Molecular and phytochemical characterization of F1 Streptocarpus hybrids and antioxidant potential of their flower extracts

Streptocarpus x hybridus is a very popular houseplant with colourful flowers arousing thus the interest of plant breeders. Its potential value is even higher since different chemical compounds could be identified and used for food and pharmaceutical industries. Therefore, the objectives of this study were: to determine genetic relationships between twelve F1 Streptocarpus hybrids and their genitors; to determine the total phenolic and flavonoid content; to evaluate the antioxidant activity of the analysed individuals. Although 12 out of the 24 RAPD primers detected polymorphism among the individuals, the UPGMA dendrogram did not show a very clear grouping pattern for flower colour. In contrast, the phytochemical dendrogram shed more light on the dissimilarities among Streptocarpus flowers in terms of their polyphenolic content. The total phenolic and flavonoid content of the flower extracts determined by the Folin-Ciocalteau and aluminium chloride colorimetric methods ranged from 680.02 to 2360.57 mg of GAE/100 g FW and from 12.52 to 78.36 mg QE/100 g FW. The radical scavenging activity against ABTS ranged from 27.17 to 130.35 µM Trolox/g FW. Due to its ornamental value, H12 was screened by HPLC-PDA-ESI-MS to identify and quantify the chemical compounds involved in flower colour. Among the six compounds that were identified and quantified (i.e. cyanidin-3-O-galactoside, cyanidin-3-O-xyloside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, peonidin-3-O-glucoside and apigenin-6-C-glucoside), isovitexin reached the highest concentration 4183 µg rutin/100 g FW. These preliminary results, showing high total polyphenolic content and ABTS antioxidant activity, suggest that Streptocarpus flowers could be a valuable source of antioxidants

Micropropagation and Assessment of Genetic Stability of Acclimatized Streptocarpus x hybridus Voss Plantlets Using RAPD Markers

A micropropagation protocol via direct shoot organogenesis from Streptocarpus x hybridus Voss. leaf explants was established in this study. The shoot induction of three Streptocarpus cultivars (‘Snow White’, ‘Black Panther’ and ‘Slumber Song’) was successfully achieved on Murashige and Skoog (MS) medium supplemented with 0.2 mg L-1 -indole-3-acetic acid (IAA) and 0.2 mg L-1 thidiazuron (TDZ). In proliferation stage, the effects of two combinations of plant growth regulators -PGR- (V1-0.2 mg/L-1 IAA + 0.5 mg/L-1 BAP and V2-1.0 mg L-1 NAA + 0.2 mg L-1 TDZ) on shoot number and length were examined. The results suggest that PGRs combinations significantly influenced shoot proliferation and root induction in all Streptocarpus cultivars. Among the treatments, 0.2 mg L-1 (IAA) in combination with 0.5 mg L-1 6-benzylaminopurine (BAP) were the most effective for in vitro shoot multiplication and rooting. The in vitro rooting percentage was also determined before subjecting the plantlets to the acclimatization process. Due to acclimatization, Streptocarpus plantlets showed a very high rate of survival (90%). The generated PCR-RAPD profiles for the selected in vitro-raised plants and donor plants were similar which indicates the clonal or true-to-type nature of the progenies

