Soybean cyst nematode (SCN, Heterodera glycines) is an obligate sedentary biotroph that poses major threats to soybean production globally. Recently, multiple miRNAome studies revealed that miRNAs participate in complicated soybean-SCN interactions by regulating their target genes. However, the functional roles of miRNA and target genes regulatory network are still poorly understood. In present study, we firstly investigated the expression patterns of miR159 and targeted GmMYB33 genes. The results showed miR159-3p downregulation during SCN infection; conversely, GmMYB33 genes upregulated. Furthermore, miR159 overexpressing and silencing soybean hairy roots exhibited strong resistance and susceptibility to H. glycines, respectively. In particular, miR159-GAMYB genes are reported to be involve in GA signaling and metabolism. Therefore, we then investigated the effects of GA application on the expression of miR159-GAMYB module and the development of H. glycines. We found that GA directly controls the miR159-GAMYB module, and exogenous GA application enhanced endogenous biologically active GA1 and GA3, the abundance of miR159, lowered the expression of GmMYB33 genes and delayed the development of H. glycines. Moreover, SCN infection also results in endogenous GA content decreased in soybean roots. In summary, the soybean miR159-GmMYB33 module was directly involved in the GA-modulated soybean resistance to H. glycines.

Soybean cyst nematode (SCN) causes heavy losses to soybean yield. In order to investigate the roles of soybean miRNAs during the early stages of infection (1 and 5 dpi), 24 small RNA libraries were constructed from SCN resistant cultivar Huipizhi (HPZ) and the susceptible Williams 82 (W82) cultivar for high-throughput sequencing. By sequencing the small RNA libraries, a total of 634 known miRNAs were identified, and 252 novel miRNAs were predicted. Altogether, 14 known miRNAs belonging to 13 families, and 26 novel miRNAs were differentially expressed and may respond to SCN infection in HPZ and W82. Similar expression results were also confirmed by qRT-PCR. Further analysis of the biological processes that these potential target genes of differentially expressed miRNAs regulate found that they may be strongly related to plant–pathogen interactions. Overall, soybean miRNAs experience profound changes in early stages of SCN infection in both HPZ and W82. The findings of this study can provide insight into miRNAome changes in both HPZ and W82 at the early stages of infection, and may provide a stepping stone for future SCN management.

Ubiquitination is a kind of post-translational modification of proteins that plays an important role in plant response to biotic and abiotic stress. The response of soybean GmPUB genes to soybean cyst nematode (SCN, Heterodera glycines) infection is largely unknown. In this study, quantitative real-time PCR (qRT‒PCR) was performed to detect the relative expression of 49 GmPUB genes in susceptible cultivar William 82 and resistant cultivar Huipizhi after SCN inoculation. The results show that GmPUB genes responded to cyst nematode infection at 1 day post-inoculation (dpi), 5 dpi, 10 dpi and 15 dpi. The expression levels of GmPUB16A, GmPUB20A, GmCHIPA, GmPUB33A, GmPUB23A and GmPUB24A were dramatically changed during SCN infection. Furthermore, functional analysis of these GmPUB genes by overexpression and RNAi showed that GmPUB20A, GmPUB33A and GmPUB24A negatively regulated soybean resistance under SCN stress. The results from our present study provide insights into the complicated molecular mechanism of the interaction between soybean and SCN.

Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is responsible for causing a major soybean disease globally. The fungal strain Penicillium janthinellum Snef1650 was evaluated against H. glycines. However, the effective determinants of the P. janthinellum strain are unknown. By performing pot experiments, a functioning compound was isolated from P. janthinellum Snef1650 through organic solvent extraction, semi-preparative HPLC, Sephadex LH-20 column chromatography, and silica gel column chromatography, and the isolated compound was identified to be scopoletin through 1H NMR, 13C NMR, and HPLC–MS. The pot experiments indicated that the treatment of soybean seeds with scopoletin drastically reduced the SCN population. The field experiments performed in 2017 and 2018 revealed that scopoletin decreased over 43.7% juveniles in the roots and over 61.55% cysts in the soil. Scopoletin treatment also promoted soybean growth and improved its yield, with an increase in plot yield by >5.33%. Scopoletin obtained from P. janthinellum Snef1650 could be used as an anti-H. glycines biocontrol agent.

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