NaHCO_3胁迫下星星草根中Ca~(2+)与Ca~(2+)-ATPase的超微细胞化学定位

利用焦锑酸盐和磷酸铅沉淀技术分别对NaHCO3胁迫条件下星星草(Puccinellia tenuiflora)根中Ca2+和Ca2+-ATPase进行超微细胞化学定位研究,旨在进一步探讨Ca2+在NaHCO3胁迫诱导胞内信号转导过程中的作用,以及Ca2+-ATPase活性定位变化与NaHCO3胁迫下星星草抗盐碱能力的关系。结果表明:在正常状态下,根毛区细胞质内Ca2+较少,主要位于质膜附近和液泡中,Ca2+-ATPase主要定位于质膜和液泡膜,有一定活性。在0.448%NaHCO3胁迫下,根毛区细胞质中Ca2+增多,液泡中Ca2+减少,且主要集中于液泡膜附近,质膜和液泡膜Ca2+-ATPase活性明显升高。在1.054%NaHCO3胁迫下,细胞质中分布的Ca2+增多,而液泡中Ca2+极少,Ca2+-ATPase活性也降低。以上结果表明,Ca2+亚细胞定位和Ca2+-ATPase活性变化在星星草响应NaHCO3胁迫的信号传递过程中具有重要作用。

Ultracytochemical Localization of Ca2+ and Ca2+-ATPase in the Root of Puccinellia tenuiflora Under NaHCO3 Stress

We aimed to further investigate the relationships between the localization of calcium and Ca²⁺-ATPase and the resistance capacity of Puccinellia tenuiflora against saline-alkali stress. We analyzed ultracytochemical localization of calcium and Ca²⁺-ATPase in the root of P. tenuiflora under NaHCO₃ stress by potassium pyroantimonate precipitation and a lead-phosphate precipitation technique, respectively. In the normal condition, calcium antimonate precipitation deposits were low in cytoplasm and mainly concentrated within the plasma membrane and vacuoles in the root hair zone. Ca²⁺-ATPase had a certain activity and mainly localized in the plasma membrane and tonoplasts. Moreover, under 0.448% NaHCO₃ stress, the distribution of Ca²⁺ precipitation particles increased in the cytoplasm, decreased in the vacuole, and mainly concentrated near tonoplasts. Meanwhile, the activity of Ca²⁺-ATPase was significantly increased in the plasma membrane and tonoplasts. Furthermore, under 1.054% NaHCO₃, Ca²⁺ precipitation particles continued to increase in the cytoplasm but were absent in the vacuole. The activity of Ca²⁺-ATPase was also reduced. All these results highlight that the changes in Ca2+ localization and Ca²⁺-ATPase activity play important roles in P. tenuiflora resistance to saline-alkali stress.