Identification and Expression Analysis of Hormone Biosynthetic and Metabolism Genes in the 2OGD Family for Identifying Genes That May Be Involved in Tomato Fruit Ripening

Abstract

Phytohormones play important roles in modulating tomato fruit development and ripening. The 2-oxoglutarate-dependent dioxygenase (2OGD) superfamily containing several subfamilies involved in hormone biosynthesis and metabolism. In this study, we aimed to identify hormone biosynthesis and metabolism-related to 2OGD proteins in tomato and explored their roles in fruit development and ripening. We identified nine 2OGD protein subfamilies involved in hormone biosynthesis and metabolism, including the gibberellin (GA) biosynthetic protein families GA20ox and GA3ox, GA degradation protein families C19-GA2ox and C20-GA2ox, ethylene biosynthetic protein family ACO, auxin degradation protein family DAO, jasmonate hydroxylation protein family JOX, salicylic acid degradation protein family DMR6, and strigolactone biosynthetic protein family LBO. These genes were differentially expressed in different tomato organs. The GA degradation gene SlGA2ox2, and the auxin degradation gene SlDAO1, showed significantly increased expression from the mature-green to the breaker stage during tomato fruit ripening, accompanied by decreased endogenous GA and auxin, indicating that SlGA2ox2 and SlDAO1 were responsible for the reduced GA and auxin concentrations. Additionally, exogenous gibberellin 3 (GA3) and indole-3-acetic acid (IAA) treatment of mature-green fruits delayed fruit ripening and increased the expression of SlGA2ox2 and SlDAO1, respectively. Therefore, SlGA2ox2 and SlDAO1 are implicated in the degradation of GAs and auxin during tomato fruit ripening.

Multi-Locus Genome-Wide Association Studies Reveal Fruit Quality Hotspots in Peach Genome

“…RNA binding proteins and serine-type endopeptidase inhibitor-related genes were identified, and previous studies revealed involvement in the regulation of flowering time ( Steffen et al, 2019 ; Zhang F. et al, 2019 ). In addition, genes functionally annotated as 2-oxoglutarate-dependent dioxygenase, drug transmembrane transport, antiporter activity, pyridine nucleotide biosynthetic process, and chromatin assembly or disassembly were associated with fruit ripening in tomato, apricot, grape, peach, apple, and strawberry ( Hanana et al, 2007 ; Farinati et al, 2017 ; Decros et al, 2019 ; Ding et al, 2020 ; García-Gómez et al, 2020 ). Furthermore, previous studies have shown that molybdopterin cofactor plays an important role in the metabolic control of avocado fruit growth and final fruit size ( Cowan et al, 2001 ) and ion/H+ exchanger genes (GO: ion transmembrane transport) were critical for providing pH regulation ( Pittman, 2012 ).…”

Hormone biosynthesis and metabolism members of 2OGD superfamily are involved in berry development and respond to MeJA and ABA treatment of Vitis vinifera L

“…As is described in the background section above, the 37 Vv2OGD-Hs are functional in six hormones biosynthesis and metabolism, GAs, IAA, ET, JAs, SAs and SLs [ 6 ]. Previous studies have proved that these six hormones play irreplaceable roles in fruit ripening or fruit quality formation process [ 18 – 20 , 29 , 30 ].…”

“…The members in DOXB are P4Hs, they participate in the post-translational modification of protein and hydroxylate proline residues by forming 4-hydroxyproline [ 3 ]. DOXC is the largest branch of 2OGD, with 99 and 159 members in Arabidopsis and tomato respectively [ 6 ]. Until now, DOXC members have been found to be involved in hormone biosynthesis or metabolism, and catalyze the synthesis of some secondary metabolites, such as flavonoids, benzylisoquinoline alkaloids, glucosinolates and tropane alkaloids, etc.…”

“…Hormones play indispensable roles during plant growth and development. According to the evolutionary tree and gene function, the hormone biosynthesis and metabolism related members in DOXC class (abbreviated as 2OGD-H below) could be divided into 9 clades [ 6 ]. 1) Gibberellin (GA) 20-oxidase (GA20ox) catalyzes two steps in two GA biosynthesis pathways respectively, GA12 → GA24 → GA9 and GA53 → GA19 → GA20.…”

“…Some of the 2OGD-H members have been reported to be involved in the ripening process, such as GA2ox, ACO, and DAO [ 6 , 12 , 29 ]. However, most of the members whether functional in ripening have not been studied, such as JOX, DMR6 and LBO, meanwhile, the related hormones JAs, SAs and SLs have already been researched and show significant involvement in berry development or quality formation [ 18 – 20 , 29 , 30 ].…”