关键词: 水稻, 盐碱胁迫, 根系形态, 生理特性, 基因表达

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