Regulatory Sequences of Pear

Abstract

Pear (Pyrus) is one of the leading and oldest cultivated fruit trees of temperate regions that is grown around the world. Compared to other Rosaceae species, pear research studies have lagged behind other members of the Rosaceae, such as strawberry, peach, and apple. However, the recent completion of whole-genome sequencing projects for pear offers ideal opportunities for pursuing regulatory sequence research studies. A regulatory sequence is a segment of nucleic acids capable of either increasing or decreasing; i.e., regulation of expression of a structural gene. Furthermore, the regulation of gene expression can be undertaken in different ways, such as during transcription, mRNA processing, translation, and via protein stability. It is commonly proposed that the regulation of gene expression occurs primarily at the transcriptional level. A plant transcriptional mechanism consists of two complimentary regulatory modules, cis-acting and trans-acting elements. Cis-acting elements are DNA sequences present in either coding or non-coding regions of the genome. Cis-acting elements can also be covered by epigenetic information. On the other hand, trans-acting factors are transcription factors (TFs) or other DNA-binding proteins that bind to specific sequences in cis-acting elements to either increase or suppress transcription of a given gene. In this instance, chromatin remodeling involves dynamic modification of histones or the DNA sequence itself to allow access of accessible regions within the DNA for trans-acting elements to regulate transcription. Furthermore, TFs may influence transcription of multiple genes, and they can function either in a complex manner or combinatorially to bind cis-regulatory components at multiple transcription factor binding sites to regulate a unique trait in a controlled pattern of gene expression.