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Salicylic acid and methyljasmonate restore the transcription of caffeine biosynthetic N-methyltransferases from a transcription inhibition noticed during late endosperm maturation in coffee.

Avinash, Kumar and Giridhar, P. (2015) Salicylic acid and methyljasmonate restore the transcription of caffeine biosynthetic N-methyltransferases from a transcription inhibition noticed during late endosperm maturation in coffee. Plant Gene (2015), 4. pp. 38-44.

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Abstract

Transcripts of the three N-methyltransferase (NMT) genes involved in the core caffeine biosynthesis of coffee are repressed during the early stages of endosperm maturation, coincident with the onset of dry weight accumulation and seed desiccation. Previously, we noticed that the exogenous application of salicylic acid (SA) and methyljasmonate (MeJ) to Coffea canephora var. robusta cv. S-274 overexpresses transcripts of the three NMTs in young leaves. Thus, transcriptional regulation of caffeine biosynthetic genes may play a vital role in caffeine accumulation. We carried out this study to find if salicylic acid (SA) (50 μM and 500 μM concentrations) and MeJ treatment of the maturing fruits is capable of restoring the transcription activity of NMT genes. MeJ leads to overexpression of the first two NMTs (XMTs and MXMTs) whereas the effect of SA appeared to be concentration-dependent. Though SA (500 μM) de-repressed all three NMTs, SA (50 μM) restored transcription of only the second NMT. Neither SA (50 μM) nor MeJ could restore transcription of the third and final NMT (DXMTs) of the pathway. Biochemical estimation of methylxanthines indicates a slight but significant increase in theobromine content (11.8% increase) in endosperms treated with 50 μM SA. Caffeine showed a statistically significant increase in both MeJ (14.4% increase) and SA (50 μM) (14.8% increase) treatments. Since derepression in DXMTs (caffeine synthase) was not observed, theobromine to caffeine conversion in MeJ and SA (50 μM) treated fruits is probably catalyzed by the basal or the extant DXMT gene product. Caffeine levels remained constant in SA (500 μM) treatments indicating a possible post-transcriptional regulation. These results are indicative of cross talk between the cascades induced by SA and MeJ and the maturation-induced regulation of caffeine accumulation and may be helpful in studying the interaction between these pathways.

Item Type: Article
Uncontrolled Keywords: Caffeine N-methyltransferase Salicylic acid Methyljasmonate Transcriptional regulation
Subjects: 500 Natural Sciences and Mathematics > 07 Life Sciences > 03 Biochemistry & Molecular Biology > 04 Biosynthesis
600 Technology > 07 Beverage Technology > 04 Coffee
Divisions: Plant Cell Biotechnology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 11 Jan 2016 07:23
Last Modified: 11 Jan 2016 07:23
URI: http://ir.cftri.com/id/eprint/12077

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