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水杨酸在白桦苗期抵御盐碱胁迫中的调控作用

Regulation of Salicylic Acid on Tolerance to Saline Alkali Stress at Seedling Stages of Betula platyphylla

    摘要
  • 摘要: 为探究盐碱胁迫下外施水杨酸（SA）对白桦（Betula platyphylla）苗生长及次生产物合成的影响，以白桦幼苗为材料，分别施加3种处理：清水处理（对照），200 mmol·L-1 NaHCO3,200 mmol·L-1 NaHCO3+360μmol·L-1 SA，检测不同处理条件下的白桦苗中部叶片相对电导率、叶绿素荧光参数、渗透物质含量、抗氧化酶活性和三萜合成途径关键基因的相对表达量，同时检测白桦苗总三萜、黄酮和多酚含量变化。结果表明：（1）在200 mmol·L-1NaHCO3胁迫下，再进行360μmol·L-1 SA处理能够显著降低白桦苗叶片的相对电导率，提高叶绿素荧光参数Fv/Fm，增加脯氨酸、可溶性蛋白含量，一定程度上增强白桦苗抗氧化酶（SOD、POD、CAT、APX）活性。（2）200 mmol·L-1NaHCO3盐碱胁迫促进了白桦苗三萜合成途径关键基因FPS、SS、SE、BPX、BPW的表达上调，并在胁迫前期显著促进了白桦苗多酚的合成（P<0.05），在胁迫后期显著促进了总三萜、黄酮物质的积累（P<0.05）。盐碱胁迫下外施SA信号促使白桦苗HMGR、FPS、SE、BPX基因表达上调较为显著，并在胁迫前期促进了黄酮的合成；在胁迫后期SA显著促进了总三萜的积累，第7天比盐碱胁迫组含量提高34%，比清水处理组提高47%。综合来看，盐碱胁迫下，适宜浓度的SA能够通过调节白桦幼苗渗透平衡、缓解光抑制、增强抗氧化防御系统、调控物质代谢等方式提高白桦幼苗的耐盐碱特性。

     

    Abstract: To investigate the effects of salicylic acid（SA） on growth and secondary production synthesis of Betula platyphylla seedling under saline alkali stress,three treatments were applied to birch seedlings:water treatment（control）,200 mmol·L-1 NaHCO3,200 mmol·L-1 NaHCO3+360μmol·L-1 SA.The relative conductivity,chlorophyll fluorescence parameters,osmotic content,anti-stress enzyme activity,the relative expression of key genes of triterpene synthesis pathway in the middle leaves of birch seedlings in response to different treatments were detected respectively,and the total triterpenoids,flavonoids and polyphenols of birch seedlings were analyzed.The results showed that:（1） under the 200 mmol·L-1 NaHCO3 treatment,then 360μmol·L-1 SA treatment significantly reduced the relative conductivity of the leaves of birch seedlings,improved the Fv/Fm value of chlorophyll fluorescence parameters of birch seedlings,increased the content of the osmotic regulator proline and soluble protein,and enhanced the activities of antioxidant enzymes（SOD,POD,CAT,APX） in birch seedlings to a certain extent.（2） 200 mmol·L-1 NaHCO3 saline alkali stress promoted the upregulation of the expression of key genes of triterpene synthesis pathway FPS,SS,SE,BPX and BPW in birch seedlings,and significantly promoted the synthesis of polyphenols in birch seedlings in the early stage,and significantly promoted the accumulation of total triterpenoids and flavonoids in the late stage of saline-alkali stress（P＜0.05）.The application of SA under saline-alkali stress promoted the upregulation of HMGR,FPS,SE,and BPX gene expression in birch seedlings,and promoted the synthesis of flavonoids in the early stage of stress,and significantly promoted the accumulation of total triterpenes in the late stage of stress,which was 34% higher than that of the saline-alkali stress group and 47% higher than that of the water treatment on 7th day.Overall,under saline-alkali stress,SA with suitable concentration improves the tolerance to saline-alkali of birch seedlings by adjusting osmotic equilibrium,alleviating light inhibition,enhancing the antioxidant defense system of birch seedlings,and regulating substance metabolism.

     

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