The study investigated the changes in IgE binding capacity, protein profiles and peptide compositions after soybeans were boiled and autoclaved. The results of ELISA showed that the IgE binding capacity of soybean was reduced by 69.3% and 88.9% after boiling and autoclaving, respectively. Above 43 and 10 kDa proteins disappeared in boiled and autoclaved soybeans from SDS-PAGE, respectively. A Venn diagram and heat map showed that there was no change in allergen types and a reduction in allergen contents in the boiled and autoclaved soybeans. The changes in peptide compositions were also observed in the boiled and autoclaved soybeans through Venn diagram, PCA and heat map. LC/MS-MS and peptide mapping analysis demonstrated that boiling and autoclaving masked many epitopes in Gly m 4 and Gly m 5, such as ALVTDADNVIPK, SVENVEGNGGPGTIKK and KITFLEDGETK of Gly m 4 and VEKEECEEGEIPRPRPRPQHPER of Gly m 5, resulting in a reduction of IgE binding capacity in the extracted proteins. By contrast, the exposure of many epitopes in Gly m 6 was observed in boiled and autoclaved soybeans, which might be mainly responsible for the existing IgE binding capacity in the treated soybean proteins. Interestingly, the IgE binding capacity of soybeans showed a positive correlation with the total contents and number of peptides in Gly m 4–Gly m 6.

Soybean is a legume crop rich in protein and oil. Symbiotic nitrogen fixation plays an important role in the growth of soybean. The type-III effectors such as NopT and NopP are the important signaling factors for the establishment of symbiosis in soybean. In this study, the analysis of nodulation in soybean after inoculation with HH103ΩNopT, HH103ΩNopP, and HH103ΩNopT&NopP indicated crosstalking between NopT and NopP. Further, we aimed to identify the genes of soybean involved in the pathway underlying the crosstalk between NopT and NopP using RNA-seq analysis. Five of the identified candidate genes were confirmed to be induced by NopT and NopP. The expression of GmPBS1 significantly increased to a much larger extent than that of the other four genes after soybean was inoculated with HH103ΩNopT, HH103ΩNopP, or HH103ΩNopT&NopP. The interaction between NopT and GmPBS1 was confirmed via bimolecular fluorescence complementation. Finally, nodulation analysis after GmPBS1 overexpression in the hairy roots indicate that GmPBS1 can regulate the negative effect of NopP on the nodulation, and this regulation is related to NopT. Collectively, our results suggested that during the nodulation in soybean, NopT and NopP have a crosstalking network and GmPBS1 is the hub gene.

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