The Role of Jasmonates in Floral Nectar Secretion

Abstract

Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far. We investigated whether jasmonates have an influence on floral nectar secretion in oil-seed rape, Brassica napus. The floral tissues of this plant produced jasmonic acid (JA) endogenously, and JA concentrations peaked shortly before nectar secretion was highest. Exogenous application of JA to flowers induced nectar secretion, which was suppressed by treatment with phenidone, an inhibitor of JA synthesis. This effect could be reversed by additional application of JA. Jasmonoyl-isoleucine and its structural mimic coronalon also increased nectar secretion. Herbivory or addition of JA to the leaves did not have an effect on floral nectar secretion, demonstrating a functional separation of systemic defence signalling from reproductive nectar secretion. Jasmonates, which have been intensively studied in the context of herbivore defences and flower development, have a profound effect on floral nectar secretion and, thus, pollination efficiency in B. napus. Our results link floral nectar secretion to jasmonate signalling and thereby integrate the floral nectar secretion into the complex network of oxylipid-mediated developmental processes of plants.

Venus flytrap carnivorous lifestyle builds on herbivore defense strategies

“…In nature, gland secretion is stimulated upon insect capture and, in the laboratory, by the application of JA or its molecular mimic COR (Radhika et al 2010). Both stimuli result in gross ultrastructural changes in gland cells.…”

Poplar Extrafloral Nectaries: Two Types, Two Strategies of Indirect Defenses against Herbivores

“…Recent studies indicate that continuous mechanical tissue damage is sufficient to trigger JA production and subsequent volatile emission (Mithöfer et al, 2005). In addition to wounding, chemical elicitors present in insect saliva also may play an important role in the extrafloral nectary response (Radhika et al, 2010). Upon wounding of Ptr, a typical JA or herbivory-linked VOC spectrum was emitted, but new nectaries or the release of nectar from existing nectaries were not observed.…”

Phenolic profiles of nectar and honey of Quillaja saponaria Mol. (Quillajaceae) as potential chemical markers

“…Secondary metabolites, generally appearing in low levels but clearly involved in ecological interactions, have been also reported (Radhika et al, 2010). Extensive research has explained the role played by the components in the antioxidant ability of honey (Busserolles et al, 2002;Schramm et al, 2003;Muñoz et al, 2007).…”