Cloning And Expression Analysis Of Dreb Genes In Lilium Longiflorum And Petunia

Lilies are one of the major cut flowers worldwide for their elegant flower styles, graceful green leaves. But they can only be grown in relatively acid soil and warm weather. Therefore, for the sake of high production costs, in northern part of China, Lilies’productions and applications are prohibited by salt soil, extremely cold weather and seasonal drought.Petunia plants are also widely used pot flowers with various beautiful colors on petals and different stem styles. However they possess little waterlogging tolerances and cold resistances which inhibit their applications.DREB transcription factors are a kind of proteins which can bind to the very specific parts of the downstream genes’ promoters and activate those genes to express. As a result, plants’tolerances to adverse conditions can be enhanced to a large extent. Thus, in order to create plants of strong tolerances, more and more researches are carried out to study the inner mechanisms of DREB TFs. With the aims to enhance the cold hardiness of both species talked above, we carried out this research to discover how DREB genes function in plants initially. In this research, we cloned DREB genes from Lilium longiflorum, Petunia inflata and Petunia axillaris and made expression analysis of some of the target genes under various stresses. Moreover we constructed the corresponding expression vectors. The main results are lying below:1. We used homology cloning combined with RACE and TAIL technologies to isolate two DREB] genes named LlDREB1-1and LlDREB1-2from the leaves of Lilium longiflorum under cold stress. From the amino acid sequences, we found that the genetic relationship of Lilium longiflorum is nearest to Palmae. And we also cloned six DREB1genes and two DREB2genes named PaDREB1a, PiDREB1b, PiDREB1c, PiDREB1f, PiDREB1i, PaDREB2a and PaDREB2c respectively from leaves of Petunia inflata and Petunia axillaris.2. In order to aquire some knowledge about the genes’ expression patterns we made expression analysis of LlDREB1genes, PiDREB1c, PiDREBlf and PiDREB1i. We found that the LlDREB1genes can be expressed for more than4days with the climax of expressing level at24h under cold stress. Under the experiments of drought and salt stresses, the genes showed transitory expression patterns. While under cold stress, PiDREB1c, PiDREBlf and PiDREB1i all had similar expression patterns with the highest expressing level at two hours and diminished quickly in three hours. These results indicate that though there are dozens of DREB genes in Petunia hybrida, these genes can not be induced long enough to activate sufficient downstream genes to express which are related to plants’resistances to adverse conditions.3. Two genes isolated from Lilium longiflorum have been constructed in the expression vector pCAMBIA as35S::LlDREB1-1and35S::LlDREB1-2. Two genes isolated from Petunia inflata and Petunia axillaris respectively have been constructed in the expression vector PMV as35S::PiDREBlf and35S::PaDREB1a.