Differences in meristem size and expression of branching genes are associated with variation in panicle phenotype in wild and domesticated African rice

K. N. Ta, H. Adam, Yannick Städler, Jürg Schönenberger, T. Harrop, J. Tregear, N. V. Do, P. Gantet, A. Ghesquiere, S. Jouannic

Background: The African rice Oryza glaberrima was domesticated from its wild relative Oryza barthii about 3000 years ago. During the domestication process, panicle complexity changed from a panicle with low complexity in O. barthii, to a highly branched panicle carrying more seeds in O. glaberrima. To understand the basis of this differential panicle development between the two species, we conducted morphological and molecular analyses of early panicle development.

Results: Using X-ray tomography, we analyzed the morphological basis of early developmental stages of panicle development. We uncovered evidence for a wider rachis meristem in O. glaberrima than in O. barthii. At the molecular level, spatial and temporal expression profiles of orthologs of O. sativa genes related to meristem activity and meristem fate control were obtained using in situ hybridization and qRT-PCR. Despite highly conserved spatial expression patterns between O. glaberrima and O. barthii, differences in the expression levels of these early acting genes were detected.

Conclusion: The higher complexity of the O. glaberrima panicle compared to that of its wild relative O. barthii is associated with a wider rachis meristem and a modification of expression of branching-related genes. Our study indicates that the expression of genes in the miR156/miR529/SPL and TAW1 pathways, along with that of their target genes, is altered from the unbranched stage of development. This suggests that differences in panicle complexity between the two African rice species result from early alterations to gene expression during reproductive development.

Department of Botany and Biodiversity Research
External organisation(s)
Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), Chinese Academy of Sciences (CAS), University of Science and Technology of Hanoi (USTH)
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
106042 Systematic botany, 106008 Botany, 106012 Evolutionary research
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