Unlocking the potential of wild progenitors to enhance water deficit stress tolerance in maize

The global challenge of water deficit stress (WDS) in maize (Zea mays L.) production, particularly in rainfed agriculture, necessitates a holistic understanding of root traits’ role in responding to this stress. While previous research has primarily focused on molecular mechanisms, acknowledging the significance of root architectural traits is essential. This study explores the development of the BC₂F₁ generation by crossing Zea diploperennis (donor) with maize inbred line LM13 (recurrent parent) to transfer water deficit tolerance attributes to maize. Efforts to develop backcross generations with Z. nicaraguensis were unsuccessful. The study investigates the response of wild maize relatives (Z. diploperennis and Z. nicaraguensis) and maize inbred line LM13 to WDS induced by osmolytes. Root trait modifications were analyzed using a root scanner, including parameters such as root projection area, length, tips, forks, segments, average root diameter, total root volume, number of metaxylem vessels, and xylem diameter. BC₂F₁ individuals, Z. diploperennis, and Z. nicaraguensis exhibited increased root projection area, total root length, and total root volume under WDS, while LM13 showed a decrease in most parameters. Scanning electron microscopy revealed increased metaxylem number in Z. diploperennis and BC₂F₁ under WDS, indicating drought tolerance. Z. nicaraguensis also displayed WDS tolerance. This study highlights the potential of wild maize relatives in conferring WDS tolerance and the feasibility of introgressing their root plasticity traits into cultivated maize for enhanced climatic resilience.