Abstract:

【Objective】The objective of this experiment is to study the drought resistance defense mechanism in tobacco plant. 【Method】 The changes of gene expression in osmotic stressed tobacco (Nicotiana tabacum L) roots were analyzed by cDNA microarray analysis. RNAs of tobacco roots with or without (CK) PEG treatment after 48 h under -1.2 MPa were extracted and subjected to analysis of cDNA microarray based on Arabidopsis genomic sequence. 【Result】 There were about 126 differently expressed genes (with ratio values ≥2 or ≤0.5) among 31 182 genes set in a microarray plate，in which 79 genes were up-regulated and 47 down-regulated by osmotic stress. Among the up-regulated genes, a lot of them such as ABA responsive protein，calcium signaling responsive protein and protein kinase were found in signaling transduction pathway, suggesting that signaling transduction in roots under osmotic stress was activating. Meanwhile, some hydrolase genes in relation to membrane system and transporter were also up-regulated under osmotic stress. But some genes regulating growth and development of tobacco plant, such as the genes of gibberellin-responsive protein, nitrate reductase 2 (NR2) and so on, were down regulated. Some genes of E3 ubiquitin ligase, the key components in ubiquitin-mediated protein degradation pathway, were also down regulated. Moreover, 58 unknown function genes were also detected in the experiment. The functions of those genes in plant osmotic stress response needed to be elucidated in the future. 【Conclusion】 By analyzing the differently expressed genes, some valuable information for explaining the molecular mechanism of drought-resistance of tobacco plant were highlighted.

Key words: tobacco root, osmotic stress, different expression, cDNA microarray