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

Abstract

In Ranunculus asiaticus L., vernalization of propagation material is a common practice for the production scheduling of cut flowers, however little is known about the plant physiology and metabolism of this species as affected by cold treatments. We investigated the influence of two hybrids, MBO and MDR, and three preparation procedures of tuberous roots, only rehydration (control, C), and rehydration plus vernalization at 3.5 °C for 2 weeks (V2) and for 4 weeks (V4), on plant growth and flowering, leaf photosynthesis, and leaf metabolic profile in plants grown in pot in a cold greenhouse. Net photosynthesis (NP) was higher in MDR than in MBO. In the two genotypes, the NP did not change in V2 and increased in V4 compared to C in MBO, while was unaffected by vernalization in MDR. Quantum yield of PSII electron transport (ΦPSII), linear electron transport rate (ETR) and non-photochemical quenching (NPQ) did not differ in the two hybrids, whereas maximal PSII photochemical efficiency (Fv/Fm) was higher in MBO than in MDR. Fluorescence indexes were unaffected by the preparation procedure, except for ETR, which decreased in V2 compared to C and V4 in MDR. A significant interaction between genotype and preparation procedure was found in plant leaf area, which was reduced only in V4 in MBO, while decreased in both the vernalization procedures in MDR. In Control plants, flowering started in 65 days in MBO and 69 days in MDR. Compared to controls, both the vernalization treatments anticipated flowering in MDR, while they were detrimental or only slightly efficient in promoting flowering in MBO. Vernalization always reduced the quality of flower stems in both the hybrids.

Applying an automated NMR-based metabolomic workflow to unveil strawberry molecular mechanisms in vernalization

“…This is achieved through proton consuming reactions involved in its synthesis, which regulates cytosolic pH; and its ROS-scavenging capacities. Finally, as cold stress lessens, GABA is turned into a Krebs cycle intermediate, enhancing plant metabolism ( Figure 4 ) (Fusco et al . 2023 ) .…”

Metabolic Profiling in Tuberous Roots of Ranunculus asiaticus L. as Influenced by Vernalization Procedure

“…These proteins are rapidly convertible to free amino acids at the end of dormancy, which is useful not only to promote fast growth but also to help the plant overcome the oxidative stress effects due to vernalization (e.g., proline and GABA). In fact, in the tuberous roots of R. asiaticus, the fast starch hydrolysis upon vernalization promotes not only the synthesis and accumulation of sucrose but also of other primary metabolites acting as osmolytes and antioxidants, like proline, alanine, and γ-aminobutyric acid (GABA) [ 17 , 18 ]. In addition, minor amino acids, and particularly branched chain amino acids (BCAAs), whose synthesis increases when hexoses increase under stress [ 19 ], may exert a scavenging function against reactive oxygen species (ROS) or an anaplerotic function by supplying intermediates to the mitochondrial electron transport chain, supporting plant metabolism and flowering [ 18 , 20 , 21 ].…”

“…We carried out a series of experiments aiming at elucidating the influence of temperature [ 17 , 18 ] and photoperiod [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ] and their interaction on plant physiology and metabolism and the flowering process of R. asiaticus . In the present experiment, we investigated the influence of three preparation procedures of tuberous roots—only rehydration and two times of exposure to cold temperatures after rehydration—on plant growth and metabolic profiles in two hybrids with different flowering earliness grown in pots in an unheated glasshouse.…”

“…In the present experiment, we investigated the influence of three preparation procedures of tuberous roots—only rehydration and two times of exposure to cold temperatures after rehydration—on plant growth and metabolic profiles in two hybrids with different flowering earliness grown in pots in an unheated glasshouse. We reported results on the responses observed in the aerial part in a previous article in this journal [ 18 ]. In the present paper, we show data on the metabolism of tuberous roots that demonstrate a different response of the two hybrids depending on the genotype and sensitivity to two different vernalization procedures.…”

“…In the present paper, we show data on the metabolism of tuberous roots that demonstrate a different response of the two hybrids depending on the genotype and sensitivity to two different vernalization procedures. We focused the targeted metabolic profiling on specific classes of metabolites, and, in particular, those of carbohydrates and amino acids, because these are preferably synthesized by plants in response to cold/oxidative stress both for their protective function, as mentioned above, but are also easily recycled for the anaplerotic provision of carbon skeletons and energy for the growth of plants upon stress relief [ 17 , 18 , 19 , 20 , 21 ]. Instead, polyphenols were chosen as a representative class of metabolites that, despite being very effective as antioxidants, have a high cost in energy terms, both for their synthesis and for their non-easy recyclability, so as to slow down the growth.…”