Trading direct for indirect defense? Phytochrome B inactivation in tomato attenuates direct anti-herbivore defenses whilst enhancing volatile-mediated attraction of predators.
Under conditions of competition for light, which lead to the inactivation of the photoreceptor phytochrome B (phyB), the growth of shade-intolerant plants is promoted and the accumulation of direct anti-herbivore defenses is down-regulated. Little is known about the effects of phyB on emissions of volatile organic compounds (VOCs), which play a major role as informational cues in indirect defense. We investigated the effects of phyB on direct and indirect defenses in tomato (Solanum lycopersicum) using two complementary approaches to inactivate phyB: illumination with a low red to far-red ratio, simulating competition, and mutation of the two PHYB genes present in the tomato genome. Inactivation of phyB resulted in low levels of constitutive defenses and down-regulation of direct defenses induced by methyl jasmonate (MeJA). Interestingly, phyB inactivation also had large effects on the blends of VOCs induced by MeJA. Moreover, in two-choice bioassays using MeJA-induced plants, the predatory mirid bug Macrolophus pygmaeus preferred VOCs from plants in which phyB was inactivated over VOCs from control plants. These results suggest that, in addition to repressing direct defense, phyB inactivation has consequences for VOC-mediated tritrophic interactions in canopies, presumably attracting predators to less defended plants, where they are likely to find more abundant prey.
IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad de Buenos Aires, Ave. San Martín 4453, C1417DSE, Buenos Aires, Argentina.|Instituto de Biología Agrícola de Mendoza, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de Cuyo, Almirante Brown 500, Luján de Cuyo, 5500, Mendoza, Argentina.
Leandro E
LE
Cortés
Laboratory of Entomology, Wageningen University, PO Box 16, NL-6700, AA Wageningen, the Netherlands.
Berhane T
BT
Weldegergis
Instituto de Biología Agrícola de Mendoza, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de Cuyo, Almirante Brown 500, Luján de Cuyo, 5500, Mendoza, Argentina.
Hernán E
HE
Boccalandro
Laboratory of Entomology, Wageningen University, PO Box 16, NL-6700, AA Wageningen, the Netherlands.
Marcel
M
Dicke
IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad de Buenos Aires, Ave. San Martín 4453, C1417DSE, Buenos Aires, Argentina.|IIB-INTECH, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de San Martín, B1650HMP, Buenos Aires, Argentina.
Carlos L
CL
Ballaré
D000818:Animals; D003517:Cyclopentanes / Q000494:pharmacology; D016002:Discriminant Analysis; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D060434:Herbivory; D016018:Least-Squares Analysis; D007915:Lepidoptera / Q000502:physiology; D018551:Solanum lycopersicum / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000469:parasitology*; D054883:Oxylipins / Q000494:pharmacology; D051939:Phytochrome B / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D011235:Predatory Behavior; D064201:Trichomes / Q000648:ultrastructure; D055549:Volatile Organic Compounds / Q000378:metabolism*
D003517:Cyclopentanes; D054883:Oxylipins; D055549:Volatile Organic Compounds; D051939:Phytochrome B; C011006:jasmonic acid
R : FR ratio; defense; indirect defense; jasmonate; phytochrome; tomato (Solanum lycopersicum); tritrophic interaction; volatile