Recent advances in rapid and sensitive screening for abiotic stress tolerance

Traditionally, screening for abiotic stress tolerance at field level was based on necrosis scores and shoot biomass reduction on stress exposure, relative to unstressed controls. However, such a measure of tolerance screening is laborious, destructive, and time consuming, and results are subjected to environmental variation. Recently, noninvasive, high-throughput screening techniques have been developed for screening abiotic stress tolerance in crops. In this direction, some physiological, biochemical, and/or molecular indicators/markers have been identified for rapid and sensitive indirect screening of germplasm. Physiological markers like membrane damage based on electrolyte leakage, stomatal conductance, chlorophyll content and so on are currently available. In addition, quick and sensitive screening in crop plants is possible with biochemical markers like status of reactive oxygen species and oxidative damage to biological macromolecules like lipids, proteins, and nucleic acids. Identification of molecular markers associated with the tolerance response has also made rapid and sensitive indirect selection possible in a few crop species. Thus, development of such methods is valuable in breeding for abiotic stress tolerance in plants.