RNA sequencing analysis provides new insights into dynamic molecular responses to Valsa mali pathogenicity in apple ‘Changfu No. 2’
Valsa canker caused by the necrotrophic pathogen Valsa mali (Vm) severely affects apple production in Eastern Asia. The molecular basis underlying the apple response to Vm infection is poorly understood. Hence, we performed RNA sequencing (RNA-seq) to investigate the dynamic gene expression profiles of a major apple cultivar, ‘Changfu No.2’, during Vm infection. Compared with the control (C), 104, 313, and 1059 differentially expressed genes (DEGs) were detected from the phloem tissue within the range of 0.9–1.3 cm (T1), 0.5–0.9 cm (T2), and 0.1–0.5 cm (T3) beyond the lesion periphery, respectively. Gene ontology (GO) enrichment analysis revealed that the DEGs associated with plant growth and development were down-regulated, whereas those related to defense responses were up-regulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that hormonal and Ca2+ signaling and phenylpropanoid biosynthesis were involved in the defense responses. In conclusion, multiple defense responses associated with ABA, JA, ET, Ca2+, and cell wall signals contributed to the defense against Vm infection in ‘Changfu No.2’. In contrast, the DEGs with inhibited expression were involved in plant growth and development; auxin signaling and several resistance genes might weaken the resistance of ‘Changfu No.2’ to pathogens. Our results offer a new insight into plant responses against necrotrophs and could benefit programs aimed at breeding for Vm resistance.
KeywordsValsa canker Apple Hormone Ca2+-signal Defense responses
Cell wall degrading enzymes
Differentially expressed genes
Methyl salicylic acid
Pathogen-associated molecular pattern
Real-time quantitative PCR
Systemic acquired resistance
We would like to thank Ph.D Lijun Bai (GeneBang Inc., Chengdu, China, www.genebang.com) for technical assistance with RNA sequencing and bioinformatic analysis.
ZC and CB conceived, designed, and coordinated the study. ZC, MJ, CM, and DH performed the experiments and collected, analyzed, and deposited the data. CZ proofread the final draft and revised the manuscript. All authors have read and approved the manuscript.
This work was supported by the Talent introduction Project of Gansu Agricultural University (GSAU-RCZX201712) and the Natural Science Foundation of China No. 31501728.
Compliance with ethical standards
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This article does not contain any studies with human participants performed by any of the authors.
Data Archiving Statement
The raw data has been deposited in the National Center for Biotechnology information (NCBI) Short Read Archive (SPA) under accession number SRP160545.
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