Effects of Water Deficit Stress on Glomalin Secretion by Glomerales in Symbiosis with Corn Plant

Glomalin is a glycoprotein which has been identified in cell walls of hyphae and spores of Glomerale fungi. Glomalin is a glue produced by fungal hyphae and deposites on soil particles which leads to the formation and stabilization of soil aggregates. Water deficit stress by affecting mycorrizal symbiosis can modify glomalin production. This study was conducted as a factorial experiment arranged in a completely randomized design (CRD) with four replications using corn (Zea mays L. Single cross 704) under greenhouse conditions. The first factor was three levels of moisture in the soil: 10-30% depletion of available water (W0), 35-55% depletion of available water (W1), 60-90% depletion of available water (W2) and the second factor was three species of mycorrhizal fungi, Glomus versiforme (Gv), Glomus intraradices (Gi), Glomus etunicatum (Ge) and non mycorrhizal control (NM). At the end of the vegetative growth, easily extractable glomalin (EEG) and total glomalin (TG) were measured using the Bradford method after extraction from soil. Shoot and root dry weights and root colonization declined by reducing soil moisture level. Water deficit significantly increased the amount of EEG and TG in soil. Also, a significant increase in glomalin production was observed at W2 level in all three fungal species compared to the W0 and W1 moisture levels. Moreover, by enhancing water deficit stress and decreasing root colonization, glomalin production per unit of root colonization was significantly increased.