Multi site polyadenylation and transcriptional response to stress of a vacuolar type H(+)-ATPase subunit A gene in Arabidopsis thaliana

BACKGROUND: Vacuolar type H(+)-ATPases play a critical role in the maintenance of vacuolar homeostasis in plant cells. V-ATPases are also involved in plants' defense against environmental stress. This research examined the expression and regulation of the catalytic subunit of the vacuolar type H(+)-ATPase in Arabidopsis thaliana and the effect of environmental stress on multiple transcripts generated by this gene. RESULTS: Evidence suggests that subunit A of the vacuolar type H(+)-ATPase is encoded by a single gene in Arabidopsis thaliana. Genome blot analysis showed no indication of a second subunit A gene being present. The single gene identified was shown by whole RNA blot analysis to be transcribed in all organs of the plant. Subunit A was shown by sequencing the 3' end of multiple cDNA clones to exhibit multi site polyadenylation. Four different poly (A) tail attachment sites were revealed. Experiments were performed to determine the response of transcript levels for subunit A to environmental stress. A PCR based strategy was devised to amplify the four different transcripts from the subunit A gene. CONCLUSIONS: Amplification of cDNA generated from seedlings exposed to cold, salt stress, and etiolation showed that transcript levels for subunit A of the vacuolar type H(+)-ATPase in Arabidopsis were responsive to stress conditions. Cold and salt stress resulted in a 2–4 fold increase in all four subunit A transcripts evaluated. Etiolation resulted in a slight increase in transcript levels. All four transcripts appeared to behave identically with respect to stress conditions tested with no significant differential regulation.