Chromatin-associated regulation of sorbitol synthesis in flower buds of peach
PpeS6PDH gene is postulated to mediate sorbitol synthesis in flower buds of peach concomitantly with specific chromatin modifications.
Perennial plants have evolved an adaptive mechanism involving protection of meristems within specialized structures named buds in order to survive low temperatures and water deprivation during winter. A seasonal period of dormancy further improves tolerance of buds to environmental stresses through specific mechanisms poorly known at the molecular level. We have shown that peach PpeS6PDH gene is down-regulated in flower buds after dormancy release, concomitantly with changes in the methylation level at specific lysine residues of histone H3 (H3K27 and H3K4) in the chromatin around the translation start site of the gene. PpeS6PDH encodes a NADPH-dependent sorbitol-6-phosphate dehydrogenase, the key enzyme for biosynthesis of sorbitol. Consistently, sorbitol accumulates in dormant buds showing higher PpeS6PDH expression. Moreover, PpeS6PDH gene expression is affected by cold and water deficit stress. Particularly, its expression is up-regulated by low temperature in buds and leaves, whereas desiccation treatment induces PpeS6PDH in buds and represses the gene in leaves. These data reveal the concurrent participation of chromatin modification mechanisms, transcriptional regulation of PpeS6PDH and sorbitol accumulation in flower buds of peach. In addition to its role as a major translocatable photosynthate in Rosaceae species, sorbitol is a widespread compatible solute and cryoprotectant, which suggests its participation in tolerance to environmental stresses in flower buds of peach.
KeywordsAbiotic stress Bud dormancy Chromatin Prunus persica (peach) Sorbitol-6-phosphate dehydrogenase (S6PDH) Aldose-6-phosphate reductase (Ald6PRase)
This work was funded by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-FEDER (RF2013-00043-C02-02) and the Ministry of Science and Innovation of Spain (AGL2010-20595). AL was funded by a fellowship co-financed by the European Social Fund and the Instituto Valenciano de Investigaciones Agrarias (IVIA). We thank Matilde González, José Martínez and José Palanca for their technical assistance.
MLB and GR conceived the study. AL, AMF and GR performed the experimental work. MA provided supervision and designed the method for sugars measurements. AL and GR prepared the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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