Cell/Development/Systems

Abstract

C-5-2 - Genetic dissection of regulatory networks controlling growth and defense

Sunday, July 15
1:23 PM - 1:43 PM

Plants respond to dynamic environments by integrating environmental cues through regulatory networks that control plant growth and development. The photoreceptor phytochrome B (phyB) senses light cues and executes photomorphogenic programs by repressing the activity of PIF transcription factors. Light quality is altered by neighboring plants, which inactivates phyB and allows PIFs to promote extension growth to increase competitive fitness. By comparison, JASMONATE ZIM-DOMAIN (JAZ) proteins control defense programs by repressing the activity of MYC transcription factors. Challenge by insects or pathogens triggers the degradation of the JAZ repressors and allows MYCs to execute defense programs. The interaction of light and jasmonate signaling appears to be a key regulatory node for plant growth vs defense conflicts. We tested this hypothesis by genetic removal of phyB and JAZs, which predicts potential concurrent activation of growth and defense. Although lower-order jaz mutants have no overt phenotypes, higher-order quintuple (jazQ) and decuple (jazD) mutants have constitutive jasmonate responses that scale with JAZ depletion, including hypersensitivity to jasmonate, higher resistance to insects and necrotrophic pathogens, and reduced vegetative growth. phyB mutation recovers growth of these jaz mutants, including apparent full uncoupling of growth and defense in the jazQ phyB mutant. By contrast, growth is only partially recovered in jazD phyB mutants. The difference between jazQ phyB and jazD phyB appears to be the persistence of stronger metabolic sinks created by jazD, suggesting an energy-sensing component to growth-defense regulation. Overall, our work with combinatorial mutants of light and jasmonate signaling is providing new insights into the regulatory mechanisms that govern growth-defense balance, and present potential avenues for manipulation of regulatory networks to drive plant fitness.


 

Co-Authors

Qiang Guo – Michigan State University; George Kapali – Michigan State University; Gregg Howe – Michigan State University

Ian T. Major

Post-doctoral Associate
MSU-DOE Plant Research Laboratory, Michigan State University

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C-5-2 - Genetic dissection of regulatory networks controlling growth and defense



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