PDF《莳萝蒿适应盐渍环境的 Na + 区域化方式和生理特征》

1 College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China

2 School of Biochemical and Environmental Engineering, Nanjing Xiaozhuang University, Nanjing, Jiangsu 211171, China Abstract: Artemisia anethifolia (Compositae) is a halophyte that is widely distributed in northern areas of China. Studying the mechanisms by which this plant adapts to high levels of salt will increase our understanding of salt adaptation in vascular plants. A. anethifolia plants were treated with 0, 100, 200, 300, and

400 mmol / L NaCl for

7 d, respectively. Then, the differences in growth and physiology were compared between salt鄄treated and control A. anethifolia plants. In particular, the Na + accumulation levels and Na + compartmentation patterns in A. anethifolia plants were analyzed in detail. Although the http:/ / www.ecologica.cn A. anethifolia plants were able to survive under

400 mmol / L NaCl, salt鄄treated plants showed lower fresh weight as the NaCl concentration increased, indicating that plant growth was inhibited by salt. The leaves of A. anethifolia showed an increased capacity for osmotic adjustment but a decreased degree of leaf succulence with increasing NaCl concentrations. Photosynthetic analyses showed that there was a gradual decline in net photosynthetic rate and stomatal conductance of salt鄄treated leaves with increasing NaCl concentrations. However, the maximal efficiency of photosystem II photochemistry (Fv / Fm ) in A. anethifolia leaves was not inhibited by salt, and the chlorophyll content even increased with increasing salt concentrations. These observations suggested that the decreased photosynthetic rate was due to stomatal factors, rather than damage to the components of the photosynthetic machinery. The Na + content in A. anethifolia plants tended to increase with increasing salt concentrations. The Na + content in leaves, stems, and roots of A. anethifolia was 321.4, 242.1, and 182.3 滋mol / g FW, respectively, in the

400 mmol / L NaCl treatment. More than 70% of the Na + absorbed by salt鄄treated A. anethifolia plants accumulated in their leaves, and approximately 98% of the Na + that accumulated in leaves was localized in leaf protoplasts. The average Na + concentration in protoplasts of A. anethifolia leaf tissue was 1.2―1.8 times that in the apoplast. These results indicate that efficient Na + compartmentation occurred in A. anethifolia leaf cells. The V鄄H+鄄ATPase proton pump activity of salt鄄treated leaves was 30%―50% higher than that of control leaves, and the tonoplast Na + / H + antiporter activity of salt鄄treated leaves was 4―7 times that in leaves of control plants. These findings suggested that A. anethifolia plants have a strong ability to compartmentalize Na + in the vacuole. As the concentrations of salt increased, the Na + distribution ratio in leaves decreased. Likewise, the range of increased V鄄H + 鄄ATPase proton pump activity and tonoplast Na + / H + antiporter activity decreased as the salt concentration increased. Na + compartmentation plays an important role in the salt tolerance of A. anethifolia plants, because it protects their photosystems and results in lower osmotic potential in the leaf cells. However, Na + compartmentation could not prevent the decrease in the degree of leaf succulence and the photosynthetic activity of A. anethifolia leaves under highly saline conditions, and so their growth was inhibited by salt. These results suggest that Na + compartmentation is necessary but not sufficient for adaptation of A. anethifolia to a saline environment. Key Words: Artemisiaanethifolia;