Genome-Wide Characterization of HSP90 Gene Family in Malus sieversii and Their Potential Roles in Response to Valsa mali Infection

Abstract

Heat shock protein 90 (HSP90) is highly conservative molecular chaperon produced by plants in response to adverse environmental stresses including fungal infection. In China, canker disease, caused by Valsa mali, is the main threat for Malus sieversii, an ancestor of the cultivated apple. In this study, a total of eight HSP90 genes were identified from the M. sieversii genome and randomly distributed on eight chromosomes. According to gene structure and phylogenetic analysis, the MsHSP90s can be divided into five categories. The transcriptome analysis of M. sieversii under V. mali infection showed that the plant pathogen interaction pathway was identified as significantly enriched. RNA-seq data and qRT-PCR analysis demonstrated that the MsHSP90-6a gene was significantly repressed by V. mali infection. We further predicted cis-regulatory elements on the promotor region of MsHSP90 genes and identified canonical SHE motifs. Our results improve our understanding of the HSP90 gene family and provide a foundation for further studies of disease prevention in M. sieversii.

Genome-wide characterization of the chitinase gene family in wild apple (Malus sieversii) and domesticated apple (Malus domestica) reveals its role in resistance to Valsa mali

“…The V. mali isolate EGI1 ( Liu et al., 2020 ) was grown on potato dextrose agar (PDA) medium (Rishui BioTechnologies, Qingdao, China) at 25°C for 3 days. Six-month-old plants were infected with V. mali as described previously ( Liu et al., 2020 ; Haxim et al., 2021 ). Briefly, mycelial plugs (diameter: 5 mm) were excised from 3-day-old cultures of isolate EGI1 on PDA medium.…”

“…The relative transcript abundance of the chitinase genes was analyzed with the 2 −ΔΔ C t method ( Livak and Schmittgen, 2001 ). The EF-1α (Elongation factor 1-α) gene has been evaluated for internal reference in apple species ( Zhu et al., 2019 ) and served as reference in our previous work ( Liu et al., 2021 ; Haxim et al., 2021 ; Liu et al., 2021 ) because of its stable expression in our previous work under V.mali infection. Therefore, the EF-1α gene was also used as an internal reference for the qPCR quantification in the present study.…”

“…The transcriptomic changes in response to V. mali infection have been investigated previously in M. sieversii ( Liu et al., 2021 ) and M. domestica ( Yin et al., 2016 ). The plant–pathogen interaction, plant hormone signal transduction, flavonoid biosynthesis, and phenylpropanoid biosynthesis pathways of M. sieversii ( Haxim et al., 2021 ; Liu et al., 2021 ), and chitin signaling pathway of M. domestica ( Yin et al., 2016 ) were significantly enriched in response to infection by V. mali. Exploration of the disease-resistance genes in apple responsive to V. mali infection is important for disease prevention in domesticated and wild apple species, especially M. sieversii .…”

Genome-Wide Identification of bHLH Transcription Factor Family in Malus sieversii and Functional Exploration of MsbHLH155.1 Gene under Valsa Canker Infection

“…Hence, it is extremely urgent to rescue and preserve the Tianshan Wild Fruit Forest. At present, Hsp20 (12 members) [ 23 ], Hsp90 (8 members) [ 24 ], and WRKY (112 members) [ 25 ] gene families have been identified in M. sieversii. However, the screening identification of functional gene resources in M. sieversii is not sufficient.…”