MicroRNAs as potential targets for improving rice yield via plant architecture modulation: Recent studies and future...

Ensuring agricultural food security is a major concern for the future world, and being the second most consumed crop, rice yield needs an urgent upliftment. Grain yield is a pleiotropic trait that employs a plethora of genes functioning in complex signalling cascades. The yield related genes are controlled by various regulatory factors including the microRNAs (miRNAs), the small 20-22 nucleotide (nt) non-coding RNAs, which have emerged as the master ribo-regulators of eukaryotic genes. Plant miRNAs can bind to highly complementary sequences in the target messenger RNAs (mRNAs) and negatively regulate gene expression to coordinate the various biological processes involved in plant development. In rice, an ideal plant architecture (IPA) has been regarded as the key to attain high yield and several miRNAs have been deciphered to play important roles in orchestrating vital regulatory procedures for achieving optimum plant morphological yield related traits like less unproductive tillers, more panicle branches and heavier grains. In this review, we present and discuss the various genetic engineering strategies undertaken to manipulate the miRNA-mRNA expression levels in order to achieve improved grain output by modulation of rice plant architecture and recent advances made in this regard.