Biotech approaches for crop improvement in the semi-arid tropics

Abstract

The semi-arid tropics (SAT) include parts of developing world that are characterized by unpredictable weather, limited rainfall and nutrient-poor soils. The crops grown in SAT region are exposed to various biotic and abiotic stresses adversely affecting the crop productivity. To meet the rising demand for food production in the context of population growth and climate variability, agricultural crops need to be improved so that they are better adapted to biotic and abiotic stresses, leading to higher crop productivity. The use of genomic approaches for the indirect selection of improved crop varieties can facilitate breeding strategies by alleviating time-consuming traditional approaches. In recent years, developments of significant amount of genomic resources in SAT crops have made them 'genomic resource rich' from the so-called 'orphan' crops. With the advent of next-generation sequencing and high-throughput genotyping methods, large numbers of molecular markers have been developed and mapped in SAT crops. Several quantitative trait loci (QTL) have been identified and are being targeted for introgression into elite lines, using marker-assisted backcrossing (MABC) approach. MABC programs underway in SAT crops include drought tolerance in chickpea, resistance to fusarium wilt and ascochyta blight in chickpea and rust in peanut. The downy mildew resistant pearl millet hybrid 'HHB 67 Improved' has been the first public-bred product of DNA-marker-assisted selection released by the International Crops Research Institute for Semi-Arid Tropics (ICRISAT). Besides, the use of transgenic technology potentially offers a more targeted gene-based approach for the genetic enhancement of field crops, thereby alleviating some of the major constraints to crop productivity that are difficult to breed due to species barriers or non-availability of traits in the germplasm collections. Transgenic crops are spreading faster than any other agricultural technology in history, and in SAT crops where several research programs are underway to develop transgenic crops.