Temperature regulation of carotenoid accumulation in the petals of sweet osmanthus via modulating expression of carotenoid biosynthesis and degradation genes.
Temperature regulation of carotenoid accumulation in the petals of sweet osmanthus via modulating expression of carotenoid biosynthesis and degradation genes.
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通过调节类胡萝卜素生物合成和降解基因的表达来调节桂花花瓣中类胡萝卜素积累的温度
DOI：
10.1186/s12864-022-08643-0
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发表时间：
2022-06-04
期刊：
影响因子：
4.4
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中科院分区：
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在许多植物中，温度参与调节类胡萝卜素的积累。桂花（osmanthus fragransLour.）的花色主要受类胡萝卜素含量的影响，在秋季受温度的影响。然而，其机制尚不清楚。在这里，为了揭示温度如何调节桂花的花色，我们对盆栽桂花“金秋桂”进行了不同的温度处理（15°C， 19°C和32°C）。研究了不同温度处理下金秋桂花瓣的花色、类胡萝卜素含量及类胡萝卜素相关基因的表达水平。结果与对照（19℃）相比，高温（32℃）使花色由黄色变为黄白色，亮度（L*）值增大，红度（a*）值减小；低温（15℃）使花色由黄色变为淡橙色，L*值减小，红度（a*）值增大。总类胡萝卜素含量和单个类胡萝卜素（α-胡萝卜素、β-胡萝卜素、α-隐黄质、β-隐黄质、叶黄素和玉米黄质）含量均受高温抑制，而低温则提高。高温下类胡萝卜素积累减少可能是由于生物合成基因ofpsy1、ofz - iso1和doflcyb1转录下调，降解基因ofnced3、OfCCD1-1、OfCCD1-2和dofccd1 -1转录上调。据预测，oflcyb1的上调、ofnced3和dofccd4 -1的下调与低温调节的类胡萝卜素积累有关。荧光素酶实验表明，oflcyb1的启动子活性在低温下被激活，在高温下被抑制。而ofccd4 -1的启动子活性在低温条件下被抑制，在高温条件下被激活。结论高温通过抑制类胡萝卜素生物合成基因的表达和激活类胡萝卜素降解基因的表达来抑制花的显色。然而，相对低温对桂花的花色和类胡萝卜素的生物合成有相反的影响。这些结果将有助于揭示温度对桂花花瓣中类胡萝卜素积累的调控机制。
BackgroundTemperature is involved in the regulation of carotenoid accumulation in many plants. The floral color of sweet osmanthus (Osmanthus fragransLour.) which is mainly contributed by carotenoid content, is affected by temperature in autumn. However, the mechanism remains unknown. Here, to reveal how temperature regulates the floral color of sweet osmanthus, potted sweet osmanthus ‘Jinqiu Gui’ were treated by different temperatures (15 °C, 19 °C or 32 °C). The floral color, carotenoid content, and the expression level of carotenoid-related genes in petals of sweet osmanthus ‘Jinqiu Gui’ under different temperature treatments were investigated.ResultsCompared to the control (19 °C), high temperature (32 °C) changed the floral color from yellow to yellowish-white with higher lightness (L*) value and lower redness (a*) value, while low temperature (15 °C) turned the floral color from yellow to pale orange with decreasedL* value and increaseda* value. Total carotenoid content and the content of individual carotenoids (α-carotene, β-carotene, α-cryptoxanthin, β-cryptoxanthin, lutein and zeaxanthin) were inhibited by high temperature, but were enhanced by low temperature. Lower carotenoid accumulation under high temperature was probably attributed to transcriptional down-regulation of the biosynthesis geneOfPSY1,OfZ-ISO1andOfLCYB1, and up-regulation of degradation genesOfNCED3,OfCCD1-1,OfCCD1-2, andOfCCD4-1. Up-regulation ofOfLCYB1, and down-regulation ofOfNCED3andOfCCD4-1were predicted to be involved in low-temperature-regulated carotenoid accumulation. Luciferase assays showed that the promoter activity ofOfLCYB1was activated by low temperature, and repressed by high temperature. However, the promoter activity ofOfCCD4-1was repressed by low temperature, and activated by high temperature.ConclusionsOur study revealed that high temperature suppressed the floral coloration by repressing the expression of carotenoid biosynthesis genes, and activating the expression of carotenoid degradation genes. However, the relative low temperature had opposite effects on floral coloration and carotenoid biosynthesis in sweet osmanthus. These results will help reveal the regulatory mechanism of temperature on carotenoid accumulation in the petals of sweet osmanthus.