Systematic Analysis of Gibberellin Pathway Components in Medicago truncatula Reveals the Potential Application of Gibberellin in Biomass Improvement

Hongfeng Wang,Hongjiao Jiang,Yan Wang,Lu Han,Lin Zhu,Xiaolin Yu,Fanjiang Kong,Chuanen Zhou,Yiteng Xu

doi:10.3390/ijms21197180

Hongfeng Wang, Hongjiao Jiang + Show 7 more

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https://doi.org/10.3390/ijms21197180

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Gibberellins (GAs), a class of phytohormones, act as an essential natural regulator of plant growth and development. Many studies have shown that GA is related to rhizobial infection and nodule organogenesis in legume species. However, thus far, GA metabolism and signaling components are largely unknown in the model legume Medicago truncatula. In this study, a genome-wide analysis of GA metabolism and signaling genes was carried out. In total 29 components, including 8 MtGA20ox genes, 2 MtGA3ox genes, 13 MtGA2ox genes, 3 MtGID1 genes, and 3 MtDELLA genes were identified in M. truncatula genome. Expression profiles revealed that most members of MtGAox, MtGID1, and MtDELLA showed tissue-specific expression patterns. In addition, the GA biosynthesis and deactivation genes displayed a feedback regulation on GA treatment, respectively. Yeast two-hybrid assays showed that all the three MtGID1s interacted with MtDELLA1 and MtDELLA2, suggesting that the MtGID1s are functional GA receptors. More importantly, M. truncatula exhibited increased plant height and biomass by ectopic expression of the MtGA20ox1, suggesting that enhanced GA response has the potential for forage improvement.

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Gibberellins (GAs), a class of well-known phytohormones, play important roles in regulating growth and development throughout the life cycle, such as seed germination, stem/internode elongation, leaf expansion, flowering, fruit development, and nodule organogenesis in legume [1,2,3,4,5,6,7,8]
GA synthesis can be divided into three steps (Figure S1): (i) biosynthesis of ent-kaurene from trans-geranyl-geranyl diphosphate by ent-copalyl diphosphate synthase (CPS) and ent-kaurene synthase (KS) in plastids; (ii) conversion of ent-kaurene to ent-kaurenic acid by ent-kaurene oxidase (KO), and (iii) conversion of ent-kaurenic acid to bioactive GAs by ent-kaurenoic acid oxidase (KAO), GA 20-oxidase (GA20ox), and GA 3-oxidase (GA3ox)
Moofl.2S3ci.c2a0n20d,i2d1a, 7te180genes were obtained in the M. truncatula genome, including 8 MtGA203ooxf, 128 MtGA3ox, and 13 MtGA2ox (Table S1)

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Introduction

Gibberellins (GAs), a class of well-known phytohormones, play important roles in regulating growth and development throughout the life cycle, such as seed germination, stem/internode elongation, leaf expansion, flowering, fruit development, and nodule organogenesis in legume [1,2,3,4,5,6,7,8]. Accumulating evidence has elucidated the molecular mechanism of GA biosynthesis, metabolism, and signaling in plants [9,10,11,12]. GA synthesis can be divided into three steps (Figure S1): (i) biosynthesis of ent-kaurene from trans-geranyl-geranyl diphosphate (trans-GGDP) by ent-copalyl diphosphate synthase (CPS) and ent-kaurene synthase (KS) in plastids; (ii) conversion of ent-kaurene to ent-kaurenic acid by ent-kaurene oxidase (KO), and (iii) conversion of ent-kaurenic acid to bioactive GAs by ent-kaurenoic acid oxidase (KAO), GA 20-oxidase (GA20ox), and GA 3-oxidase (GA3ox).

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