Identification of Regulatory Networks of MicroRNAs and Their Targets in Response to Colletotrichum gloeosporioides in Tea Plant (Camellia sinensis L.).

Anburaj Jeyaraj,Shuangshuang Wang,Ran Zhang,Xuewen Wang,Shengrui Liu,Chaoling Wei,Ailin Wu

doi:10.3389/fpls.2019.01096

Anburaj Jeyaraj, Shuangshuang Wang + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2019.01096

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Abstract

Anthracnose disease is caused by Colletotrichum gloeosporioides, and is common in leaves of the tea plant (Camellia sinensis). MicroRNAs (miRNAs) have been known as key modulators of gene expression in response to environmental stresses, disease resistance, defense responses, and plant immunity. However, the role of miRNAs in responses to C. gloeosporioides remains unexplored in tea plant. Therefore, in the present study, six miRNA sequencing data sets and two degradome data sets were generated from C. gloeosporioides-inoculated and control tea leaves. A total of 485 conserved and 761 novel miRNAs were identified. Of those, 239 known and 369 novel miRNAs exhibited significantly differential expression under C. gloeosporioides stress. One thousand one hundred thirty-four and 596 mRNAs were identified as targets of 389 conserved and 299 novel miRNAs by degradome analysis, respectively. Based on degradome analysis, most of the predicted targets are negatively correlated with their corresponding conserved and novel miRNAs. The expression levels of 12 miRNAs and their targets were validated by quantitative real-time PCR. A negative correlation between expression profiles of five miRNAs (PC-5p-80764_22, csn-miR160c, csn-miR828a, csn-miR164a, and csn-miR169e) and their targets (WRKY, ARF, MYB75, NAC, and NFY transcription factor) was observed. The predicted targets of five interesting miRNAs were further validated through 5’RLM-RACE. Furthermore, Gene Ontology and metabolism pathway analysis revealed that most of the target genes were involved in the regulation of auxin pathway, ROS scavenging pathway, salicylic acid mediated pathway, receptor kinases, and transcription factors for plant growth and development as well as stress responses in tea plant against C. gloeosporioides stress. This study enriches the resources of stress-responsive miRNAs and their targets in C. sinensis and thus provides novel insights into the miRNA-mediated regulatory mechanisms, which could contribute to the enhanced susceptibility of C. gloeosporioides in tea plant.

Highlights

Plants have evolved to respond to biotic and abiotic stresses through a repertoire of mechanisms, which regulate gene expression to maximize chances of survival in hostile conditions (Dorantes-Acosta et al, 2012)
We found that some miRNAs and their corresponding target genes are involved in the regulation of transcription factors, hormone signaling, and crosstalk between defense-related signaling hormones (ABA, salicylic acid (SA), jasmonic acid (JA), ET, and auxin) as well as phenylpropanoid biosynthesis; this is consistent with previous studies, which showed that SA signaling is an integral part of both the PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI) defense responses (Yi et al, 2014, Chen et al, 2017)
Our results show that several important miRNAs are differentially expressed in C. gloeosporioides–infected leaves

Summary

Introduction

Plants have evolved to respond to biotic and abiotic stresses through a repertoire of mechanisms, which regulate gene expression to maximize chances of survival in hostile conditions (Dorantes-Acosta et al, 2012). Plants trigger two layers of immunity against pathogens, which are pathogen-associated molecular patterns (PAMPs) triggered immunity (PTI) and effector-triggered immunity (ETI). Perception of PAMPs triggers basal defense, known as PTI, which encompasses the immune responses against most pathogens (Jones and Dangl, 2006). Effective pathogens have evolved mechanisms to counteract the basal defense by delivering PTI interfering effector proteins into the plant cells (Chisholm et al, 2006). Many plants have evolved another layer of immunity, ETI. Most studies of plant immunity have focused on the transcriptional regulation of protein-coding genes. It has been found that diverse miRNAs are responsive to infection and stress, and function in plant responses to both biotic and abiotic stresses (Xin et al, 2010; Chen et al, 2017)

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