Durum wheat with the introgressed TaMATE1B gene shows resistance to terminal drought by ensuring deep root growth in acidic and Al³⁺-toxic subsoils

Background and aims: High aluminum (Al³⁺) concentrations associated with subsoil acidity is a major constraint to durum wheat (Triticum turgidum) production as it inhibits root growth affecting crop tolerance to drought. This study evaluated the introgressed TaMATE1B gene on drought resistance and Al³⁺ toxicity in durum wheat. Methods: Durum wheat lines Jandaroi–TaMATE1B (introgressed with the TaMATE1B gene) and Jandaroi–null (without TaMATE1B gene) were grown in 1-m deep columns filled with re-constructed field soil with Al³⁺-rich acid subsoil in a glasshouse under well-watered conditions until the onset of ear emergence (Z₅₁), before imposing well-watered and terminal drought treatments. Results: Jandaroi–TaMATE1B produced 25.3 % higher grain yield than Jandaroi–null under well-watered conditions and 49.0 % higher grain yield under terminal drought. Terminal drought reduced grain yield by 47.7 % in Jandaroi–TaMATE1B and 72 % in Jandaroi–null, relative to well-watered conditions. The effects of TaMATE1B on grain yield can be attributed to increased root growth and proliferation below 0.4 m in Al³⁺-toxic soil. Jandaroi–TaMATE1B had 34.5 and 32.0 % more total root biomass than Jandaroi–null in the well-watered and terminal drought treatments, respectively (P ≤ 0.05). Jandaroi–TaMATE1B had a significantly higher root: shoot ratio than Jandaroi–null at Z₅₁. Introgression of the TaMATE1B gene did not affect grain-filling duration, but terminal drought reduced it by 24 days in both lines. Conclusions: Introgression of the Al³⁺-tolerant TaMATE1B gene into durum wheat improved terminal drought resistance by enabling root growth and proliferation into deep layers of Al³⁺-rich acidic soil.