跳枝碧桃花色变异的分子机理研究

Flower color plays important role in versatile biological processes, which has also figured into the most important phenotypic characteristics for the horticultural plants. Uncovering the mystery about the determination and regulation of flower color has long been a fascinating research topic for scientists majoring in different disciplines. Chimeric peach, resulted from somatic mutation specific in flower color, provides a desirable plant material to study the molecular mechanism triggering the variation in flower pigmentation. In this project, we plan to use chimeric peach and employ experimental approaches, such as measure the compositions and quantities of the compounds relevant to flower colors, analyze the differential expression of transcriptomes by high depth sequencing, compare the expression profiles of the differentially expressed genes, to clarify the molecular mechanism underlying flower color variation in chimeric peach. Based on the extensive efforts of numerous scientists, we already have profound knowledge about the physiological and biochemical basis for flower color determination, and understand the genetic regulation for flower pigmentation well. However, most of this knowledge is derived from a limited number of species including Petunia, Antirrhinum, Zea mays, Ipomoea and Arabidoposis. Studies on flower color determination with other plant species are much rarer. It is desirable to carry out such studies with special plant materials of other species. Meanwhile, chemeric-peach-type mutation creates attractive phenotype. Therefore, to uncover the underlying genetic mechanism is not only important for improving our cognizance for molecular regulation of flower color, but also essential for facilitating the flower breeding programs.

植物的花色具有重要的生物学功能，也是观赏植物最重要的表型特征。花色是如何决定和调控的一直是人们长期以来非常感兴趣的科学问题。"跳枝碧桃"为花色特异的体细胞突变体，是研究植物花色变异分子机理的理想实验材料。本项目拟以跳枝碧桃为研究材料，通过花色素成份及含量测定、转录组深度测序差异表达分析、差异表达基因测序和表达谱分析等手段，阐明跳枝碧桃花色变异的分子机理。尽管科学家对植物花色决定的生理生化基础已经有了较清晰的了解，对花色的遗传调控也有了比较深入的认识，但目前对花色表达调控的认识主要是通过对金鱼草、矮牵牛、玉米、木薯及拟南芥的研究获得的。针对其它植物开展的相关研究则相对较少，因此，利用其它植物的特殊材料开展研究具有特殊重要的意义。同时，跳枝碧桃式的表型变异本身具有十分重要的观赏价值。阐明其分子机理，不仅对加深花色调控分子机理的认识有重要意义，而且在花卉育种中也具有十分重要价值。

花色是观赏植物最重要的表型特征。花色是如何决定和调控的一直是人们长期以来非常感兴趣的科学问题。本项目以跳枝碧桃为研究材料，尝试阐明导致其花色变异的分子机理。项目执行过程中，我们通过高效液相色谱分析，在红色花瓣中共鉴定出了天竺葵色素、矢车菊色素和芍药色素类等共7种物质，但在白色花瓣中未检测出任何物质。通过数字表达谱分析，共筛选出514 个在红花和白花中差异表达的基因。对红花和白花进行转录组KEGG 代谢通路分析，结果显示在参与花色素合成相关的代谢通路中，有367个基因在红花样本中高度表达，有147个基因在白花样本中高度表达。利用RACE技术，我们分别在红花和白花中克隆了CHS、CHI、F3'H、DFR、ANS和UFGT等基因的cDNA全长序列。将之与桃花基因组序列进行比对，发现白色花瓣中ANS基因编码区序列较红花多了129bp。转录本测序发现，白色花瓣中129bp的插入是由于可变剪切产生的。不同的剪切方式使ANS基因翻译成不同的蛋白质。白花中ANS基因发生可变剪切产生ANS蛋白，不能催化花葵素和花青素的合成，而红色花瓣中ANS基因则能正常催化花葵素和花青素的合成。结合HPLC的分析结果，我们确定ANS基因为影响跳枝碧桃花色变异的候选基因，该基因的可变剪切可能是导致跳枝碧桃产生花色变异的遗传基础。研究结果对我们理解碧桃跳枝现象产生的原因提供了理论依据，丰富了我们对花色变异遗传机制的认识，研究结果在指导观赏植物的花色改良方面有一定的理论意义和潜在应用价值。