Recent advances in breeding for drought and salt stress tolerance in soybean

Drought and salinity are two important abiotic factors limiting soybean production worldwide and drought alone accounts for about 40% crop loss. Irrigation and soil reclamation are not economically viable options for soybean production under drought and salinity. Hence, genetic improvement for drought and salt tolerance are cost effective. Conventional breeding has made a significant contribution to soybean improvement in the last 50 years. Through conventional breeding, it is easy to manipulate simply inherited qualitative traits which are less sensitive to environmental variation, but quantitative traits like yield or tolerance to abiotic stress are significantly influenced by environment. Most agronomically important traits are quantitatively inherited and are difficult to improve through conventional breeding. Molecular marker technologies can dissect quantitative traits into individual components, known as quantitative trait loci enabling marker assisted selection of desired traits in much shorter time avoiding labor intensive, conventional, phenotypic selection. A molecular breeding approach can supplement the conventional breeding system. Well developed molecular genetic maps, functional genomic resources, and other molecular tools are available for soybean. Effective use of these resources will allow a greater understanding of basic mechanisms of tolerance to abiotic stress. Integration of these genomic tools coupled with well-designed breeding strategies will help to develop soybean varieties with higher tolerance to drought and salt