Conservation, Divergence, and Abundance of MiRNAs and Their Effect in Plants

More than 80% of our food comes from seed, flower, and fruit parts. Therefore, understanding the genetic networks that regulate how these organs are formed is important. Transcription factors are one of the main regulators. In addition, it has been demonstrated that another level of regulation includes epigenetic mechanisms. Epigenetic mechanisms include changes in DNA methylation, histone modifications, and noncoding RNAs. Noncoding RNAs include miRNAs that regulate gene expression, at the transcriptional or posttranscriptional level. Next-generation sequencing has demonstrated the expression, conservation, and divergence of miRNAs. Furthermore, functional studies of miRNAs have allowed elucidating their important roles in many developmental processes, including in flower and fruit development, providing potential applications of the use of miRNAs in crop improvement. In this chapter, we describe the conservation and divergence of miRNAs in plants and the advance in the elucidation of their functions.