Exploring Root Morphological and Anatomical Plasticity Among Cereals to Enhance Adaptation to Water Limited Conditions

Exploring genetic diversity in rooting morphology and anatomy provides tremendous opportunities for enhancing resilience to water-deficit stress conditions among field crops. Across the spectrum, we have cereals that are predominantly grown under fully flooded conditions (example rice) and some that are productive where water availability is significantly lower (example Sorghum). Our initial investigation included physiological, morphological and anatomical comparison of root-shoot dynamics, involving contrasting rice and wheat accessions, exposed to saturated and water-deficit stress conditions (60% Water Holding Capacity). Thicker roots and leaves and moderate tillering facilitated wheat to conserve water more effectively under water-deficit condition, compared to rice. Additionally, plasticity in stele and xylem diameter and xylem number along the root length in wheat cultivars facilitated efficient use of available moisture under water-deficit stress condition. A similar phenomena in root anatomical plasticity was not seen in popular rice cultivar (IR64) adapted to flooded conditions but some indications of plasticity were recorded in upland rice cultivar (N22). Based on the above findings two different studies were initiated (i) Comparative analysis of 23 different wild rice accessions with popular rice cultivars and other upland cereals including wheat, sorghum and maize (ii) Genome Wide Association Mapping for root morphological and anatomical parameters using ~290 diverse indica rice accessions exposed to saturated and water-deficit stress during maximum tillering stage. Opportunities for genetic modification of rice root morphology and anatomy, targeted root traits and chromosomal regions that can potentially induce greater resilience to water-deficit stress in rice cultivars will be discussed.