Joint Sino-German-Project: Functional analysis and mutagenesis of GDSL genes for breeding oilseed rape (B. napus) with higher oil content GDSL

油菜是中国和德国重要的大田作物，也是植物油的主要来源。2013年4月3日至6日，首届中德Rapidae遗传学与生物技术研讨会在杭州举行。在研讨会上，浙江大学姜立喜教授和德国基尔大学基尔教授Christian Jung教授等共同探讨了拟南芥种子脂肪酸还原酶（SFAR）基因的系统克隆和分析，以及甘蓝型油菜BnSFAR基因敲除突变体的鉴定。为了提高种子含油量，人们在提高油脂生物合成效率方面做了很多努力，但在油脂积累过程中如何阻断油脂的分解却很少受到关注。SFARs被定义为在种子中表达的GDSL型脂肪酶基因。它们水解三酰甘油并减少种子脂质的积累。姜教授小组的初步研究指出，拟南芥中的25个SFAR。5个基因（SFAR 1-SFAR 5）的破坏导致种子中脂肪酸（FA）的显着增加。此外，多个sfar基因座的功能丧失对促进种子油产量具有加性效应。由于拟南芥和油菜（Brassica napus）属于油菜科，因此预期它们共享相同的调节机制来控制代谢途径。因此，我们推断BnSFAR的破坏增加了B中的种子油产量。napus，而Bnsfar突变体的含油量甚至更高。中国农业大学的Jungs教授小组已经建立了一个油菜突变体群体，可以通过TILLING（靶向诱导基因组局部损伤）方案轻松筛选。本项目的主要目的是：（1）系统克隆拟南芥SFAR基因，并研究其功能和调控机制;（2）鉴定5个SFAR基因（AtSFAR 1-AtSFAR 5）在B中的同源序列。napus中的Bnsfar突变体，并筛选敲低突变体;（3）表征Bnsfar突变体对油菜种子含油量的影响，并研究油菜（B. napus）。

Rapeseed is an important field crop and the major source of plant edible oil in both China and Germany. The first Sino-German Workshop on Genetics and Biotechnology of Rapeseed took place in Hangzhou on April 3-6, 2013. During the workshop Prof. Lixi Jiang of Zhejiang University (ZJU), Prof. Christian Jung of Christian-Albrechts-University Kiel (CAU) and their coworkers discussed the cooperation to systemically clone and analyze Seed Fatty Acid Reducer (SFAR) genes in Arabidopsis and identify BnSFAR knock-out mutants in Brassica napus. To increase seed oil content, many efforts have been made on the promotion of lipid biosynthesis efficiency, but little attention has been paid on the blocking of lipid decomposition in the process of oil accumulation. SFARs are defined as GDSL-type lipase genes that are expressed in seeds. They hydrolyze triacylglycerol and reduce the accumulation of seed lipids. Preliminary studies from Prof. Jiangs group pointed at ca. 25 SFARs in Arabidopsis. The disruption of 5 genes (SFAR1 - SFAR5) resulted in significant increases of fatty acids (FA) in seeds. Moreover, the loss of function at multiple sfar loci had an additive effect on promoting seed oil production. Since Arabidopsis thaliana and oilseed rape (Brassica napus) belong to the Brassicaceae family, it is expected that they share the same regulatory mechanisms to control metabolic pathways. Therefore we reason that disruption of a BnSFAR increases seed oil production in B. napus, and pyramiding Bnsfar mutants could lead to an even higher seed oil content. Prof. Jungs group at CAU has established a rapeseed mutant population which can be easily screened by a TILLING (targeting induced local lesions in genomes) protocol. The proposed joint project aims to (1) systematically clone putative Arabidopsis SFARs and to understand their functions and regulation, (2) to identify the orthologs of 5 SFAR genes (AtSFAR1 - AtSFAR5) in B. napus and to select knock down mutants, and (3) to characterize the effect of Bnsfar mutations on seed oil content and pyramide bnsfar mutations in oilseed rape (B. napus).