Gene expression and metabolite profiling of gibberellin biosynthesis during induction of somatic embryogenesis in Medicago truncatula Gaertn

• Published in: PloS one Vol. 12; no. 7; p. e0182055
• Main Authors: Igielski, Rafał, Kępczyńska, Ewa
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.07.2017; Public Library of Science (PLoS)
• Subjects: Alfalfa; Analysis; Biocompatibility; Biology and Life Sciences; Biosynthesis; Biosynthetic Pathways - drug effects; Biosynthetic Pathways - genetics; Callus; Chemical reactions; Computer and Information Sciences; Cytoplasm; Embryonic development; Embryonic growth stage; Embryos; Endoplasmic reticulum; Enzymes; Explants; Flowers & plants; Gene expression; Gene Expression Profiling - methods; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant; Genetic aspects; Gibberellins; Gibberellins - biosynthesis; Hydroxylation; Medicago truncatula - drug effects; Medicago truncatula - embryology; Medicago truncatula - genetics; Medicago truncatula - metabolism; Metabolism; Metabolites; Metabolomics - methods; Physiological aspects; Plant growth; Plant Leaves - anatomy & histology; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Somatic Embryogenesis Techniques; Plants (botany); Plastids; Research and Analysis Methods; Seeds; Seeds - drug effects; Seeds - genetics; Seeds - metabolism; Somatic embryogenesis; Substrates; Triazoles - pharmacology
• DOI: 10.1371/journal.pone.0182055
• ISSN: 1932-6203

Gibberellins (GAs) are involved in the regulation of numerous developmental processes in plants including zygotic embryogenesis, but their biosynthesis and role during somatic embryogenesis (SE) is mostly unknown. In this study we show that during three week- long induction phase, when cells of leaf explants from non-embryogenic genotype (M9) and embryogenic variant (M9-10a) were forming the callus, all the bioactive gibberellins from non-13-hydroxylation (GA4, GA7) and 13-hydroxylation (GA1, GA5, GA3, GA6) pathways were present, but the contents of only a few of them differed between the tested lines. The GA53 and GA19 substrates synthesized by the 13-hydroxylation pathway accumulated specifically in the M9-10a line after the first week of induction; subsequently, among the bioactive gibberellins detected, only the content of GA3 increased and appeared to be connected with acquisition of embryogenic competence. We fully annotated 20 Medicago truncatula orthologous genes coding the enzymes which catalyze all the known reactions of gibberellin biosynthesis. Our results indicate that, within all the genes tested, expression of only three: MtCPS, MtGA3ox1 and MtGA3ox2, was specific to embryogenic explants and reflected the changes observed in GA53, GA19 and GA3 contents. Moreover, by analyzing expression of MtBBM, SE marker gene, we confirmed the inhibitory effect of manipulation in GAs metabolism, applying exogenous GA3, which not only impaired the production of somatic embryos, but also significantly decreased expression of this gene.