Maize root responses to drought stress depend on root class and axial position

Area of Science:

• Plant Biology
• Agricultural Science
• Drought Stress Physiology

Background:

• Drought stress significantly impacts crop yield and water use efficiency.
• Understanding plant root system adaptations is crucial for developing resilient crops.
• Maize (Zea mays L.) exhibits diverse root architectures that may respond differently to water scarcity.

Purpose of the Study:

• To investigate the anatomical and architectural root responses to drought stress in maize (Zea mays L.) cultivars.
• To determine if root responses to drought vary among different root classes and along root axes.
• To identify specific root traits that contribute to drought tolerance in maize.

Main Methods:

• Phenotyping of four maize (Zea mays L.) sweet corn genotypes (SC1-SC4) under well-watered and drought conditions in greenhouse mesocosms.
• Evaluation of anatomical and architectural root responses to drought for each root class.
• Assessment of lignin distribution using laser ablation tomography and image processing of root cross-sections.

Main Results:

• Cultivars SC3 and SC4 showed enhanced lateral root development on apical segments of axial roots under drought, promoting growth into deeper, moister soil zones.
• Apical segments of axial and lateral roots in drought-stressed plants (especially SC3 and SC4) were thicker with greater theoretical axial water conductance compared to basal segments.
• Basal segments of crown roots in SC3 and SC4 exhibited increased lignification of the stele under drought conditions.

Conclusions:

• Root anatomical and architectural responses to drought are complex, varying significantly among maize cultivars, root classes, and along root axes.
• Enhanced lateral root proliferation in apical axial root segments under drought can improve deep water acquisition.
• Increased lignification in basal crown root segments may aid in preserving axial water transport during drought stress.