Tolerance responses in wheat landrace Bolani are related to enhanced metabolic adjustments under drought stress.

Physio-biochemical adaptations of wheat landraces may have great importance in their growth, survival and yield under drought stress. Here, we evaluated the effects of drought stress on some defense systems of wheat cultivar "Sistan" (drought-sensitive) and landrace "Bolani" (drought-tolerant). Under drought stress, Bolani plants showed lower increases in hydrogen peroxide content compared to Sistan ones, which was accompanied with significant decrease in malondialdehyde and electrolyte leakage indices. Increasing the transcript levels and activity of enzymatic and non-enzymatic antioxidants along with phenylpropanoid metabolites improved relative tolerance to drought-induced oxidative stress, particularly in Bolani plants, results which may be confirmed by a significant decrease in the damage indices. In the phenylpropanoid pathway, the biosynthetic pathway of total phenol, flavonoids and anthocyanins was more active than lignin-biosynthetic pathway, which could early respond to drought stress. These results may be confirmed by their negative significant correlations with damage indices as well as a non-significant correlation of lignin with most enzymatic and non-enzymatic antioxidants in plants. Lower decrease of chlorophyll (Chl) and carotenoid contents in Bolani plants compared to Sistan ones indicated the relative stability of photosynthetic pigments under drought stress. Our results suggested that integrating metabolic pathways could coordinately alleviate oxidative stress that can lead to introducing suitable genetic sources for drought tolerance.