• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.5
• /
• pp.611-616
• /
• 1993

This study was carried out to investigate change in the polygalacturonase and ${\beta}-galactosidase$ activities, pectins, cell wall structure of persimmon fruit during ripening and softening. Polygalacturonase and ${\beta}-galactosidase$ activities were not detected at turning stage. However polygalacturonase activities of mature and soft persimmon fruits were 55.01 and 206.70units/100g-fresh weight(fr. wt.), respectively. ${\beta}-Galactosidase$ activities of mature and soft persimmon fruits were 21.79 and 380.23unit/100g-fr. wt. respectively. The contents of total and insoluble pectins increased during maturation but decreased during softening. The content of water-soluble pectin increased during maturation and softening. The intercellular space was in larged during ripening, and middle lamella was degraded in mature persimmon fruit, and the cells of soft persimmon fruit were separated each other.

• Korean Journal Plant Pathology
• /
• v.13 no.4
• /
• pp.225-231
• /
• 1997

Activities of polygalacturonase, laccase, and intra- and extra-cellular $\beta$-glucosidase produced by 20 Botrytis cinerea isolates in liquid culture media containing cucumber cell was as a carbon source were measured and their relationships to the pathogenicity were analyzed. No significant correlations between these enzyme activities and the pathogenicity of B. cinerea were found. Mycelial growth rate on Bayendamm media, however, was higthly correlated with the pathogenicity (r=0.522) anong these isolates. Immuno-blot analysis of the culture filtrate using antibody against against exo-polygalacturonase revealed that only one band with molecular weight of 66 kDa was detected amone 34 tested isolates. It appears that these enzymes may not be primary factors in dermining the pathogenicity of B. cinerea.

• The Plant Pathology Journal
• /
• v.35 no.2
• /
• pp.91-99
• /
• 2019

Mitogen-activated protein kinase (MAPK) cascades in fungi are ubiquitously conserved signaling pathways that regulate stress responses, vegetative growth, pathogenicity, and many other developmental processes. Previously, we reported that the AbSte7 gene, which encodes a mitogen-activated protein kinase kinase (MAPKK) in Alternaria brassicicola, plays a central role in pathogenicity against host cabbage plants. In this research, we further characterized the role of AbSte7 in the pathogenicity of this fungus using ${\Delta}AbSte7$ mutants. Disruption of the AbSte7 gene of A. brassicicola reduced accumulation of metabolites toxic to the host plant in liquid culture media. The ${\Delta}AbSte7$ mutants could not efficiently detoxify cruciferous phytoalexin brassinin, possibly due to reduced expression of the brassinin hydrolase gene involved in detoxifying brassinin. Disruption of the AbSte7 gene also severely impaired fungal detoxification of reactive oxygen species. AbSte7 gene disruption reduced the enzymatic activity of cell walldegrading enzymes, including cellulase, ${\beta}$-glucosidase, pectin methylesterase, polymethyl-galacturonase, and polygalacturonic acid transeliminase, during host plant infection. Altogether, the data strongly suggest the MAPKK gene AbSte7 plays a pivotal role in A. brassicicola during host infection by regulating multiple steps, and thus increasing pathogenicity and inhibiting host defenses.