Abstract

Environmental stresses, both abiotic and biotic, are the main factors reducing crops productivity. Biotic stresses caused by fungi, viruses, bacteria and insects are the major threats. However, abiotic stresses have more adverse effects on crop yield and crop survival. Hitherto, tolerant plants were mainly produced by classical breeding techniques. Success in breeding for better adapted varieties to abiotic and biotic stresses depends on the concerted efforts of various research domains including plant and cell physiology, molecular biology, genetics and breeding. However, such process is time consuming. The production of transgenic plants by genetic engineering allows a much faster progress. This review focuses on stress tolerance on tobacco. Tolerance to salt, drought, water stress, low and high temperature, heavy metals, pathogens and pests were enhanced via overexpression of specific stress related genes from different sources.