AUTHOR=Cheng Jun , Ma Jingjing , Zheng Xianbo , Lv Honglin , Zhang Mengmeng , Tan Bin , Ye Xia , Wang Wei , Zhang Langlang , Li Zhiqian , Li Jidong , Feng Jiancan 

TITLE=Functional Analysis of the Gibberellin 2-oxidase Gene Family in Peach

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.619158

DOI=10.3389/fpls.2021.619158

ISSN=1664-462X

ABSTRACT=<p>Peach (<italic>Prunus persica</italic> L. Batsch) trees grow vigorously and are subject to intense pruning during orchard cultivation. Reducing the levels of endogenous gibberellins (GAs) represents an effective method for controlling branch growth. Gibberellin 2-oxidases (GA2oxs) deactivate bioactive GAs, but little is known about the GA2ox gene family in peach. In this study, we identified seven <italic>PpGA2ox</italic> genes in the peach genome, which were clustered into three subgroups: C<sub>19</sub>-GA2ox-I, C<sub>19</sub>-GA2ox-II, and C<sub>20</sub>-GA2ox-I. Overexpressing representative genes from the three subgroups, <italic>PpGA2ox-1</italic>, <italic>PpGA2ox-5</italic>, and <italic>PpGA2ox-2</italic>, in tobacco resulted in dwarf plants with shorter stems and smaller leaves than the wild type. An analysis of the GA metabolic profiles of the transgenic plants showed that PpGA2ox-5 (a member of subgroup C<sub>19</sub>-GA2ox-II) is simultaneously active against both C<sub>19</sub>-GAs and C<sub>20</sub>-GAs,which implied that C<sub>19</sub>-GA2ox-II enzymes represent intermediates of C<sub>19</sub>-GA2oxs and C<sub>20</sub>-GA2oxs. Exogenous GA<sub>3</sub> treatment of shoot tips activated the expression of all seven <italic>PpGA2ox</italic> genes, with different response times: the <italic>C</italic><sub>19</sub>-<italic>GA2ox</italic> genes were transcriptionally activated more rapidly than the <italic>C<sub>20</sub>-GA2ox</italic> genes. GA metabolic profile analysis suggested that C<sub>20</sub>-GA2ox depletes GA levels more broadly than C<sub>19</sub>-GA2ox. These results suggest that the <italic>PpGA2ox</italic> gene family is responsible for fine-tuning endogenous GA levels in peach. Our findings provide a theoretical basis for appropriately controlling the vigorous growth of peach trees.</p>