目的 研究外源蔗糖对盐胁迫甘草Glycyrrhiza uralensis幼苗根系生长的缓解效应。方法 以甘草幼苗为实验材料,测定不同浓度的外源蔗糖处理下对盐胁迫条件下甘草幼苗生长、有效成分量、可溶性糖量、脯氨酸量及酶活性的影响及测定相关指标,数据采用SPSS 19.0软件分析。结果 在盐胁迫条件下,添加一定浓度的外源蔗糖后,甘草幼苗的日相对生长率呈升高趋势;总黄酮量和苯丙氨酸解氨酶(PAL)活性呈极显著升高,外源蔗糖对盐胁迫下甘草幼苗根系生长的缓解作用在很大程度上与PAL活性的增强所引起的黄酮量的增加有关,外源蔗糖的浓度为10 mmol/L时,PAL的活性达到最大,当外源蔗糖的浓度为15 mmol/L时,PAL的活性又成下降趋势;在施加不同浓度的外源蔗糖后甘草酸量比在盐胁迫条件下高,达到未受盐胁迫时的水平,外源蔗糖的浓度梯度对甘草酸积累的影响不明显。脯氨酸和可溶性糖量的变化呈现出相关性,两者皆在施加15 mmol/L的外源蔗糖时达到对照水平,当外源蔗糖的浓度在此基础上增加时,甘草幼苗体内的可溶性糖和脯氨酸的量又呈现上升趋势。超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性与未经盐胁迫处理的幼苗相比,盐胁迫下幼苗中的SOD及CAT活性均上调,一定浓度的外源蔗糖可降低盐胁迫幼苗中的SOD及CAT活性。结论 外源蔗糖可提高甘草幼苗体内抗氧化酶的活性,从而维持了幼苗体内较低的活性氧水平,降低了细胞受过氧化伤害的程度,提高了甘草幼苗对盐胁迫的耐受性。

Objective To explore the mitigation effect of exogenous sucrose on the root growth of licorice (Glycyrrhiza uralensis) seedlings under salt stress conditions. Methods Licorice seedlings were taken as experimental materials, an experiment was conducted to study the effects of exogenous sucrose at different concentration on the growth and content of active ingredients, soluble sugar, proline, and activity of enzyme in licorice seedlings under NaCl stress conditions; Then to determine related indicators and analyze data by using the software SPSS 19.0. Results This study showed that: Under salt stress conditions, after adding a certain concentration of exogenous sucrose, the relative growth rate of licorice seedlings per day was increasing, and this stress could be a significantly weakening effect, indicating that exogenous sucrose had salt stress-relieving effect. The total flavonoids and phenylalanine ammonia lyase (PAL) activity were significantly increased, the exogenous sucrose could mitigate the seedling roots under the salt stress, the licorice flavonoid content in the enhanced growth was largely, due to the activity of PAL, increased, when the concentration of exogenous sucrose was 10 mmol/L, PAL activity reaching a maximum; While the concentration of exogenous sucrose was 15 mmol/L, PAL activity turned into a downward trend, the results indicating that this mitigation had the effect depended on the concentration. After applying exogenous sucrose at different concentration, the content of licorice acid was higher than that under salt stress and reached the level without salt stress; The impact of exogenous sucrose at gradient concentration on licorice acid accumulation was not obvious. The content changes of proline and soluble sugar showed the correlation between the two. When 15 mmol/L of exogenous sucrose was applied both of them reached the controlled level; While the concentration of exogenous sucrose increasing on this basis, the contents of soluble sugar and proline in licorice seedlings were also on the rise. Compared with seedlings without salt stress treatment, the SOD and CAT activity in seedlings under the salt stress was increased; Certain concentration of exogenous sucrose could reduce the activity of SOD and CAT in seedlings under the salt stress. Conclusion The exogenous sucrose may increase the activity of antioxidant enzymes in licorice seedlings, thereby maintaining a low level of reactive oxygen species in seedlings, and reducing the hurting degree of peroxide to cell, and improving the tolerance of licorice seedlings to the salt stress.

甘肃农业大学盛彤笙科技创新基金(GSAU-STS-1429)