College of Biological Sciences
One-third of all crop species produce floral nectar and are dependent on animals for reproduction. Moreover, crops such as cotton, bean, pea, apple, cherry, peach, and blueberry all produce extrafloral nectar to attract mutualistic predatory insects, which protect plants from herbivores. U.S. pollinator-dependent crops alone have an annual value of nearly $25 billion, and extrafloral nectar represents one of the few defense mechanisms for which stable effects on plant health and fitness have been demonstrated. However, to date, a holistic and coordinated effort to study the mechanisms involved in the synthesis and secretion of nectar components across species and nectary types has been lacking. The central hypothesis driving this work is that the genetic programs underlying nectar synthesis, secretion, and function are at least partially conserved between diverse species and nectary types. To address this hypothesis, gene expression in nectary tissues will first be characterized throughout the secretory process to characterize the steps centrally involved in the formation of an active nectary, and to identify genes directly required for the de novo synthesis and concurrent secretion of nectar components. Lastly, the composition of the secreted nectar will be characterized, with select components being tested in assays for their ecological function. Thus, the integration of all three major levels of study will reveal genes, molecular processes, and nectar components that mediate plant-animal mutualisms. Understanding the genetic and molecular mechanisms that control nectar production, as well as plant-animal interactions mediated by specific nectar components, will allow targeted studies to improve overall pollination efficiency, enhance biological control of pests that attack crops, and have the potential to greatly impact apiculture.