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Characterisation of the phosphoenolpyruvate carboxylase gene family in sugarcane (Saccharum spp.)

Besnard G., Pinçon G., D'Hont A., Hoarau J.Y., Cadet F., Offmann B.G.. 2003. Theoretical and Applied Genetics, 107 (3) : p. 470-478.

DOI: 10.1007/s00122-003-1268-2

Phosphoenolpyruvate carboxylases (PEPCs) are encoded by a small multigenic family. In order to characterise this gene family in sugarcane, seven DNA fragments displaying a high homology with grass PEPC genes were isolated using polymerase chain reaction-based cloning. A phylogenetic study revealed the existence of four main PEPC gene lineages in grasses and particularly in sugarcane. Moreover, this analysis suggests that grass C4 PEPC has likely derived from a root pre-existing isoform in an ancestral species. Using the Northern-dot-blot method, we studied the expression of the four PEPC gene classes in sugarcane cv. R570. We confirmed that transcript accumulation of the C4 PEPC gene (ppc-C4) mainly occurs in the green leaves and is light-induced. We also showed that another member of this gene family (ppc-aR) is more highly transcribed in the roots. The constitutive expression for a previously characterised gene (ppc-aL2) was confirmed. Lastly, the transcript accumulation of the fourth PEPC gene class (ppc-aL1) was not revealed. Length polymorphism in non-coding regions for three PEPC gene lineages enabled us to develop sequence-tagged site PEPC markers in sugarcane. We analysed the segregation of PEPC fragments in self-pollinated progenies of cv. R570 and found co-segregating fragments for two PEPC gene lineages. This supports the hypothesis that diversification of the PEPC genes involved duplications, probably in tandem.

Mots-clés : saccharum; phosphoenolpyruvate carboxylase; photosynthèse; pool de gènes; identification; technique analytique

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