Expression And Promoter Cloning Of The LFY Homologous Gene In Longan (Dimocarpus Longan Lour.)

Longan (Dimocarpus longan Lour.) is an important fruit in China, and very competitive in the international market, but there are some problems in longan production such as biennial bearing, the inadequate annual market supply of fresh fruit which are closely related to flower bud differentiation of in longan.LFY gene exists in flowering and non-flowering plants, it is an essential gene that decides the form of floral meristem and play a key role in linking signals of flowering induction and activating floral organ determining genes during the flower formation.Guan Lei (2007) cloned the LFY homologous gene in longan(LLFY) and preliminary studied expression of LLFY by semi-quantitative RT-PCR analysis, the results showed LLFY genes were related to inflorescence differentiation and growth. On the basis of previous study, we detected the expression of LLFY gene further by RT-PCR in this article, meanwhile, LLFY's expression in"sijimi"longan was also studyed. In addition, the partial promoter sequence of longan LLFY was cloned by genome walking method, and the promoter sequence was analyzed by software. The main results showed as follows:1 The expression research of longan LFY gene.In order to study the expression of LLFY gene in different periods of flower bud differentiation, we selected"Honghezi"leaf buds and terminal inflorescence buds from February to April. The results showed that, the function of LLFY was related to not only the inflorescence differentiation, but also the flower bud differentiation. Meanwhile, the results showed the increasing expression of LLFY gene in"sijimi"may be related to its characteristics of early flowering and flowering throughout the growing season.2 Cloning and analysing the promoter sequence of longan LFY gene.Specific primers were designed and 800bp long sequence of LLFY promoter was cloned by genome walking method. Sequence analysis showed that LLFY's promoter region contained not only two major components, the TATA-box and CAAT-box, but also several potential cis-acting elements such as MYB binding site,ABA responsive elements(ABRE) and some light responsive elements-GA-box,GAG-motif,I-box, etc. which means the expression of LLFY gene is related to drought, light, ABA.