Screening genes associated with autotoxicity in Cucumis sativus L. roots using expressed sequence tags

Cucumber (Cucumis sativus L.) is important vegetable and has autotoxic potential. Till now, the genomic information and the gene expression patterns of cucumber are very scarce. In this study, we have constructed a cDNA library of cucumber roots and sequenced more than 2700 randomly selected clones. By sequence analysis, 1548 unique genes were identified, of which 971 showed significant similarities to the sequences in public databases. These database-matched ESTs were further grouped into 13 functions categories viz., metabolism (21.63%), energy (4.63%), cell growth and division (2.27%), transcription (7.62%), protein synthesis (7.93%), protein destination and storage (7.51%), transport (7.00%), intracellular traffic (0.82%), cell structure (7.51%), signal transduction (11.02%), defence (9.27%), secondary metabolism (1.85%) and others (10.92%). Forty three unique genes share significant similarities to known plant genes potentially implicated in autotoxic responses. These genes are associated with detoxification, reactive oxygen scavengers, signaling components and transcriptional regulators. Our study provides an overview of mRNA expression profile and a diverse genetic resource for cucumber plant research.