Proteomic analysis of the rice (Oryza officinalis) provides clues on molecular tagging of proteins for brown planthopper resistance

Abstract

Background: Among various pests, the brown planthopper (BPH) that damages rice is the major destructive pests. Understanding resistance mechanisms is a critical step toward effective control of BPH. This study investigates the proteomics of BPH interactions with three rice cultivars: the first resistant (PR) to BPH, the second susceptible (PS), and the third hybrid (HR) between the two, in order to understand mechanisms of BPH resistance in rice.

Results: Over 4900 proteins were identified from these three rice cultivars using iTRAQ proteomics study. A total of 414, 425 and 470 differentially expressed proteins (DEPs) were detected from PR, PS and HR, respectively, after BPH infestation. Identified DEPs are mainly enriched in categories related with biosynthesis of secondary metabolites, carbon metabolism, and glyoxylate and dicarboxylate metabolism. A two-component response regulator protein (ORR22) may participate in the early signal transduction after BPH infestation. In the case of the resistant rice cultivar (PR), 6 DEPs, i.e. two lipoxygenases (LOXs), a lipase, two dirigent proteins (DIRs) and an Ent-cassa-12,15-diene synthase (OsDTC1) are related to inheritable BPH resistance. A heat shock protein (HSP20) may take part in the physiological response to BPH infestation, making it a potential target for marker-assisted selection (MAS) of rice. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed eight genes encoding various metabolic proteins involved in BPH resistance. During grain development the expressions of these genes varied at the transcriptional and translational levels.

Conclusions: This study provides comprehensive details of key proteins under compatible and incompatible interactions during BPH infestation, which will be useful for further investigation of the molecular basis of rice resistance to BPH and for breeding BPH-resistant rice cultivars.

Keywords: Brown planthopper (BPH); Molecular mechanism; Proteomics; Resistance; Rice.

Fig. 1

Occurrence and symptom of different rice genotypes inoculated by brown rice planthopper. a Damage of brown rice planthopper in rice field and typical symptom in dictated at the right corner. b Phenotypes of rice genotypes inoculated by brown rice planthopper. Hybrid generations BPH was inoculate with (HR_B) and without (HR) brown rice planthopper; Different lines of hybridization generations BPH, O. officinalis, and O. sativa were inoculated with brown rice planthopper (HR_B, PR_B, PS_B) while treated without pest as mocks (HR, PR, PS), respectively

Fig. 2

The number of differentially expressed proteins in the three cultivars. The x-axis indicates the comparisons between each two samples. The left y-axis shows the number of differentially expressed proteins

Fig. 3

Venn diagram of DEPs in resistant and susceptible rice cultivars after inoculation with BPH. a Venn diagram of comparisons among HR_B-VS-HR, PS_B-VS-PS and PR_B-VS-PR. b Venn diagram of comparisons among HR_B-VS-HR, PS_B-VS-PS, PR_B-VS-PR, PR-VS-PS and HR-VS-PS

Fig. 4

Gene Ontology (GO) classification of DEPs in rice haulm after BPH infection

Fig. 5

Pathway enrichment analysis of DEPs in rice haulm after BPH infection

Fig. 6

Comparative analysis of protein and mRNA profiles of eight proteins. The x-axis represents comparisons between PS_B and PS, HR_B and HR, PR_B and PR respectively. The left y-axis indicates the relative protein level, whereas the right y-axis pertains to the relative mRNA level. The blue line represents the pattern of protein expression, and the orange line indicates the pattern of mRNA expression

Fig. 7

Fold change of proteins involved in rice inheritable resistance against BPH. The x-axis indicates the protein accession number of Uniprot database. The left y-axis shows the fold change of differentially expressed proteins