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Plants have a mechanism called cold acclimation that improves freezing tolerance by sensing low temperatures. Previous studies have reported that galactan, a side chain of pectin in the cell wall, increases during the cold acclimation. It was also found that arabinan, another major side chain of pectin, is increased in galactan-synthesizing mutants during the cold acclimation. Therefore, in this study, we generated a mutant deficient in enzymes that synthesize both side chains of pectin (arad1 gals2 gals3). Sugar composition analysis of the pectin fraction in the mutant showed that both arabinan and galactan were reduced. Although, freezing tolerance was evaluated, there was no difference in freezing tolerance between the wild type and the mutant. However, analysis of the physical properties of non-acclimated and cold acclimated leaves showed that the changes in cell wall properties due to the cold acclimation in the wild type were no longer observed in the mutant. These results suggest that less amount of arabinan and galactan does not affect freezing tolerance, but the change in cell wall properties during cold acclimation is controlled by the amount of arabinan and galactan. [ABSTRACT FROM AUTHOR]

In the sugar analysis of fruits, it is known that sucrose is hydrolyzed by the influence of enzymes contained in fruits and the sugar composition is changed. Regarding the pretreatment method for microwave heating, which has been reported as a method for inactivating enzymes, a pretreatment method for obtaining more suitable analysis results was investigated. The study was conducted using persimmons, which are fruits on which enzymes act, and 100 g of fruits were microwave-heated for 1 minute using a microwave oven with an output of 700 W. As a result, good analytical results were obtained in which the influence of the enzyme was suppressed. Sugar analysis was performed on various fruits that had undergone microwave heating pretreatment and simpler pretreatment with ethanol, the effects of enzymes were confirmed, and the analysis results of each pretreatment method were compared and examined. From the analysis results, the effect of the enzyme was confirmed on about half of the fruits. It was also suggested that the suitable pretreatment method may differ depending on the fruit. [ABSTRACT FROM AUTHOR]