Malekzadeh Parviz, Khara Jalil, Farshian Shadi
Department of Biology, Faculty of Science, Urmia University, Urmia, Iran.
Pak J Biol Sci. 2007 Jun 15;10(12):2008-13. doi: 10.3923/pjbs.2007.2008.2013.
Soil microorganisms have been shown to possess several mechanisms capable of altering metal bioavailability for uptake into roots. In addition, root mycorrhizal associations have been shown to affect the rate of metal uptake. There is evidence that exposure of plants to excess concentrations of heavy metals such as Cu results in oxidative injury. In this study, effect of arbuscular mycorrhizal fungus Glomus etunicatum on tolerance of Cu toxicity in tomato plants was studied. In order to prepare seedling medium, we used washed and sterilized sand and agricultural soil. Tomato seeds were surface sterilized and planted in two pots. One filled just with sterilized sand (for non-mycorrhizal treatments) and the other filled with sterilized sand mixed with G. intraradices mycorrhizal inoculum. We were certain about complete colonization after 4 weeks, so we transferred three seedlings to each main pot. Plants grew in growth chamber for nine weeks. During growth period plants received modified Hoagland's solution (with half P content) with Cu concentration of 0, 1.5, 3.5, 5.5, 7.5 mM CuSO4 in triplicates. Antioxidant enzymes activity, Ascorbate Peroxidase (APX) and Guaiacol Peroxidase (GPX) and Root Length Colonization (RLC) percentage in mycorrhizal and non-mycorrhizal plants were measured. APX activity in mycorrhizal shoots increased but there was no significant correspondent increase in roots of these plants. GPX activity in mycorrhizal roots increased but there was no significant correspondent increase in shoots of these plants. Activity of this enzyme in roots and shoots of mycorrhizal plantshigher than non-mycorrhizal plants. Estimation of root length colonizatinon by gridline intersect method, increase in Cu concentration, colonization percentage decreased significantly. The data show the possible role of mycorrhiza in plant protection against Cu toxicity.
土壤微生物已被证明具有多种机制，能够改变金属的生物有效性，使其被根系吸收。此外，根系与菌根的共生关系已被证明会影响金属的吸收速率。有证据表明，植物暴露于过量浓度的重金属（如铜）中会导致氧化损伤。在本研究中，研究了丛枝菌根真菌幼套球囊霉对番茄植株铜毒性耐受性的影响。为了制备幼苗培养基，我们使用了经过清洗和灭菌的沙子和农业土壤。番茄种子进行表面灭菌后种植在两个花盆中。一个花盆只填充灭菌沙子（用于非菌根处理），另一个花盆填充与根内球囊霉菌根接种物混合的灭菌沙子。我们确定4周后完全定殖，因此将三株幼苗转移到每个主花盆中。植株在生长室中生长9周。在生长期间，植株接受改良的霍格兰溶液（磷含量减半），其中硫酸铜浓度分别为0、1.5、3.5、5.5、7.5 mM，重复三次。测量了菌根和非菌根植株中的抗氧化酶活性、抗坏血酸过氧化物酶（APX）和愈创木酚过氧化物酶（GPX）以及根长定殖率（RLC）百分比。菌根地上部分的APX活性增加，但这些植株的根系中没有相应的显著增加。菌根根系中的GPX活性增加，但这些植株的地上部分没有相应的显著增加。该酶在菌根植株根系和地上部分的活性高于非菌根植株。通过网格交叉法估计根长定殖情况，随着铜浓度的增加，定殖百分比显著下降。数据表明菌根在植物抵御铜毒性方面可能发挥的作用。
