Morphological, anatomical and DNA methylation changes of tree peony buds during chilling induced dormancy release
Morphological, anatomical and DNA methylation changes of tree peony buds during chilling induced dormancy release
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低温诱导休眠解除过程中牡丹芽形态、解剖和DNA甲基化的变化
DOI：
10.1016/j.plaphy.2019.09.017
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发表时间：
2019
影响因子：
6.5
通讯作者：
Gai Shupeng
中科院分区：
文献类型：
--
作者：
Xin Hua;Zhang Yuxi;Wang Xueting;Liu Chunying;Feng Weirong;Gai Shupeng
以120株牡丹为材料，在0-4 °C人工气候室中以周为间隔，处理0-28 d，利用扫描电镜和石蜡切片研究了牡丹芽休眠过程中形态结构的变化。转入温室30 d后进行休眠状态评价。结果表明：在低温积累过程中，随着萼片、花瓣、雄蕊和心皮的不断伸长，花蕾直径沿着逐渐增大。休眠的解除以花瓣侧脉木质部导管的建立为标志。同时，利用高效液相色谱和免疫化学技术检测了DNA甲基化水平，旨在阐明DNA甲基化在休眠解除中的作用，发现低温处理28 d后，5 mC水平从39.4%下降到24.2%。这些结果与免疫化学分析结果一致，且与移棚后30 d的发芽率呈负相关。外源施用5-氮胞苷（5azaC）降低了DNA甲基化水平，同时提高了芽萌发能力，而S-腺苷甲硫氨酸（SAM）的效果则相反。低温处理可促进牡丹复合芽的进一步分化和发育，导致DNA甲基化水平降低，促进休眠解除。
Bud endodormancy in tree peony is a growth cessation-like state, and sufficient chilling perception is necessary to break it. In this study, 120 plants were subjected to 0–4 °C climate chamber for 0–28 d with a weekly interval, morphology and structure changes of buds were studied with a scanning electron microscope (SEM) and paraffin sections during the dormancy process. Dormancy status was evaluated after being transferred to greenhouse for 30 d. Results showed that the diameter of the buds gradually expanded, along with continuous elongation of sepals, petals, stamens and carpels in the chilling accumulation process. Notably, dormancy release was marked with the establishment of xylem vessels in lateral vein of the petal. Meanwhile, DNA methylation was detected by HPLC and immunochemical technology, aimed to illuminate the role of DNA methylation in the dormancy release, we found that 5 mC level fell from 39.4% to 24.2% after exposed to 28 d chilling. These results were consistent with the immunochemical analysis, and inversely related to the sprouting rate after being moved to greenhouse for 30 d. Exogenous application of 5azaC (5-azacytidine) decreased DNA methylation level, accompanied by an improved bud sprouting capacity, while the effect of SAM (S-adenosylmethionine) was the opposite. In summary, prolonged chilling was accompanied by further differentiation and development of the compound bud, which resulted in DNA hypomethylation and promoted dormancy release in tree peony.