过表达FtbZIP5提高苦荞毛状根黄酮积累及其耐盐性

The Overexpression of FtbZIP5 Improves Accumulation of Flavonoid in the Hairy Roots of Tartary Buckwheat and Its Salt Tolerance

bZIP转录因子不仅在植物盐胁迫网络中起着重要的作用,还可调节植物类黄酮的积累。在苦荞品种川荞1号中克隆了1个具有转录激活活性的bZIP家族基因FtbZIP5。FtbZIP5基因能被Na Cl和脱落酸(ABA)诱导表达,在茎和叶中的表达高于根中。对过表达FtbZIP5基因毛状根的总黄酮含量进行检测,结果显示,总黄酮含量在过表达株系中显著高于野生株系。同时检测其类黄酮合成途径中关键酶基因的表达量,其中黄烷酮-3-羟化酶基因(F3H)的表达量较高。可推测该过表达毛状根株系中总黄酮的积累与F3H的表达有关。在NaCl(100mmol/L)胁迫下,各株系的总黄酮积累受到抑制,过表达株系的含量减少至0.63mg/g。并且,在这种压力下,F3H的表达水平仍然高于对照。植株在受到胁迫后,对照株系的过氧化氢酶(CAT)活性显著低于过表达株系。随着野生型植株受到胁迫的增强丙二醛(MDA)含量增加,但过表达株系的含量趋于稳定。以上结果表明,在过表达FtbZIP5毛状根中,总黄酮的积累可能是通过关键酶基因F3H的上调表达来调节的。并且FtbZIP5可提高苦荞毛状根耐盐性。通过解析FtbZIP5对苦荞毛状根中总黄酮积累及植株耐盐性的影响,为荞麦耐盐性和解析其耐盐机制研究奠定基础。

The bZIP transcription factors, with an important role in salt stress network, can regulate flavonoid accumulation in plant. In this paper, the bZIP family gene FtbZIP5, with transcriptional activation activity, was cloned from the ‘Chuanqiao 1’. Expression of FtbZIP5 gene in stems and leaves was higher than that in root when treated by NaCl and abscisic acid. Flavonoid detection was carried out on hairy roots of overexpressing the FtbZIP5 gene strain, and results showed that flavonoid accumulation in overexpressing strains was significantly higher than that in wild-type plants. And the expression of key enzyme gene flavanone-3-hydroxylase(F3 H) in flavonoid synthesis pathway was high, which can speculate that accumulation of total flavonoids in overexpressed hair root strains was associated with F3H expression. Under the stress of 100 mmol/L NaCl, the accumulation of total flavonoids in all lines was suppressed, and the content of total flavonoids in overexpression lines decreased to 0.63 mg/g, and the expression of F3H was still higher than that of the control. Catalase activity of the control was significantly lower than that of the overexpressing strains after stressing. After stressing by NaCl, the content of malondialdehyde in wild-type plants increased and that in overexpressing strains was stable. The above results indicated that overexpressing the FtbZIP5 gene in the hairy roots, the increase in total flavonoid content may be regulated by the up-regulation of the key enzyme gene F3H;and FtbZIP5 also improved the salt tolerance of tartary buckwheat roots. This paper analyzed the role of FtbZIP5 in the accumulation of total flavonoids and salt tolerance in the hairy roots of tartary buckwheat, and laid a foundation of studying the salt tolerance of buckwheat and analyzing the salt tolerance mechanism of buckwheat.