[1] Univ Pretoria, Dept Biochem, ZA-0002 Pretoria, South Africa
[2] Univ Pretoria, African Ctr Gene Technol, ZA-0002 Pretoria, South Africa
[3] Univ Grenoble 1, Inst Rech & Technol & Sci le Vivant, CEA,UMR 5168 CNRS CEA INRA, Physiol Cellulaire Vegetale Lab, F-38054 Grenoble 09, France
[4] Princeton Univ, Lewis Sigler Inst Integrat Genom, Dept Mol Biol, Princeton, NJ 08544 USA