Phenotypical, physiological and molecular assessment of drought tolerance of five Egyptian teosinte genotypes

Prolonged drought presents a serious challenge to the agricultural sector. The main concern of this work was to assess the phenotypical, physiological, and molecular responses of five teosinte (Zea mexicana Schrad L.) genotypes (Ba, Gm1, Gm2, Gm3 and Gm4). In a two-season (2020 and 2021) field experiment, fifteen-day-old teosinte plants were subjected to well-watered (15-day watering frequency) as a control, moderate drought (25-day watering frequency), and extreme drought (35-day watering frequency) treatments. Drought negatively affected growth, yield, chlorophyll, and POD activity of all genotypes, but promoted soluble sugars and proteins, osmoregulatory molecules (glycinebetaine, amino acids, and proline), non-enzymatic antioxidants (phenols, flavonoids, and alkaloids), and SOD activity. Furthermore, long-term water stress upregulated MOCOS, Rad17, NCED1, CAT1, and P5CS genes expression, with Gm3 and Gm4 being the most drought-tolerant genotypes. These findings could be employed in breeding programs to develop tolerant genotypes to address the challenges posed by climate changes like drought.