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Glomus genus has more adaptability and adjusting pattern of sporulation under stress conditions than other genera of AMF (Jacobson 1997). Our spore taxonomic study results supports the previous finding where Glomus genus was found to be well adapted to HMM contaminated soil (Hassan et al. 2011). In addition, relative abundance of Glomus genus was found to be higher in all three study sites used in the present work. Gonzalez-Chavez et al. (2002) and Schneider et al. (2013) also reported dominance of Glomus genus in an arsenic mining site. Significant increase in Glomus genus spore count was observed with increasing concentrations of soil As, Cd, Cu, Pb and Zn. These results support our hypothesis that Glomus species could be the dominant genus in the vicinity of an abundant Janghang smelter. In our spore taxonomic study, we have used spore morphological characters only to analyze genus level diversity due to the difficulties in species level differentiation. Community structure analysis by T-RFLP revealed that AMF species present in soil vary with respect to soil HMM concentration. Further, MiCA analysis confirmed the presence of G. mosseae, G. coronatum, G. geosporum and G. intraradices in all three sites. These AMF species might have developed adaptation and tolerance mechanism(s) to different levels of soil HMM concentrations. Metal tolerant AMF species could germinate and colonize plant roots even at high Pb, Cd and Zn concentrations in soil and improve plant tolerance against metal stress (Pawlowska and Charvat 2004). Experimental evidences showed that metal tolerant G. mosseae improved Medicago truncatula Gaertn. growth in soils with high concentration of As (200 mg/kg of soil) (Xu et al. 2008). Our results supported the p... ... middle of paper ... ...mosseae and uncultured Glomus were dominant in all three sites. In contradiction to our T-RFLP results, dominant bands sequenced from DGGE revealed the presences of G. intraradices only in highly contaminated soils. This may be due to less number of bands sequenced, however interestingly similar migration patterns for G. intraradices were found in moderately and highly contaminated soils. In DGGE, DNA are separated based on the melting behavior of DNA under increasing gradients of denaturants. Same migration distance of DNA fragments in DGGE gel probably indicates same AMF species (Liang et al. 2008). Glomus genus richness and Shannon diversity indices increased as soil As, Cd and Zn concentration increased. In line with this, many authors reported Glomus genus dominance in heavy metal contaminated sites (Renker et al. 2005; Vallino et al. 2006; Zarei et al. 2010).

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