The role of reactive oxygen species and β -1, 3 glucanase in the mechanism of resistance induction in wheat plants against leaf rust.

Abstract

Plants were sprayed by different concentrations of Mono potassium phosphate (KH2PO4), Jasmonic acid (JA) and Acetyl salicylic acid (ASA) at the flag leaf stage (70 days old) then challenge inoculated by uredia of Puccinia triticina. A significant reduction in controlling leaf rust was obtained by spraying wheat plants with the KH2PO4 (50 μg /ml & 100 μg /ml), JA (15 μg/ml) and ASA (1000 μg/ml) on both tested wheat cultivars i.e. moderately resistant (Sakha- 93) and susceptible (Sids-1). The highest increase of peroxidase activity was detected for KH2PO4 (50 μg /ml) and the infected treated plants showed higher activity as compared to healthy treated wheat plants. However, resistance was also associated with high activity of β-1, 3 glucanase as well as lignin accumulation especially when plants treated with KH2PO4 and JA. At the pre-penetration stage during appressoria formation, KH2PO4 and JA induce H2O2 to accumulate in the stomatal guard cells for both cultivars and in the mesophyll cells surrounding the sites of infection (stomata area). However, O2 - accumulation was mainly detected only in the mesophyll cells (72, 120 h, after inoculation).