低氮胁迫诱导木薯幼苗花青素积累及其基因表达

Anthocyanin Accumulation and Its Gene Expression Induced by Low Nitrogen Stress in Cassava Seedlings

为明确氮素浓度和形态与木薯花青素产生和积累的关系,基于氮素胁迫能够在拟南芥等植物中促进花青素产生的研究结果,以木薯品种Arg7为研究对象,研究木薯无菌幼苗在添加了(1)40 mmol/L NO_(3)^(-)+20 mmol/L NH_(4)^(+),(2)40 mmol/L NO_(3)^(-),(3)20 mmol/L NH_(4)^(+),(4)0.4 mmol/L NO_(3)^(-)+0.2 mmol/L NH_(4)^(+),(5)0.4 mmol/L NO_(3)^(-),(6)0.2 mmol/L NH_(4)^(+),(7)1 mmol/L(N),(8)5 mmol/L(N),(9)9 mmol/L(N),(10)13 mmol/L(N)10种氮素浓度和形态的MS培养基中生长40 d的农艺性状,以及对花青素合成相关结构基因的诱导和花青素积累的差异。结果表明,木薯品种Arg7无菌幼苗在添加有40 mmol/L NO_(3)^(-)+20 mmol/L NH_(4)^(+),40 mmol/L NO_(3)^(-)和20 mmol/L NH_(4)^(+)的MS缺氮培养基中生长至40 d,没有观察到花青素产生;与40 mmol/L NO_(3)^(-)+20 mmol/L NH_(4)^(+)处理条件相比,在40 mmol/L NO_(3)^(-)条件下的株高和初生根根长没有显著差异,但初生根根数显著减少,而在20 mmol/L NH_(4)^(+)条件下其株高、初生根根长和初生根根数都受到极显著抑制;木薯品种Arg7无菌苗在含有0.4 mmol/L NO_(3)^(-)+0.2 mmol/L NH_(4)^(+),0.4 mmol/L NO_(3)^(-)和0.2 mmol/L NH_(4)^(+)的MS缺氮培养基中生长至40 d,3种处理条件下的木薯茎秆和叶柄中花青素积累明显,花青素合成相关结构基因被诱导表达;与40 mmol/L NO_(3)^(-)+20 mmol/L NH_(4)^(+)条件下相比,在0.4 mmol/L NO_(3)^(-)+0.2 mmol/L NH_(4)^(+),0.4 mmol/L NO_(3)^(-)和0.2 mmol/L NH_(4)^(+)条件下的株高、初生根根长和根数极显著降低,而花青素含量极显著增加,且花青素含量随着氮素浓度增加呈负相关关系(R^(2)=0.96)。由此表明,木薯品种Arg7无菌幼苗植株中花青素的诱导表达只与氮素浓度有关,而与氮素形态无关。

In order to clarify the relationship between the nitrogen and the anthocyanin in cassava,we studied the agronomic traits and the inductions of anthocyanin synthesis-related genes and anthocyanin accumulation differences of cassava Arg7 sterile seedlings growing in the modified MS media for 40 d with 1)40 mmol/L NO_(3)^(-)+20 mmol/L NH_(4)^(+),2)40 mmol/L NO_(3)^(-),3)20 mmol/L NH_(4)^(+),4)0.4 mmol/L NO_(3)^(-)+0.2 mmol/L NH_(4)^(+),5)0.4 mmol/L NO_(3)^(-),6)0.2 mmol/L NH_(4)^(+),7)1 mmol/L(N),8)5 mmol/L(N),9)9 mmol/L(N),and 10)13 mmol/L(N),based on the previous research results of that nitrogen deficiency accelerates anthocyanin synthesis and accumulation in Arabidopsisetc.Results showed that no anthocyanin was observed in the seedlings of cassava variety Arg7 in any of the three modified MS media containing 40 mmol/L NO_(3)^(-)alone,20 mmol/L NH_(4)^(+)alone or their combination for 40 d.Compared to cassava seedlings in the combination of 40 mmol/L NO_(3)^(-)and 20 mmol/L NH_(4)^(+),the plant height and length of primary roots under 40 mmol/L NO_(3)^(-)alone treatment were not significantly different,but the number of primary roots was significantly reduced.And the plant height,the length and number of primary roots of the seedlings in media with 20 mmol/L NH_(4)^(+)were significantly inhibited.The anthocyanins accumulated significantly in the stem and petiole of seedlings in any of three MS media supplemented with 0.4 mmol/L NH_(4)^(+),0.2 mmol/L NH_(4)^(+),or combination of 0.4 mmol/L NO_(3)^(-)and 0.2 mmol/L NH_(4)^(+)for 40 d,as well as genes related to anthocyanin synthesis were induced to be expressed.Compared to the combination of 40 mmol/L NO_(3)^(-)and 20 mmol/L NH_(4)^(+),the plant height,the lengths and the number of primary roots under MS media with 0.4 mmol/L NO_(3)^(-),0.2 mmol/L NH_(4)^(+),or combination of 0.4 mmol/L NO_(3)^(-),and 0.2 mmol/L NH_(4)^(+)significantly decreased,but the anthocyanin content significantly increased.Furthermore,there was a negative correlation between anthocyanin content and nitrogen concentration(R^(2)=0.96).This indicates that the induced expression of anthocyanins in cassava Arg7 seedlings was only related to nitrogen concentration,but not to the form.