Unlocking the hidden potential of genetic diversity to improve durum wheat tolerant to heat stress

According to the Intergovernmental Panel on Climate Change report, the average global temperature will increase by 0.5 to 4°C in the 21st century, leading to a reduction in crop yields. Wheat is one of the world’s oldest and most widespread food crops and an important component of the human diet; it is very sensitive to heat stress (HS), and it is considered that for every 1°C increase in average temperature during the reproductive phase, wheat production is estimated to decrease by 6%. Moreover, the fast increases in food demand due to population growth must be considered. A strategy to overcome the ongoing climate change is to understand the morphological and physiological traits associated with tolerance to high temperatures to produce crops more tolerant to abiotic stresses. Possible approaches to succeed in maintaining high crop yields include (i) the exploitation of natural and induced mutations; (ii) the exploitation of available genetic resources to produce new genetic material that is more tolerant to HS and related secondary stresses; (iii) improve the ability to identify available sources of resilience; and (iv) developing new selection techniques. The involvement of sHsp26 in the heat stress response was analyzed, by dissecting the natural mutations of TdHsp26 in some durum genotypes belonging to a germplasm collection. A PCR target enrichment approach, followed by sequencing and by using KASP molecular markers, several SNPs were identified and assigned to a specific genotype, identifying 17 haplotype combinations. A phenotyping analysis was performed on the target genotypes subjected to thermal stress in three different phases of wheat development: seedlings (Z10), accession (Z31) and anthesis (Z65) Biochemical, morphological and physiological traits were recorded during the experiment and contrasting genotypes were identified and selected through the experiments. Cultivated varieties were also included in the trials. On the bases of the results obtained SSD69 and SSD 397 were finally identified as putative tolerant and susceptible to heat stress. These results support the importance of plant phenotyping of the identification of superior genotypes under heat stress.