Isolation, characterization and expression analyses of two cell wall invertase genes in maize

摘要

Acid invertases [beta-fructofuranosidase] are glycoproteins that catalyse the hydrolysis of sucrose to glucose and fructose, and are associated with metabolic sink tissues in a variety of plant species. Acid invertases are divided into cell wall-bound invertases (INCW) and soluble invertases based on their location in the cell. This paper describes the isolation and characterization of two cell wall invertase cDNA (Incw1 and Incw2) and genomic clones. Since the deduced amino acid sequences of Incw1and Incw2 clones are more similar to carrot cell wall invertases than they are to maize soluble invertase, it is concluded that Incw1 and Incw2 represent cell wall-bound invertases. Both genomic clones have 6 introns and 7 exons, typical of most other acid invertase genes. Incw1 mRNA is present in cell suspension culture, etiolated shoots, roots and, at much reduced steady state levels, in developing endosperm. In contrast, Incw2 mRNA is present in shoots and developing endosperm, but lacking in rootsand the miniature1 (mn1-1) mutant endosperm. In situ hybridization studies showed that Incw2 mRNA is confined to the basal endosperm transfer cells in a developing kernel. Nucleotide sequence data for Icnw2 cDNA, and Icnw1 and Icnw2 genomic clones will appear in the GenBank databases under the respective accession numbers AF050631, AF050129 and AF050128.