Influence of arbuscular mycorrhizal fungi on growth and selenium uptake by garlic plants

Abstract

The aim of this study is to investigate the effects of arbuscular mycorrhizal fungi (AMF) on garlic plants growth and the uptake of selenium (Se). Garlic plants were grown in the pots inoculated with Glomus fasciculatum and G. mosseae and maintained in a greenhouse. Three weeks after planting, the pots had received different concentrations of Se (5, 10, 15, 20, 25 mg kg⁻¹ of soil) in the form of selenium dioxide (SeO₂) at 3 weeks intervals up to 12 weeks. For physiological and biochemical analysis, the samples were randomly collected from five plants of each experiment. Maximum AM infection, spore population and plant biomass were observed in the roots of mycorrhizal-mediated plants without Se, and they were gradually declined in both mycorrhizal and non-mycorrhizal (NM) plants with increasing concentrations of Se. Among the two Glomus species tested, G. fasciculatum-mediated plants showed higher AM infection, spore population and plant biomass than G. mosseae. No differences were observed for the uptake of Se in mycorrhizal plants and NM plants. However, NM plants uptake more Se than mycorrhizal plants. Higher contents of total chlorophyll and sugars were observed in plants inoculated with G. fasciculatum without Se and they were decreased in the presence of Se. In contrast, increased amount of glutathione peroxidase was observed at increasing concentrations of Se up to 20 mg kg⁻¹. High-performance liquid chromatography data revealed that SeO₂ converted to organic form of Se as γ-glutamyl-Se-methylselenocysteine. These results are basis for further investigations on the role of AMF on plant growth and uptake of Se in crop plants.

Keywords:

• garlic
• AM fungi
• selenium
• glutathione peroxidase
• HPLC

Acknowledgements

The authors thank the Director of the Centre for Advanced Studies in Botany, University of Madras, for providing facilities.