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Remote sensing of future competitors: impacts on plant defenses
Miriam M Izaguirre1, Carlos A Mazza, Mariela Biondini
1Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas, and Universidad de Buenos Aires, Avenida San Martín 4453, C1417DSE Buenos Aires, Argentina.
Summary
Plants use far-red radiation (FR) as a signal for competition. This study shows FR down-regulates chemical defenses, increasing herbivore success in wild tobacco and tomato plants.
Area of Science:
- Plant biology
- Ecology
- Evolutionary biology
Background:
- Plants perceive competition through far-red radiation (FR) reflected by neighbors.
- This FR perception triggers the shade-avoidance syndrome, promoting growth towards light.
- The impact of competition signals on plant defense expression remains largely unexplored.
Purpose of the Study:
- To investigate how FR signals of competition affect plant chemical defenses.
- To determine if FR influences susceptibility to herbivores.
- To elucidate the role of photoreceptors in mediating these responses.
Main Methods:
- Experiments using wild tobacco (Nicotiana longiflora) exposed to FR.
- Analysis of defense-related gene expression and phenolic compound accumulation.
- Assessing the performance of the specialist herbivore Manduca sexta.
- Complementary studies with tomato to identify photoreceptor involvement.
Main Results:
- Reflected FR significantly down-regulated chemical defenses in wild tobacco.
- FR altered defense gene expression and reduced herbivore-induced phenolic compounds.
- FR exposure enhanced the performance of the herbivore Manduca sexta.
- Phytochrome B was identified as a key photoreceptor mediating FR effects on defenses.
Conclusions:
- Shade-intolerant plants like wild tobacco and tomato reduce defenses in response to FR-mediated competition signals.
- This trade-off prioritizes light acquisition over defense, even without actual resource competition.
- Competition signals can functionally alter plant-herbivore interactions, expanding the shade-avoidance syndrome definition.