Molecular and Genetic Analysis of Abiotic Stress Resistance of Forage Crops

Abstract

Abiotic stress, brought about by salinity, drought, extreme temperatures and oxidative stress are serious threats to agriculture and result in a huge reduction of production. Drought and salinity are becoming major threats throughout the world. Abiotic stress leads to a series of morphological, physiological, biochemical and molecular changes that adversely affect plant growth and development (Wang et al., 2001). In order to survive from these harsh stresses, forage plants have developed precise and complicated tolerance mechanisms at the morphological, physiological and molecular levels. Under serious threat, forage plants can change the shape of the leaves and roots to decrease the water loss. Some plants have evolved special structures, such as salt glands to excrete salt. At the physiological adjustments etc. all change in order to resist stress (Chaves, 1991; Sheng, 2010; Yang et al., 2007). In fact, all of level, respiratory, photosynthesis metabolism and osmotic these changes are related to gene expression. The complex plant response to abiotic stress involves many genes and molecular mechanisms. In the past several decades, multiple genes responding to drought, salt, low-temperature and oxidative stress have been identified. These genes are divided into two groups (Shinozaki et al., 2003). The first group functions to directly protect the plant against stress, involving key enzymes for osmolyte biosynthesis, LEA (late embryogenesis abundant) proteins, detoxification enzymes and enzymes involved in many metabolic processes. The other group consists of contained protein factors involved in the regulation of signal transduction, including various transcription factors, proteins kinases, protein phosphatases, enzymes involved in phospholipid metabolism, and other signaling molecules (Yamaguchi-Shinozaki & Shinozaki, 2006). Genes have been used extensively to improve the stress-tolerance in crop and forage crops. The investigation of stress-tolerance genes will increase our knowledge of tolerance mechanisms, which could in turn be used to promote improvements in forage crop plants tolerance.