Dwarf and Increased Branching 1 controls plant height and axillary bud outgrowth in Medicago truncatula

We examined a tobacco retrotransposon Tnt1-tagged mutant collection of M. truncatula and identified dwarf and increased branching 1, which exhibited extreme dwarfism and increased numbers of lateral branches

Xiaojia Zhang; Liangliang He; Baolin Zhao; Shaoli Zhou; Youhan Li; Hua He; Quanzi Bai; Weiyue Zhao; Shiqi Guo; Yu Liu; Jianghua Chen

2020

Scholarcy highlights

  • Optimizing plant architecture is an efficient approach for breeders to increase crop yields, and phytohormones such as gibberellins play an important role in controlling growth
  • Endogenous concentrations of GA4 and GA1 are decreased in the dib mutant, and exogenous application of GA3 rescues the mutant phenotypes, indicating that DIB1 is necessary for GA biosynthesis in M. truncatula
  • The results from our RT-qPCR analysis showed that MtGA3ox had a different pattern of expression compared with DIB1: first, the expression of MtGA3ox was higher in all the organs that we examined, and second, MtGA3ox transcripts were more abundant in seeds at 10 d after pollination and 30 DAP than at 20 DAP, with highest expression being observed at 10 DAP
  • We identified the dib mutant in M. truncatula, which resulted in a dwarf phenotype with increased branching, and we cloned the DIB1 gene
  • The contents of the bioactive GA1 and GA4 were reduced in the dib mutant compared with the WT, indicating that DIB1 catalysed the synthesis of bioactive GAs
  • In contrast to the aerial parts of the plants, there was no significant difference in root length between the dib mutant and WT seedlings at 2 weeks old
  • DIB1 was responsible for the last step in the synthesis of bioactive GAs and it was detected in elongating organs and seeds, which might be expected to have a high content of bioactive GAs
  • We cloned DIB1, which encodes a gibberellin 3β-hydroxylase, and we propose a model in which DIB1 controls plant height and shoot branching in M. truncatula via regulation of bioactive GAs

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