ABSTRACT
Plant growth in the natural environment is often adversely affected by a number of factors. These include environmental factors such as low temperature, heat, drought, wind, ultraviolet light, anoxia, and high salinity and biological factors such as pathogens (bacteria, viruses, and fungi). Abiotic and biotic factors that limit growth and development of plants and eventually productivity are considered stress factors. Crop losses due to these various abiotic and biotic stresses are in the billions of dollars annually. It has been estimated that stress factors (abiotic and biotic) depress the yield of agronomically important crops in the United States by 78%, of which about 70% is due to unfavorable environmental conditions [1,2]. Plants possess built-in mechanisms to cope with the abiotic and biotic stress factors. Plant scientists have been studying the effects of various stresses on plants to better elucidate the mechanisms by which plants respond to stress signals. It is hoped that knowledge derived from the increased understanding of plant responses to biotic and abiotic stresses would eventually help in developing new plant varieties that are resistant to these stress factors. Advances in molecular and cellular biology are offering a variety of new approaches to investigate plant responses to stresses.
