Summary
Flower color, which is determined by various chemical pigments, is a vital trait for ornamental plants, in which anthocyanin is a major component. However, the epigenetic regulation of anthocyanin biosynthesis remains poorly understood.
During chrysanthemum cultivation, we found a heterochromatic chrysanthemum accession (YP) whose progeny generated by asexual reproduction contained both yellow‐flowered (YP‐Y) and pink‐flowered (YP‐P) plants. In this study, we aimed to elucidate the epigenetic mechanisms of different flower colors in the YP plant progeny.
Metabolome and transcriptome analyses revealed that the difference in flower color between YP‐Y and YP‐P was caused by expression variation of the anthocyanin biosynthesis gene CmMYB6. Bisulfite sequencing revealed that methylation at the CmMYB6 promoter, especially in the CHH context, was higher in YP‐Y than YP‐P. After demethylation of the CmMYB6 promoter using the dCas9‐TET1cd system, the flower color returned from yellow to pink.
Furthermore, the methylation status of the CmMYB6 promoter was higher in YP‐Y over three consecutive generations, indicating that this methylation status was heritable mitotically. Finally, investigation of other chrysanthemum cultivars showed that the methylation of CmMYB6 decreased gradually with the increase in anthocyanin content. These results lay an epigenetic foundation for the improvement of flower color in horticultural plants.
Hydrolysis
of LiAlH4 is a promising path to supply hydrogen
at low temperatures due to its high hydrogen storage capacity, where
an anti-icing aqueous solution is necessary. However, no hydrolysis
kinetics of LiAlH4 with an anti-icing aqueous solution
has been reported due to its complexity. Herein, an optimized anti-icing
aqueous solution with 27.1 wt% KOH and 30.0% ethylene glycol has been
found to obtain full and controllable hydrolysis kinetics of LiAlH4 at −40 to 0 °C. The effects of compactness, mass,
and temperature on the hydrolysis of LiAlH4 have been investigated.
The LiAlH4 tablet with compactness of 92.7% was demonstrated
to obtain a wide constant reaction region (>95%) and be suitable
for
the hydrolysis reactions. The hydrogen release rates at constant reaction
regions were found to follow a linear relationship with the 0.42 power
of the mass of a compacted LiAlH4 tablet. A strong temperature-dependent
hydrolysis was observed, where the activation energy was deduced from
experimental data to be 6.83 ± 0.34 kJ·mol–1. The hydrolysis products of LiAlH4 with the adopted anti-icing
aqueous solution after washing with deionized water were found to
be the same as those directly with water, indicating no consumption
of KOH and ethylene glycol in the reactions. The hydrolysis reaction
of LiAlH4 with the adopted solution at −40 to 0
°C has been demonstrated to follow the shrinking core model controlled
by liquid film diffusion.
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