中文摘要：

油菜（Brassica napus）和拟南芥（Arabidopsis thaliana）均属于十字花科植物,脂肪酸合成和调控机制相似。油菜是我国重要的油料作物,提高种子含油量多年来一直是油菜育种者的重要目标,而拟南芥种子油脂含量介于20%~35%之间,是研究种子油脂机制的理想模式植物。脱落酸（abscisic acid,ABA）是调控种子发育、成熟与休眠的重要内源激素,然而ABA对于十字花科油籽脂肪酸形成的影响却未见报道。为了探究ABA对油籽脂肪酸含量、组分以及种子储藏蛋白含量的影响及其机制。本研究通过用不同浓度的外源ABA喷施油菜与拟南芥植株,并用含有不同浓度的ABA培养基对受精后28 d的油菜受精胚进行体外培养。结果表明,ABA能够促进拟南芥叶片与油菜荚果变黄及早衰,抽薹前喷施200μmol/L ABA抑制拟南芥荚果发育;喷施ABA通过抑制脂肪酸碳链延长（fatty acid elongation 1,FAE1）基因,抑制芥酸等超长链脂肪酸（C〉20 very long chain fatty acids,VLCFA）合成,间接促进十八碳不饱和脂肪酸（polyunsaturated fatty acid,PUFA）相对含量,蛋白质含量下降。体外培养油菜受精胚实验显示,ABA抑制编码脂肪酸去饱和酶（fatty acid desaturation,FAD）基因的表达,使得PUFA含量下降,芥酸等超长链脂肪酸相对含量增加,蛋白质含量增加。结果表明,激素的浓度对于油脂积累的影响具有关键作用。高浓度的ABA对于多数油脂合成途径上的基因表达具有抑制作用,选择不同的ABA浓度可以对十字花科油籽油脂积累进行不同方向（有利油脂积累或者有利油脂消减）的调节。该项研究丰富了对于ABA功能的认识,加深了对于油料种子脂肪酸积累分子机制的理解。

英文摘要：

Rapeseed （Brassica napus） and Arabidopsis thaliana belonging to the same family Cruciferae have analogical mechanisms in regulating seed fatty acid （FA） accumulation. Rapeseed is a significant oil crop in China. Elevate its seed oil content is an important goal for rapeseed breeders since many decades. The seed oil content of Arabidopsis varies 20%-35%, andArabidopsis can serve as an ideal model to study the mechanism of synthesis of FAs and other storage compound in seeds. Abscisic acid （ABA） is a plant endogenous hormone that regulates seed development, maturation and the acquisition of seed dormancy. However, little is known about the effect of ABA on accumulation of FAs and storage proteins in cruciferae oilseeds. In this study, ABA with different concentrations was applied to rapeseed as well as Arabidopsis plants which were at reproductive stage. In order to explore the effect of ABA on biosynthesis of FAs and other storage compounds such as protein in seeds, a series of culturing mediums containing various concentrations of ABA were used for the culture of fertilized rapeseed embryos 28 days after pollination （DAP）. The results showed that ABA promoted the senescence of Arabidopsis leaves and rapeseed pods reflected by early yellowing. The spray of ABA （200 p.mol/L） on Arabidopsis plants before bolting inhibited the development of siliques. Moreover, the spray of ABA repressed the expression of fatty acid elongation 1 （FAE1）, inhibited the biosynthesis of very long chain fatty acids （VLCFA, C〉20）, elevated the proportion of 18-carbon polyunsaturated fatty acid （PUFA）, and decreased the proportion of storage protein, indirectly. On the other hand, the culturing of fertilized rapeseed embryos in vitro demonstrated that ABA repressed the expression of fatty acid desaturases （FADs）, which further resulted in the reduction of PUFA the increases of VLCFAs and storage proteins. Taken together, the concentration of ABA is critical to seed FA accumulation, i.e., high （or low?