|Application:||Gene expression microarray analysis|
|Number of samples:||8|
|Release date:||Jul 24 2007|
|Last update date:||Mar 17 2012|
|Chemicals:||Aluminum, Glucose, Phosphates, Sucrose, Glutamic Acid|
|Dataset link||Expression profiling of chickpea responses to drought, cold and high-salinity stresses|
Total RNA was extracted from separately pooled leaf/flower/root tissues at each time-point (including control samples) using the RNeasy® Plant Mini Kit (Qiagen, Valencia, CA). The quantity and quality of the total RNA samples were assessed by OD260/OD280 ratios and gel electrophoresis respectively. Fluorescent-labeled targets were prepared and hybridized to array slides as described [Coram, TE. and Pang, ECK. 2006. Expression profiling of Chickpea genes differentially regulated during a resistance response to Ascochyta rabiei. Plant Biotechnology Journal. 4(6), 647–666]. All hybridizations were performed with six technical replicates and three biological replicates, incorporating dye-swapping (i.e. reciprocal labelling of Cy3 and Cy5) to eliminate any dye bias. Slides were scanned at 532 nm (Cy3 green laser) and 660 nm (Cy5 red laser) at 10 µm resolution using an Affymetrix® 428™ array scanner (Santa Clara, CA), and captured with the Affymetrix® Jaguar™ software (v. 2.0, Santa Clara, CA). Image analysis was performed using Imagene™ 5 (BioDiscovery, Marina Del Rey, CA) software. Quantified spot data was then compiled and transformed using GeneSight™ 3 (BioDiscovery, Marina Del Rey, CA). Data transformations consisted of a local background correction (mean intensity of background was subtracted from mean signal intensity for each spot), omitting flagged spots, LOWESS normalisation of the entire population, creating a Cy5/Cy3 mean signal ratio, taking a shifted log (base 2), and combination of duplicated spot data. To identify differentially expressed (DE) genes, expression ratio results were filtered to eliminate genes whose 95% confidence interval for mean fold change (FC) did not extend to 2-fold up or down, followed by Students t test with False Discovery Rate (FDR) multiple testing correction to retain only genes in which expression changes versus untreated control were significant at P < 0.05.