Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 1.06

MOLECULAR CHARACTERIZATION OF THE gl1 GENE OF MAIZE

M. STURARO, H. HARTINGS, R. VELASCO, M. GATTUSO, M. MOTTO

Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo

epicuticular waxes, glossy mutants, drought adaptation, transposon tagging

Epicuticular waxes, a complex mixture of long chain lipidic compounds, cover the aerial organs of terrestrial plants and represent a preformed defense against several biotic and abiotic stresses. Many mutants impaired in their biosynthesis have been isolated in different species, including maize and Arabidopsis, helping the elucidation of some steps of the poorly defined pathways leading to wax synthesis and deposition.

In maize, two different pools of waxes are produced from two distinct biosynthetic pathways, the former throughout the entire plant life cycle, while the latter is restricted to the juvenile developmental phase (up to 5 to 6 leaf stage). At least 18 different glossy (gl) loci have been defined by mutations affecting maize juvenile wax biosynthesis but only a few of them have been characterized with molecular or biochemical approaches.

The glossy 1 mutant shows a strong reduction of total juvenile waxes suggesting a specific block at an early step of the corresponding biosynthetic pathway or a role of the gene product in the translocation of wax components onto the plant surface.

In an attempt to characterize this mutant at the molecular level, we performed a transposon tagging with the En/Spm element which led to the isolation of the glossy 1 gene, and we cloned the corresponding cDNA by RT-PCR. These genomic and cDNA sequences differ from the putative gl1 gene and transcript previously identified by others. The protein encoded by gl1 shows significant homology with the entire sequence of the CER1 gene product, a putative aldehyde decarbonylase involved in cuticular wax production in Arabidopsis. Additional insights into Gl1 activity were obtained from the analysis of a collection of 20 stable independent mutations. The gl1 gene is actively transcribed in response to water stress.