Laboratorio de Alelopatía, Departamento de Ecología Funcional, Instituto de Ecología, UNAM, Circuito Exterior s/n anexo al Jardín Botánico Exterior, Ciudad Universitaria, Delegación Coyoacán, C.P. 04510, México D.F., México.
Physiol Plant. 2012 Feb;144(2):134-45. doi: 10.1111/j.1399-3054.2011.01527.x. Epub 2011 Nov 21.
In acidic soils, an excess of Al³⁺ is toxic to most plants. The Melastomataceae family includes Al-accumulator genera that tolerate high Al³⁺ by accumulating it in their tissues. Conostegia xalapensis is a common shrub in Mexico and Central America colonizing mainly disturbed areas. Here, we determined whether C. xalapensis is an Al accumulator, and whether it has internal tolerance mechanisms to Al. Soil samples collected from two pastures in the state of Veracruz, Mexico, had low pH and high Al³⁺ concentrations along with low Ca²⁺ levels. Leaves of C. xalapensis from pastures showed up to 19,000 mg Al kg⁻¹ DW (dry weight). In laboratory experiments, 8-month-old seedlings treated with 0.5 and 1.0 mM AlCl₃ for 24 days showed higher number of lateral roots and biomass. Pyrocatechol violet and hematoxylin staining evidenced that Al localized in epidermis and mesophyll cells in leaves and in epidermis and vascular pith in roots. Scanning electron microscope-energy dispersive X-ray microanalysis of Al-treated leaves corroborated that Al is in abaxial and adaxial epidermis and in mesophyll cells (31.2%) in 1.0 mM Al-treatment. Roots of Al-treated plants had glutathione reductase (EC 1.6.4.2) and superoxide dismutase (EC 1.15.1.1) activity higher, and low levels of O₂*⁻ and H₂O₂. C. xalapensis is an Al-accumulator plant that can grow in acidic soils with higher Al³⁺ concentrations, and can be considered as an indicator species for soils with potential Al toxicity.
在酸性土壤中，过量的 Al³⁺ 对大多数植物是有毒的。野牡丹科包含一些能够耐受高浓度 Al³⁺的 Al 积累属，这些属通过将 Al 积累在组织中来耐受高浓度 Al³⁺。Conostegia xalapensis 是墨西哥和中美洲常见的灌木，主要在受干扰的地区生长。在这里，我们确定 C. xalapensis 是否是 Al 的积累者，以及它是否具有对 Al 的内部耐受机制。从墨西哥韦拉克鲁斯州的两个牧场采集的土壤样本 pH 值低，Al³⁺浓度高，Ca²⁺水平低。来自牧场的 C. xalapensis 的叶子显示出高达 19,000 mg Al kg⁻¹ DW（干重）。在实验室实验中，用 0.5 和 1.0 mM AlCl₃ 处理 8 个月大的幼苗 24 天，显示出更多的侧根和生物量。邻苯二酚紫和苏木精染色表明 Al 定位于叶片的表皮和叶肉细胞以及根的表皮和维管束髓。用 Al 处理的叶片的扫描电子显微镜-能量色散 X 射线微分析证实，Al 存在于 1.0 mM Al 处理的叶片的下表皮和上表皮以及叶肉细胞（31.2%）中。用 Al 处理的植物的根具有更高的谷胱甘肽还原酶（EC 1.6.4.2）和超氧化物歧化酶（EC 1.15.1.1）活性，以及较低水平的 O₂*⁻和 H₂O₂。C. xalapensis 是一种能够在高 Al³⁺浓度的酸性土壤中生长的 Al 积累植物，可被视为具有潜在 Al 毒性的土壤的指示物种。
