LC-MS/MS based comparative proteomics of floral nectars reveal different mechanisms involved in floral defense of Nicotiana spp. P. hybrida and D. stramonuim

ABSTRACT: Floral nectar is a rich secretion produced by nectaries offered as an attractive reward to pollinators. Floral nectaries secrete an aqueous solution largely composed of sugars and amino acids as well as an array of proteins called nectarins. These provide one of the main mechanisms of floral defense in Nicotiana nectar. Due to its composition, floral nectar provides an ideal source of nutrients for specialized microorganisms that can change the nectar composition. Understanding of floral defenses and the role of nectar proteins is essential to predict the impacts in microbial growth, nectar composition, and relationships between plants and pollinators. In order to deepen knowledge about Nicotiana spp. nectar proteins, we used LC-MS/MS-based comparative proteomic analysis to identify 22 proteins from Petunia hybrida, 35 proteins from Datura stramonium, and 144 proteins from 23 different species of Nicotiana. GO enrichment analysis and secretory signal peptide prediction demonstrated that defense/stress was the largest group of proteins in nectars with differential abundance and distribution throughout genus Nicotiana. The Nicotiana spp. proteome consisted of 105 exclusive proteins such as lipid transfer proteins (LTPs), Nectar Redox Cycle proteins, proteases inhibitors (PI), and PR-proteins. Analysis by taxonomic sections demonstrated that LTPs were the most abundant group of proteins in the nectar of Undulatae and Noctiflora sections while nectarins were more abundant proteins in Rusticae, Suaveolens, Polydicliae, and Alata sections. Peroxidases (Pox) and chitinases (Chit) were exclusive to P. hybrida nectar, while D. stramonium proteome had only seven unique proteins. Significant differences were identified between the proteome of taxonomic sections providing relevant insights into the group of proteins related to defense/stress associated with Nectar Redox Cycle, antimicrobial proteins and signaling pathways. The activity of floral nectar proteins is suggested impact the microbial growth. The knowledge about these proteomes provides significant insights into the diversity of proteins secreted in the nectars and the array of mechanisms used by Nicotiana spp. in its floral defense.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Nicotiana Bonariensis Nicotiana X Sanderae Nicotiana Longiflora Nicotiana Maritima Nicotiana Plumbaginifolia Datura Stramonium Nicotiana Glutinosa Nicotiana Alata Nicotiana Rustica Nicotiana Langsdorffii Nicotiana Forgetiana Nicotiana Clevelandii Nicotiana Noctiflora Nicotiana Repanda Nicotiana Sylvestris Nicotiana Tabacum (common Tobacco) Petunia Hybrida (petunia) Nicotiana Africana Nicotiana Glauca Nicotiana Paniculata Nicotiana Gossei Nicotiana Quadrivalvis Nicotiana Benthamiana Nicotiana Benavidesii

TISSUE(S): Nectar

SUBMITTER: Fredy Silva  

LAB HEAD: Robert Thornburg

PROVIDER: PXD014760 | Pride | 2020-01-08

REPOSITORIES: Pride