Genome-Wide Identification and Functional Analysis of the Roles of SAUR Gene Family Members in the Promotion of Cucumber Root Expansion

Abstract

Auxin serves as an essential regulator of the expression of many different genes in plants, thereby regulating growth and development. The specific functional roles of members of the SAUR (small auxin-up RNA) auxin early response gene family in the development of cucumber plants, however, remain to be fully clarified. Here, 62 SAUR family genes were identified, followed by their classification into 7 groups that included several functionally associated cis-regulatory elements. Phylogenetic tree and chromosomal location-based analyses revealed a high degree of homology between two cucumber gene clusters and other plants in the Cucurbitaceae family. These findings, together with the results of an RNA-seq analysis, revealed high levels of CsSAUR31 expression within the root and male flower tissues. Plants overexpressing CsSAUR31 exhibited longer roots and hypocotyls. Together, these results provide a basis for further efforts to explore the roles that SAUR genes play in cucumber plants, while also expanding the pool of available genetic resources to guide research focused on plant growth and development.