Proteomic analysis of pathogen-responsive proteins from maize stem apoplast triggered by Fusarium verticillioides

Abdul Haseeb Hafiz,Zhang Jun,Guo Yu-Shuang,Gao Mei-Xu,Guo Wei

doi:10.1016/s2095-3119(21)63657-2

Abstract

During the attack of a pathogen, a variety of defense-associated proteins are released by the host plant in the apoplast to impede the perceived attack. This study utilized the mass spectrometry (LC-MS/MS) and label-free quantification method to analyze the apoplastic fluid (APF) from maize stalk and identified the proteins responsive to the Fusarium verticillioides infection. We have identified 742 proteins, and among these, 119 proteins were differentially accumulated (DAPs), i.e., 35 up-regulated, 18 down-regulated, and 66 proteins were only induced by the pathogen infection. The differentially accumulated proteins were analyzed for their Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes (KEGG) pathway enrichment. The highly enriched Biological Process (BP) term was the L-serine biosynthesis process, whereas the most enriched Molecular Function (MF) term was the cysteine-type endopeptidase inhibitor activity. It was also found that the pathways related to the biosynthesis of amino acid, biosynthesis of secondary metabolites, protein processing in the endoplasmic reticulum, and carbohydrate metabolic pathways were significantly enriched. Moreover, 61 out of 119 differentially accumulated proteins were predicted as secretory proteins. The secretory pathways analysis showed that a greater number of proteins were secreted through the conventional secretion system compared to the unconventional secretion system. The identified secreted proteins were related to a variety of pathways in defense responses including cell redox homeostasis, cell wall modification, signal transduction, carbohydrate metabolism, binding proteins (metal ion binding, RNA binding and heme-binding), maintenance and stabilization of other proteins, indicating a complex response from the plant to the fungal infection. Our data suggested that a number of host proteins belonging to various pathways have been modulated in the apoplastic region.

Highlights

MethodsThe seeds of maize (B73), obtained from the Chinese Crop Germplasm Information System (CGRIS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, were surface sterilized by dipping in 2% Sodium Hypochlorite (NaOCl) solution followed by treatment with 70% Ethanol for 5 minutes each and washed at least three times with sterilized water
Plant apoplast is the frontline battlefield between the host and the invading pathogen
Our data suggested that the maize plants carried out a rigorous reprogramming of the proteins in the apoplastic region to cope with the attack of F. verticillioides

Summary

Methods

The seeds of maize (B73), obtained from the Chinese Crop Germplasm Information System (CGRIS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, were surface sterilized by dipping in 2% Sodium Hypochlorite (NaOCl) solution followed by treatment with 70% Ethanol for 5 minutes each and washed at least three times with sterilized water. The seeds were allowed to germinate in a contamination-free and humiditycontrolled growth facility at 25 oC with a 16 hours light/8 hours dark cycle and relative humidity of 80% for 72 hours. To apoplastic fluid was extracted from maize seedlings, which were grown in pots filled with solid substrate mixture and placed in a greenhouse at 25 oC temperature and 16 hours light/8 hours dark period. F. verticillioides (LNF15-11) strain was maintained on potato dextrose agar at 25 oC under 12 hours light/12 hours dark cycle for 7 days to induce conidiation.

Results

Discussion

Conclusion