Effect of high carbon dioxide concentration on PAL activity and phenolic contents in ripening cherimoya fruit

Abstract

Cherimoya fruit (Annona cherimola, Mill.) were kept at 20°C in air or in 20% CO 2 for 3 days and then transferred to air, to study the effect of a high CO 2 treatment on phenolic metabolism and ripening-related changes. Total polyphenol levels remained constant while a rapid decline in lignin content was observed in cherimoyas stored in air. However, a sharp increase in PAL activity up to the second day at 20°C was observed. The maximum ethylene production was observed 2 days later. At the end of the CO 2 treatment, ethylene production was inhibited and PAL activity was similar to that found in air-treated fruit. These data suggest that the increase in PAL activity at 20°C was not affected by high CO 2 and does not relate to ethylene. The CO 2 treatment inhibited flesh softening and maintained lignin at levels found in freshly harvested fruit. Exposure to 20% CO 2 also improved internal colour and increased the non-tannin polyphenol fraction, but prevented the decline in the tannin fraction otherwise observed upon ripening in air. We concluded that high CO 2 treatment at 20°C did not enhance PAL activity and lignin deposition although treated fruits retained more lignin after transfer to air. The possible involvement of PAL activity in the supply of important metabolic compounds for early events of ripening will be discussed.

Effect of 24-epibrassinolide treatment on the metabolism of eggplant fruits in relation to development of pulp browning under chilling stress

“…Phenylalanine ammonia-lyase (PAL) assay was performed according to a modified method of Assis et al (2001). Approximately 1 g of pulp tissue from 6 fruits was homogenized with 5 mL of 0.2 M borate buffer (pH 8.8) containing 6 g of polyvinylpyrrolidone.…”

Synergistic effect of acetyl salicylic acid and DL-Beta-aminobutyric acid on biocontrol efficacy of Bacillus strains against tomato bacterial wilt

“…Phenylalanine ammonia-lyase (PAL) assay was investigated as described by Assis et al (2001). The enzyme extract 300 µL was incubated with 1 mL 0.02 M L-phenylalanine (suspended in double distilled water) and 2 mL of the PAL extracting buffer at 24°C for 2 min, and absorbance at 290 nm was measured in an ultraviolet spectrophotometer.…”

SEASONAL PATTERNS OF PHENYLALANINE AMMONIA-LYASE ACTIVITY AND TOTAL PHENOL AND TANNIN CONTENTS IN<i> Stryphnodendron adstringens</i> (Mart.) Coville

“…PAL activity was assayed using the method described by Assis et al (2001), in a reaction medium containing 0.1 M borate buffer, pH 8.8, 30 mM L-phenylalanine, and an aliquot of the leaf extract containing the enzyme in a total volume of 3 mL. PAL activity was determined based on the production of cinnamate for 90 min at 30 o C under continuous shaking, and measured as the change in absorbance at 290 nm (ZUCKER, 1965).…”

“…The concentration of tannins is a highly plastic trait; it varies with plant genotype, tissue developmental stages and environmental conditions (BARBEHENN;CONSTABEL, 2011). The tannins (20-30%) in the stem bark of Stryphnodendron adstringens (Mart.)…”