A Pathogenesis-Related Protein-Like Gene Is Involved in the Panax notoginseng Defense Response to the Root Rot Pathogen.

Shan Li,Hongjun Chen,Bifeng Tang,Diqiu Liu,Lilei Zheng,Feng Ge,Xiuming Cui,Zie Wang

doi:10.3389/fpls.2020.610176

Shan Li, Hongjun Chen + Show 6 more

Open Access

https://doi.org/10.3389/fpls.2020.610176

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Abstract

Pathogenesis-related proteins (PRs) are a class of proteins that accumulate in response to biotic and abiotic stresses to protect plants from damage. In this study, a gene encoding a PR-like protein (PnPR-like) was isolated from Panax notoginseng, which is used in traditional Chinese herbal medicines. An analysis of gene expression in P. notoginseng indicated that PnPR-like was responsive to an infection by the root rot pathogen Fusarium solani. The expression of this gene was induced by several signaling molecules, including methyl jasmonate, ethephon, hydrogen peroxide, and salicylic acid. The PnPR-like-GFP fusion gene was transiently expressed in onion (Allium cepa) epidermal cells, which revealed that PnPR-like is a cytoplasmic protein. The purified recombinant PnPR-like protein expressed in Escherichia coli had antifungal effects on F. solani and Colletotrichum gloeosporioides as well as inhibited the spore germination of F. solani. Additionally, the in vitro ribonuclease (RNase) activity of the recombinant PnPR-like protein was revealed. The PnPR-like gene was inserted into tobacco (Nicotiana tabacum) to verify its function. The gene was stably expressed in T2 transgenic tobacco plants, which exhibited more RNase activity and greater disease resistance than the wild-type tobacco. Moreover, the transient expression of hairpin RNA targeting PnPR-like in P. notoginseng leaves increased the susceptibility to F. solani and decreased the PnPR-like expression level. In conclusion, the cytoplasmic protein PnPR-like, which has RNase activity, is involved in the P. notoginseng defense response to F. solani.

Highlights

Plants are sessile organisms that are usually subjected to a variety of biotic and abiotic stresses during growth
We proved that treating P. notoginseng roots with exogenous methyl jasmonate (MeJA) can significantly improve the resistance of plants to F. solani, and the expression levels of many P. notoginseng PR genes changed in response to an exogenous MeJA treatment and F. solani infection through transcriptome sequencing (Liu D. et al, 2019)
To further elucidate the PnPR-like function, PnPRlike expression was suppressed via RNAi, which resulted in P. notoginseng leaves that were more susceptible to F. solani than the WT leaves in vitro. These findings clearly indicate that PnPR-like is a defense response gene in P. notoginseng that protects plants against F. solani infections

Summary

Introduction

Plants are sessile organisms that are usually subjected to a variety of biotic and abiotic stresses during growth. Fungal diseases account for 70–80% of all plant diseases. Effectortriggered immunity (ETI) is an important part of plant innate immunity that protects against pathogen infections (Zhang J. et al, 2018). ETI is established via the recognition of. PnPR-Like Responsed to Pathogen Infection virulence effectors by the corresponding receptor resistance (R) proteins in a specific gene-to-gene manner (Zhang W. et al, 2018). The ETI induction mechanism in plants is activated, leading to the accumulation of pathogenesis-related proteins (PRs) (Mazumder et al, 2013). The accumulated PRs help plants prevent reinfections, resulting in the development of systemic acquired resistance (Zhang et al, 2013)

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