Effects of hexachlorocyclohexane on rhizosphere fungal propagules and root colonization by arbuscular mycorrhizal fungi in Plantago lanceolata

Abstract

SummaryLindane (-hexachlorocyclohexane or -HCH) is an organochlorine insecticide previously used extensively for the control of agricultural pests. We studied the effects of soil HCH contamination on vegetation and its associated arbuscular mycorrhizas (AM). The polluted and unpolluted plots had similar plant cover, with the same species richness and abundance. Plantago lanceolata plants were selected for mycorrhizal analysis because of their presence in both plots and known mycotrophy. The presence of HCH appeared to have no significant effect on the extent of colonization of Plantago roots by AM, suggesting a similar functionality of the fungal symbionts. However, infective AM propagules, the density of AM spores and viable AM hyphae in the rhizosphere were much less in the HCH-polluted soil than in the unpolluted plot. Pre-inoculation of four plant species with an isolate of Glomus deserticola obtained from the HCH-contaminated soil resulted in increased growth and fungal colonization of roots compared with plants pre-inoculated with the introduced fungus G. macrocarpum or colonized by the consortium of indigenous AM fungal species, when those plants were transplanted to an HCHcontaminated soil. This suggests that the fungus increases the tolerance of plants to the toxic soil environment. We conclude that herbaceous and woody plants can grow in soil with little P contaminated with <100 mg HCH kg À1 with the help of tolerant AM, despite the detrimental effect of HCH on AM fungal propagules in soil. The effects of AM fungi on plant growth and soil microbial community structure in HCH-polluted sites could be important for remediation of the pollutant through the microbial activity in the rhizosphere.

Insights Into the Biodegradation of Lindane (γ-Hexachlorocyclohexane) Using a Microbial System

“…Therefore, plant-microbe-associated bioremediation techniques were reported as cost-efficient and eco-friendly methods of cleaning polluted sites. Sainz et al (2010) investigated the effects of lindane pollution on vegetables and the associated arbuscular mycorrhiza. Their research indicated that the fungus increases the plant's tolerance toward the toxic effects of soil conditions.…”

Effects of Bifenthrin on Mycorrhizal Colonization and Growth of Corn

“…The question remains as to why mycorrhizal colonization increased the dry weight of the mycorrhizal plants grown with 15 and 25 ppm of bifenthrin and helped to overcome the potential negative effects caused by bifenthrin on the growth of nonmycorrhizal plants. Other studies have also shown that mycorrhizal colonization reduced the phytotoxic effects of some pesticides (e.g., Sainz et al, 2006). However, the complex interactions of insecticides and mycorrhizal colonization on plant growth deserve further investigation because insecticides and AM fungi are also known to alter soil microbial communities and plant nutrient availability (Azcó n-Aguilar and Barea, 1997; Das and Mukherjee, 2000).…”

“…While several chemicals inhibit the development of mycorrhizal associations, others do not affect the symbiosis, and the use of certain pesticides even stimulate root colonization by AM fungi and increase their sporulation (Menge, 1982;Trappe et al, 1984). In some cases, contradictory results have been obtained with the same chemical products because the effects of pesticides on mycorrhizal colonization are influenced by the combination of plant species, AM fungi species, pesticide, and dose of application (Sainz et al, 2006;Schweiger and Jakobsen, 1998). Therefore, in horticultural management practices that include the use of AM fungi, it is important to assess the impact of pesticides on the mycorrhizal association.…”

Bacterial Bio-Resources for Remediation of Hexachlorocyclohexane

“…For instance, mycorrhizal fungi form symbioses with a broad range of plant species and can contribute to plant growth and survival by reducing stresses associated with toxic wastes. The effects of soil HCH contamination on vegetation and its associated arbuscular mycorrhizas was investigated by Sáinz et al [127]. The authors found that a preinoculation of four plant species with an isolate of Glomus deserticola obtained from the HCH-contaminated soil resulted in increased growth and fungal colonization of roots, suggesting that the fungus increases the tolerance of plants to the toxic soil environment.…”