Evaluation of biochemical traits to complement empirical selection for wheat (Triticum aestivum) under heat stress

Terminal heat stress has drastic effect on the wheat growth and development causes reduction in the quantity and quality of grains. A wide genetic diversity has been reported in wheat for heat stress tolerance; information on biochemical traits and mechanism is scarce. Here, we have tried to find the suitable biochemical trait for screening wheat germplasm for thermotolerance. Seventy three different genotypes of wheat from our mini core subset were screened for the thermotolerance using different biochemical parameters like non-reducing sugar, protein content, proline accumulation and total antioxidant capacity (TAC) at grain-filling stage. Based on the variations in biochemical traits, lines were classified into three different groups with genotypes having non-reducing sugar > 2.0%, protein content > 20 mg g⁻¹ fresh weight, proline content > 2.5 pmole g⁻¹ fresh weight and total antioxidant capacity > 4.0 mmole g⁻¹ fresh weight were considered as highly tolerant against heat stress. Similarly lines having non-reducing sugar, protein, proline and TAC less than 1.5%, 15 mg g⁻¹ fresh weight, 1 pmole g⁻¹ fresh weight and 2.0 mmole g⁻¹ fresh weights were considered as sensitive to heat stress (HS). Since series of genes and proteins network has been identified to involve in heat stress tolerance of wheat, it will be more authentic to use different biochemical traits to screen more germplasm within less time. It will accelerate the work of breeder for the screening and identification of suitable line for breeding program.