Responses to Salt Stress in Portulaca: Insight into Its Tolerance Mechanisms

[EN] Climate change and its detrimental effects on agricultural production, freshwater availability and biodiversity accentuated the need for more stress-tolerant varieties of crops. This requires unraveling the underlying pathways that convey tolerance to abiotic stress in wild relatives of food crops, industrial crops and ornamentals, whose tolerance was not eroded by crop cycles. In this work we try to demonstrate the feasibility of such strategy applying and investigating the effects of saline stress in different species and cultivars of Portulaca. We attempted to unravel the main mechanisms of stress tolerance in this genus and to identify genotypes with higher tolerance, a procedure that could be used as an early detection method for other ornamental and minor crops. To investigate these mechanisms, six-week-old seedlings were subjected to saline stress for 5 weeks with increasing salt concentrations (up to 400 mM NaCl). Several growth parameters and biochemical stress markers were determined in treated and control plants, such as photosynthetic pigments, monovalent ions (Na+, K+ and Cl-), different osmolytes (proline and soluble sugars), oxidative stress markers (malondialdehyde-a by-product of membrane lipid peroxidation-MDA) and non-enzymatic antioxidants (total phenolic compounds and total flavonoids). The applied salt stress inhibited plant growth, degraded photosynthetic pigments, increased concentrations of specific osmolytes in both leaves and roots, but did not induce significant oxidative stress, as demonstrated by only small fluctuations in MDA levels. All Portulaca genotypes analyzed were found to be Na+ and Cl- includers, accumulating high amounts of these ions under saline stress conditions, but P. grandiflora proved to be more salt tolerant, showing only a small reduction under growth stress, an increased flower production and the lowest reduction in K+/Na+ rate in its leaves.This research and publication was supported by the funds from the National Research Development Projects to finance excellence (PFE)-37/2018-2020 granted by the Romanian Ministry of Research and Innovation.Borsai, O.; Al Hassan, M.; Negrusier, C.; Raigón Jiménez, MD.; Boscaiu, M.; Sestras, RE.; Vicente, O. (2020). Responses to Salt Stress in Portulaca: Insight into Its Tolerance Mechanisms. Plants. 9(12):1-24. https://doi.org/10.3390/plants9121660S124912Grime, J. P. (1977). Evidence for the Existence of Three Primary Strategies in Plants and Its Relevance to Ecological and Evolutionary Theory. 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(2017). Comparison of two halophyte species (Salsola soda and Portulaca oleracea)for salt removal potential under different soil salinity conditions. TURKISH JOURNAL OF AGRICULTURE AND FORESTRY, 41, 183-190. doi:10.3906/tar-1611-82Hammami, H., Parsa, M., Mohassel, M. H. R., Rahimi, S., & Mijani, S. (2015). Weeds ability to phytoremediate cadmium-contaminated soil. International Journal of Phytoremediation, 18(1), 48-53. doi:10.1080/15226514.2015.1058336Zaman, S., Bilal, M., Du, H., & Che, S. (2020). Morphophysiological and Comparative Metabolic Profiling of Purslane Genotypes (Portulaca oleracea L.) under Salt Stress. BioMed Research International, 2020, 1-17. doi:10.1155/2020/4827045Alam, M. A., Juraimi, A. S., Rafii, M. Y., Hamid, A. A., Aslani, F., & Hakim, M. A. (2016). Salinity-induced changes in the morphology and major mineral nutrient composition of purslane (Portulaca oleracea L.) accessions. Biological Research, 49(1). doi:10.1186/s40659-016-0084-5Mulry, K. R., Hanson, B. A., & Dudle, D. A. (2015). Alternative Strategies in Response to Saline Stress in Two Varieties of Portulaca oleracea (Purslane). PLOS ONE, 10(9), e0138723. doi:10.1371/journal.pone.0138723Borsai, O., Hassan, M. A., Boscaiu, M., Sestras, R. E., & Vicente, O. (2018). The genus Portulaca as a suitable model to study the mechanisms of plant tolerance to drought and salinity. The EuroBiotech Journal, 2(2), 104-113. doi:10.2478/ebtj-2018-0014Guralnick, L. J., Gilbert, K. E., Denio, D., & Antico, N. (2020). The Development of Crassulacean Acid Metabolism (CAM) Photosynthesis in Cotyledons of the C4 Species, Portulaca grandiflora (Portulacaceae). Plants, 9(1), 55. doi:10.3390/plants9010055Grigore, M.-N., & Toma, C. (2017). Succulence. Anatomical Adaptations of Halophytes, 41-124. doi:10.1007/978-3-319-66480-4_3Grigore, M.-N., & Toma, C. (2017). Kranz Anatomy. Anatomical Adaptations of Halophytes, 241-272. doi:10.1007/978-3-319-66480-4_6Bernstein, L. (1963). OSMOTIC ADJUSTMENT OF PLANTS TO SALINE MEDIA. II. DYNAMIC PHASE. American Journal of Botany, 50(4), 360-370. doi:10.1002/j.1537-2197.1963.tb07204.xDUBEY, S., BHARGAVA, A., FUENTES, F., SHUKLA, S., & SRIVASTAVA, S. (2020). Effect of salinity stress on yield and quality parameters in flax (Linum usitatissimum L.). Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 48(2), 954-966. doi:10.15835/nbha48211861HAND, M. J., TAFFOUO, V. D., NOUCK, A. E., NYEMENE, K. P. J., TONFACK, B., MEGUEKAM, T. L., & YOUMBI, E. (2017). Effects of Salt Stress on Plant Growth, Nutrient Partitioning, Chlorophyll Content, Leaf Relative Water Content, Accumulation of Osmolytes and Antioxidant Compounds in Pepper (Capsicum annuum L.) Cultivars. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 45(2), 481-490. doi:10.15835/nbha45210928Ayala-Astorga, G. I., & Alcaraz-Meléndez, L. (2010). Salinity effects on protein content, lipid peroxidation, pigments, and proline in Paulownia imperialis (Siebold & Zuccarini) and Paulownia fortunei (Seemann & Hemsley) grown in vitro. Electronic Journal of Biotechnology, 13(5), 0-0. doi:10.2225/vol13-issue5-fulltext-13Bayuelo-Jiménez, J. S., Jasso-Plata, N., & Ochoa, I. (2012). Growth and Physiological Responses ofPhaseolusSpecies to Salinity Stress. International Journal of Agronomy, 2012, 1-13. doi:10.1155/2012/527673Akcin, A., & Yalcin, E. (2015). Effect of salinity stress on chlorophyll, carotenoid content, and proline in Salicornia prostrata Pall. and Suaeda prostrata Pall. subsp. prostrata (Amaranthaceae). Brazilian Journal of Botany, 39(1), 101-106. doi:10.1007/s40415-015-0218-yAl Hassan, M., Chaura, J., López-Gresa, M. P., Borsai, O., Daniso, E., Donat-Torres, M. P., … Boscaiu, M. (2016). Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species. 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Effects of salt and drought stress on seed germination and seedling growth in Portulaca

