油用牡丹油脂生物合成关键调控基因的筛选与功能分析

Paeonia ostii ‘Feng Dan’, which belongs to novel woody oilseed crops oilseed penoy, is wildly planted in China owing to its strong growth adaptability and high seed yield. However, the oil yield and quality of penoy seeds are seriously affected by their low oil content and unstable α-linolenic acid content. Screening out key regulatory genes in oil biosynthesis would be helpful for genetic improvement and molecular breeding in oilseed penoy. We found three major oil accumulation periods in the Paeonia ostii ‘Feng Dan’ seed development in the previous research: slow-footed oil formation, high speed oil accumulation and retarded oil increasing stage. In this research, we will carry out transcriptome analysis of three stages of penoy seed development, analyze the expression profiles of key regulatory genes in oil biosynthesis during the time-course of penoy seed development, and clon several important oil biosynthesis related genes. Furthermore, we will heterologously overexpress these oil biosynthesis related genes in transgenic Arabidopsis and detect seed oil content and fatty acid composition of transgenic plant, which will contribute to preliminary elucidate their functions. These results will help to obtain key oil biosynthesis regulatory genes in oilseed penoy, which would be useful for molecular breeding of oilseed penoy cultivars with high quality and high oil content.

油用牡丹中的凤丹牡丹以生长适应性强、种子产量高等特点在全国大面积推广。但凤丹牡丹籽含油量偏低且α-亚麻酸含量不稳定，严重影响牡丹籽油的产量和品质。筛选出调控凤丹牡丹含油量与脂肪酸组分的关键调控基因将有助于其遗传改良和分子育种。本课题组前期发现凤丹牡丹种子在发育过程中其油脂积累分为三个时期：油脂缓慢形成期、油脂快速增长期和油脂减缓增长期。本研究拟通过开展凤丹牡丹种子3个不同发育时期的转录组学研究，分析油脂生物合成关键基因在种子发育不同阶段的表达模式，筛选调控其油脂生物合成的关键候选基因并进行分子克隆。在拟南芥种子中超量表达这些关键候选基因进行转基因功能验证，检测转基因植株种子的含油量和脂肪酸组分及含量，初步分析凤丹牡丹油脂合成关键基因的生物学功能。这些结果将有助于获得调控凤丹牡丹含油量与脂肪酸组分的主效基因，为凤丹牡丹的遗传改良和研究油用牡丹种子油含量和油质的分子调控机制提供理论依据。

目前油用牡丹（种子含油量超过20%的牡丹品种）作为一种新型木本食用油料植物引起大家的广泛关注，其中凤丹牡丹以生长适应性强、种子产量高等显著特点在全国大面积种植。本项目拟通过筛选调控凤丹牡丹含油量与脂肪酸组分的关键基因并分析其生物学功能，为凤丹牡丹的遗传改良和研究油用牡丹种子油含量和油质的分子调控机制提供理论依据。项目研究主要进展如下：1）研究了凤丹牡丹种子的含油量和不同脂肪酸组分的累积规律，发现授粉后30天至80天是种子油脂形成的关键时期；2）评估了12个内参基因在凤丹牡丹种子不同发育阶段及不同器官的稳定性，发现UBQ是最合适的内参基因；3）分析了36个油脂合成关键基因在凤丹牡丹种子不同发育阶段及不同器官的表达模式，其表达模式的聚类分析显示该36个基因在种子发育过程中形成了5类表达模式。其中I类模式的9个基因表达模式与油脂累积模式类似；4）克隆了凤丹牡丹19个与油脂合成相关的基因，分别为PoSAD1、PoSAD2、PoFAD2-1、PoFAD2-2、PoFAD3-1、PoFAD3-2、PoFAD6、PoFAD7、PoDGAT1、PoDGAT2、PoDGAT3、PoG3PDH1、PoG3PDH2、PoG3PDH3、PoGPAT1、PoGPAT2、PoLPAAT1、PoLPAAT2、PoLEC1，构建了超量表达载体并进行了转基因拟南芥验证，转基因拟南芥的油脂性状相关数据还需进一步测定以验证其生物学功能。