Abstract:

Attempt to study the drought resistance defense mechanism in tobacco plant, the changes of gene expression in osmotic stressed tobacco (Nicotiana tabacum L.) leaves were analyzed by cDNA micro-array analysis. RNAs of tobacco leaves with or without (CK) PEG treatment for 48 h under －1.2 MPa were extracted and subjected to analysis of cDNA microarray based on Arabidopsis genomic sequence. There were about 135 differently expressed genes (with ratio values≥2 or ≤0.5) among 31 182 genes set in a microarray plate, in which 50 appeared to be up-regulated and 85 appeared to be down-regulated by osmotic stress. Functional analysis showed that some were defensive genes such as trehalose synthase (ATTPS11) and universal stress protein (USP), and the others were related to replication, transcription, translation and protein folding including bZIP family transcription factors, zinc finger proteins, histone H1-3, DREB1C, the WRKY, molecular chaperones and so on. All genes mentioned above were up-regulated by osmotic stress. Gene of MAPKK (At1g51660), a key player in signal transduction pathway, was up-regulated dramatically by 3.94 times. Among down-regulated genes there were 6 genes of light harvesting complex in photosystem Ⅰ and photosystem Ⅱ, including lhca3, lcb1, lcb2, lcb5, lcb6, and lcb4.2. The gene lcb6 (At1g15820) was most down-regulated by 3.9 times. What’s more, 38 unknown function genes were also detected in the experiment. The functions of those genes in plant osmotic stress response need to be elucidated in the future. By analyzing the differently expressed genes some valuable information underlining plant osmotic stress response were highlighted.

Key words: Tobacco, Osmotic stress, Different expression, cDNA microarray