Functional Regulation of miRNAs in Cardamom

MicroRNAs (miRNAs) are long noncoding RNAs of about 18–24 nucleotide length. It is reported in plants, animals and in few viruses. The major function of miRNAs is the negative regulation of targeted mRNAs/genes through the complementary binding in the seed region and eventually leads to target cleavage or translational repression. The differential expression of miRNAs in various conditions confirms the strict functional regulation in various plant developmental processes and stress responses. Moreover, in every plant species, there exists many less conserved miRNAs which shows the functional regulation of miRNAs in almost every aspect of plant biological processes. This chapter explores the regulation of microRNAs in growth, development, yield and drought stress response in small cardamom (Elettaria cardamomum Maton). Cardamom is a monocot and ‘queen of spices’, which is used as a food flavouring agent and also in ayurvedic preparations for digestive problems, mouth ulcers and even for mild depression conditions. There are several miRNAs identified in small cardamom population which exhibited diversity both in its number and position of mature miRNA length and sequences of precursor microRNAs. The differential expression pattern between wild and cultivar pattern showed that 19 miRNAs were differentially expressed and most of the miRNAs were over expressed in cultivar cardamom population. In wild cardamom population, the miR169 was down regulated and miR529 was upregulated suggests that the wild small cardamom populations hold stronger drought stress resistance and increased floral development than its cultivar population. There are 17 miRNAs got differentially expressed in wild cardamom population under drought stress which play significant role in several biological processes to improve drought stress tolerance in plants.