Metabolic elicitors of Pseudomonas fluorescens N 21.4 elicit flavonoid metabolism in blackberry fruit

• Published in: Journal of the science of food and agriculture 2021-01, Vol.101 (1), p.205-214
• Main Authors: Martin‐Rivilla, Helena, Garcia‐Villaraco, Ana, Ramos‐Solano, Beatriz, Gutierrez‐Manero, Francisco J, Lucas, José A
• Format: Article
• Language: English
• Subjects: Accumulation; Anthocyanins; blackberries; Catechin; Crop Production; Cultivars; Epicatechin; flavonoid metabolism; Flavonoids; Flavonoids - chemistry; Flavonoids - metabolism; Fruit - chemistry; Fruit - growth & development; Fruit - metabolism; Fruit - microbiology; Fruits; Gene expression; Kaempferol; metabolic elicitors; Metabolism; Metabolites; Phenolic compounds; Phenols; Plant Proteins - genetics; Plant Proteins - metabolism; Pseudomonas fluorescens; Pseudomonas fluorescens - physiology; Pseudomonas fluorescens N 21.4; Quercetin; Ripening; Rubus - chemistry; Rubus - growth & development; Rubus - metabolism; Rubus - microbiology; RuCHS gene; RuDFR gene; Secondary Metabolism; Secondary metabolites
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/jsfa.10632

Background The beneficial rhizobacterium, Pseudomonas fluorescens N 21.4, and its metabolic elicitors were inoculated in commercial cultivars of blackberry plants (Rubus cv. Loch Ness). Phenolic compounds present in red and black fruit and the expression of structural marker genes of the phenylpropanoid pathway during fruit ripening were studied. Results An inverse relationship between gene expression and accumulation of metabolites was seen, except for the RuDFR gene, which had a direct correlation with cyanidin 3‐O‐glucoside synthesis, increasing its content 1.3 times when RuDFR was overexpressed in the red fruit of plants inoculated with the metabolic elicitors of P. fluorescens N 21.4, compared with red fruit of plants inoculated with N 21.4. The RuCHS gene also had a fundamental role in the accumulation of metabolites. Both rhizobacterium and metabolic elicitors triggered the flavonoid metabolism, enhancing the catechin and epicatechin content between 1.1 and 1.6 times in the case of red fruit and between 1.1 and 1.8 times in the case of black fruit. Both treatments also boosted the anthocyanin, quercetin, and kaempferol derivative content, highlighting the effects of metabolic elicitors in red fruit and the effects of live rhizobacterium in black fruit. Conclusion The metabolic elicitors' capacity to modulate gene expression and to increase secondary metabolites content was demonstrated. This work therefore suggests that they are effective, affordable, easily manageable, and ecofriendly plant inoculants that complement, or are alternatives to, beneficial rhizobacteria. © 2020 Society of Chemical Industry