%0 Journal Article
%A Chaokui NIU
%A Chenjing SHEN
%A Jing YIN
%A Jingzhe WANG
%A Xinyuan LIANG
%T Regulation of Salicylic Acid on Tolerance to Saline Alkali Stress at Seedling Stages of <i>Betula platyphylla</i>
%D 2023
%R 10.7525/j.issn.1673-5102.2023.03.007
%J Bulletin of Botanical Research
%P 379-387
%V 43
%N 3
%X <p>To investigate the effects of salicylic acid（SA） on growth and secondary production synthesis of <i>Betula platyphylla</i> seedling under saline alkali stress， three treatments were applied to birch seedlings： water treatment（control）， 200 mmol·L<sup>-1</sup> NaHCO<sub>3</sub>， 200 mmol·L<sup>-1</sup> NaHCO<sub>3</sub>+360 μmol·L<sup>-1</sup> 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： ①under the 200 mmol·L<sup>-1</sup> NaHCO<sub>3</sub> treatment， then 360 μmol·L<sup>-1</sup> SA treatment significantly reduced the relative conductivity of the leaves of birch seedlings， improved the <i>F</i><sub>v</sub>/<i>F</i><sub>m</sub> 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. ②200 mmol·L<sup>-1</sup> NaHCO<sub>3</sub> saline alkali stress promoted the upregulation of the expression of key genes of triterpene synthesis pathway <i>FPS</i>， <i>SS</i>， <i>SE</i>， <i>BPX</i> and <i>BPW</i> 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（<i>P</i>&lt;0.05）. The application of SA under saline-alkali stress promoted the upregulation of <i>HMGR</i>， <i>FPS</i>， <i>SE</i>， and <i>BPX</i> 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 7<sup>th</sup> 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.</p>
%U https://bbr.nefu.edu.cn/EN/10.7525/j.issn.1673-5102.2023.03.007