[EN] The effects of salt and water deficit on seed germination and early seedling growth were studied in six Portulaca accessions (P. oleracea L. ssp. oleracea, P. grandiflora Hook., P. grandiflora cvs. `Sundial Mango¿, `Double Pink¿ and `Double White¿, and P. halimoides L.). The aims of the study were to evaluate their responses to abiotic stress and to establish the relative degree of tolerance of the selected taxa. Seeds were germinated in the presence of increasing concentrations of NaCl or polyethylene glycol 6000 (to mimic drought conditions), generating the same osmotic potentials: 0, -0.25, -0.5 and -0.1 MPa. Germination percentage, mean germination time, seedling fresh weight and vigour index, and radicle, hypocotyl and cotyledon lengths were determined. Seed germination and seedling development decreased in all taxa in the presence of PEG and NaCl, in a concentration-dependent manner, although the effect of salt was stronger than that of PEG, at the same osmotic potentials. Germination and seedling parameters varied for the different accessions but, in practical terms, considering only the final germination percentages under stress, P. halimoides L. appears to be the taxon most tolerant to water deficit, whereas P. grandiflora Hook. would be the most tolerant to salt stress..Borsai, O.; Al Hassan, M.; Boscaiu, M.; Sestras, RE.; Vicente, O. (2018). Effects of salt and drought stress on seed germination and seedling growth in Portulaca. Romanian Biotechnological Letters. 23(1):13340-13349. http://hdl.handle.net/10251/123496S133401334923

