Cloning And Functional Analysis Of Transcription Factor ABI3(Linum Usitatissimum L.)

As one of the five oil crops of China, flax is the main source of dry vegetable oil for industrial purposes as well as of the edible oil among the people in production areas. The flaxseed has important economic and nutritive values. As people’s living standard has been increasing during recent years, flaxseed oil is getting well-known for its high quality, and for this reason, fundamental researches on it are also being carried out. ABI3, a transcription factor short for Abscisic Acid-insensitive 3, is one that contains the B3 domain which is typical only of vegetables. As the central regulatory factor of ABA signal pathway, it is integral not only to the development and dormancy of the seeds, but also to the metabolism of fatty acid. This research was based on Zhangya 2, focused on the distribution and function of ABI3 in flax genome. The major results are presented as follows:1. ABI3 genomic sequence and CDS sequence were cloned in the cultivar Zhangya 2. Through sequencing, we found ABI3 has three transcripts in flax.2. We found and analysed the endogenous expression of the three transcripts in Zhangya 2, which played distinct roles in the ripening of siliquese.3. We constructed the positioning vectors for the subcellulars of the transcripts and found Lu ABI3-W1 and Lu ABI3-W2 in cell nucleus while there was no positioning signal of Lu ABI3-W3, which proved that Lu ABI3-W3 bears no function.4. We then constructed expression vectors for the transcripts and transformed into Arabidopsis thaliana. Experiments on the phenotype of T2 transgenic plant indicated that during ABA signal pathway, Lu ABI3-W1 and Lu ABI3-W2 responded to the ABA plant hormone as well as stimulated the seed germination, while Lu ABI3-W3 did not. This demonstrates that Lu ABI3-W1 and Lu ABI3-W2 are involved in ABA signal pathway and therefore lessen the dormancy as enhance the germination of the seeds.5. Analysis of bioinformatics revealed that the three transcripts come from two flax genes. Hence, through cloning two promoters of Zhangya2 genome, we produced GUS vector-transformed Arabidopsis thaliana.6. This research further studied the effects of ABA plant hormone on the germination-related gene expression in T2 transgenic plant, and proved it depends on ABA plant hormone instead of on Lu ABI3-W1 or Lu ABI3-W2.