Abstract
MicroRNA families are important regulators of plant resistance to diverse stressors, but the miRNA families expressed in
response to drought, and the levels thereof, in sugarcane (an important commercial source of both sugar and biofuel) remain
poorly understood. In the present study, we determined the expression profile of miRNA families synthesized by leaves of
the drought-resistant cultivar ROC22 stressed by addition of PEG to the growth substrate. Totals of 23 conserved miRNA
families and 34 new miRNA families were identified, and 438 putative target genes of 44 miRNA families were described.
Expression analysis revealed that 11 miRNA families were differentially expressed in control and drought-exposed plants. Of
these, nine families were up-regulated and two down-regulated. The potential targets of the 11 miRNA families were genes
associated with plant growth and stress resistance, specifically SPBP, MYB, the AGO1-like gene, NCBP, BCP, CPI, and LSG. With the exceptions of SPBP, NCBP and BCP, the other genes were down-regulated in response to drought stress. Our
preliminary identification of 11 relevant miRNA families expressed by ROC22, and their targets, suggest that these miRNA
families may regulate the response to drought stress and forms a basis for planned future work. The other new miRNA
families identified, along with their targets, may exert novel effects on various metabolic pathways relevant to sugarcane
growth and development.
