Identification of Arbuscular Mycorrhiza Fungi Responsive microRNAs and Their Regulatory Network in Maize.

Suwen Zhu,Xuewen Wang,Wei Wang,Yunjian Xu,Fang Liu,Beijiu Cheng,Guomin Han

doi:10.3390/ijms19103201

Abstract

Maize can form symbiotic relationships with arbuscular mycorrhiza (AM) fungus to increase productivity and resistance, but the miRNAs in maize responsible for this process have not been discovered. In this study, 155 known and 28 novel miRNAs were identified by performing high-throughput sequencing of sRNA in maize roots colonized by AM fungi. Similar to the profiles in other AM-capable plants, a large proportion of identified maize miRNAs were 24 nt in length. Fourteen and two miRNAs were significantly down- and up-regulated in response to AM fungus Glomus intraradices inoculation, respectively, suggesting potential roles of these miRNAs in AM symbiosis. Interestingly, 12 of 14 significantly down-regulated known maize miRNAs belong to the miR399 family, which was previously reported to be involved in the interaction between Medicago truncatula and AM fungi. This result indicated that the miR399 family should regulate AM symbiosis conservatively across different plant lineages. Pathway and network analyses showed that the differentially expressed miRNAs might regulate lipid metabolism and phosphate starvation response in maize during the symbiosis process via their target genes. Several members of the miR399 family and the miR397 family should be involved in controlling the fatty acid metabolism and promoting lipid delivering from plants to AM fungi. To the best of our knowledge, this is the first report on miRNAs mediating fatty acids from plant to AM fungi. This study provides insight into the regulatory roles of miRNAs in the symbiosis between plants and AM fungi.

Highlights

Plant microRNAs are a class of short non-coding RNAs, generally 21–24 nt, that regulate the transcripts of target genes at transcriptional and post-transcriptional levels by forming the RISC (RNA-induced silencing complex) [1,2]
To study the role of miRNAs during the development of mycorrhiza, small RNA libraries derived from the maize roots with or without arbuscular mycorrhiza (AM) fungi inoculation were sequenced (Figure S1)
After the removal of adaptor sequences and low-quality reads, 1,332,127 and 1,460,953 high-quality clean reads, on average, were obtained from fungus Glomus intraradices—infected samples and the control samples, respectively (Table S1). 90.28% reads from fungal infected roots were perfectly mapped onto maize genome, while 83.67% reads from roots without fungal inoculation were perfectly mapped (Table S1)

Summary

Introduction

Plant microRNAs (miRNAs) are a class of short non-coding RNAs, generally 21–24 nt, that regulate the transcripts of target genes at transcriptional and post-transcriptional levels by forming the RISC (RNA-induced silencing complex) [1,2]. MiRNAs play important roles in plant development, nutrient signaling, hormonal signaling, organogenesis, and resistance to abiotic stresses [4,5]. Several miRNAs have been reported to be involved in biotic stresses [7]. MiR393 in Arabidopsis was the earliest identified miRNA which could control pathogen resistance by negatively regulating transcripts of auxin receptors [8]. MiRNA863-3p in Arabidopsis positively regulates plant immunity upon infection by sequentially targeting negative regulators [9]

Methods

Results

Conclusion