Phytophthora root rot, caused by Phytophthora sojae, is a devastating soilborne disease of soybean (Glycine max). However, the epigenetic regulation of soybean responses to P. sojae remains incompletely understood. Here, using genetic, molecular and biochemical approaches, we characterized the functions of LIKE HETEROCHROMATIN PROTEIN 1 (GmLHP1) and its downstream regulatory network. We demonstrated that GmLHP1, as a reader of H3K27me3, negatively regulates soybean resistance to P. sojae. GmLHP1 binds to H3K27me3 peptides in vitro and colocalizes with H3K27me3 marks genome-wide in vivo. The integrated chromatin immunoprecipitation sequencing and RNA sequencing analysis identified the ethylene biosynthesis pathway gene 1-AMINO-CYCLOPROPANE-1-CARBOXYLATE SYNTHASE 18 (GmACS18) as being enriched for H3K27me3 and bound by GmLHP1, leading to its transcriptional downregulation. Notably, GmLHP1 associates with the GmACS18 promoter by directly binding to AATTAA motifs and recognizing H3K27me3 marks. Moreover, GmACS18 enhances defense against P. sojae by accumulating the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). Further analysis unveiled that recognition of H3K27me3 by GmLHP1 is essential for regulating soybean resistance to P. sojae through repressing GmACS18 transcription and decreasing ACC accumulation. Our findings reveal a novel epigenetic regulatory mechanism in which the H3K27me3 reader GmLHP1 blocks soybean resistance to P. sojae by repressing ethylene precursor ACC accumulation.
Xin Fang, Wen-Hao Ni, Jing-Can Sun et al.· New Phytologist· 0 citations
ABSTRACT Phytophthora root rot, a devastating disease caused by Phytophthora sojae, poses a significant threat to worldwide soybean ( Glycine max ) production. Therefore, enhancing crop resistance to this pathogen is a major breeding objective. However, the signalling mechanisms underlying the response of soybean plants to P. sojae infection, and the networks and targets of key transcription factors TFs, are not yet fully understood. Here, we reveal the mechanisms and function of GmERF109, which differs in expression between soybean cultivars resistant and susceptible to P. sojae race 1 and encodes an AP2/ERF transcription factor. Molecular evaluation and disease resistance analysis show that GmERF109 is a nucleus‐localized transcription factor that positively regulates soybean resistance to P. sojae. We also demonstrate that GmERF109 targets and activates the expression of GmG4DT‐like, a gene whose role in the biosynthesis of the phytoalexin glyceollin was confirmed through overexpression and RNA interference (RNAi) analyses. GmG4DT‐like also enhances P. sojae resistance. GmG4DT‐like and GmERF109 greatly increased the content of the glyceollin I isomer. Overall, our results suggest that GmERF109 enhances glyceollin accumulation by positively regulating the expression of its target gene GmG4DT‐like, thereby improving soybean resistance to P. sojae. These findings provide novel insights into soybean resistance to Phytophthora root rot and will be useful in efforts to create resistant soybean cultivars.
