Functional Implications of Root Cortical Senescence For Soil Resource Capture

open_access
Open Access
Author:
Schneider, Hannah Marie
Graduate Program:
Horticulture
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 02, 2017
Committee Members:
Jonathan Paul Lynch, Dissertation Advisor/Co-Advisor
Jonathan Paul Lynch, Committee Chair/Co-Chair
Kathleen Marie Brown, Committee Member
Armen Ricardo Kemanian, Committee Member
Gabriele Brigitte Monshausen, Outside Member
Keywords:
Roots
Root Cortical Senescence
Anatomy
Barley
Abstract:
Root phenes play a primary role in plant adaptation to edaphic stress. The identification and understanding of the functional implications of root phenes may enable breeding and the development of crop varieties with improved soil resource acquisition. Root cortical senescence (RCS) is a type of programmed cell death in cortical cells of several Triticeae species. Until recently there has been very little attention as to the functional implications of RCS for water and nutrient capture. My research used physiology studies in the laboratory, greenhouse, and field and in silico experiments to characterize the development of RCS and understand its adaptive value and genetic control. This dissertation explores the functional implications of RCS for water and nutrient capture including its effects on root respiration and radial water and nutrient transport. Simulation results suggest that RCS improves plant growth in edaphic stress conditions. Empirical experiments demonstrated its development of RCS is modulated by ethylene. RCS may be a useful trait for water and nutrient acquisition, particularly in edaphic stress conditions. RCS may be an adaptive trait for nutrient acquisition by reallocating nutrients from senescing tissue and secondarily by reducing root respiration. As RCS progresses, less metabolic resources need to be invested in cortical maintenance, which could permit greater resource allocation to the growth of shoots, other roots, and reproduction. These results suggest that RCS merits investigation as a breeding target for enhanced soil resource acquisition and edaphic stress tolerance. The development of crops with enhanced soil resource acquisition would impact global agriculture, since merits of RCS may be analogous to other species which also form RCS including wheat, oats, and triticale.