Avenues to realize potential of phenomics to accelerate crop breeding for heat tolerance

Abstract

High-temperature stress is one of the significant abiotic stresses that reduce crop yields across the world. Heat stress is more prevalent in arid and semiarid regions of the tropics, and its occurrence has become more frequent in the subtropical areas. However, concerns related to this stress are significant due to the predicted rise in ambient temperatures due to global warming. It necessitates renewed phenotyping methods and crop breeding strategies to develop high-temperature tolerant crop cultivars. These strategies have a higher chance of success if the trait-based selection approach is implemented to achieve higher productivity under hotter environments. Hence, trait identification and phenotyping for key traits will play a crucial role in breeding programmes aiming at developing heat-tolerant crops. Although the concept has been around for decades, trait-based breeding has always been a challenge as screening large number genotypes for traits of interest is laborious and time-intensive. However, recent advances in phenomics have opened up new avenues to address this bottleneck efficiently and rapidly. It is attributed to the potential of phenomics tools to capture temporal and spatial changes in morphology and physiology and then related to the biochemistry of plants. These changes can provide clues about useful traits that can be used for selection of heat-tolerant lines in breeding programs. For this purpose, however, intensified efforts are needed to translate existing knowledge of mechanisms underlying heat tolerance into heritable traits and also into protocols for high throughput screening. In this regard, this review attempts to summarize the current status of breeding efforts to improve heat tolerance in crop plants and avenues for employing phenomic tools.