Transcriptomic and Proteomic Profiling Reveal the Key Role of AcMYB16 in the Response of Pseudomonas syringae pv. actinidiae in Kiwifruit.

Xiaojie Wang,Yawei Li,Yuanyuan Liu,Bing Jia,Pu Liu,Min Ni,Li-Wu Zhu,Wei Heng,Dongle Zhang,Zemin Fang

doi:10.3389/fpls.2021.756330

Xiaojie Wang, Yawei Li + Show 8 more

Open Access

https://doi.org/10.3389/fpls.2021.756330

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Abstract

Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa), is an important disease of kiwifruit (Actinidia Lind.). Plant hormones may induce various secondary metabolites to resist pathogens via modulation of hormone-responsive transcription factors (TFs), as reported in past studies. In this study, we showed that JA accumulated in the susceptible cultivar Actinidia chinensis ‘Hongyang’ but decreased in the resistant cultivar of A. chinensis var. deliciosa ‘Jinkui’ in response to Psa. Integrated transcriptomic and proteomic analyses were carried out using the resistant cultivar ‘Jinkui’. A total of 5,045 differentially expressed genes (DEGs) and 1,681 differentially expressed proteins (DEPs) were identified after Psa infection. Two pathways, ‘plant hormone signal transduction’ and ‘phenylpropanoid biosynthesis,’ were activated at the protein and transcript levels. In addition, a total of 27 R2R3-MYB transcription factors (TFs) were involved in the response to Psa of ‘Jinkui,’ including the R2R3-MYB TF subgroup 4 gene AcMYB16, which was downregulated in ‘Jinkui’ but upregulated in ‘Hongyang.’ The promoter region of AcMYB16 has a MeJA responsiveness cis-acting regulatory element (CRE). Transient expression of the AcMYB16 gene in the leaves of ‘Jinkui’ induced Psa infection. Together, these data suggest that AcMYB16 acts as a repressor to regulate the response of kiwifruit to Psa infection. Our work will help to unravel the processes of kiwifruit resistance to pathogens and will facilitate the development of varieties with resistance against bacterial pathogens.

Highlights

Kiwifruit of the genus Actinidia Lind. is an economically important fresh fruit worldwide because of its rich nutritional value
The results showed that abscisic acid (ABA) and salicylic acid (SA) were increased in both cultivars after Pseudomonas syringae pv. actinidiae (Psa) inoculation at different times, but jasmonic acid (JA) accumulated in ‘Hongyang’ and decreased in ‘Jingkui’ (Figure 1) at 1 dpi
62.54% of reads mapped to the kiwifruit reference genome A. chinensis var. chinensis ‘Red 5’ (Wei et al, 2020)

Summary

Introduction

Kiwifruit of the genus Actinidia Lind. is an economically important fresh fruit worldwide because of its rich nutritional value. Actinidiae (Psa), has already become an economic threat to the kiwifruit industry worldwide (Tahir et al, 2019; Li et al, 2021). Many efforts have been made to uncover the population structure of Psa, and at least five types of populations, including biovars 1, 2, 3, 5, and 6, have been defined based on their virulence, toxin production, and host range, of which biovar 3 is responsible for the global pandemic (He et al, 2019). Most of the globally cultivated cultivars of kiwifruit, including Actinidia chinensis var. Deliciosa, as well as accessions from Actinidia arguta and Actinidia kolomikta, are natural hosts of Psa (Tahir et al, 2019). Chinensis, including ‘Hongyang,’ ‘Hort16A,’ and ‘Jintao’, are considered more susceptible to biovar 3 than A. chinensis var. Many cultivars of A. chinensis var. chinensis, including ‘Hongyang,’ ‘Hort16A,’ and ‘Jintao’, are considered more susceptible to biovar 3 than A. chinensis var. deliciosa, including ‘Jinkui’ and ‘Xuxiang’ (Li et al, 2020; Wang et al, 2020)

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