铝转运蛋白基因调控绣球花色变蓝的机制研究

Hydrangea macrophylla is an important ornamental and high aluminum-tolerant plant. The flower color of some cultivars can change from red to blue or blue-violet in acidic soil containing aluminum, thus their ornamental value can be enhanced by manual adjustment. Studies have shown that the main reason for the changing color from red to blue is the formation of the delphinidin-3-O-glucoside and Al3+ complex in sepals. The former results by our group showed that there is a significant difference in Al3+ contents of sepals between Al3+-sensitive and insensitive cultivars after Al2(SO4)3 treating. Therefore, it can be reasonably speculated that the aluminum transporter genes play an important role in directional transport of Al3+ to sepals, which is the key role for the formation of blue flowers. Based on these results, the present project was designed to take the Al3+-sensitive and insensitive cultivars as research materials, and the aluminum transporter genes which regulate sepal color to turn blue will be identified by transcriptome sequencing and bioinformatics analysis in hydrangea with Al2(SO4)3 treatment. Furthermore, the sequence characteristics, expression pattern and tissue or cell localization will be analyzed to determine the regulation mechanism of aluminum transporter genes on flower color changes in different cultivars. Finally, the function of aluminum transporters will be proved using the yeast heterologous expression system and transgenic plants. The implementation of this project will elucidate the differences and molecular mechanisms of different hydrangea cultivars on Al3+ transporting. It will provide a molecular basis and guidance for the improvement of blue color in hydrangea, and lay a theoretical basis for breeding other blue flowers.

绣球是重要的观赏植物和强耐铝植物，部分品种在酸性含铝的土壤中花序由红色变为蓝色或蓝紫色，可据此进行人工调色以提高其观赏价值。已有研究表明，绣球花色变蓝的主要原因是萼片中飞燕草色素-3-O-葡萄糖苷与Al3+络合物的形成。本团队前期研究发现，硫酸铝处理后铝离子敏感与不敏感品种间仅萼片Al3+含量存在极显著差异，因此，绣球花色能够变蓝的关键是Al3+向萼片的定向转运，而铝转运蛋白基因发挥着重要作用。基于此，本项目拟以铝离子敏感与不敏感品种为材料，采用硫酸铝处理，通过转录组测序及生物信息学分析，获得调控绣球花色变蓝的关键铝转运蛋白基因；对其序列特征、表达模式及组织定位进行分析，明确铝转运蛋白基因调控不同品种绣球花色变化差异机制；最后利用利用酵母异源表达系统、植物转基因技术验证基因功能，初步揭示铝转运蛋白基因调控绣球花色变蓝的分子机制，为绣球花色改良提供技术指导，也为进一步定向培育蓝色花奠定理论基础。

绣球是少有的强耐铝观赏植物，部分品种在酸性含铝的土壤中花序由红色变为蓝色或蓝紫色。已有研究表明，绣球花色变蓝的主要原因是萼片中飞燕草色素-3-O-葡萄糖苷与Al3+络合物的形成。本团队前期研究发现，硫酸铝处理后铝离子敏感与不敏感品种间萼片Al3+含量存在极显著差异。因此推测绣球花色能够变蓝的关键是Al3+向萼片的定向转运，而铝转运蛋白基因发挥着重要作用。本项目在此基础上，采用转录组学、生物信息学、分子生物学等手段解析铝转运蛋白基因调控绣球花色变蓝的分子机理。主要得到以下结果：（1）Al2(SO4)3处理后，铝离子敏感品种‘无尽夏’萼片中飞燕草-3-O-葡萄糖苷含量显著增加；（2）‘无尽夏’具有较高的铝吸收与转运能力；（3）组学分析解示绣球萼片铝胁迫响应和耐性的关键基因与途径，如金属转运蛋白、活性氧(ROS)清除酶、植物激素信号转导和类黄酮生物合成途径特异存在于铝离子敏感品种‘无尽夏’；（4）WGCNA分析表明ABC转运蛋白（TRINITY_DN1053_c0_g1、TRINITY_DN3377_c0_g2）、阳离子氨基酸转运蛋白（TRINITY_DN9684_c0_g2）、寡肽转运蛋白（TRINITY_DN1147_c0_g2）和黄酮醇合酶（TRINITY_DN15902_c0_g1）在绣球耐铝性与花色变蓝过程中起着重要作用；（5）HmABCI17（TRINITY_DN1053_c0_g1）和HmABCG1均能够提高酵母与拟南芥耐铝性；（6）从绣球花的转录组数据中鉴定出11个ALMT转运蛋白家族成员。对其理化性质、系统发育、蛋白质结构与表达模式进行了分析；（7）HmALMT5、HmALMT9和HmALMT11可以增强过表达酵母的耐铝性。本研究的结论有助于阐明不同绣球品种耐铝性的差异及其分子机理，并为绣球及其他观赏植物蓝花育种的分子辅助筛选提供新的思路。