Use of Alien Diversity to Combat Some Major Biotic Stresses in Triticum aestivum L.

Abstract

Crop plants experience a collection of environmental stresses that involve biotic (biological) and abiotic (physical) factors. The biotic factors include pathogens including viruses, bacteria, fungi and microbes, birds, pests, weeds, insects, and invasive species. These are crucial for sessile organisms such as plants because plants cannot enhance production and even survive unless they show resistance towards undesirable changes in the surrounding environment. Both biotic and abiotic stresses negatively affect plant survival, production, and ultimately yield. Biotic stresses can deteriorate biomass at any stage of plant development by adversely affecting crop yield. Therefore, biological factors limit crop production and food security globally. The ability to adapt or tolerate these stresses by effectively countering these constraints is a very complex phenomenon. The most important biological stresses of wheat that significantly reduce yield are fungal diseases and among these the most damaging are rusts (leaf, stem, and stripe) and the emergence of new races of the pathogen that gradually cause a decline in the prevalent disease resistance of wheat cultivars. One option to combat this is the introgression of alien genes from wild and related progenitor species into common wheat. This underutilized genetic diversity can be exploited through conventional plant breeding modes utilizing diverse genetic resources across landraces, close and distant progenitor species of the recipient cultivars. Different methodologies to access alleles from the species have been practiced after first developing all the important hybrids that generate chromosome translocations, substitutions, or additions. For the identification of the chromosomal introgression, C-banding technique and genomic in situ hybridization (GISH) are ideally aided diagnostically by new molecular inputs. Although the merits of concentrating on primary and secondary gene pool genera are high, the practical contribution of Thinopyrum curvifolium, Th. distichum, and Secale cereale also adds credence to the continued use of a tertiary pool resource. The genetic diversity using a tertiary gene pool also is an added valuable resource. In order to encounter the overall wheat production challenge magnificently, plant scientists need to be cognizant of the various aspects of these stresses in view of the current development from genetic molecules to adaptive ecosystems.