Plant age, communication, and resistance to herbivores: young sagebrush plants are better emitters and receivers
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Plants progress through a series of distinct stages during development, although the role of plant ontogeny in their defenses against herbivores is poorly understood. Recent work indicates that many plants activate systemic induced resistance after herbivore attack, although the relationship between resistance and ontogeny has not been a focus of this work. In addition, for sagebrush and a few other species, individuals near neighbors that experience simulated herbivory become more resistant to subsequent attack. Volatile, airborne cues are required for both systemic induced resistance among branches and for communication among individuals. We conducted experiments in stands of sagebrush of mixed ages to determine effects of plant age on volatile signaling between branches and individuals. Young and old control plants did not differ in levels of chewing damage that they experienced. Systemic induced resistance among branches was only observed for young plants. Young plants showed strong evidence of systemic resistance only if airflow was permitted among branches; plants with only vascular connections showed no systemic resistance. We also found evidence for volatile communication between individuals. For airborne communication, young plants were more effective emitters of cues as well as more responsive receivers of volatile cues.
KeywordsArtemisia tridentata Defense Development Eavesdropping Induced resistance
This research was supported by a grant from the Japan Society for the Promotion of Science. Fieldwork was conducted at the University of California Sagehen Creek Reserve and on adjacent land in Tahoe National Forest. We thank Dr Junji Takabayashi, Dr Hitoshi Nishimura, Dr Goku Takimoto, Aki Fujimoto, and Jeff Brown for facilitating our fieldwork. This manuscript was improved by Mikaela Huntzinger and Andy McCall.
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