ORIGINAL PAPER Oligosaccharins and Pectimorf Ò stimulate root elongation and shorten the cell cycle in higher plants Lien Gonza ´lez-Pe ´rez • Alenna Va ´zquez-Gları ´a • Lara Perrotta • Alexis Acosta • Sarah A. Scriven • Robert Herbert • Juan Carlos Cabrera • Dennis Francis • Hilary J. Rogers Received: 31 March 2011 / Accepted: 19 April 2012 / Published online: 3 May 2012 Ó Springer Science+Business Media B.V. 2012 Abstract The aim was to test promotive effects of oli- gosaccharins on root growth and development at the root apical meristem and the cell cycle using the model systems, Arabidopsis thaliana and the tobacco (Nicotiana tabacum) BY-2 cell line. Arabidopsis was grown on medium sup- plemented with 0.1 mg L -1 oligoxyloglucan (OX), 10 mg L -1 Pectimorf Ò (P) or 0.5 mg L -1 indole butyric acid (IBA). Primary root length, number of lateral root pri- mordia, root apical meristem (RAM) length and epidermal cell length were recorded. Three genotypes were used: wild type (WT) and transgenic lines expressing either Schizo- saccharomyces pombe (Sp) cdc25 or over-expressing (oe) Arath;WEE1. All treatments promoted primary root elon- gation but repressed lateral root production. Only P had a clear positive effect on meristem length whereas all other genotype 9 treatment interactions showed shorter RAMs. Whilst IBA, OX and P induced an increase in cell length in Spcdc25, the same treatments caused a significant decrease in WEE1 oe . Mitotic indices were also significantly higher in roots treated with oligosaccharins suggesting a shortening of the cell cycle. This hypothesis was tested in the BY-2 cell line. Both OX and P shortened the cell cycle exclu- sively through a shortening of G1 whilst mitotic cell size remained constant between treatments. In conclusion, both OX and P do indeed stimulate growth and shorten the cell cycle in higher plants and at the cellular level are able to reverse large and small cell size phenotypes normally exhibited by WEE1 oe and Spcdc25 genotypes, respectively. Keywords Arabidopsis thaliana  BY-2 cells  Cell cycle  Lateral roots  Nicotiana tabacum  Oligosaccharins  Plant growth regulators  Root elongation  Root morphology Introduction In higher plants, primary root elongation is the product of cell division in root apical meristems and elongation of cells that are displaced from the meristem (Pritchard 1988; Francis 1998). A species-dependent elaboration of a bran- ched root system occurs through an iterative growth pattern whereby secondaries arise from the pericycle of the pri- mary, tertiaries from the pericycle of the secondaries and so on. The root system both anchors the above ground part of the plant and acts as a highly elaborate absorptive organ, enabling nutrients to be absorbed and transported to the rest of the plant. Both abiotic and biotic factors affect root growth. For example, for plants in temperate environments, optimum L. Gonza ´lez-Pe ´rez (&)  A. Va ´zquez-Gları ´a Plant Biology Department, Faculty of Biology, University of Havana, Street 25 No. 455 Vedado, City of Havana, Cuba e-mail: liengonza@yahoo.es L. Perrotta Department of Botanical, Ecological and Geological Sciences, University of Sassari, Sassari, Italy A. Acosta Biotechnology Institute, National Autonomous University of Mexico (UNAM), Cuernavaca, Morelos, Mexico S. A. Scriven  D. Francis  H. J. Rogers School of Biosciences, Cardiff University, Cardiff, UK R. Herbert Institute of Science and the Environment, Worcester University, Worcester, UK J. C. Cabrera Unite ´ de Biotechnologie, MATERIA NOVA, Rue des Foudriers, 1, 7822 Ghislenghien, Belgium 123 Plant Growth Regul (2012) 68:211–221 DOI 10.1007/s10725-012-9709-z