Comparative Analysis Of Gene Expression Profiles Of Tobacco Trichomes

Flue-cured tobacco K326 were taken as the material, We constructed a trichome full-length cDNA library , made a cDNA chip and studied the the changes of gene expression in trichomes of tobacco (Nicotiana tabacum L) which were planted in Henan and Fujian.The results were as follows:1. The recombination rates of the cDNA library was 99. 5 % and the titer of the amplified library was 1.01×106pfu/mL.24 positive clones were selected randomly and sequenced ,the results indicated that the size of inserts was about 800～1 000 bp.Merging the 24 sequences and 23 unigenes were obtained . Sequence analysis results indicated that 21 sequences were found that they have significant similarity with data in GenBank and 14 of them were the full-length sequences.2. The results of sequencing and functional analysis showed that: sequenced by the 5139 sequences, the ratio of the sequence length above 500 bp reach to 89.80%,full-length analysis showed that the total length rate up to 66.9%. All the 5139 sequences were compared to the NCBI datebase,2830 Unigene (55.07%) were obtained. The unique genes were classified into 10 functional groups according to blast (go pipe). The largest group of unknown trichome sequences, containing nearly half of all unique genes (46%), shows homology with genes coding for predicted proteins with unknown function, and 1% unique sequences have no homologs, as revealed by BLAST analysis against NR (the nonredundant proteins database). The second largest group (489, 17%) is represented by proteins putatively involved in metabolism. Another large group(448, 16%) is composed of proteins putatively involved in biosynthesis and modification of DNA,RNA and protein. Other groups were respectively related to intracellular protein transportation (193, 7%), defense (125, 4%), energy (116, 4%), regulation (97, 3%), development (91, 3%) and signal transportation (75, 3%).3. The results showed that there were 445 differently expressed genes(with ratio values≥2 or≤0.5)in total , in which, 239 appeared to be up-regulated in Hennan and other 206 appeared to be up-regulated in Fujian tobacco trichomes.Have analysed the molecular function of the different genes , we found that the ones related to carbolic metabolism processes high expressed in Fujian , while the others related to chloroplast development and tepenoid metabolism pathway high expressed in Henan. Besides ,we also found that there were a great deal of resistance and defense genes in trichomes that probably respected to their specific circumstance . In addition, 9 novel genes were also detected in the experiment. Those genes are supposed to be related to formation of aroma style .