Departamento Biologia Vegetal, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas, 13083-970 Campinas, SP, Brazil.
Sci Total Environ. 2010 Oct 15;408(22):5381-91. doi: 10.1016/j.scitotenv.2010.07.064. Epub 2010 Aug 15.
Studies on mycorrhizal symbiosis effects on metal accumulation and plant tolerance are not common in perennial crops under metal stress. The objective of this study was to evaluate the influence of mycorrhization on coffee seedlings under Cu and Zn stress. Copper (Cu) and zinc (Zn) uptake and some biochemical and physiological traits were studied in thirty-week old Coffea arabica seedlings, in response to the inoculation with arbuscular mycorrhizal fungi (AMF) and to increasing concentrations of Cu or Zn in soil. The experiments were conducted under greenhouse conditions in a 2×4 factorial design (inoculation or not with AMF and 0, 50, 150 and 450mgkg(-1) Cu or 0, 100, 300 and 900mgkg(-1) Zn). Non-mycorrhizal plants maintained a hampered and slow growth even in a soil with appropriate phosphorus (P) levels for this crop. As metal levels increased in soil, a greater proportion of the total absorbed metals were retained by roots. Foliar Cu concentrations increased only in non-mycorrhizal plants, reaching a maximum concentration of 30mgkg(-1) at the highest Cu in soil. Mycorrhization prevented the accumulation of Cu in leaves, and mycorrhizal plants showed higher Cu contents in stems, which indicated a differential Cu distribution in AMF-associated or non-associated plants. Zn distribution and concentrations in different plant organs followed a similar pattern independently of mycorrhization. In mycorrhizal plants, only the highest metal concentrations caused a reduction in biomass, leading to significant changes in some biochemical indicators, such as malondialdehyde, proline and amino acid contents in leaves and also in foliar free amino acid composition. Marked differences in these physiological traits were also found due to mycorrhization. In conclusion, AMF protected coffee seedlings against metal toxicity.
在金属胁迫下，多年生作物的菌根共生对金属积累和植物耐性的影响研究并不常见。本研究的目的是评估菌根化对铜（Cu）和锌（Zn）胁迫下咖啡幼苗的影响。在温室条件下，采用 2×4 因子设计（接种或不接种丛枝菌根真菌（AMF）以及土壤中 0、50、150 和 450mgkg（-1）Cu 或 0、100、300 和 900mgkg（-1）Zn），研究了 30 周龄阿拉比卡咖啡幼苗对 Cu 和 Zn 的吸收以及一些生化和生理特性。非菌根化植物即使在适合该作物的磷（P）水平的土壤中，生长也受到阻碍且缓慢。随着土壤中金属水平的升高，根系保留的总吸收金属的比例增加。叶面 Cu 浓度仅在非菌根化植物中增加，在土壤中 Cu 最高时达到 30mgkg（-1）的最大值。菌根化防止了 Cu 在叶片中的积累，并且菌根化植物的茎中 Cu 含量较高，这表明 AMF 相关或非相关植物中 Cu 分布存在差异。不同植物器官中 Zn 的分布和浓度模式相似，与菌根化无关。在菌根化植物中，只有最高的金属浓度导致生物量减少，从而导致叶片中丙二醛、脯氨酸和氨基酸含量以及叶片中游离氨基酸组成等一些生化指标发生显著变化。由于菌根化，这些生理特性也存在明显差异。总之，AMF 保护咖啡幼苗免受金属毒性的影响。
