Mateos-Naranjo E, Redondo-Gómez S, Cambrollé J, Luque T, Figueroa M E
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Avenida Reina de Mercedes s/n, Seville, Spain.
Plant Biol (Stuttg). 2008 Nov;10(6):754-62. doi: 10.1111/j.1438-8677.2008.00098.x.
Spartina densiflora Brongn. is found in coastal marshes of southwest Spain, growing over sediments containing 100-4800 ppm Zn. A glasshouse experiment was designed to investigate the effect of Zn from 0 to 100 mmol.l(-1) on the growth and photosynthetic apparatus of S. densiflora, by measuring relative growth rate, leaf elongation rate, number of tillers, height of tillers, chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. We also determined total ash, Zn, calcium, magnesium and phosphorus concentrations, and the C/N ratio. At 100 mmol.l(-1) Zn, S. densiflora showed a 48% biomass reduction after 1 month of treatment. Long-term effects of Zn on growth of S. densiflora consisted mainly of variations in net photosynthesis. Modification of the Zn/Mg ratio was linked to a strong decrease in RuBP carboxylase (Zn was favoured in local competition with Mg, so that the affinity of RuBisCO for CO(2) decreased), oxygenase activity of RuBisCO acting as a substitute for the photosynthetic function. Also, Zn had a marked overall effect on the photochemical (PSII) apparatus and the synthesis of photosynthetic pigments. However, the results indicate that S. densiflora is capable of tolerating very high and continued exposure to Zn, as this species lowers the translocation of Zn from the nutrient solution to roots and controls Zn ion transport into leaves. Therefore, S. densiflora could be useful in the phytostabilization of soils.
密花米草生长在西班牙西南部的沿海沼泽地，生长于锌含量为100 - 4800 ppm的沉积物上。设计了一个温室实验，通过测量相对生长速率、叶片伸长率、分蘖数、分蘖高度、叶绿素荧光参数、气体交换和光合色素浓度，研究0至100 mmol·l⁻¹的锌对密花米草生长和光合器官的影响。我们还测定了总灰分、锌、钙、镁和磷的浓度以及碳氮比。在100 mmol·l⁻¹锌处理下，密花米草在处理1个月后生物量减少了48%。锌对密花米草生长的长期影响主要表现为净光合作用的变化。锌/镁比例的改变与核酮糖-1,5-二磷酸羧化酶的显著降低有关（锌在与镁的局部竞争中占优势，导致核酮糖-1,5-二磷酸羧化酶对二氧化碳的亲和力下降），核酮糖-1,5-二磷酸羧化酶的加氧酶活性起到了替代光合功能的作用。此外，锌对光化学（PSII）装置和光合色素的合成有显著的总体影响。然而，结果表明密花米草能够耐受非常高且持续的锌暴露，因为该物种降低了锌从营养液向根部的转运，并控制锌离子向叶片的运输。因此，密花米草可用于土壤的植物稳定修复。
