Abstract: The effects of saline‑alkali mixed stress（saline‑alkali concentration of 100 mmol/L with Na₂SO₄‑NaHCO₃‑NaCl ratio of 1∶2∶1，pH 8.41）on the root growth，physiological characteristics and expression levels of saline‑alkali tolerance related genes of rice seedlings were studied with Ningjing 52 and Chen 2 as materials，and the differences in the response of different types of rice roots to saline‑alkali stress were revealed from the physiological and molecular levels. The results showed that there was no obvious difference in most root morphological indexes，physiological indexes and the expression level of saline‑alkali tolerance related genes between the two types of rice under normal condition.Under saline‑alkali stress，the total root length of Ningjing 52 significantly reduced by 26.40% compared with Chen 2，but the total root surface area and root volume significantly increased by 18.17% and 21.72%，respectively.The root activity，total root absorption area，peroxidase（POD）and catalase（CAT）activities of Ningjing 52 significantly increased by 31.95%，34.49%，16.95% and 41.67%，respectively，compared with Chen 2，while the contents of malondialdehyde（MDA）and hydrogen peroxide（H₂O₂）significantly reduced by 13.85% and 24.63%，respectively.The expression levels of OsCATC，OsP5CS，OsSOS1 and SKC1 genes in the roots of Ningjing 52 were significantly higher than those of Chen 2 at 1 h under saline‑alkali stress，which were 16.15，1.54，20.34 and 9.73 times that of Chen 2，respectively.The expression levels of OsNIN3 and ALT1 genes were 2.35 and 4.53 times higher than those of Chen 2 at 3 h under saline‑alkali stress，respectively.Correlation analysis showed that the total root length of rice was significantly positively correlated with the total root surface area，and the activities of POD，CAT and free proline content of Ningjing 52 and Chen 2 were significantly positively correlated with the expression levels of OsNIN3 and SKC1 genes.The content of H₂O₂ in the roots of Ningjing 52 was significantly negatively correlated with the expression levels of OsP5CS and OsNIN3 genes，and the total volume，vigor and total absorption area of Chen 2 roots were significantly positively correlated with CAT activity and free proline content，respectively.In conclusion，compared with Chen 2，Ningjing 52 enhances tolerance to saline‑alkali stress by improving root structure，root vigor，antioxidant enzyme activity and expression levels of saline‑alkali tolerance related genes.

Key words: Rice, Saline?alkali stress, Root morphology, Physiological characteristics, Gene expression

摘要： 以宁粳52 和陈2 为试验材料，研究盐碱混合胁迫（盐碱浓度100 mmol/L，摩尔比为Na₂SO₄∶NaHCO₃∶NaCl=1∶2∶1，pH值8.41）对水稻幼苗根系生长、生理特性和耐盐碱相关基因表达量的影响，从生理与分子层面揭示不同类型水稻根系响应盐碱胁迫的差异。结果表明，正常条件下，2种类型水稻材料的大多数根系形态指标、生理指标和耐盐碱相关基因表达量均无明显差异。在盐碱胁迫下，宁粳52的根总长比陈2显著降低26.40%，但根总表面积和根总体积分别比陈2显著提高18.17%和21.72%。宁粳52的根系活力、根系总吸收面积、过氧化物酶（POD）和过氧化氢酶（CAT）活性分别比陈2显著提高31.95%、34.49%、16.95% 和41.67%，而丙二醛（MDA）和过氧化氢（H₂O₂）含量分别比陈2 显著降低13.85%和24.63%。宁粳52根系中OsCATC、OsP5CS、OsSOS1、SKC1基因表达量在盐碱胁迫1 h时明显高于陈2，分别是陈2的16.15、1.54、20.34、9.73倍；OsNIN3、ALT1基因表达量在胁迫3 h时分别是陈2的2.35、4.53倍。相关性分析结果表明，粳52和陈2的根总长与根总表面积均呈极显著正相关，POD活性、CAT活性和游离脯氨酸含量均与OsNIN3、SKC1的表达量呈显著正相关。宁粳52根系中H₂O₂ 含量与OsP5CS、OsNIN3的表达量均呈极显著负相关，陈2的根总体积、根系活力、根系总吸收面积均与CAT活性、游离脯氨酸含量呈显著正相关。综上，相较于陈2，宁粳52通过改善根系结构，提高根系活力、抗氧化酶活性和耐盐碱相关基因表达量来增强对盐碱胁迫的耐受性。

关键词: 水稻, 盐碱胁迫, 根系形态, 生理特性, 基因表达