Correlation between arginine decarboxylase expression during abiotic stress and polyamine content in Withania somnifera

Abstract

(Abstract selected from presentation in National Conference on Biodiversity of Medicinal and Aromatic Plants: Collection, Characterization and Utilization, held at Anand, India during November 24-25, 2010)

 

In plants, polyamines are generally synthesized by the ornithine decarboxylase and arginine decarboxylase (ADC) through polyamine pathway. In the current study, attempt was made to clone and characterize a gene encoding arginine decarboxylase from Withania somnifera. A full-length ADC cDNA (WsADC) with the longest open reading frame of 828 nucleotides, encoding a 275 amino acids polypeptide was developed by primer walking. WsADC mRNA was expressed in organs such as flower when tested for different plant organs like leaf, root, callus, stem and whole plantlet. Expression level of WsADC in different tissues of ashwagandha was spatially regulated. Transcripts of WsADC in ashwgandha shoots were induced either transiently in response to various abiotc stresses. Treatment of ashwgandha shoots on chilling and wounding remarkably induced accumulation of WsADC mRNA whereas UV light down- regulated the mRNA expression levels. This is the first direct evidence of a function of polyamines in the chilling, wounding and UV light response. Presented results suggest that the transcript of ADC gene involved in polyamine biosynthesis show different profile of expression in response to environmental stress. To establish the distinct correlation between expression of WsADC on stress response, polyamine and withanoilde content analysis is underway.