Understanding the role of miRNAs for improvement of tea quality and stress tolerance.

Abstract MicroRNAs (miRNAs) are an emerging class of small non-coding RNAs that exhibit important role in the regulation of gene expression, mostly through the mechanism of cleavage and/or inhibition of translation of the target mRNAs during or after transcription. Although much has been unravelled about the role of miRNAs in diverse biological processes like maintenance of functional integrity of genes and genome, development, metabolism, and adaptive responses towards biotic and abiotic stresses in plants, not much is known on their specific roles in majority of cash crops an area of investigation with potentially significant and gainful economic implications. Tea (Camellia sinensis) is globally the second most consumed beverage after water and its cultivation has major agro-economic and social implications. In recent years global tea production has been greatly challenged by many biotic and abiotic stress factors and a deeper understanding of molecular processes regulating stress adaptation in this largely under investigated crop stands to significantly facilitate potential crop improvement strategies towards durable stress tolerance. This review endeavours to highlight recent advances in our understanding of the role of miRNAs in regulating stress tolerance traits in tea plant with additional focus on their role in determining tea quality attributes. We also present an overview of stress responsive genes and pathways in tea plant and studying their potential roles as miRNA targets will be greatly insightful for improving agronomically important attributes in this highly economic crop.