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Accueil du site → Doctorat → États-Unis → 2020 → Rice roots for drought tolerance : Functional roles and genetic components of root anatomical and architectural traits in Oryza sativa

Pennsylvania State University (2020)

Rice roots for drought tolerance : Functional roles and genetic components of root anatomical and architectural traits in Oryza sativa

Reeger, Jenna

Titre : Rice roots for drought tolerance : Functional roles and genetic components of root anatomical and architectural traits in Oryza sativa

Auteur : Reeger, Jenna

Université de soutenance  : Pennsylvania State University

Grade : Doctor of Philosophy (PhD) 2020

Résumé
Drought reduces yields in the majority of agricultural crops each year, and we expect these effects to become more severe in many areas as the climate continues to change and resources are more limited. Rice is the most important food crop in the world, as it is a staple food for the poorest populations, and it is extremely susceptible to yield loss from drought. Plant scientists aim to understand the biology of crop plants to develop stress tolerant varieties so that farmers can produce stable yields under variable stresses. Roots are responsible for intercepting water and nutrients that sustain plant growth. Developing varieties with root systems that are more efficient at intercepting, absorbing, and transporting water and nutrients would promote abiotic stress tolerance and is a sustainable solution to promote agricultural production and ultimately food security. Root phenotypes that promote drought tolerance as well as their genetic controls must therefore be identified. Root anatomical traits have been neglected in studies of crop plants, particularly in rice, and their interaction with root architectural and shoot traits needs to be elucidated to understand how they impact drought tolerance. The following work identifies single and integrated root phenotypes that associate with drought tolerance in rice in the greenhouse and field. Phenotypes that promote deeper rooting, reduced metabolic cost of the root system, and efficient water transport promote growth in rice in drought stress conditions. Root trait plasticity was also beneficial in most cases. Genomic regions and candidate genes were also identified for root anatomical traits using genome-wide association analysis, and methods to reduce error in these analyses were established. Candidate genes for metaxylem vessel traits were validated using CRISPR-Cas9 mutants under drought stress. This work builds on a growing body of research on root anatomical phenotypes for drought tolerance in crop plants and contributes new insights on function and control of the rice root system.

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