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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

THE GLOSSY GENES FROM MAIZE (ZEA MAYS L.): MOLECULAR CHARACTERIZATION OF THE GLOSSY1 AND RELATED LOCI

GAVAZZI F.*, ALLEGRI L.*, VELASCO R.**, LAZZARONI N.*, HARTINGS H.*

* Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo, Via Stezzano 24, 24126 Bergamo

hartings@iol.it

** Istituto Agrario di S. Michele all’Adige, Lab. Biologia molecolare, Via Mach 1, 38010 San Michele all’Adige

maize, cuticular wax, glossy, expression pattern, genomic structure

The aerial surfaces of plants are covered with a complex mixture of lipids and fatty acid derived polymers termed cuticular waxes. The cuticle plays a central role in the plant’s defence against bacterial and fungal pathogens and in plant-insect interactions. The lipid compounds in the cuticle are synthesized from cellular fatty acids through a series of reactions, many of which have been identified by means of biochemical and molecular genetics investigations.

One of the maize loci involved in cuticular wax synthesis is the glossy1 (gl1) gene. Loss of functionality of the gl1 gene determines both a quantitative and qualitative alteration in cuticular waxes. Previously, we described the identification of a mutable gl1 allele, induced through En/Spm transposon insertion. The identified gl1 locus encodes a putative protein similar in length to that of CER1 of Arabidopsis thaliana, another locus involved in cuticular wax biosynthesis, and to previously described sequences from rice and Kleinia odora. Similar to CER1, the deduced Gl1 protein sequence contains three His-rich regions, that are thought to be important for protein functioning.

We, herein, report the identification of a gl1-homologous cDNA sequence obtained from maize silk tissue. The expression levels of this homologous gene, as well as of the gl1 gene and a shorter gl1 splicing variant were assayed in different maize tissues by means of “Massively Parallel Signature Sequencing” (MPSS). MPSS revealed a high expression of the gl1-homologue in immature ear shoots, tassels, and silking ears, while gl1 expression was observed in mesocotyl, leaf, and stalk tissue. The expression levels of the gl1 splicing variant were considerably lower than those obtained for the remaining two transcripts, with expression almost exclusively confined to young seedlings.

Finally, the genomic organization of the above-mentioned glossy loci was studied. Southern analyses identified a single hybridising fragment homologous to gl1, while multiple regions hybridised with the gl1-homologue with varying signal intensities. Hence, the latter locus is likely a member of a multi-gene family. The genomic region encompassing the gl1 locus was further analysed. For this purpose, a maize BAC library was screened and a clone comprising the entire gl1 coding region together with extended flanking regions was identified and analysed at the sequence level.