Inhibition of SAH-hydrolase activity during seed germination leads to deregulation of flowering genes and altered flower morphology in tobacco
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Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.
KeywordsDNA methylation Nicotiana tabacum Plant development S-adenosyl-l-homocysteine hydrolase inhibitor DHPA MADS box genes DEFICIENS/APETALA 3 GLOBOSA/PISTILLATA PLENA/AGAMOUS FLORICAULA/LEAFY
We thank Dr. Jiří Široký for the help with pollen microscopy. The scintillation method to detect uptake and transport of DHPA was introduced by Dr. Richard Tykva at the Institute of Organic Chemistry and Biochemistry AS CR, v.v.i. and tested in tobacco plants at the Institute of Experimental Botany AS CR, v.v.i. in Prague. We further thank an anonymous referee for the idea to analyze floral gene expression. This research was funded by the Grant Agency of the Czech Republic (206/09/1751, P501/10/0208, P501/11/P667) and the Academy of Sciences of the Czech Republic (AVOZ50040507 and AVOZ50040702).
Conflict of interest
The authors declare that they have no conflict of interest.
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