Tracking of heavy metals tolerance gene(s) in cultivated Egyptian Vicia faba varieties

Abstract

Vicia faba which is known as fava bean is one of the most important crops which is grown worldwide. It’s important because it is a major food source, its agronomic importance and improving soil properties. Heavy metals contamination has great adverse effects on all forms of life specially in agriculture it is a serious threat to food security. Contamination with heavy metals has many sources such as automobile, emission, fertilisers and mining. CAT gene which encodes for catalase enzyme that is a key antioxidant enzyme found in all living organisms to convert hydrogen peroxide to water. Catalase prevent the production of reactive oxygen species (ROS) which is produced due to the presence of heavy metals contamination. The purpose of this study was tracking heavy metals tolerant gene(s) in cultivated Egyptian Vica faba varieties to explore the response of CAT gene and the effects of soil contamination by selected metals such as Zinc (Zn), cadmium (Cd) and lead (Pb). The expression levels of CAT gene were measured in two varieties Wadi 1 and Giza 716 in 5 different locations in Egypt North and Central Delta, South Delta and Central Egypt, New reclaimed lands in the Nubaria, Upper Egypt and El Wadi El Gedeed. In addition, heavy metals concentrations were measured. The results shown that in Giza 716 variety the highest heavy metals concentration (Cd and Pb) was in Upper Egypt while the lowest concentration was in North and Central Delta while Zinc concentration was ordered as following Upper Egypt > Nubaria >North and Central Delta. While in Wadi 1 variety the highest concentration was in South Delta and Central Egypt and the lowest concentration was in El Wadi El Gadeed. The CAT gene was over expressed in the roots of the two varieties in all locations. The highest expression was in Wadi 1 that is cultivated in South Delta and Central Egypt with approximately 23 folds and the lowest expression was in Wadi 1 that is cultivated in El Wadi El Gadeed with approximately 3 folds. CAT gene expression is related to metal exposure and appeared to metal specific. In addition, its 9 expression is related to biotic and abiotic such as drought and salinity. We recommend the use of Rhizobium and PGPR whether wild or modified strains.