In this article we will discuss about the gene expression profiles in response to stress.
Microarray technology has been the useful tool for analyzing gene expression pattern in stressed plants. Full-length cDNA microarray analysis identified 44 drought-inducible genes. Fourteen of these genes were reported to be drought-inducible genes, such as rd 29A/cor 78, cor 15a, kin 1, kin 2, rd 17/cor 47, erd 10 and rd 20.
In addition, the 30 new drought-inducible genes have been reported. Thanks to the microarray technology for revealing these genes — FL3-5A3, FL6-55, FL5-1N11, FLS-2024, FLS-2H15 and FL1-159.
Further investigation added up 19 cold- inducible genes by the cDNA microarray analysis. Among them, specifically nine comes under the category of cold-inducible genes such as rd 29A, cor 15a, kin 1, kin 2, rd 17, erd 10, erd 7 and erd 4. Among these, new cold-inducible genes that have not been reported as cold response are FL3-5A3, FLS-3A15, FLS-3P12, FLS-90, FLS-2122 and FL1-159 (Fig. 15.2).
Recently, 299 drought-inducible genes and 245 ABA-inducible genes were identified using cDNA microarray containing around 7000 Arabidopsis full-length cDNA groups. Kazuoshinozaki et al. (2003) extended studies reveals that majority of the drought-inducible genes are also induced by high salinity indicating the existence of crosstalk among the drought, high salinity and ABA responses. Interestingly, only 10% of the drought-inducible genes were induced by cold stress.
Gene expression profiles led to certain hypothesis that atleast four independent signal transduction pathways function in the activation of stress-inducible genes under dehydration conditions: two are ABA-dependent (pathways I and II) and two are ABA- independent (pathways III and IV). The cis- and trans-acting factors involved in ABA-induced gene expression have been studied in ABA-dependent pathway (pathway II).