Microbial tradeoffs of root cortical aerenchyma in maize
Open Access
- Author:
- Galindo-Castaneda, Tania
- Graduate Program:
- Horticulture
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 20, 2018
- Committee Members:
- Jonathan P. Lynch, Dissertation Advisor/Co-Advisor
Jonathan P. Lynch, Committee Chair/Co-Chair
Kathleen M. Brown, Committee Member
Gretchen A. Kuldau, Committee Member
Mary Ann Victoria Bruns, Outside Member
Gregory W. Roth, Committee Member - Keywords:
- RhizosphereArbuscular mycorrhiza
Fusarium verticillioides
root anatomy
root rot
Zea mays
Arbuscular mycorrhiza Fusarium verticillioides
arbuscular mycorrhiza
rhizobacteria
phosphorus
nitrogen
microbiome
root phenotype - Abstract:
- The formation of air pockets in the root cortex, or root cortical aerenchyma, is a phenotype that has been associated to improved maize growth and grain yield under drought and low-nitrogen stress. A growing number of studies supports the hypothesis that roots with increased aerenchyma growing under edaphic stress have reduced demands of carbon and nutrients, or reduced metabolic burden and that aerenchyma formation may be adaptive in maize growing under nutrient and water limitations. Modeling approaches predict that maize growing under phosphorus limiting conditions would benefit by having increased aerenchyma, but the utility of aerenchyma in maize growth and productivity remains to be determined. In this research I studied the utility of increased root aerenchyma in maize growing under suboptimal phosphorus availability finding that the reduction of living cortical tissue resulting from the formation of aerenchyma was associated to better growth and grain yield. Promising root phenotypes that may confer stress tolerance in maize, such as increased aerenchyma, should not compromise beneficial microbial associations or disease resistance. Since the root cortical tissue is the habitat of microorganisms, plants with increased aerenchyma may offer a completely different environment for microbial associations compared to plants with reduced aerenchyma. It is important to study the microbial tradeoffs of aerenchyma to inform breeding programs targeting roots with reduced metabolic burden. With this research I also explored the effects of aerenchyma on root microbial associations under optimal and suboptimal nutrient availability by evaluating mycorrhizal and Fusarium verticilliodes colonization, root rots, as well as the bacterial composition of the rhizosphere soil of maize plants with contrasting levels of root aerenchyma. I found that root phenotypes differentially affect mutualistic, endophytic and pathogenic root associations.