Identification of a novel α-L-arabinofuranosidase gene associated with mealiness in apple

Abstract

In order to investigate the genetic bases of the physiological syndrome mealiness that causes abnormal fruit softening and juice loss in apples, an integrative approach was devised, consisting of sensory, instrumental, biochemical, genetic, and genomic methods. High levels of activity of α-L-arabinofuranosidase (α-AFase), a hydrolase acting on the pectic component of the cell walls, were found in individuals exhibiting the mealiness phenotype in a segregating population. The expression levels of the previously uncharacterized apple AF gene MdAF3 are higher in fruits from plants consistently showing mealiness symptons and high α-AFase activity. The transcription of MdAF3 is differentially regulated in distinct genomic contexts and appears to be independent of ethylene. Thus, it is likely to be controlled by endogenous developmental mechanisms associated with fruit ripening. The use of integrative approaches has allowed the identification of a novel contributor to the mealiness phenotype in apple and it has been possible to overcome the problems posed by the unavailability of near-isogenic lines to dissect the genetic bases of a complex physiological trait in woody perennial species.

Analysis of the dynamic mechanical properties of apple tissue and relationships with the intracellular water status, gas distribution, histological properties and chemical composition

“…Arabinose is one of the major sugar component of pectic rhamnogalacturonan-I side chains that have been shown in vitro to form hydrogen bond with cellulose (Zykwinska et al, 2005). Furthermore, arabinofuranosidase activity and arabinofuranosidase gene MdAF3 expression were positively correlated with apple mealiness (Nobile et al, 2011). All these data suggest that the putative bonds of pectic arabinan side chains to cellulose and their regulation by enzymes may play a critical role on cell wall mechanical properties and fruit texture.…”

Genomic dissection of a ‘Fuji’ apple cultivar: re-sequencing, SNP marker development, definition of haplotypes, and QTL detection

“…Nobile et al (2011) reported that the gene expression and enzyme activity of α- l -arabinofuranosidase (α-AFase), acting on the pectic component of the cell wall, were correlated with mealiness. By transcriptome analysis, the expression of a pectin methylesterase gene ( MdPME2 ) was found to be significantly higher in non-mealy fruits than in mealy fruits during fruit development, ripening, and post-harvest (Segonne et al 2014).…”

Transcriptome analysis reveals delaying of the ripening and cell‐wall degradation of kiwifruit by hydrogen sulfide

“…5 Due to ripening and senescence after harvest, kiwifruit quality will be seriously affected, and the storage period will be shortened because of membrane deterioration, cell-wall degradation, cell-structure modification, and cell death. 6 Cell-wall degradation is associated with cell-wall hydrolases, including pectinesterase (PME), 7 polygalacturonase (PG), 8,9 ⊎-gal, 10 ⊍-arabinofuranosidase (⊍-L-af), 11,12 xyloglucan endotransglycosylase / hydrolase (XTH), 13,14 and cellulase. 15 Pectinesterase catalyzes the demethylesterification of cell-wall polygalacturonans, 16 which promotes the hydrolysis of polygalacturonic acid by PG.…”