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Open Access Research article

Some ethylene biosynthesis and AP2/ERF genes reveal a specific pattern of expression during somatic embryogenesis in Hevea brasiliensis

Piyanuch Piyatrakul12, Riza-Arief Putranto13, Florence Martin1, Maryannick Rio1, Florence Dessailly1, Julie Leclercq1, Jean-François Dufayard1, Ludovic Lardet1 and Pascal Montoro1*

Author Affiliations

1 CIRAD, UMR AGAP, F-34398, Montpellier, France

2 Rubber Research Institute, Chatuchak, Bangkok, 10900, Thailand

3 Indonesian Biotechnology Research Institute for Estate Crops, Bogor, Indonesia

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BMC Plant Biology 2012, 12:244  doi:10.1186/1471-2229-12-244

Published: 26 December 2012

Abstract

Background

Ethylene production and signalling play an important role in somatic embryogenesis, especially for species that are recalcitrant in in vitro culture. The AP2/ERF superfamily has been identified and classified in Hevea brasiliensis. This superfamily includes the ERFs involved in response to ethylene. The relative transcript abundance of ethylene biosynthesis genes and of AP2/ERF genes was analysed during somatic embryogenesis for callus lines with different regeneration potential, in order to identify genes regulated during that process.

Results

The analysis of relative transcript abundance was carried out by real-time RT-PCR for 142 genes. The transcripts of ERFs from group I, VII and VIII were abundant at all stages of the somatic embryogenesis process. Forty genetic expression markers for callus regeneration capacity were identified. Fourteen markers were found for proliferating calli and 35 markers for calli at the end of the embryogenesis induction phase. Sixteen markers discriminated between normal and abnormal embryos and, lastly, there were 36 markers of conversion into plantlets. A phylogenetic analysis comparing the sequences of the AP2 domains of Hevea and Arabidopsis genes enabled us to predict the function of 13 expression marker genes.

Conclusions

This first characterization of the AP2/ERF superfamily in Hevea revealed dramatic regulation of the expression of AP2/ERF genes during the somatic embryogenesis process. The gene expression markers of proliferating callus capacity to regenerate plants by somatic embryogenesis should make it possible to predict callus lines suitable to be used for multiplication. Further functional characterization of these markers opens up prospects for discovering specific AP2/ERF functions in the Hevea species for which somatic embryogenesis is difficult.

Keywords:
Gene expression; Plant hormone; Plant regeneration; Recalcitrant; Rubber; Signalling; Transcription factor