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

• Main Authors: Qiangqiang Ding, Feng Wang, Juan Xue, Xinxin Yang, Junmiao Fan, Hong Chen, Yi Li, Han Wu
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: International Journal of Molecular Sciences
• Subjects: genome-wide identification; expression analysis; 2OGD family; hormone biosynthetic and metabolism genes; tomato fruit ripening
• Online Access: https://www.mdpi.com/1422-0067/21/15/5344
• ISSN: 1661-6596; 1422-0067

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 <i>SlGA2ox2</i>, and the auxin degradation gene <i>SlDAO1</i>, 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 <i>SlGA2ox2</i> and <i>SlDAO1</i> 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 <i>SlGA2ox2</i> and <i>SlDAO1</i>, respectively. Therefore, <i>SlGA2ox2</i> and <i>SlDAO1</i> are implicated in the degradation of GAs and auxin during tomato fruit ripening.