A microRNA Profile Of Drought-Challenged Sorghum Seedlings Using Microarray Detection

In order to understand whole plant microRNA expression as a response to drought we carried out a three replicate microarray experiment on aseptically grown 14-day-old sorghum seedlings. We detected 94 microRNA signals from 80 families over 9 species using miRBase registry release 13. These microRNAs target 366 annotated sorghum genes of which roughly a third of them (91 coding gene transcripts) are upregulated as a response to drought. More than a third of the detected microRNA signals were from deep ancestral species such as Chlamydomonas reinhardtii, Physcomitrella patens and Selaginella moellendorffii. The Chlamydomonas Genome Project has shown that no microRNA gene is shared with any of the land plants. Array signals most probably are generated by newly evolved non-conserved microRNA loci evolved convergently. Finding genomic coordinates of these non-conserved microRNA loci and SorghumCyc-based painting of 366 drought response genes on the entire sorghum metabolic pathway network will provide insight into complexities of drought response in this well-adapted species.