Enhanced Utilization of Plant Genetic Resources in Crop Improvement Programmes

Abstract

On domestication, the crop species typically inherited a small fraction of the natural genetic variation present in their wild progenitors. On-farm crop diversity diminished further with the advent of modern plant breeding, resulting in the creation of plant varieties that optimized adaptation at the cost of adaptability. Every quantum jump in productivity was also accompanied by a narrowing down of the breeders’ crossing block. Once a new thresh hold is reached, plant breeders tend to make crosses within the small and related set of this newly improved germplasm only. This has led us to a predicament of stagnation in genetic gains. Changes in biotic and abiotic stress regimes on account of climate change and natural resource depletion are expected to pose serious challenges in view of the narrow genetic base of breeding programmes. The problem is likely to be accentuated by restricted germplasm flow in deference to propriety concerns. Enhanced utilization of plant genetic resources (PGR) is clearly warranted. Impediments to use of PGR including lack of local adaptation and linkage drag are discussed along with measures to overcome them. ‘Genetic incorporation’ as a PGR utilization strategy in contrast to the generally followed ‘gene introgression’ is highlighted. It is a base broadening exercise which gradually improves current adaptation of breeding material and has the potential to cater to unforeseen breeding needs. Crop wild relatives (CWR) are a subset of PGR which show great scope for enhanced utilization as they represent distinct, genetically diverse but underutilized gene pools for crop improvement. Instances of commercial deployment of genes from the wild are listed. Salient pre-breeding work for wheat improvement at PAU is discussed as an illustration for enhancing use of PGR.