Discovery of MicroRNAs in Cardamom (Elettaria cardamomum Maton) under Drought Stress

Abstract

MicroRNAs (miRNAs) are endogenous, 19–24-nucleotide-long, noncoding RNAs found in animals, plants, and some viruses. Drought is one of the major limiting factors that negatively affect productivity of plants. To date, nothing is known about the regulatory roles of miRNAs in response to drought stress in cardamom. Cardamom collected from the natural forest area in Therakkudi in the Idamalayar forest range was selected for the study. Total RNA was isolated from leaves and stems of control and drought treated cardamom plant, which was used for library construction. Ion torrent sequencing of the two small RNA libraries prepared from plants raised under well irrigated and drought stressed treatments, respectively, created 3,938,342 and 4,083,181 primary reads. A total of 150 conserved and 20 novel microRNAs were identified from both the control and the treated libraries. Discovery of 17 differentially expressed miRNAs under drought stress suggests that these might have been involved in various biological processes to improve plant tolerance to water stress. This study is the first report of drought responsive miRNAs and their targets in cardamom. The outcome of this research could provide insights into the miRNA based regulatory mechanisms in response to drought stress in monocot plants.