cDNA cloning of carrot extracellular beta-fructosidase and its expression in response to wounding and bacterial infection.
We isolated a full-length cDNA for apoplastic (extracellular or cell wall-bound) beta-fructosidase (invertase), determined its nucleotide sequence, and used it as a probe to measure changes in mRNA as a result of wounding of carrot storage roots and infection of carrot plants with the bacterial pathogen Erwinia carotovora. The derived amino acid sequence of extracellular beta-fructosidase shows that it is a basic protein (pl 9.9) with a signal sequence for entry into the endoplasmic reticulum and a propeptide at the N terminus that is not present in the mature protein. Amino acid sequence comparison with yeast and bacterial invertases shows that the overall homology is only about 28%, but that there are short conserved motifs, one of which is at the active site. Maturing carrot storage roots contain barely detectable levels of mRNA for extracellular beta-fructosidase and these levels rise slowly but dramatically after wounding with maximal expression after 12 hours. Infection of roots and leaves of carrot plants with E. carotovora results in a very fast increase in the mRNA levels with maximal expression after 1 hour. These results indicate that apoplastic beta-fructosidase is probably a new and hitherto unrecognized pathogenesis-related protein [Van Loon, L.C. (1985). Plant Mol. Biol. 4, 111-116]. Suspension-cultured carrot cells contain high levels of mRNA for extracellular beta-fructosidase and these levels remain the same whether the cells are grown on sucrose, glucose, or fructose.
Sturm
A
A
Friedrich Miescher-Institute, Basel, Switzerland.
Chrispeels
M J
MJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D005786:Gene Expression Regulation / Q000502:physiology*; D015723:Gene Library; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D014675:Vegetables / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D043324:beta-Fructofuranosidase
D010940:Plant Proteins; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase