Maps of the Arabidopsis BAC F24o1 and the AtSTM gap-repair construct. A: A physical map of BAC F24o1, showing the relative positions of the 21 coding sequences (CDS), including STM (CDS 9) and its immediate neighbours (CDS 7, 8 and 10) which, are illustrated in different colours and greater detail to show the exon blocks making up each open reading frame. Grey arrows show the orientations of the serine protease, predicted pentatricopeptide repeat protein (PPR), SHOOTMERISTEMLESS (STM) and Zinc Finger Protein (ZFP) open reading frames. B: The gap-repair construct and a schematic representation of the basic protocol used to generate the AtSTM downstream (yellow vertical dashed line: W - X) and upstream (blue diagonal dashed line: Y - Z) homology arms to create it in the pBluescriptII KS+ vector backbone. W, X, Y and Z are the PCR primers used to generate each homology arm fragment The Sal I, Sph I, and Hind III cloning sites were incorporated into the PCR primers, the sequences of which are given in Additional file 1.