Introduction of the harpinXooc-encoding gene hrf2 in soybean enhances resistance against the oomycete pathogen Phytophthora sojae
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Phytophthora root and stem rot (PRR) caused by an oomycete pathogen Phytophthora sojae is one of the most devastating and widespread diseases throughout soybean-producing regions worldwide. The diversity and variability of P. sojae races make effective control of the pathogen challenging. Here, we introduced an elicitor of plant defense response, the harpinXooc-encoding hrf2 gene from the rice bacterial pathogen Xanthomonas oryzae pv. oryzicola into soybean and evaluated resistance to P. sojae infection. Molecular analysis confirmed the integration and expression of hrf2 in the transgenic soybean. After inoculation with P. sojae, non-transformed control (NC) plants exhibited typical PRR symptoms, including necrotic and wilting leaves, and plant death, whereas most of the transgenic plants showed slightly chlorotic leaves and developed normally. Through T3 to T5 generations, the transgenic events displayed milder disease symptoms and had higher survival rates compared to NC plants, indicating enhanced and stable resistance to P. sojae infection, whereas without P. sojae inoculation, no significant differences in agronomic traits were observed between the transgenic and non-transformed plants. Moreover, after inoculation with P. sojae, significant upregulation of a set of plant defense-related genes, including salicylic acid- and jasmonic acid-dependent and hypersensitive response-related genes was observed in the transgenic plants. Our results indicate that hrf2 expression in transgenic soybean significantly enhanced resistance to P. sojae by eliciting multiple defense responses mediated by different signaling pathways. The potential functional role of the hrf2 gene in plant defense against P. sojae and other pathogens makes it a promising tool for broadening disease resistance in soybean.
KeywordsSoybean Phytophthora stem and root rot Phytophthora sojae hrf2 Harpin Defense response
This work was supported by Grants from Jilin Provincial Agricultural Science & Technology Innovation Project (c8223001010, c7208000307) and National Natural Science Foundation of China (31701448). We thank Prof. Xuewen Gao (Nanjing Agricultural University, China) for providing the pM18-hrf2 plasmid. We would also like to thank Editage (www.editage.cn) for English language editing.
XY designed the experiments. LN conducted the experiments and wrote the manuscript. GX, DG, LS, and QZ performed Agrobacterium-mediated transformation experiments. JZ conducted the hypocotyl inoculation assay. HH, JY, and XZ participated in molecular screening and qRT-PCR analyses. All authors have read the manuscript and contributed to its revision.
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Conflict of interest
The authors declare no conflict of interest.
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