Study of the genetic variability of durum wheat (Triticum durum Desf.) in the face of combined stress: water and heat

Abstract

The devastating effects and extent of abiotic stress on cereal production continue to increase globally, affecting food security in several countries including Tunisia. Heat waves and the scarcity of rainfall strongly affect durum wheat yields. The present study aims to screen for tolerance to combined water and heat stresses in durum wheat at the juvenile stage. Three combined treatments were tested, namely: T0 (100% field capacity (FC) at 24°C), T1 (50% FC at 30°C), and T2 (25% FC at 35°C). The screening was carried out based on morphological, physiological, and biochemical criteria. The results showed that the combined stress significantly affects all the measured parameters. The relative water content (RWC) decreased by 37.6% under T1 compared to T0. Quantum yield (Fv/m) and photosynthetic efficiency (Fv/0) decreased under severe combined stress (T2) by 37.15% and 37.22%, respectively. Under T2 stress, leaf temperature increased by 63.7%. A significant increase in osmo-protective solutes was also observed, including proline, which increased by 154.6% under T2. Correlation analyses of the combination of water and heat stress confirm that the traits RWC, chlorophyll b content (Chlb), Fv/m, proline content (PC), Fv/0, and leaf temperature (LT), can be used as reliable screening criteria for the two stresses combined. The principal component analysis highlighted that Aouija tolerates the two levels of stresses studied, while the genotypes Karim and Hmira are the most sensitive. The results show that the tolerance of durum wheat to combined water and heat stress involves several adaptation mechanisms proportional to the stress intensity.

Genetic diversity of durum wheat (Triticum turgidum ssp. durum) to mitigate abiotic stress: Drought, heat, and their combination

“…It is interesting to note, from PCA results, that, under both individual and combined stress, the landrace Aouija was the only genotype that kept the same tolerance to both abiotic stresses, which indicates that Aouija is the most stable genotype and could be considered as tolerant to drought or/and heat stresses. Furthermore, the landrace Aouija showed the same behavior under drought stress and combined drought and heat stresses in previous studies at the seedling stage [101,104] Enzymatic (GPX and CAT) and non-enzymatic (Phenolic compounds) antioxidants are defense metabolites against the toxicity of ROS as H 2 O 2 under abiotic stresses [105]. Under combined stress, the results showed an increase in these antioxidants in all genotypes.…”

“…It is interesting to note, from PCA results, that, under both individual and combined stress, the landrace Aouija was the only genotype that kept the same tolerance to both abiotic stresses, which indicates that Aouija is the most stable genotype and could be considered as tolerant to drought or/and heat stresses. Furthermore, the landrace Aouija showed the same behavior under drought stress and combined drought and heat stresses in previous studies at the seedling stage [ 101 , 104 ]…”