Fofana Bourlaye, Ghose Kaushik, Somalraju Ashok, McCallum Jason, Main David, Deyholos Michael K, Rowland Gordon G, Cloutier Sylvie
Charlottetown Research and Development Centre, Agriculture and Agri-Food CanadaCharlottetown, PE, Canada.
Department of Biology, University of British ColumbiaKelowna, BC, Canada.
Front Plant Sci. 2017 Sep 21;8:1638. doi: 10.3389/fpls.2017.01638. eCollection 2017.
Flax secoisolariciresinol (SECO) diglucoside (SDG) lignan is an emerging natural product purported to prevent chronic diseases in humans. SECO, the aglycone form of SDG, has shown higher intestinal cell absorption but it is not accumulated naturally . Recently, we have identified and characterized a UDP-glucosyltransferase gene, , that glucosylates SECO into its monoglucoside (SMG) and SDG forms when expressed in yeast. However, whether this gene is unique in controlling SECO glucosylation into SDG is unclear. Here, we report on the use of in reverse and forward genetics to characterize an ethyl methane sulfonate (EMS) mutagenized flax population from cultivar CDC Bethune and consisting of 1996 M2 families. EMS mutagenesis generated 73 SNP variants causing 79 mutational events in the exonic regions of 93 M2 families. The mutation frequency in the exonic regions was determined to be one per 28 Kb. Of these mutations, 13 homozygous missense mutations and two homozygous nonsense mutations were observed and all were transmitted into the M3 and M4 generations. Forward genetics screening of the population showed homozygous nonsense mutants completely lacking SDG biosynthesis while the production of SMG was observed only in a subset of the M4 lines. Heterozygous or homozygous M4 missense mutants displayed a wide range of SDG levels, some being greater than those of CDC Bethune. No additional deleterious mutations were detected in these mutant lines using a panel of 10 other genes potentially involved in the lignan biosynthesis. This study provides further evidence that is unique in controlling SDG formation from SECO and this is the first report of non-transgenic flax germplasm with simultaneous knockout of SDG and presence of SMG .
亚麻籽异落叶松脂醇（SECO）二葡萄糖苷（SDG）木脂素是一种新兴的天然产物，据称可预防人类慢性疾病。SECO是SDG的苷元形式，已显示出较高的肠道细胞吸收能力，但它不会自然积累。最近，我们鉴定并表征了一个UDP - 葡萄糖基转移酶基因，该基因在酵母中表达时可将SECO糖基化为其单葡萄糖苷（SMG）和SDG形式。然而，该基因在控制SECO糖基化为SDG方面是否独特尚不清楚。在此，我们报告了利用正向和反向遗传学对来自品种CDC白求恩的1996个M2家系的亚麻籽群体进行表征，该群体经甲基磺酸乙酯（EMS）诱变处理。EMS诱变在93个M2家系的外显子区域产生了73个SNP变异，导致79个突变事件。外显子区域的突变频率确定为每28 Kb一个。在这些突变中，观察到13个纯合错义突变和2个纯合无义突变，且所有突变都传递到了M3和M4代。对该群体的正向遗传学筛选表明，纯合无义突变体完全缺乏SDG生物合成，而仅在一部分M4品系中观察到SMG的产生。杂合或纯合的M4错义突变体表现出广泛的SDG水平，有些高于CDC白求恩的水平。使用一组其他10个可能参与木脂素生物合成的基因，在这些突变品系中未检测到其他有害突变。本研究提供了进一步的证据，证明该基因在控制从SECO形成SDG方面是独特的，这是关于同时敲除SDG并存在SMG的非转基因亚麻种质的首次报道。
