转DAS/DAK基因天竺葵甲醛代谢途径与吸收能力研究

Metabolic Pathways and Absorptive Capacity of Formaldehyde in Geranium Introduced DAS/DAK Genes

以天竺葵(Pelargoniumsp.Frensham)为材料,通过在天竺葵的叶绿体中过量表达来自甲基营养型酵母同化甲醛(HCHO)途径的关键基因二羟基丙酮激酶基因(DAS)和二羟基丙酮合酶基因(DAK),获得具有DAS/DAK HCHO同化途径的转基因天竺葵,利用13 C-NMR技术对液体H13 CHO胁迫下野生型和转基因天竺葵H13 CHO代谢产物进行了比较分析,并测定了气体HCHO胁迫下野生型和转基因天竺葵的生理生化指标。结果显示:(1)2mmol·L-1液体H13 CHO胁迫下,过表达DAS/DAK基因增强了卡尔文循环在转基因天竺葵H13 CHO代谢中的作用,使糖类物质生成量增加约2.85倍,同时改变了天竺葵中原有HCHO代谢途径。(2)48μg·L-1的气体HCHO胁迫下,转基因天竺葵叶片中H2O2、丙二醛和蛋白羧基的含量显著小于野生型。(3)在环境污染气体HCHO的胁迫下,转基因天竺葵叶片的HCHO吸收效率和气孔传导率显著高于野生型。研究表明,过表达DAS/DAK基因能够有效地提高天竺葵净化环境中污染气体HCHO的能力。

This study overexpressed dihydroxyacetone synthase （DAS） and dihydroxyacetone kinase （DAK） genes,which are two key genes for formaldehyde （HCHO） assimilation in methylotrophic yeasts, in chloroplasts of geranium to obtain transgenic geranium with DAS/DAK HCHO assimilation pathway, The metabolites of wild type and transgenic geranium under liquid H13 CHO stress were comparatively analyzed by ^13C-NMR,and the physiological and biochemical indexes of wild type and transgenic geranium un- der 48μg·L^-1 gaseous HCHO stress were measured. The results showed that： （1）Under 2 mmol·L^-1 liquid H13CHO stress,overexpression of DAS/DAK genes enhanced the role of Calvin cycle during the H13 CHO metabolism in transgenic geranium, thereby the yield of sugars increased approximately 2.85-fold, and simultaneously changed the original HCHO metabolic pathways of geranium. （2）Under 48μg·L^-1 gaseous HCHO stress, the contents of H2O2, malondialdehyde and protein carbonyl in transgenic geranium leaves were much less than those of wild type. （3）Under environment-polluted gaseous HCHO stress,the absorptive capacity of HCHO and stomata conductance in transgenic geranium leaves remained significantly higher than those of wild type. These results suggest that overexpression of DAS/DAK genes can effectively improve the ability of geranium to purify the environmental-polluted gaseous HCHO.