Diverse Roles of Strigolactone Signaling in Maize Architecture and the Uncoupling of a Branching-Specific Subnetwork

Our findings indicate that in maize, uncoupling of the Teosinte branched1 subnetwork from SL signaling has profoundly altered the balance between conserved roles of SLs in branching and diverse aspects of plant architecture

Jiahn Chou Guan; Karen E. Koch; Masaharu Suzuki; Shan Wu; Susan Latshaw; Tanya Petruff; Charles Goulet; Harry J. Klee; Donald R. McCarty

2012

Scholarcy highlights

  • Strigolactones control lateral branching in diverse species by regulating transcription factors orthologous to Teosinte branched1
  • To facilitate genetic analysis of SL signaling in maize, we focused on identifying steps in the maize SL pathway that were encoded by single genes
  • Mutants in SL biosynthesis and signaling increase branching in diverse plant species, including Arabidopsis, pea, and petunia, as well as tomato, kiwifruit, and rice
  • In contrast with the prevailing model, which places SLs upstream of Tb1 orthologs in a linear pathway of branching control, our results indicate that Tb1 mediates a branchingspecific subnetwork that has become independent of SL
  • The remaining centrally positioned gene in the Setaria spp. cluster, SiCCD8c, would have been duplicated in the lineage that led to sorghum, while the D10-like paralog shared by Setaria spp. and rice was apparently lost in the sorghum/maize lineage
  • Our analyses of gene expression confirm that regulation of Tb1 transcript level is uncoupled from SL signaling in maize, where we find that expression of Tb1 is not reduced in zmccd8 mutants or up-regulated by GR24 treatment
  • The evolution of SL-independent regulation of branching in maize and variation in CAROTENOID CLEAVAGE DIOXYGENASE8 paralog diversity in grass genomes suggest that innovation and functional diversification of the SL signaling network have had significant roles in the evolution of grasses

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