Comparative analysis of polygalacturonase in the fruit of strawberry cultivars

Abstract

ABSTRACT. The role of polygalacturonase (PG) in the development, ripening, and softening of fruit from two strawberry cultivars with different flesh firmness and softening characteristics was compared. Changes in PG activity and gene expression during development, ripening and softening were measured. The PG genes from each cultivar were cloned and analyzed, and were classified with other PG genes using phylogenetic analysis. In Toyonoka fruit, PG activity increased gradually, reaching a peak during the pink stage, and remained at this level during post-harvest softening. Changes in PG gene expression were consistent with PG activity in these softer fruits. In the firmer Sweet Charlie fruits, PG activity was detected during the initial development stage, reaching a peak at the white stage, thereafter decreasing gradually with ripening and remaining at this lower level throughout softening. Changes in PG gene expression and PG activity were not consistent in these fruit. For both Toyonoka and Sweet Charlie PG genes (FaTPG and FaSCPG, respectively), the open reading frame was 1218 bp, encoding 405 amino acids. Five different nucleotide sites were observed between the two sequences, leading to two amino acid sequence mutations. FaTPG, FaSCPG, and PG genes from the Fragaria vesca genome were classified into three clades using phylogenetic analysis. The clade containing PG genes involved in fruit

Properties of Pectin Extracted from Vietnamese Mango Peels

“…Meanwhile, the polygalacturonase activity was very low in unripe fruit [24]. Moreover, pectinolytic enzyme activities, especially polygalacturonase, have been reported to be different between fruit cultivars [9]. Therefore, the differences in amounts of pectin observed at different maturity stages and cultivars may be due to the different activities of both pectin methyl esterase and polyglacturonase, which are active during the development of the fruit [8,9,24].…”

“…Moreover, pectinolytic enzyme activities, especially polygalacturonase, have been reported to be different between fruit cultivars [9]. Therefore, the differences in amounts of pectin observed at different maturity stages and cultivars may be due to the different activities of both pectin methyl esterase and polyglacturonase, which are active during the development of the fruit [8,9,24]. The yield of pectin recovered in this study was much higher than recovered from other mango cultivars, including Améliorée (10.1 g/100 g DW), Mango (15.3 g/100 g DW) [2] and Tommy Atkins (17.6 g/100 g DW) [25].…”

“…The solubility of the pectin extracted from the three different cultivars in this study were significantly different (p < 0.05): overall the levels increased as the fruits matured. The increase in solubility of the pectin extracted as the fruit matures results from the increase in the pectinolytic enzyme activities, especially polygalacturonase and these have been reported to be different between fruit cultivars [9]. The main effect appears to be variations in the reductions of the pectin chain width and removal of the neutral sugars from the side chains [31].…”

“…High levels of pectins are found in almost all fruit fractions including peels, pulp and kernels [5][6][7]; however, the pectin yield depends very much on the cultivars and the maturity stages when a fruit is harvested and analysed [8,9].…”

Comparative analysis of pectate lyase in relation to softening in strawberry fruits

“…Toyonoka fruit with soft flesh was much softer after ripening than Sweet Charlie fruit with hard flesh. The firmness of Toyonoka fruits was only 54.5% that of Sweet Charlie fruits at the red fruit stage (Zhou et al 2015).…”