The 2HA line of Medicago truncatula has characteristics of an epigenetic mutant that is weakly ethylene insensitive

Kurdyukov, Sergey, Mathesius, Ulrike, Nolan, Kim E., Sheahan, Michael B., Goffard, Nicholas, Carroll, Bernard J. and Rose, Ray J. (2014) The 2HA line of Medicago truncatula has characteristics of an epigenetic mutant that is weakly ethylene insensitive. BMC Plant Biology, 14 174: 1-16. doi:10.1186/1471-2229-14-174


Author Kurdyukov, Sergey
Mathesius, Ulrike
Nolan, Kim E.
Sheahan, Michael B.
Goffard, Nicholas
Carroll, Bernard J.
Rose, Ray J.
Title The 2HA line of Medicago truncatula has characteristics of an epigenetic mutant that is weakly ethylene insensitive
Formatted title
The 2HA line of Medicago truncatula has characteristics of an epigenetic mutant that is weakly ethylene insensitive
Journal name BMC Plant Biology   Check publisher's open access policy
ISSN 1471-2229
Publication date 2014-06-21
Year available 2014
Sub-type Article (original research)
DOI 10.1186/1471-2229-14-174
Open Access Status DOI
Volume 14
Issue 174
Start page 1
End page 16
Total pages 16
Place of publication London United Kingdom
Publisher BioMed Central
Collection year 2015
Language eng
Formatted abstract
Background

The Medicago truncatula 2HA seed line is highly embryogenic while the parental line Jemalong rarely produces embryos. The 2HA line was developed from one of the rare Jemalong regenerates and this method for obtaining a highly regenerable genotype in M. truncatula is readily reproducible suggesting an epigenetic mechanism. Microarray transcriptomic analysis showed down regulation of an ETHYLENE INSENSITIVE 3-like gene in 2HA callus which provided an approach to investigating epigenetic regulation of genes related to ethylene signalling and the 2HA phenotype. Ethylene is involved in many developmental processes including somatic embryogenesis (SE) and is associated with stress responses.

Results

Microarray transcriptomic analysis showed a significant number of up-regulated transcripts in 2HA tissue culture, including nodule and embryo specific genes and transposon-like genes, while only a few genes were down-regulated, including an EIN3-like gene we called MtEIL1. This reduced expression was associated with ethylene insensitivity of 2HA plants that was further investigated. The weak ethylene insensitivity affected root and nodule development. Sequencing of MtEIL1 found no difference between 2HA and wild-type plants. DNA methylation analysis of MtEIL1 revealed significant difference between 2HA and wild-type plants. Tiling arrays demonstrated an elevated level of miRNA in 2HA plants that hybridised to the antisense strand of the MtEIL1 gene. AFLP-like methylation profiling revealed more differences in DNA methylation between 2HA and wild-type. Segregation analysis demonstrated the recessive nature of the eil1 phenotype and the dominant nature of the SE trait.

Conclusions

We have demonstrated that EIL1 of Medicago truncatula (MtEIL1) is epigenetically silenced in the 2HA seed line. The possible cause is an elevated level of miRNA that targets its 3’UTR and is also associated with DNA methylation of MtEIL1. Down regulation of MtEIL1 makes it possible to form nodules in the presence of ethylene and affects root growth under normal conditions. Segregation analysis showed no association between MtEIL1 expression and SE in culture but the role and mechanism of ethylene signalling in the process of plant regeneration through SE requires further investigation. The work also suggests that epigenetic changes to a particular gene induced in culture can be fixed in regenerated plants.
Keyword 2HA seed line
Somatic embryogenesis
Ethylene insensitivity
Nodulation
Root growth
Medicago truncatula
Epigenetics
DNA methylation
miRNA
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
 
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