Construction and analysis of an Oryza sativa (cv. MR219) salinity-related cDNA library

To identify salt-responsive genes, we constructed a cDNA subtractive library from a salt-tolerant rice cultivar, MR219. Treatments of the whole plant were carried out with 150 mM sodium chloride for 0, 2, 4, 8, 12 and 24 h. The extraction of total RNA from 14-day-old seedlings was conducted on the shoots and roots of both treated and untreated plants. The treated plants were utilized as ‘drivers’ while the untreated plants were utilized as ‘testers’. Equal amounts of the extracted total RNA from the 12 samples were pooled together and subjected to mRNA isolation. A reverse transcription of tester and driver cDNAs from the mRNA of two pools of the samples was conducted. In total, 300 clones were sequenced and analysed using bioinformatics tools. The 260 high-quality sequences were assembled and 83 contigs and 42 singletons were generated, producing a total of 125 UTs. The majority of the UTs showed significant homology with sequences in the NCBI database. A total of 330 gene ontology terms were grouped into three categories, of which 144 UTs fell under biological process, 108 fell under cellular component and 78 fell under molecular function. Also, RT-PCR was utilized to substantiate the elevation in expression of six candidate genes (( MR219SAP8 (JZ532324) and salT (JZ532363), low molecular weight heat shock (JZ532334), phospholipid hydroperoxide glutathione (JZ532371), Acetamidase (JZ532408), Ferredoxin-1 and chloroplastic (JZ532374)) subjected to salinity stress at varying timepoints.