Taste and physiological responses to glucosinolates: seed predator versus seed disperser.
In contrast to most other plant tissues, fleshy fruits are meant to be eaten in order to facilitate seed dispersal. Although fleshy fruits attract consumers, they may also contain toxic secondary metabolites. However, studies that link the effect of fruit toxins with seed dispersal and predation are scarce. Glucosinolates (GLSs) are a family of bitter-tasting compounds. The fleshy fruit pulp of Ochradenus baccatus was previously found to harbor high concentrations of GLSs, whereas the myrosinase enzyme, which breaks down GLSs to produce foul tasting chemicals, was found only in the seeds. Here we show the differential behavioral and physiological responses of three rodent species to high dose (80%) Ochradenus' fruits diets. Acomys russatus, a predator of Ochradenus' seeds, was the least sensitive to the taste of the fruit and the only rodent to exhibit taste-related physiological adaptations to deal with the fruits' toxins. In contrast, Acomys cahirinus, an Ochradenus seed disperser, was more sensitive to a diet containing the hydrolyzed products of the GLSs. A third rodent (Mus musculus) was deterred from Ochradenus fruits consumption by the GLSs and their hydrolyzed products. We were able to alter M. musculus avoidance of whole fruit consumption by soaking Ochradenus fruits in a water solution containing 1% adenosine monophosphate, which blocks the bitter taste receptor in mice. The observed differential responses of these three rodent species may be due to evolutionary pressures that have enhanced or reduced their sensitivity to the taste of GLSs.
Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel; Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
Michal
M
Samuni-Blank
Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
Ido
I
Izhaki
Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon 3600672, Israel.
Yoram
Y
Gerchman
Department of Biology, University of Utah, Salt Lake City, UT 84103, United States of America.
M Denise
MD
Dearing
Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI 53706, United States of America.
William H
WH
Karasov
Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
Beny
B
Trabelcy
Department of Biology, Sewanee: The University of the South, Sewanee, TN 37383, United States of America.
Thea M
TM
Edwards
Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Zeev
Z
Arad
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005638:Fruit / Q000378:metabolism; D005961:Glucosinolates / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D011235:Predatory Behavior / Q000502:physiology; D031951:Resedaceae / Q000378:metabolism; D012377:Rodentia / Q000502:physiology*; D058614:Seed Dispersal / Q000502:physiology; D013649:Taste / Q000502:physiology*
D005961:Glucosinolates