• PDF / 4,359,631 Bytes
• 17 Pages / 595.276 x 790.866 pts Page_size
• 100 Downloads / 203 Views

DOWNLOAD

REPORT

---

dhm1, an Arabidopsis mutant with increased sensitivity to alkamides shows tumorous shoot development and enhanced lateral root formation Ramo´n Pelagio-Flores • Randy Ortiz-Castro Jose´ Lo´pez-Bucio

•

Received: 20 July 2012 / Accepted: 3 February 2013 / Published online: 15 February 2013 Ó Springer Science+Business Media Dordrecht 2013

Abstract The control of cell division by growth regulators is critical to proper shoot and root development. Alkamides belong to a class of small lipid amides involved in plant morphogenetic processes, from which N-isobutyl decanamide is one of the most active compounds identified. This work describes the isolation and characterization of an N-isobutyl decanamide-hypersensitive (dhm1) mutant of Arabidopsis (Arabidopsis thaliana). dhm1 seedlings grown in vitro develop disorganized tumorous tissue in petioles, leaves and stems. N-isobutyl decanamide treatment exacerbates the dhm1 phenotype resulting in widespread production of callus-like structures in the mutant. Together with these morphological alterations in shoot, dhm1 seedlings sustained increased lateral root formation and greater sensitivity to alkamides in the inhibition of primary root growth. The mutants also show reduced etiolation when grown in darkness. When grown in soil, adult dhm1 plants were characterized by reduced plant size, and decreased fertility. Genetic analysis indicated that the mutant phenotype segregates as a single recessive Mendelian trait. Developmental alterations in dhm1 were related to an enhanced expression of the cell division marker CycB1uidA both in the shoot and root system, which correlated with altered expression of auxin and cytokinin responsive gene markers. Pharmacological inhibition of auxin transport decreased LR formation in WT and dhm1 seedlings in

Electronic supplementary material The online version of this article (doi:10.1007/s11103-013-0023-6) contains supplementary material, which is available to authorized users. R. Pelagio-Flores
R. Ortiz-Castro
J. Lo´pez-Bucio (&) Instituto de Investigaciones Quı´mico-Biolo´gicas, Universidad Michoacana de San Nicola´s de Hidalgo, Edificio B3, Ciudad Universitaria, C. P. 58030 Morelia, Michoaca´n, Mexico e-mail: [email protected]

a similar manner, indicating that auxin transport is involved in the dhm1 root phenotype. These data show an important role of alkamide signaling in cell proliferation and plant architecture remodeling likely acting through the DHM1 protein. Keywords Alkamides
Auxin
Cytokinins
Root development
Cell division

Introduction Plant growth and development are regulated by environmental stimuli and specific genetic programs. The characteristics of the different plant organs are determined by the balance between cell division, cell growth and differentiation. Cell proliferation takes place in meristems, in which cells divide at appropriate times to sustain plant growth (Sarkar et al. 2007; Stahl and Simon 2010). During shoot development, stem branches are initiated as primordia from apical and lateral meristems. Alt