Biotic Stress and Breeding of Plants for Stress Resistance

Among the different environmental challenges that affect crop production, biotic stress factors are more devastating. They reduce crop yield and pose serious threats to food security. Legumes constitute a large number of crop varieties that are seriously affected by different biotic stress factors. To enhance their growth in the face of these different stressful factors and preserve their useful genomic and functional growth properties, leguminous crops are subjected to continuous genetic manipulations for stress resistance. Successful breeding of stress-tolerant varieties for cultivation under different farming systems may result in reduced crop losses and production costs, limited use of agrochemicals, and eventual yield increases. Crops that are resistant to biotic stress also exhibit better growth and yield characteristics. As established several decades ago, the revolution in genomic research led to the development of many sophisticated and advanced crop improvement techniques that can be applied across a whole range of leguminous crop species such as cowpea, faba bean, lentil, mungbean, pea, soybean, etc. However, interest in genetic engineering, chemically-or-physicaly-based mutation breeding, marker-assisted selection, quantitative trait loci and genome editing (CRISPR-Cas) have expanded research beyond biotic stress resistance. These techniques play a key role in applications such as the manufacturing of bioenergy, and crop engineering for the expression of valuable bioactive compounds and recombinant proteins. This chapter briefly reviews the diversity of biotic stress factors (bacteria, fungi, insects, parasitic nematodes and viruses) and possible ways in which these stress factors can be managed and eradicated using various breeding methods. The review shows that the biotechnological tools mentioned above provide beneficial functions in pest management through genetic, physiological and morphological improvements, especially when coupled with other farming practices. 

Keywords: Biotic stress, Genetic engineering, Resistance, Leguminous crops