Huanhuan Hu

Valsa canker, caused by Valsa pyri (Vp), severely threatens global pear production. The VAMP72 family modulates plant immunity, but its role in Valsa canker resistance remains unclear. In this study, it was found that PbeVAMP724, encoding a membrane-localized SNARE protein, was significantly induced by Vp infection and Abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA) in the resistant pear rootstock Pyrus betulaefolia. Transient overexpression of PbeVAMP724 in ‘Huangguan’ fruits reduced Vp-induced lesions, and the lesion diameter was reduced by 23.1% at 48 h and 20.0% at 72 h compared to the empty vector control (pFGC-5941), whereas VIGS silencing compromised the resistance. Stable overexpression in suspension cells ‘Duli-G03’ (P. betulifolia) enhanced tolerance to Vp metabolites (VpM), alleviated cell death, and induced ROS bursts and defense responses. Weighted gene co-expression network analysis (WGCNA) revealed that phloem/xylem histogenesis-related genes (GWHGAAYT028948, GWHGAAYT039435) are co-expressed with PbeVAMP724. In conclusion, we demonstrate that PbeVAMP724 integrates hormone signaling, triggers ROS bursts, and activates defense responses to positively regulate resistance to Valsa canker in pear, representing a promising candidate for breeding Valsa canker-resistant pear varieties.

Valsa canker, caused by Valsa mali (Cytospora mali) or V. pyri, is a destructive fungal disease affecting apple and pear production. NAC transcription factors have been shown to participate in multiple immune signaling pathways. However, the key members of this family involved in Valsa canker resistance remain largely unknown. In this study, we demonstrate that PbeNAC72, an NAC transcription factor responsive to Valsa canker signals in Pyrus betulifolia, positively regulates resistance in apple and pear fruits. In ‘Duli-G03’ (P. betulifolia) suspension cells, overexpression of PbeNAC72 significantly enhanced resistance to Valsa canker and induced reactive oxygen species bursts, as well as the expression of salicylic acid and jasmonic acid-related genes. Subsequent weighted gene co-expression network analysis revealed that PbeNAC72 is primarily linked to genes associated with “DNA replication” and “microtubule-based movement.” We therefore suggest that PbeNAC72 activates genes related to core signaling pathways and fundamental cellular processes, which further contribute to the positive regulation of Valsa canker resistance. Our results provide novel insights into the resistance mechanism and identify a candidate gene for future molecular breeding efforts.

The ATP-binding cassette (ABC) transporter family plays a critical role in plant growth, development, and disease resistance. However, the evolution and functional characteristics of the ABC gene family in Rosaceae species have not been fully studied. In this study, we performed the first whole-genome identification, as well as an evolutionary analysis and comparative analysis of ABC genes in Rosaceae plants. We identified 3037 ABC genes in 20 plant species, classifying them into eight subfamilies. Comparative analysis revealed significant variations in family size and expansion patterns among species, suggesting adaptive evolution. Tandem duplication (TD: where genes are duplicated in sequence) and whole-genome duplication (WGD: duplication of the entire genome) were identified as the primary drivers of ABC family expansion. In pears, gene pairs produced by WGD underwent purifying selection. Gene ontology (GO) enrichment analysis indicated the involvement of ABC proteins in transmembrane transport and signal transduction pathways. Under Valsa pyri infection, most ABC genes were upregulated in the early stages, highlighting the role of ABCG genes in pathogen response. A weighted gene co-expression network analysis (WGCNA) identified five key ABCG genes potentially involved in pathogen resistance regulation. Our findings provide insights into the evolutionary adaptability of the ABC gene family and their potential applications in plant disease defense.