Deboo G B, Albertsen M C, Taylor L P
Department of Horticulture, Washington State University, Pullman 99164-6414, USA.
Plant J. 1995 May;7(5):703-13. doi: 10.1046/j.1365-313x.1995.07050703.x.
Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anthocyanins. Flavonols are required for functional pollen in maize whereas anthocyanins are non-essential pigments. A cDNA for F3H was isolated from Zea mays using a heterologous sequence from Antirrhinum majus. Comparison of the deduced amino acid sequence of maize F3H with other F3H sequences confirmed that the protein is highly conserved among widely divergent plant species. The F3H gene is present in a single copy located at the tip of chromosome 2S. High levels of F3H gene expression were detected in pigmented husk and 26-day postpollination kernels; lower levels in 18-day postpollination kernels and in coleoptiles of germinating seedlings. Slot blot analysis showed that F3H transcript levels in young seedlings are increased by high fluence-rate white light treatment in the presence of the anthocyanin regulatory gene -r. HPLC analysis of extracts from developmentally staged anthers showed that flavonol accumulation begins at the uninucleate microspore stage, continues until maturity, and is not controlled by -r. When the expression pattern of several flavonoid biosynthetic genes was analyzed during microsporogenesis, only F3H transcript accumulation was coordinate with the appearance of flavonols in anthers.
黄烷酮3 - 羟化酶（F3H）活性对于黄酮醇和花青素的合成都是必需的。黄酮醇是玉米功能性花粉所必需的，而花青素是非必需色素。利用来自金鱼草的异源序列从玉米中分离出了F3H的cDNA。将玉米F3H推导的氨基酸序列与其他F3H序列进行比较，证实该蛋白在广泛不同的植物物种中高度保守。F3H基因以单拷贝形式存在于2S染色体末端。在有色颖壳和授粉后26天的籽粒中检测到高水平的F3H基因表达；在授粉后18天的籽粒和发芽幼苗的胚芽鞘中水平较低。狭缝印迹分析表明，在花青素调控基因-r存在的情况下，高光通量率白光处理可提高幼苗中F3H转录本水平。对发育阶段花药提取物的HPLC分析表明，黄酮醇积累始于单核小孢子阶段，持续到成熟，且不受-r控制。当在小孢子发生过程中分析几种类黄酮生物合成基因的表达模式时，只有F3H转录本积累与花药中黄酮醇的出现同步。
