Evolution is based on diversity, and sexual reproduction is key to creating a diverse population that secures competitiveness in nature. Plants had to solve a problem: they needed to find ways to spread their genetic material. Flying pollinators—insects, birds, and bats—were nature's solution. Charles Darwin's "abominable mystery" highlighted the coincidence of flowering plant and insect diversification about 120 million years ago and ascribed it to the coordinated specialization of flowers and insects in the context of insects serving as pollen carriers. To make sure the flying pollinators would come to the flowers to pick up pollen, plants evolved special organs called nectaries to attract and reward the animals. These nectaries are secretory organs that produce perfumes and sugary rewards. Yet despite the obvious importance of nectar, the process by which plants manufacture and secrete it has largely remained a mystery. New research from a team led by the Carnegie Institute of Science’s (Washinton, D.C.) Dr. Wolf Frommer, director of the Plant Biology Department, in collaboration with the Carter lab in Minnesota and the Baldwin lab in Jena, Germany, has now identified key components of the sugar synthesis and secretion mechanisms. Their work also suggests that the components were recruited for this purpose early during the evolution of flowering plants. Their work was published online on March 16, 2014 in Nature. The team used advanced techniques to search for transporters that could be involved in sugar transport and were present in nectaries. They identified the transport protein SWEET9 as a key player in three diverse flowering plant species and demonstrated that it is essential for nectar production.
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