Journal of Biotechnology & Biomaterials
Open Access

Abstract

Plant growth and development, metabolism and stress responses, as well as a myriad of other functions, depend on the correct regulation of gene expression. This is achieved by multiple mechanisms, with perhaps the most important control being exerted at the level of transcription. However, with the recent discovery of microRNAs (miRNAs) another ubiquitous mode of gene regulation that occurs at the post-transcriptional levels has been identified. miRNAs are 21-nt non-coding RNAs that can silence the target genes by targeting complementary or partially complementary mRNAs for degradation or translational inhibition. Sugarcane (Saccharum spp. hybrid) is one of the leading agricultural crops of the world as a source of sugar and energy, and a large number of other by-products. The production and the productivity of sugarcane are challenged by various biotic and abiotic factors. Among these, drought is the foremost abiotic stress which adversely affects cane productivity by having deleterious effects on plant metabolic processes including stomatal movement, nutrient uptake, production of photosynthetic assimilates, and crop yield. Several microRNAs that mediate post-transcriptional regulation during water stress have been described in other crop species. They function as critical post-transcriptional regulators of drought-responsive genes and control their expression. Recently, an increasing number of drought stress-responsive miRNAs have been described in sugarcane by using high-throughput small RNA deep sequencing. Sugarcane varieties differ in their ability to withstand drought while maintaining sucrose accumulation. miRNAs that are differentially expressed under drought stress have been identified from sugarcane cultivars having differential drought response (tolerant vs. sensitive). The target genes predicted for many of these differentially expressed mature miRNAs contain transcription factors, transporters, and proteins, and some of these targets have been validated by RT-qPCR. Essentially, most of these miRNAs target genes encode transcription factors, which place miRNAs at the centre of gene regulatory networks. This paper dwells upon miRNA-associated complex regulatory networks and their target genes involved in drought stress response in sugarcane, thereby deciphering their role vis-à-vis potential in paving future efforts to improve drought stress tolerance in sugarcane.

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