Genetics and Genomics of Stomatal Traits for Improvement of Abiotic Stress Tolerance in Cereals

Abstract

In traditional breedingTraditional breedingprogrammes for improving abiotic stress toleranceAbiotic stress toleranceof cerealsCereals, direct selectionDirect selectionfor grain yield is slow and costly, requiring many years and sites of field trials. Grain yield largely depends on the flag leaf characteristics and functions and is correlated to the ability of the plant to regulate its water content and to synthesize, store and relocate carbohydrates from leaves to grains. Despite the recognition of the importance of the flag leaf in cerealsCereals, little is known about genetic control of its cellular structure and development under stress. The leaf stomata cells regulate water loss by transpiration and photosynthetic CO2 uptake in plants. In order to maintain a high photosynthetic rate for higher yield under droughtDroughtand salinitySalinityconditions, it is critical to explore the mechanisms of control of stomata. A major crucial challenge in breeding for abiotic stress toleranceAbiotic stress toleranceis the knowledge about the physiological and genetic mechanisms that regulate stomatal morphologyStomatalmorphologyand development connected to grain yield. Quantitative trait lociQuantitative trait locus(QTL) mapping has been used to identify the genes that are subject to natural variation of stomatal traitsStomataltraitsin wheat, barley and rice. Over the last decade, several studies have demonstrated the importance of stomatal density and size and their positive association with physiological processes in grain yield. Further, considerable genetic variation exists for stomatal and epidermal cell traits that could be exploited for marker-assisted breeding and used for creation of new effective traits in cerealsCereals.