花色素苷对拟南芥耐盐性的影响

为探讨花色素苷在盐胁迫中的防御作用及其机制,以模式植物拟南芥(Arabidopsis thaliana)花色素苷合成途径相关基因缺失突变体(DFR基因缺失突变体tt3,CHS基因缺失突变体tt4,CHS、DFR基因双缺失突变体tt3tt4)及其野生型(WT)为材料,采用叶绿素荧光和超氧阴离子(O_2·~–)组织定位等方法,分析了tt3,tt4,tt3tt4和WT对盐胁迫处理的生理响应。结果表明,盐胁迫下3种缺失突变体叶片花色素苷含量的增加显著低于野生型,与WT相比,叶绿素荧光参数Fv/Fm、Yield、ETR、q P和NPQ下降较快,膜渗漏率升高显著,叶片O_2·~–积累程度为tt3tt4tt3/tt4WT。这表明花色素苷在植物抵御盐胁迫过程中起着重要作用,它可能是作为渗透调节剂及抗氧化剂来增强植物的耐盐性。因此,花色素苷含量可以作为筛选耐盐作物的指标。

Effect of Anthocyanins on Salt Tolerance in Arabidopsis thaliana

To reveal the defense mechanism of anthocyanins under salt stress, the physiological responses to NaCl stress in three Arabidopsis mutants (tt3, tt4 and tt3tt4) deficient in anthocyanin biosynthesis and wild type (WT) plants were studied. The mutants tt3, tt4 and tt3tt4 are deficient in dihydroflavonol 4-reductase gene (DFR), chalcone synthase gene (CHS) and both DFR and CHS, respectively, these genes encode enzymes that act in the anthocyanin biosynthesis pathway. The results showed that, under salinity stress, the three mutants with lower anthocyanin accumulation exhibited greater reductions in PSII maximum quantum yield (Fv/Fm), effective quantum yield (Yield), electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (NPQ) and greater increases in lipid peroxidation, than the WT. Histochemical stains with nitroblue tetrazolium (NBT) showed that superoxide anion free radical (O₂·^-) in tt3tt4 was the highest, followed by tt3 or tt4, and then by WT. These suggest that anthocyanins play an important role in plant adaptations to salinity stress, possibly via serving as a kind of osmo-regulator and antioxidant. Therefore, anthocyanin contents can be used as an indicator for screening of salt-tolerant crops.