu SQS1 P.pastoris were significantly higher than that in the rest recombinant P.pastoris strains.In conclusion,the CNVs of Gu SQS1 influence the content of secondary metabolites in the MVA pathway.The present study provides a basis for over-expressing Gu SQS1 and increasing the content of glycyrrhizin in G.uralensis cultivars.