However, given the wider dynamic range and greater sensitivity of real-time PCR, the variation of differentially expressed genes from real-time PCR was more significant than that from the microarray analysis; we found that 22 DAP is an important turning point

in ear germination. MicroRNAs play integral roles in gene regulatory networks as one of the most abundant classes of gene regulators. The expression and activity of plant miRNAs can be regulated in many ways, including transcriptional control, as well as regulation imposed at the levels of miRNA processing and action. Moreover, changes in the expression of even a single miRNA could have a significant impact on the outcome of diverse cellular activities regulated by the product selleck screening library of that mRNA. Repression of the target transcript by miRNAs may occur through translational inhibition, accelerated exonucleolytic mRNA decay, or slice HDAC inhibitor within miRNA–mRNA base pairing [58]. Beyond the strict conservation of miRNAs across different species, some miRNAs appear to be species-specific. Compared with computational or heterologous approaches, direct miRNA cloning has the advantage of identifying non-conserved and new miRNAs. There are a number of highly conserved miRNA families in maize. In the present study, cloning and expression

analysis led to the identification of 26 miRNA variants belonging to 21 miRNA families, as well as 5 new miRNAs and 16 putatively new miRNAs. Non-conserved plant miRNAs presumably emerge and dissipate in short evolutionary time scales. Representation of many known and novel miRNAs in this single library indicates the presence of miRNAs that are

not yet discovered. The identification of a large number of miRNAs that are not previously reported in maize, at least 10 of which are conserved in monocots, suggests that many more monocot- or maize-specific miRNAs are yet to be identified. Certainly, additional tissues should be evaluated for further discovery of miRNAs in maize, coupled with similar studies in related monocots. This will help establish how many of the currently maize-specific miRNAs are conserved in other monocot species. Moreover, both in-depth analysis of the existing library GBA3 and organ-specific analysis of individual miRNAs will give insights into the functional mechanisms and pathways involved in particular in ear germination and ear development in general. Recent studies have demonstrated that miRNAs in Arabidopsis, rice, and other plant species target transcripts that encode proteins involved in diverse physiological processes by predominantly targeting transcription factors [25], [37], [44] and [59]. In this study, we predicted 90 unigenes as putative miRNA targets in maize ears, with one-third of the predicted targets of miRNAs being mRNAs of transcription factors, including AUX_IAA, MYB, ARF, bZIP, bHLH and MADS.