Soil and Water Science Department, University of Florida, Gainesville, Fl 32611-0290, USA.
Environ Pollut. 2009 Aug-Sep;157(8-9):2300-5. doi: 10.1016/j.envpol.2009.03.036. Epub 2009 Apr 29.
This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of four-month old Pteris vittata (arsenic - hyperaccumulator) and Pteris ensiformis (non-arsenic-hyperaccumulator) plants. The arsenic treatments (0, 150, and 300 microM as sodium arsenate) in hydroponics had adverse effects on the root and frond dry weights, and this effect was more evident in P. ensiformis than in P. vittata. Nitrate reductase and nitrite reductase activities of arsenate-treated plants were reduced more in P. ensiformis than in P. vittata. This effect was accompanied by similar decreases in tissue NO(3)(-) concentrations. Therefore, this decrease is interpreted as being indirect, i.e., the consequence of the reduced NO(3)(-) uptake and translocation in the plants. The study shows the difference in the tolerance level of the two Pteris species with varying sensitivity to arsenic.
本研究调查了砷对四个月大的凤尾蕨（砷超富集植物）和井边凤尾蕨（非砷超富集植物）的根、根茎和叶片中硝酸盐代谢相关酶（硝酸还原酶和亚硝酸还原酶）的体外活性的影响。水培中的砷处理（0、150 和 300 μM 作为砷酸钠）对根和叶片干重有不良影响，这种影响在井边凤尾蕨中比在凤尾蕨中更为明显。砷酸盐处理植物的硝酸还原酶和亚硝酸还原酶活性在井边凤尾蕨中比在凤尾蕨中降低得更多。这一效应伴随着组织中 NO3-浓度的相似下降。因此，这种下降被解释为间接的，即植物中 NO3-吸收和转运减少的结果。研究表明，两种凤尾蕨物种的耐受水平存在差异，对砷的敏感性也不同。
