Deciphering the regulatory mechanisms of Abiotic stress tolerance in plants by Genomic approaches

  

 Plant productivity is severely affected by abiotic stress like salinity, drought and temperature. As a result, physiological and biochemical responses in plants vary and cellular aqueous and ionic equilibriums are disrupted. Hundreds of genes and their products respond to these stresses at transcriptional and translational level.

 

              Global expression profiling was performed on Arabidopsis plants subjected to stress treatments of 4°C, 100 mm NaCl, or 200 mm mannitol, respectively. Using Genechip microarray, identified 2,678 probe sets representing a combined total of 2,409 unique stress related genes that displayed >2 fold change in expression compared with control. Result shown that the majority of changes were stimulus specific (Kreps et al., 2002).

 

               Transcript regulation in response to high salinity was investigated for salt-tolerant rice (var Pokkali) with microarrays including 1728 cDNAs from libraries of salt-stressed roots. Compared the behavior of Pokkali with that of the salt-sensitive variety IR29. The upregulated functions observed with Pokkali at different time points during stress adaptation changed over time (Kawasaki et al., 2001).     

          A DNA cassette containing an Arabidopsis C repeat/dehydration-responsive element binding factor 1 (CBF1) cDNA and a nos terminator, driven by 35S promoter, was transformed into the tomato genome. These transgenic tomato plants were more resistant to water deficit stress than the wild-type plants. Catalase activity increased and hydrogen peroxide concentration decreased in transgenic tomato plants compared with the wild-type plants under water deficit stress. These results indicated that the heterologous Arabidopsis CBF1 can confer water deficit resistance in transgenic tomato plants (Hsieh et al., 2002).

Three DREB homologue genes, GmDREBa GmDREBb and GmDREBc, were isolated from soybean. Each of the deduced proteins contains an AP2 domain of 64 amino acids. The transcriptions of GmDREBa and GmDREBb were induced by salt, drought and cold stresses in leaves of soybean seedlings. The expression of GmDREBc was not significantly affected in leaves but apparently induced in roots by salt, drought and ABA treatments. The results suggest that these three genes function specifically in response to abiotic stresses in soybean (Ping Li et al., 2005).

Key words: Arabidopsis, Genechip microarray, cDNAs, DREB, QTLs.

References:

 Hsieh, T.H., Lee, J.T., Charng, Y.Y., Chan, M.T., 2002. Tomato plants ectopically expressing Arabidopsis CBF1 show enhanced resistance to water deficit stress. Plant Physiol. 130: 618–626.

Kawasaki, S., Borchert, C., Deyholos, M., Wang, H., 2001. Gene expression profiles during the initial phase of salt stress in rice. Plant Cell 13: 889–905.

Kreps, J.A., Wu, Y.J., Chang, H.S., Zhu, T., Wang, X., Harper, J.F., 2002. Transcriptome changes for Arabidopsis in response to salt, osmotic and cold stress. Plant Physiol. 130: 2129–2141

Rahman, H., Pekic, S. and Shah, M.M., 2011. Molecular mapping of quantitative trait loci for draught tolerance in maize plants. Genet Mol Res. 10(2): 8889-901.

Wang, Z.I., Fredricksen, M., Kim, C.S., 2004. Expressed sequence tags from Thellungiella halophila, a new model to study plant salt-tolerance. Plant Sci. 166: 609–616.

Xue-Ping Li., Ai-Guo Tian., Guang-Zuo Luo., 2005. Soybean DRE-binding transcription factors those are responsive to abiotic stresses. Theor Appl Genet. 110:1355-1362.