Effects of Arbuscular Mycorrhizal Fungi on Metals Uptake, Physiological and Biochemical Response of Medicago Sativa L. with Increasing Zn and Cd Concentrations in Soil

The effect of mycorrhizal symbiosis on metal accumulation and plant tolerance are not commonly studied in medicinal plants under metal stress. The objective of this study was to assess the impact of mycorrhiza on alfalfa plants with the increase of Zn and Cd toxicity. The experiment was conducted under controlled laboratory conditions. Zinc (Zn) and cadmium (Cd) uptake, some biochemical and physiological parameters were studied in eight-week-old alfalfa plants in response to inoculation or not with arbuscular mycorrhizal fungi (AMF) and with the increase of Zn (0, 100, 300, 900 mg·kg-1) and Cd concentrations (0, 100, 300, 600 mg·kg-1) in soil. The results showed that mycorrhizal (M) plants exhibited tolerance to Zn and Cd up to 300 mg·kg-1 in comparison to non-mycorrhizal (NM) plants which exhibited a significant growth reduction at the same soil Zn and Cd level. M inoculation reduced the Zn and Cd accumulation in shoot and showed higher Zn and Cd contents in roots which showed a different Zn and Cd distribution in AMF associated or non-associated plants. Mycorrhizal plants increased phosphorus (P) contents at all Zn and Cd concentrations except the highest (600 and 900 mg·kg-1) leading significant alterations in biochemical contents such as proline, antioxidant enzymes in leaves and also in nutrients (N, P, K, Cu, Ni, Fe, Mn). Zn and cadmium toxicity cause to increase the proline content in shoot of NM plants, however, proline contents are lower in M plants. Results confirmed that AMF protected alfalfa plants against Zn and Cd toxicity. Mycorrhizal colonization was able to form an efficient symbiosis with alfalfa plants in moderately contaminated Zn and Cd soils (300 mg·kg-1) and play an important role in food quality and safety.

[1]  H. Alikhani,et al.  Influence of arbuscular mycorrhizal fungi and an improving growth bacterium on Cd uptake and maize growth in Cd-polluted soils , 2011 .

[2]  K. Turnau,et al.  The effect of mycorrhiza on the growth and elemental composition of Ni-hyperaccumulating plant Berkheya coddii Roessler. , 2011, Environmental pollution.

[3]  Sally E. Smith,et al.  Roles of arbuscular mycorrhizas in plant nutrition and growth: new paradigms from cellular to ecosystem scales. , 2011, Annual review of plant biology.

[4]  O. Alizadeh,et al.  Mycorrhizal Symbiosis , 1986, Forest Science.

[5]  Xi Xiao,et al.  Effects of the arbuscular mycorrhizal fungus Glomus mosseae on growth and metal uptake by four plant species in copper mine tailings. , 2007, Environmental pollution.

[6]  Xiaoke Wang,et al.  Ground-level ozone in China: distribution and effects on crop yields. , 2007, Environmental pollution.

[7]  F. Assefa,et al.  Composition of coffee shade tree species and density of indigenous arbuscular mycorrhizal fungi (AMF) spores in Bonga natural coffee forest, southwestern Ethiopia , 2007 .

[8]  H. Bothe,et al.  Arbuscular mycorrhiza and heavy metal tolerance. , 2007, Phytochemistry.

[9]  A. G. Khan.  Role of soil microbes in the rhizospheres of plants growing on trace metal contaminated soils in phytoremediation. , 2005, Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements.

[10]  C. Leyval,et al.  Arbuscular mycorrhizal fungi can decrease the uptake of uranium by subterranean clover grown at high levels of uranium in soil. , 2004, Environmental pollution.

[11]  P. Schweiger,et al.  Laboratory and field methods for measurement of hyphal uptake of nutrients in soil , 2000, Plant and Soil.

[12]  R. Chaney,et al.  Soil pH, rhizobia, and vesicular-arbuscular mycorrhizae inoculation effects on growth and heavy metal uptake of alfalfa (Medicago sativa L.) , 1989, Biology and Fertility of Soils.

[13]  I. D. Teare,et al.  Rapid determination of free proline for water-stress studies , 1973, Plant and Soil.

[14]  J. Barea,et al.  Beneficial effects of indigenous Cd-tolerant and Cd-sensitive Glomus mosseae associated with a Cd-adapted strain of Brevibacillus sp. in improving plant tolerance to Cd contamination , 2003 .

[15]  A. Goel,et al.  Changes in oxidative stress enzymes during artificial ageing in cotton (Gossypium hirsutum L.) seeds. , 2003, Journal of plant physiology.

[16]  R. Strasser,et al.  Cadmium accumulation and buffering of cadmium-induced stress by arbuscular mycorrhiza in three Pisum sativum L. genotypes. , 2002, Journal of experimental botany.

[17]  Fahu Chen,et al.  Relations Between Soil Properties and Selected Heavy Metal Concentrations in Spring Wheat (Triticum aestivum L.) Grown in Contaminated Soils , 2002 .

[18]  M. Gupta,et al.  Effect of the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum on the essential oil yield related characters and nutrient acquisition in the crops of different cultivars of menthol mint (Mentha arvensis) under field conditions. , 2002, Bioresource technology.

[19]  M. Kaldorf,et al.  The Zinc Violet and its Colonization by Arbuscular Mycorrhizal Fungi , 1999 .

[20]  D. Hoffman.  Handbook of Ecotoxicology , 1995 .

[21]  R. Chaney,et al.  Effects of vesicular-arbuscular mycorrhizal fungi on heavy metal uptake by soybeans , 1990 .

[22]  K. Asada,et al.  Hydrogen Peroxide is Scavenged by Ascorbate-specific Peroxidase in Spinach Chloroplasts , 1981 .

[23]  Manuela Giovannetti,et al.  AN EVALUATION OF TECHNIQUES FOR MEASURING VESICULAR ARBUSCULAR MYCORRHIZAL INFECTION IN ROOTS , 1980 .

[24]  I. Thornton,et al.  Trace Elements in Soils and Plants , 1980 .

[25]  J. Hiscox,et al.  A method for the extraction of chlorophyll from leaf tissue without maceration , 1979 .

[26]  N. Gorin,et al.  Peroxidase activity in Golden Delicious apples as a possible parameter of ripening and senescence. , 1976, Journal of agricultural and food chemistry.

[27]  N. C. Schenck,et al.  Response of Nodulating and Nonnodulating Soybeans to a Species of Endogone Mycorrhiza 1 , 1973 .

[28]  I. Fridovich,et al.  Superoxide dismutase: improved assays and an assay applicable to acrylamide gels. , 1971, Analytical biochemistry.

[29]  F. Smith,et al.  Colorimetric Method for Determination of Sugars and Related Substances , 1956 .

[30]  O. H. Lowry,et al.  Protein measurement with the Folin phenol reagent. , 1951, The Journal of biological chemistry.