A New Molecular Mechanism Regulating Shoot Branching Revealed

Recently, the Innovation Team of Crop Functional Genomics Research from the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences (ICS, CAAS) and collaborators from the University of Queensland (UQ) in Australia, identified molecular targets where sucrose and strigolactone antagonize each other during plant branching regulation, using molecular and genetic methods. On October 29th, the main findings were published online in the prestigious journal New Phytologist.

As Professor Li Xueyong said, plant branching is regulated by many factors. Auxin and strigolactone inhibit plant branching, while sugar and cytokinin promote shoot branching. The inhibitory effect of auxin on plant branching is partially mediated by strigolactone. Apical dominance affects plant type through the distribution of auxin. Decapitation can break the apical dominance of the plant, but the auxin treatment is not enough to restore the apical dominance. The initial bud growth has nothing to do with the consumption of auxin in the stem, but with the rapid mobilization of sugar to the bud. Previous studies have pointed out that sugar and strigolactone coordinately regulate plant branching and tillering, but the mechanism of their interaction is not clear.

This study found that sucrose can antagonize the inhibitory effect of strigolactone on rice tillering. At the mechanism level, sucrose promotes the accumulation of D53 protein, the key negative regulator of strigolactone signaling, and antagonizes the degradation of D53 protein induced by strigolactone. Sucrose can inhibit the transcription of the D3 gene encoding an E3 ubiquitin ligase responsible for the degradation of D53 protein, and overexpression of D3 can relieve the stabilizing effect of high concentrations of sucrose on the D53 protein and the promotion of tillering. Sucrose can also prevent strigolactone-induced degradation of D14 protein, and overexpression of D14 can promote the accumulation of D53 protein and sucrose-induced tillering. This study revealed the mechanism of sucrose and strigolactone interaction to regulate branching and tillering at the molecular level.

Professor Li Xueyong (ICS, CAAS), Professor Christine A. Beveridge and Postdoctoral fellow Francois F. Barbier (UQ) are the co-corresponding authors of this paper. Suyash B. Patil (PhD student of ICS, CAAS), Francois F. Barbier, and Associate Professor. Zhao Jinfeng (ICS, CAAS) are the co-first authors. This study was funded by the National Natural Science Foundation of China, the Ministry of Agriculture and Rural Affairs, the China Scholarship Council, and the Australian Research Council.

Original link: https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17834

Molecular Mechanism of Sucrose and Strigolactone Synergistically Regulating Plant Branching/Rice Tillering