Metabolic Profile and Performance Responses of Ranunculus asiaticus L. Hybrids as Affected by Light Quality of Photoperiodic Lighting

Abstract

Ranunculus asiaticus is a quantitative long day plant grown for cut flowers and flowering potted plants production. We evaluated the influence of light spectrum of three light sources for end-of-day photoperiodic treatments, with different phytochrome photoequilibria (PPE) induced at plant level, on the metabolic profiling of two hybrids of R. asiaticus L., MBO and MDR, in plants from vernalized tuberous roots. The following treatments were compared with natural day length (NL): white fluorescence lamp (FL, PPE 0.84), light emitting diodes (LEDs) Red:Far Red light at 3:1 ratio (R:FR 3:1, PPE 0.84), and LEDs Red:Far Red light at 1:3 ratio (R:FR 1:3, PPE 0.63). Measurements were carried out to evaluate the time course of carbohydrate, amino acid, and protein levels throughout the growing cycle in tuberous roots and leaves, in relation to the different plant stages (pre-planting, vegetative phase, and flowering). The study of metabolic profiling suggested that the differences between the tuberous root reserves of the two R. asiaticus hybrids could be responsible for the capacity of MBO to exert an early flowering. In particular, the proton-consuming synthesis during the pre-planting of two amino acids, alanine and γ-aminobutyric acid (GABA), is able to buffer the cytoplasmic acidosis and pH altered by the vernalization process, and GABA itself can efficiently scavenge reactive oxygen species. This fast response to the stress caused by vernalization allows MBO plants to accelerate the process of vegetative development and flowering. Some other changes in metabolites profile were certainly related to the different responses to day length and photoperiodic light quality in the two hybrids, such as dose exerted by low R:FR lighting in both MBO and MDR. However, most of the responses are under a strict genetic control.

Vernalization Procedure of Tuberous Roots Affects Growth, Photosynthesis and Metabolic Profile of Ranunculus asiaticus L.

“…This non protein amino acid, deriving from the decarboxylation of glutamate catalysed by glutamate decarboxylase, can exert a strong ROS scavenger activity thus protecting membranes and macromolecules from oxidative stress [ 28 ]. GABA and alanine are able to buffer the cytoplasmic acidosis and pH altered by the vernalization process as reported in [ 12 ], thus helping plants to cope with stress. In addition, the costs for their synthesis are compensated by the fact that after relief from oxidative stress alanine can be transaminated to pyruvate and converted to acetyl-Coenzyme A in the mitochondrial matrix, whereas GABA shunt can provide NADH and/or succinate to Krebs cycle playing an anaplerotic function [ 29 ] that can accelerate flowering in the subsequent growth stage.…”

“…Cultivation of Ranunculus asiaticus L. has been rising during the last years all over the world, also thanks to the breeding and the development of new hybrids, and vernalization of propagation material is a common practice for the production scheduling of cut flowers, as in many ornamental geophytes [ 1 ]. Despite this, little is known about the plant physiology of this species and, apart from some our recent studies [ 11 , 12 , 13 , 14 ], no information seems to be available on the primary and secondary metabolism as affected by cold treatments of propagation material. We investigated the influence of two hybrids of R. asiaticus L., characterized by different flowering earliness, and three preparation procedures of tuberous roots, including only rehydration and two times of exposure to cold temperature after rehydration, on photosynthesis, metabolic profile and flowering of plants grown in pot in cold glasshouse.…”

Morpho-Anatomical, Physiological, and Mineral Composition Responses Induced by a Vegetal-Based Biostimulant at Three Rates of Foliar Application in Greenhouse Lettuce

“…The loading plot and score plot of all analyzed parameters was determined after principal component analysis (PCA) by using Minitab ® 18 statistical software (Minitab LLC, State College, PA, USA) [ 68 ]. The heat map results were calculated as Logarithm base 1.5 (Log 1.5 ) of the treatment to control ratio and visualized using a false-color scale, with red indicating an increase and blue a decrease of values [ 69 ].…”

Ascophyllum nodosum Based Extracts Counteract Salinity Stress in Tomato by Remodeling Leaf Nitrogen Metabolism

“…Primary amino acids and proline extraction was performed by mixing 50 mg of powdered pooled leaves with 1 mL of ethanol:water in the ratio 2:3 ( v / v ), kept overnight at 4 °C and centrifuged at 14,000× g at 4 °C for 10 min. Amino acids were estimated by HPLC after pre-column derivatization by o -phthaldialdehyde (OPA) according to [ 79 ] using a 5 µm ZORBAX Eclipse Plus C18, 250 × 4.6 mm inte70% BNS al diameter; (Agilent Technologies Italia S.p.A, Cernusco sul Naviglio (MI), Italy) protected by a C18 Security Guard pre-column (4 × 3 mm ID; Phenomenex Inc., Torrance, CA, USA). Proline was determined according to [ 67 ].…”