Responses of the tree peony (Paeonia suffruticosa, Paeoniaceae) cultivar 'Yu Hong' to heat stress revealed by iTRAQ-based quantitative proteomics

Abstract

Horticulture productivity has been increasingly restricted by heat stress from growing global warming, making it far below the optimum production capacity. As a popular ornamental cultivar of tree peony, Paeonia suffruticosa 'Yu Hong' has also been suffering from heat stress not suitable for its optimal growth. To better understand the response mechanisms against heat stress of tree peony, investigations of phenotypic changes, physiological responses, and quantitative proteomics were conducted. Phenotypic and physiological changes indicated that 24 h of exposure to heat stress (40 °C) was the critical duration of heat stress in tree peony. The proteomic analyses revealed a total of 100 heat-responsive proteins (HRPs). According to bioinformatic analysis of HRPs, the heat tolerance of tree peony might be related to signal transduction, synthesis/degradation, heat kinetic proteins, antioxidants, photosynthesis, energy conversion, and metabolism. Our research will provide some new insights into the molecular mechanism under the response against the heat stress of tree peony, which will benefit the future breeding of heat-resistant ornamental plants.

Keywords: Abiotic stress; Heat-responsive proteins; Omics analyses; Ornamental plant; Physiological response.

Fig. 1

Phenotypic changes of ‘Yu Hong’ leaves under heat stress for 0, 12, 24, and 36 h, respective, indicated by A to D

Fig. 2

Changes of physiological parameters of ‘Yu Hong’ leaves with treatment time. The physiological parameters include superoxide dismutase content (A), peroxidase content (B), proline content (C), malondialdehyde content (D), soluble protein content (E), and the relative electric conductivity (F). Different letters indicate a significant difference (p < 0.05) using Duncan’s multiple range test

Fig. 3

The change of HRPs in response to heat stress based on the proteomics data. CK1, CK2, CK3 represent three control groups, and TE1, TE2, TE3 represent three experimental groups

Fig. 4

COG annotation analysis of HRPs. Frequency indicates the number of HRPs in each COG functional classification

Fig. 5

GO annotation of HRPs. Biological process (A), Cellular component (B), Molecular function (C)

Fig. 6

KEGG pathway enrichment of HRPs

Fig. 7

Classification of HRPs into eight categories. A, Heat shock protein; B, Protein synthesis/degradation; C, Antioxidants; D, Energy conversion; E, Signal transduction; F, Photosynthesis; G, Metabolism; and H, Other unknown functional HRPs

Fig. 8

The model of tree peony response to heat stress. Cal, Calmodulin; CDPK, Calcium-dependent protein kinase; ABC, ABC transporter family member; LHCB, Chlorophyll a / b binding protein; NDH, NADH dehydrogenase; FtsH, FtsH protease; cytP450, Cytochrome P450; CS, Citrate synthase; FBA, Fructose- 1,6- bisphosphate aldolase; MDH, Malate dehydrogenase; Cox, Cytochrome C oxidase; GS, Glutamine Synthetase; PAL, Phenylalanine ammonia lyase; ACC, Acetyl-CoA catablerboxylase; sHSP, Small heat shook protein; HSP70, Hsp70 family protein; HSP90, Hsp90 family protein; POD, Peroxidase; APX, Ascorbate peroxidase; GPX, Glutathione peroxidase; CAT, Catalase; AaAER, 2-alkenal reductase; 40S r-protein, 40S Ribosomal protein; 60S r-protein, 60 s ribosomal protein L26-1; ClpB, Chaperone-protein ClpB; PPI, Peptidylprolyl isomerase; E2-17Ka, Ubiquitin-binding enzyme E2-17Ka; UBL, Ubiquitin-like family protein