Genome-Wide Analysis of the Gibberellin-Oxidases Family Members in Four Prunus Species and a Functional Analysis of PmGA2ox8 in Plant Height

Gibberellins (GAs), enzymes that play a significant role in plant growth and development, and their levels in plants could be regulated by gibberellin-oxidases (GAoxs). As important fruit trees and ornamental plants, the study of the mechanism of plant architecture formation of the <i>Prunus</i> genus is crucial. Here, 85 <i>GAox</i> genes were identified from <i>P. mume</i>, <i>P. armeniaca</i>, <i>P. salicina</i>, and <i>P. persica</i>, and they were classified into six subgroups. Conserved motif and gene structure analysis showed that GAoxs were conserved in the four <i>Prunus</i> species. Collinearity analysis revealed two fragment replication events of <i>PmGAox</i>s in the <i>P. mume</i> genome. Promoter cis-elements analysis revealed 24 <i>PmGAox</i>s contained hormone-responsive elements and development regulatory elements. The expression profile indicated that <i>PmGAox</i>s have tissue expression specificity, and GA levels during the dormancy stage of flower buds were controlled by certain <i>PmGAox</i>s. After being treated with IAA or GA₃, the transcription level of <i>PmGA2ox8</i> in stems was significantly increased and showed a differential expression level between upright and weeping stems. GUS activity driven by <i>PmGA2ox8</i> promoter was detected in roots, stems, leaves, and flower organs of <i>Arabidopsis</i>. <i>PmGA2ox8</i> overexpression in <i>Arabidopsis</i> leads to dwarfing phenotype, increased number of rosette leaves but decreased leaf area, and delayed flowering. Our results showed that GAoxs were conserved in <i>Prunus</i> species, and <i>PmGA2ox8</i> played an essential role in regulating plant height.