BACKGROUND Pectin methylesterase (PME) catalyses the hydrolysis of the methyl ester of pectin, yielding free carboxyl groups and methanol. PME is widely used in the food, cosmetic and pharmaceutical industries. RESULTS PME from Aspergillus niger was constitutively expressed to a high level in the yeast Pichia pastoris. The recombinant PME was purified by a combination of ammonium sulfate frac...

Many plants release airborne volatile compounds in response to wounding due to pathogenic assault. These compounds serve as plant defenses and are involved in plant signaling. Here, we study the effects of pectin methylesterase (PME)-generated methanol release from wounded plants ("emitters") on the defensive reactions of neighboring "receiver" plants. Plant leaf wounding resulted in the synthe...

Plants naturally emit methanol as volatile organic compound. Methanol is toxic to insect pests; but the quantity produced by most of the plants is not enough to protect them against invading insect pests. In the present study, we demonstrated that the over-expression of pectin methylesterase, derived from Arabidopsis thaliana and Aspergillus niger, in transgenic tobacco plants enhances methanol...

The cell wall in plants offers protection against invading organisms and is mainly composed of the polysaccharides pectin, cellulose, and hemicellulose, which can be degraded by plant cell wall degrading enzymes (PCWDEs). Such enzymes are often synthesized by free living microorganisms or endosymbionts that live in the gut of some animals, including certain phytophagous insects. Thus, the abili...

Plants grow in a wondrous assortment of patterns, from simple to complex, with near mathematical precision. Honeysuckles sprout leaf pairs at regular intervals along their stems, for instance, whereas some succulents form double spirals turning in opposite directions. The big question is how do they do this? New research reported in this issue of PLoS Biology suggests that mechanical stress is ...

Pawpaw fruit were harvested at the advent of the ripening process and were ripened at room temperature. Based on fruit fi rmness and respiration and ethylene production rates at harvest and during ripening, fruit were classifi ed into one of four categories: preripening (no to very slight loss of fi rmness; preclimacteric), early ripening (some softening; increasing rates of ethylene and CO2 pr...

Liao, C. H., and Wells, J. M. 1987. Association of pectolytic strains of Xanthomonas campestris with soft rots of fruits and vegetables at retail markets. Phytopathology 77:-418-422. Five strains of pectolytic, yellow-pigmented bacteria were isolated from xanthomonads might represent an unusual cluster of X. campestris that rotted specimens of tomato, bell pepper, cucumber, and papaya collected...

Dear Editor, During recent decades, a novel mechanism of secretion has been identified in a wide range of mammalian cells. It involves the release of bioactive membrane nanovesicles (30–100 nm), termed exosomes, upon the fusion of multivesicular bodies with the plasma membrane (Théry et al., 2009). Exosomes are implicated in diverse functions, such as scavenging of archaic proteins, intercellul...

The soluble invertase activty in etiolated Avena seedlngs was highest at the apex of the coleoptile and much lower in the primary leaf, mesocotyl, and root. The activity in all parts of the seeding consisted of two invertases (I and II) which were separated by chromatography on diethylaminoethylcellulose. Both enzymes appeared to be acid invertases, but they dHffered in molecular size, pH optim...

Taylor, R. J., and Secor, G. A. 1988. An improved diffusion assay for quantifying the polygalacturonase content of Erwinia culture filtrates. Phytopathology 78:1101-1103. The agar diffusion procedure for quantifying pectolytic enzyme activity punched in the agarose with a # 1 cork borer. After incubation at 37 C for 17 was modified to optimize assay sensitivity and simplify its implementation. ...