Differential Responses of OsMPKs in IR56 Rice to Two BPH Populations of Different Virulence Levels.

Satyabrata Nanda,San-Yue Yuan,Feng-Xiang Lai,Wei-Xia Wang,Qiang Fu,Pin-Jun Wan

doi:10.3390/ijms19124030

Satyabrata Nanda, San-Yue Yuan + Show 4 more

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https://doi.org/10.3390/ijms19124030

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Abstract

The conserved mitogen-activated protein kinase (MAPK) cascades play vital roles in plant defense responses against pathogens and insects. In the current study, the expression profiles of 17 OsMPKs were determined in the TN1 and IR56 rice varieties under the infestation of brown planthopper (BPH), one of the most destructive hemimetabolous rice pests. The virulent IR56 BPH population (IR56-BPH) and the avirulent TN1 BPH population (TN-BPH) were used to reveal the roles of OsMPKs in the compatible (IR56-BPH infested on the TN1 and IR56 rice varieties, and TN1-BPH infested on the TN1 rice variety) and the incompatible (TN1-BPH infested on the IR56 rice variety) interaction. The statistical analysis revealed that rice variety, BPH population type, and infestation period have significant effects on the transcription of OsMPKs. Out of these genes, five OsMPKs (OsMPK1, OsMPK3, OsMPK7, OsMPK14, and OsMPK16) were found to exhibit upregulated expression only during incompatible interaction. Six OsMPKs (OsMPK4, OsMPK5, OsMPK8, OsMPK9, OsMPK12, and OsMPK13) were associated with both incompatible and compatible interactions. The transcription analysis of salicylic acid, jasmonic acid, and ethylene phytohormone signaling genes revealed their roles during the rice–BPH interactions. The upregulated expression of OsC4H, OsCHS, and OsCHI in the incompatible interaction implied the potential defense regulatory roles of phenylpropanoids. In both varieties, the elevated transcript accumulations of OsGST and OsSOD, and the increased enzyme activities of POD, SOD, and GST at 1 day post-infestation (dpi), but not at 3 dpi, indicated that reactive oxygen species (ROS) signaling might be an early event in rice–BPH interactions. Furthermore, upregulated transcription of OsLecRK3 and OsLecRK4 was found only during an incompatible interaction, suggesting their involvement in the BPH resistance response in the IR56 rice variety. Lastly, based on the findings of this study, we have proposed a model of interactions of IR56 rice with TN1-BPH and IR56-BPH that depicts the resistance and susceptibility reactions, respectively.

Highlights

The brown planthopper (Nilaparvata lugens Stål, hereafter referred to as BPH) is the most harmful pest to rice (Oryza sativa), and causes huge crop damage and billions of dollars of economic loss in Asia [1]
IR56 rice had higher (p < 0.01) mRNA levels of OsMPK7 and OsMPK16 than those in TN1 rice, and vice versa for OsMPK8 and OsMPK13. These results revealed that six O. sativa MAPKs (OsMPKs) (OsMPK3, OsMPK5, and OsMPK13 in both rice varieties, OsMPK8 in TN1 rice, and OsMPK7 and OsMPK16 in IR56 rice) were upregulated in response to wounding in rice, while two OsMPKs (OsMPK4 in both rice varieties and OsMPK6 in TN1 rice) were downregulated
The findings from the study suggested that multiple factors, including rice variety, BPH population type, and infestation period have significant effects on the expression of the OsMPKs

Summary

Introduction

The brown planthopper (Nilaparvata lugens Stål, hereafter referred to as BPH) is the most harmful pest to rice (Oryza sativa), and causes huge crop damage and billions of dollars of economic loss in Asia [1]. It is a typical monophagous vascular feeder that sucks the rice phloem sap, resulting in the wilting and fatal drying of rice plants, a phenomenon known as ‘hopperburn’ [1]. The BPH-resistant sources were first identified in 1967 [2], and in 1970, Bph (from Mudgo) and bph (from ASD7), the two BPH resistance genes, were identified in rice [3]. The molecular mechanism underlying the interaction between IR56-BPH and its host plant has not been well-elucidated

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