海岛棉苗期盐胁迫下形态学和生理学指标变化

【目的】在300 mmol·L-1 Na Cl胁迫下,观察并测定海岛棉耐盐性强的品系越海9号和耐盐性弱的品系PS-7叶片、茎细胞解剖结构和生理学指标,从形态学和生理学两个水平研究海岛棉苗期响应盐胁迫的应答机制,为棉花耐盐材料的筛选提供理论依据和技术方案。【方法】采用水培方法,待棉苗生长至3叶期时,开始进行300 mmol·L-1 Na Cl胁迫处理。运用光学显微技术及生理学指标测定法,在不同Na Cl胁迫处理时间下,对海岛棉耐盐性强的品系越海9号和耐盐性弱的品系PS-7进行形态学观察及生理学指标分析。【结果】2份海岛棉材料对Na Cl胁迫的反应不同。随着300 mmol·L-1 Na Cl处理时间的延长,与对照相比,越海9号和PS-7的叶片和茎的横切面面积均显著变小,处理24 h时,分别变小14.10%、54.69%与45.30%、87.90%,PS-7的变化幅度大于越海9号;处理12 h时,PS-7维管束中木质部已经损害严重,越海9号维管束中木质部则没有明显变化;PS-7的栅栏组织细胞在处理24 h时由长圆柱形变为卵圆形,越海9号的栅栏组织细胞的形状则没有变化。生理学研究表明,越海9号叶片中的叶绿素含量、超氧化物歧化酶和过氧化物酶活性在整个处理过程中均高于PS-7,而其丙二醛含量却明显低于PS-7;在300 mmol·L-1 Na Cl处理8 h时,越海9号和PS-7中的丙二醛含量、叶绿素含量、超氧化物歧化酶和过氧化物酶活性均达到了显著性差异。【结论】叶片中栅栏组织和茎中木质部可能是海岛棉响应盐胁迫的最敏感部分,叶绿素、丙二醛、超氧化物歧化酶和过氧化物酶可作为鉴定耐盐棉花材料的生理学指标。

Morphological and Physiological Mechanism of Salt Tolerance in Gossypium barbadense to Salt Stress at Seedling Stage

【Objective】The changes of cell structures and physiological characteristics in leaves and stems of two Gossypium barbadense varieties, Yuehai 9 (salt tolerance) and PS-7 (salt sensitive), were investigated under different salt stress conditions. Morphological and physiological mechanism of salt tolerance in Gossypium barbadense to salt stress at seedling stage was studied to offer a theoretical basis and technical reference for selecting salt-tolerant genes in cotton cultivars. 【Method】In a water culture experiment, three-leaf cotton seedlings were treated with NaCl at 300 mmol·L^-1 NaCl for different times. This study involved observation of morphological features and comparison of physiological indexes of two Gossypium barbadense, Yuehai 9 (salt tolerance) and PS-7 (salt sensitive) under different salt stress treatments by means of optical microscopy and measurement of physiological indices.【Result】There was a difference in effect on two cotton cultivars by salt stress. At 300 mmol·L^-1 of NaCl, with the prolongation of treatment period, the transections of the leaves and stems of Yuehai 9 and PS-7 were both significantly smaller compared with the control groups, decreased, respectively, by 14.10%, 54.69% and 45.30%, 87.90% at 300 mmol·L^-1 of NaCl after 24 h, and the variation range of PS-7 was larger than that of Yuehai 9. The xylem of the vascular bundle of PS-7 was severely damaged while the xylem of the vascular bundle of Yuehai 9 showed no significant change in 300 mmol·L^-1 of NaCl treatment for 12 h. The long cylindrical palisade tissue cell of PS-7 became smaller and ovoid in 300 mmol·L^-1 of NaCl treatment after 24 h while the shape of the palisade tissue cell of Yuehai 9 showed no change. The chlorophyll contents, superoxide dismutase and peroxidase activities in leaves of Yuehai 9 were significantly higher than those of PS-7, while its malondialdehyde contents was lower than that of PS-7. Yuehai 9 and PS-7 were different in chlorophyll contents, malondialdehyde contents, superoxide dismutase and peroxidase activities, and the differences reached a significant level at 300 mmol·L^-1 of NaCl after 8 h. 【Conclusion】 The most sensitive plant part to salt stress may be the palisade tissues of leaves and xylem in the stem. The chlorophyll, malondialdehyde, superoxide dismutase and peroxidase can be used as the physiological indexes for evaluating and selecting salt tolerance cotton materials.