Dataset Information

Proteomics and gene expression analysis of Nicotiana tabacum nectar proteins

ABSTRACT: Floral nectar proteins (nectarins) are mainly enzymes and play important roles in inhibiting microbial growth in nectar and tailoring nectar chemistry before or after secretory. Nectar proteomes are usually small, but only very few plant species have had their nectar proteomes thoroughly investigated. Nectarins from Nicotiana tabacum (NT) were separated using two-dimensional gel electrophoresis, and then analyzed using mass spectrometry. Glycoproteins were isolated from raw NT nectar, separated by SDS-PAGE, and identified by mass spectrometry. All eight identified nectarins and four invertase genes’ expression were analysed by qPCR. Sugars composition, total sugar concentration, protein content, polyphenol content and hydrogen peroxide content were compared at different time intervals in extracted nectar and nectar in situ after secretion. Totally, eight nectarins were detected in NT nectar in which only two are glycoproteins, beta-xylosidase and a protein with unknown function. All of the eight nectarin genes expression was not nectary-specific and not synchronous along with the nectary development. After secretion, NT nectar in flower tube changed from sucrose–rich to hexose-rich type even though no free invertase or its activity was detected in NT nectar. No sugar composition changes observed in extracted nectar after incubating at 30 ℃ up to 48 hours in plastic tubes. Our results indicate that nectar post-secretory changes could be a complex process and tissue closely contact with nectar might function in it.

INSTRUMENT(S): 4800 Plus MALDI TOF/TOF

ORGANISM(S): Nicotiana Tabacum (common Tobacco)

SUBMITTER: Hong-Guang Zha

LAB HEAD: Hong-Guang Zha

PROVIDER: PXD011658 | Pride | 2019-08-20

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	NTpeaks.zip	Other
	NTraw.zip	Other
	NTresult.zip	Other

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Publications

Proteomics and post-secretory content adjustment of Nicotiana tabacum nectar.

Ma Xue-Long XL Milne Richard I RI Zhou Hong-Xia HX Song Yue-Qin YQ Fang Jiang-Yu JY Zha Hong-Guang HG

Planta 20190814 5

<h4>Main conclusion</h4>The tobacco nectar proteome mainly consists of pathogenesis-related proteins with two glycoproteins. Expression of nectarins was non-synchronous, and not nectary specific. After secretion, tobacco nectar changed from sucrose rich to hexose rich. Floral nectar proteins (nectarins) play important roles in inhibiting microbial growth in nectar, and probably also tailoring nectar chemistry before or after secretion; however, very few plant species have had their nectar proteo ...[more]

PMID: 31414205

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Project description:Cucurbita maxima c.v. Big Max is a monoecious plant with separate male and female flowers which utilizes nectar as a floral reward for the attraction of bees to the flowers. Maintenance of this mutualism with bees is essential for the reproductive success in this economically valuable crop. In this study, the sex-dependent variation in composition of male and female nectar and the nectaries were defined using a combination of GC-MS based metabolomics and LC-MS/MS based proteomics. Nectar proteins were detected non-quantitatively using LC-MS/MS coupled to Orbitrap. The male and female nectary proteomes were quantified using iTRAQ labeled peptides which were fractioned and concatenated prior to detection using LC-MS/MS coupled to Orbitrap. The nectar proteome consists of 46 proteins, of which 70% overlap between nectar types. Only two proteins are unique to female nectar, and 10 are specific to male nectar. Nectarins (nectar proteins) commonly alter nectar carbohydrates. In our datasets, significant differences in carbohydrate abundance, specifically galactose and sucrose, may be explained by the unique presence of galactinol--sucrose galactosyltransferase 2 (functioning in galactose metabolism) and invertase (catalyzes the hydrolysis of sucrose to glucose and fructose) in the nectar of female and male flowers respectively. The nectary proteome contained 339 identifiable proteins, 71% of which were descriptively annotatable by homology to Plantae. The abundance of 45 proteins differs significantly between male and female nectaries. GO slim analysis revealed a high abundance of proteins related to transport, protein metabolism, carbohydrate metabolism, response to stress, and amino acid metabolism. Comparisons of relative protein abundance revealed that 45 proteins displayed differential expression between male and female nectaries (p-value <0.05); 20 of these proteins were more abundant in male nectaries and 25 were more abundant in female nectaries. GO enrichment of nectary proteins with increased female abundances indicate that female-enriched GO terms are associated with proteins functioning as plasma membrane proton pumps and central metabolism. Proteins associated with male nectary-enriched GO terms were related to cinnamic acid biosynthesis and neutralization of superoxide radicals and hydrogen peroxide.