Cloning of Defense Related Genes against pathogens in Forest Trees

Abstract

In nature, plants including trees come in frequent contact with potentially pathogenic organisms like fungi, bacteria, viruses, and others like nematodes, mites, insects, mammals etc. By their stationary nature, plants cannot avoid these and hence have to protect themselves in other ways. These multitude of stress conditions are also known as biotic stresses. In addition plants also have to deal with a variety of abiotic stresses, such as those imposed by less or excess water (drought and flooding), presence of excess salts (salinity and alkalinity), low and high temperature, heavy metals, ozone, UV irradiation etc.. Biotic and abiotic stresses adversely affect growth and yield of crop plants including tree crops. There is a great deal of urgency in improving the performance of plants against various stress factors. Plant genetic engineering has already produced successfully improved virus, herbicide and insect resistant plants. During the past five years there has been progress in developing plants for abiotic stress also. However, high level tolerance against biotic and abiotic stresses still remains a challenge (Vierling and Kimpel, 1992).