Effect of root-knot nematode and two species of crown gall on antioxidant activity of grape leaves

Agrobacterium tumefaciens and Agrobacterium vitis significantly reduced the entire criteria (galls, embedded stages, final population, Pf/Pi and egg production) of the root-knot nematode, Meloidogyne incognita, when they were in concomitance with grape (Vitis vinifera var) superior roots. Greater suppression in such criteria was observed with high inoculum levels (5X107 cfu/pot) than with lower (2.5X107 cfu/pot) ones. All treatments resulted in the increase of leaves contents of H2O2 and lipid peroxidation (TBARS) dramatically, which were considered the most damaging stresses in plant cells. The contents of AsA, GSH, TPH and PAL specific activity increased as a strongly antioxidant defense compound against induced oxidative damage. In addition, the increase in the activity of various antioxidant defense specific enzymes (SOD, APX, CAT and GST) represented the protective activity used to counteract the oxidative injury promoted by nematode and nematode-bacteria infections. The rate of the chemical increase was significantly higher in interaction treatments than in the leaves of plants treated singly with M. incognita. Moreover, higher inoculum levels resulted in higher values of the measured chemicals. Symptoms appearance at low levels of nematode and bacterial treatments were significantly preceded by significant induction of AsA, GSH and TPH contents, and APX, CAT, SOD, GST and PAL activities in grape leaves. However, under high levels of nematode and bacteria, an obvious depletion at all non-antioxidants enzymes’ levels and antioxidants enzymes’ activities was observed. It is supposed that stimulated antioxidative processes contributed to the suppression of necrotic symptom development in grape leaves depending on the level of pathogen inoculum.Key words: Meloidogyne incognita, grape, crown gall, Agrobacterium tumefaciens, Agrobacterium vitis,antioxidant activity

Bioavailability of Iron, Zinc, Phytate and Phytase Activity during Soaking and Germination of White Sorghum Varieties

The changes in phytate, phytase activity and in vitro bioavailability of iron and zinc during soaking and germination of three white sorghum varieties (Sorghum bicolor L. Moench), named Dorado, Shandweel-6, and Giza-15 were investigated. Sorghum varieties were soaked for 20 h and germinated for 72 h after soaking for 20 h to reduce phytate content and increase iron and zinc in vitro bioavailability. The results revealed that iron and zinc content was significantly reduced from 28.16 to 32.16% and 13.78 to 26.69% for soaking treatment and 38.43 to 39.18% and 21.80 to 31.27% for germination treatments, respectively. Phytate content was significantly reduced from 23.59 to 32.40% for soaking treatment and 24.92 to 35.27% for germination treatments, respectively. Phytase enzymes will be activated during drying in equal form in all varieties. The results proved that the main distinct point is the change of phytase activity as well as specific activity during different treatment which showed no significant differences between the varieties used. The in vitro bioavailability of iron and zinc were significantly improved as a result of soaking and germination treatments