Tobacco plant thwarts caterpillar attack by opening flowers in the morning

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Washington, January 22 (ANI): A team of scientists has discovered that the tobacco plant thwarts an onslaught by caterpillars by opening its flowers in the morning, instead of the night.

This finding was made by scientist Ian Baldwin and colleagues by studying the pollination of a wild tobacco species living in the Southwestern United States.

This tobacco plant, Nicotiana attenuata, normally opens its flowers at night, during which it is visited, and pollinated, by the night-active hawkmoth.

In exchange for transferring pollen, the hawkmoth is provided with a sugary reward.

Such a quid pro quo relationship would seem to be all fine and dandy for N. attenuata, but as it turns out, the hawkmoth also likes to lay its eggs on the plant-eggs that develop into voracious, leaf-eating caterpillars.

This is obviously not an ideal outcome from the plant's perspective, but N. attenuata has an interesting trick up its sleeve.

Stimulated by oral secretions released by the munching caterpillars, N. attenuata performs an astonishing change in flower phenology (the timing of flower opening) in which the flowers open in the morning instead of at night.

This change in flower phenology, as well as other alterations, including a metamorphosis in flower shape and the loss of key chemical attractants, leads to a switch in pollinators from the hawkmoth to a local hummingbird.

The latter, unlike the hawkmoth, is normally active during the day and seems to be satisfied with just a nectar treat.

Looking to the field of plant-pollinator interactions more generally, the findings have some potentially broad implications.

For one, plants face another dilemma, related to the one described by Baldwin and colleagues, in which traits that attract a pollinator can also attract herbivores, resulting in an inevitable trade-off.

Thus, it is possible that herbivore-induced changes to flower phenology could be used more generally to mitigate the unwanted side effects associated with flowers that are attractive to both pollinators and herbivores.

Also, in studying how the caterpillars' oral secretions induce the switch in flower phenology, Baldwin and colleagues discovered that a chemical pathway crucial to many defense responses in plants is required.

The role of such a common defense pathway raises the interesting possibility that the effects of herbivore attack described in the study may be common in plants. (ANI)

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