Articles
Deciphering the molecular mechanisms of enzymatic browning of apple pulp
Article number
1412_47
Pages
313 – 320
Language
English
Abstract
The organoleptic properties and fruit quality of apples are affected by enzymatic browning resulting in market-value loss.
While several metabolic pathways and factors such as PPO activity and phenolic content have been shown to be related to pulp browning, the complete molecular explanation underlying this phenomenon is still unknown.
Uncovering potential biomarkers for assessing the risk of browning development could lead to the production of non-browning apple cultivars and contribute to the expansion of the apple market (fresh-cut industry). To gain a comprehensive understanding of the molecular mechanisms underlying enzymatic browning, a careful selection of three genotypes was made from CITA’s apple germplasm collection.
This selection included a commercial cultivar (‘Royal Gala’) and two local mountainous apple cultivars (‘Borau-01’ and ‘Manzana amarilla de octubre’), covering a range of enzymatic browning severity levels: low, medium, and high, respectively.
Transcriptomic changes during browning were studied for outer-pulp tissue at three oxidation time points (0, 30 and 60 min after fresh cutting) to identify differences in gene expression between times and cultivars.
Gene expression analysis showed differences in the number of differentially expressed genes revealing a broader gene expression response in ‘Royal Gala’. The number of overexpressed genes was higher than the number of downregulated genes for all oxidation times and cultivars.
Gene Ontology revealed a higher number of enriched terms for ‘Royal Gala’ and ‘Manzana amarilla de octubre’ and pointed to the existence of a transcription factor regulation network involved in enzymatic browning.
Enriched Biological Process terms differed between cultivars, suggesting that different molecular mechanisms play crucial roles in the regulation of each cultivars’ enzymatic browning.
Furthermore, basal expression of four phenylalanine-ammonia lyase isoforms was lower in ‘Royal Gala’ than more enzymatic browning susceptible cultivars´. This study confirms the complexity of this fruit affliction and demonstrates the importance of traditional cultivars as a pool of genetic diversity.
While several metabolic pathways and factors such as PPO activity and phenolic content have been shown to be related to pulp browning, the complete molecular explanation underlying this phenomenon is still unknown.
Uncovering potential biomarkers for assessing the risk of browning development could lead to the production of non-browning apple cultivars and contribute to the expansion of the apple market (fresh-cut industry). To gain a comprehensive understanding of the molecular mechanisms underlying enzymatic browning, a careful selection of three genotypes was made from CITA’s apple germplasm collection.
This selection included a commercial cultivar (‘Royal Gala’) and two local mountainous apple cultivars (‘Borau-01’ and ‘Manzana amarilla de octubre’), covering a range of enzymatic browning severity levels: low, medium, and high, respectively.
Transcriptomic changes during browning were studied for outer-pulp tissue at three oxidation time points (0, 30 and 60 min after fresh cutting) to identify differences in gene expression between times and cultivars.
Gene expression analysis showed differences in the number of differentially expressed genes revealing a broader gene expression response in ‘Royal Gala’. The number of overexpressed genes was higher than the number of downregulated genes for all oxidation times and cultivars.
Gene Ontology revealed a higher number of enriched terms for ‘Royal Gala’ and ‘Manzana amarilla de octubre’ and pointed to the existence of a transcription factor regulation network involved in enzymatic browning.
Enriched Biological Process terms differed between cultivars, suggesting that different molecular mechanisms play crucial roles in the regulation of each cultivars’ enzymatic browning.
Furthermore, basal expression of four phenylalanine-ammonia lyase isoforms was lower in ‘Royal Gala’ than more enzymatic browning susceptible cultivars´. This study confirms the complexity of this fruit affliction and demonstrates the importance of traditional cultivars as a pool of genetic diversity.
Authors
F.J. Bielsa, J. Grimplet, P. Irisarri, P. Errea, A. Pina
Keywords
browning degree, genetic diversity, Malus × domestica Borkh, local cultivars, metabolic pathways, RNA sequencing, transcriptomics
Online Articles (65)