Journal Article

Expression of a divergent expansin gene is fruit-specific and ripening-regulated

Lee, H.H, Rose, J.K.C. (University of California, Davis, CA.), Bennett, A.B

1997

Overview

Expansins are proteins that induce extension in isolated plant cell walls in vitro and have been proposed to disrupt noncovalent interactions between hemicellulose and cellulose microfibrils. Because the plant primary cell wall acts as a constraint to cell enlargement, this process may be integral to plant cell expansion, and studies of expansins hew focused on their role in growth. We report the identification of an expansin (LeExp1) from tomato that exhibits high levels of mRNA abundance and is specifically expressed in ripening fruit, a developmental period when growth has ceased but when selective disassembly of cell wall components is pronounced. cDNAs closely related to LeExp1 were also identified in ripening melons and strawberries, suggesting that they are a common feature of fruit undergoing rapid softening. Furthermore the sequence of LeExp1 and its homologs from other ripening fruit define a subclass of expansin genes. Expression of LeExp1 is regulated by ethylene, a hormone known to coordinate and induce ripening in many species. LeExp1 is differentially expressed in the ripening-impaired tomato mutants Nr, rin, and nor, and mRNA abundance appears to be influenced directly by ethylene and by a developmentally modulated transduction pathway. The identification of a ripening-regulated expansin gene in tomato and other fruit suggests that, in addition to their role in facilitating the expansion of plant cells, expansins may also contribute to cell wall disassembly in nongrowing tissues, possibly by enhancing the accessibility of noncovalently bound polymers to endogenous enzymic action

• Publisher: National Academy of Sciences of the United States of America,National Acad Sciences,National Academy of Sciences,The National Academy of Sciences of the USA
• Subject: ADN / Amino Acid Sequence / amino acid sequences / Amino acids / ANTIMETABOLITE / ANTIMETABOLITOS / ARN MENSAJERO / ARN MESSAGER / Base Sequence / Biological Sciences / biosynthesis / Cell Wall / Cell Wall - metabolism / Cell walls / chemistry / Complementary DNA / COMPOSICION QUIMICA / COMPOSITION CHIMIQUE / DNA Primers / DNA probes / DNA, Complementary / drug effects / ETHYLENE / Ethylenes / Ethylenes - pharmacology / ETILENO / EXPRESION GENICA / EXPRESSION DES GENES / FRUITS / FRUTAS / GENE / gene expression / Gene Expression Regulation, Plant / Gene Expression Regulation, Plant - drug effects / GENES / Genes, Plant / Genetic Variation / GENETICA / genetics / GENETIQUE / LYCOPERSICON ESCULENTUM / Lycopersicon esculentum - genetics / Lycopersicon esculentum - physiology / MADURAMIENTO / Messenger RNA / metabolic inhibitors / metabolism / Molecular Sequence Data / MURISSAGE / MUTANT / MUTANTES / mutants / nucleotide sequences / PARED CELULAR / PAROI CELLULAIRE / pharmacology / Phylogeny / physiology / plant proteins / Plant Proteins - biosynthesis / Plant Proteins - chemistry / Plants / Plants - genetics / Polymerase Chain Reaction / PROTEINAS VEGETALES / PROTEINE VEGETALE / Proteins / Restriction Mapping / Ribonucleic acid / Ripening / RNA / SECUENCIA NUCLEOTIDICA / Sequence Homology, Amino Acid / SEQUENCE NUCLEOTIDIQUE / Solanum lycopersicum / Solanum lycopersicum var. lycopersicum / structural genes / Tomatoes