Sucrose affects the developmental transition of rhizomes in Oryza longistaminata
Oryza longistaminata, the African wild rice, can propagate vegetatively through rhizomes. Rhizomes elongate horizontally underground as sink organs, however, they undergo a developmental transition that shifts their growth to the surface of the ground to become aerial stems. This particular stage is essential for the establishment of new ramets. While several determinants such as abiotic stimuli and plant hormones have been reported as key factors effecting developmental transition in aerial stem, the cause of this phenomenon in rhizome remains elusive. This study shows that depletion of nutrients, particularly sucrose, is the key stimulus that induces the developmental transition in rhizomes, as indicated by the gradient of sugars from the base to the tip of the rhizome. Sugar treatments revealed that sucrose specifically represses the developmental transition from rhizome to aerial stem by inhibiting the expression of sugar metabolism and hormone synthesis genes at the bending point. Sucrose depletion affected several factors contributing to the developmental transition of rhizome including signal transduction, transcriptional regulation and plant hormone balance.
KeywordsRhizome Oryza longistaminata Sucrose Developmental transition Gravitropism
We are grateful to Drs. T. Furuta and S. Reuscher from the Laboratory of Plant Molecular Biosystem of Nagoya University for the insightful discussions and providing the genome information of O. longistaminata, line no. IRGC110404. We thank Ms. J. Ramos and Dr. K. K. Jena from IRRI for sharing the material, IRGC110404. We thank Dr. J. Murase from Nagoya University for teaching how to measure the sugar absorbance.
This work was supported by Advanced Low Carbon Technology Research and Development Program from the Core Research for Evolutional Science and Technology by JST.
Compliance with ethical standards
Conflict of interest
No conflicts of interest declared.
Supplementary material 1. The rhizome bud penetrates the surrounding leaf sheath to elongate its internode horizontally. This movie was observed in hydroponic culture media by Brinno TLC200pro. (MOV 15795 KB)
Supplementary material 2. Elongating rhizome horizontally acquires negative gravitropism and goes upward to develop as a new individual. This movie was observed in hydroponic culture media by Canon EOS 40D. (MP4 8807 KB)
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