The genus Portulaca as a suitable model to study the mechanisms of plant tolerance to drought and salinity

[EN] Drought and soil salinity are at present the major factors responsible for the global reduction of crop yields, and the problem will become more severe in the coming decades because of climate change effects. The most promising strategy to achieve the increased agricultural production that will be required to meet food demands worldwide will be based on the enhancement of crop stress tolerance, by both, traditional breeding and genetic engineering. This, in turn, requires a deep understanding of the mechanisms of tolerance which, although based on a conserved set of basic responses, vary widely among plant species. Therefore, the use of different plant models to investigate these mechanisms appears to be a sensible approach. The genus Portulaca could be a suitable model to carry out these studies, as some of its taxa have been described as tolerant to drought and/or salinity. Information on relevant mechanisms of tolerance to salt and water stress can be obtained by correlating the activation of specific defence pathways with the relative stress resistance of the investigated species. Also, species of the genus could be economically attractive as `new¿ crops for `saline¿ and `arid¿, sustainable agriculture, as medicinal plants, highly nutritious vegetable crops and ornamentals.Borsai, O.; Al Hassan, M.; Boscaiu, M.; Sestras, RE.; Vicente, O. (2018). The genus Portulaca as a suitable model to study the mechanisms of plant tolerance to drought and salinity. The Eurobiotech Journal. 2(2):104-113. https://doi.org/10.2478/ebtj-2018-0014S1041132

Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species

Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in “La Albufera” Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves—where they are presumably compartmentalized in vacuoles—and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na+ and Cl− contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K+ transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level—estimated from malondialdehyde accumulation—was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.Work in the UPV laboratories was partly funded by a grant to OV from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.Peer reviewedPeer Reviewe

Genetic Diversity and Relatedness Among Six Ranunculus Species Unraveled by SRAP Markers

The main aim of this study was to investigate the genetic diversity and phylogenetic relationships of six Ranunculus species using SRAP markers. The genotyping of 73 Ranunculus accessions showed that 12 primer pairs generated a total number of 212 polymorphic fragments with a 99.53 % level of polymorphism. Nei’s gene diversity ranged between 0.2237 and 0.3436 with an average of 0.3001. The UPGMA method with Nei72’s similarity coefficient ranging from 0.23 to 1.11 separated 73 accessions into two distinct groups (A and B). Cluster-A included R. acris members, while cluster-B included the rest of the tested species. Cluster-B was subsequently divided into two sub-groups (I and II). Subgroup-I consisted of R. carpaticus and R. serpens subsp. nemorosus accessions, while subgroup-II included the members of R. platanifolius, R. polyanthemos, and R. repens. R. polyanthemos and R. repens were founded the most closely related species. These findings provide a brand-new understanding of the evolutionary relationships of above mentioned Ranunculus species and may be useful tools for plant breeding and conservation purposes

Effects of Salt on Seed Germination and Seedling Growth of Three Portulaca Species

[EN] We have determined the relative tolerance to osmotic/ionic stress of three Portulaca species (P. halimoides, P. grandiflora and P. oleracea) at the seed germination and early seedling development stage. The three species are relatively resistant to stress, although at high concentrations NaCl strongly inhibited germination, whereas at the same osmotic potential PEG did not. Seedling growth was more clearly inhibited, in a concentration-dependent manner, with salt stress showing again a relatively stronger effect. Our data indicate that P. oleracea is the most salt-tolerant of the tested species and therefore the most promising candidate for saline agriculture , to be cultivated using low-quality, saline water for irrigationBorsai, O.; Al Hassan, M.; Boscaiu Neagu, MT.; Vicente Meana, Ó.; Sestras, A.; Sestras, R. (2015). Effects of Salt on Seed Germination and Seedling Growth of Three Portulaca Species. Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Horticulture. 72(2):450-451. doi:10.15835/buasvmcn-hort:11545S45045172