Naturalization of <Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch. in Western Siberia

The process of the Fragaria × ananassa naturalization in Western Siberia lasts approximately 80 years from the moment of the appearance of first garden strawberry cultivars at agricultural experimental stations in 1933. The species invasive status changed slightly for such a long period of time (from casual alien plants to naturalized plants), and it corresponds to colonophytes in regards to degree of naturalization. The ornitochory is one reason the F. × ananassa appears in natural phytocenoses. At present, the F. × ananassa naturalization occurs in two directions, including genetic transformations in long-living coenopopulations and the reinvasion of new ecotypes of the same species in natural phytocenoses. The high death of seedlings in naturalized F. × ananassa does not allow the species to actively occupy regeneration niches in natural phytocenoses, which precludes the invasive plant status for the F. × ananassa at this stage of the F. × ananassa naturalization in Western Siberia.     

Characterization of mixed disomic and polysomic inheritance in the octoploid strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis>) using AFLP mapping

A two-way pseudo-testcross strategy, combined with Single Dose Restriction Fragment (SDRF) marker analysis, was used for genetic mapping in the octoploid cultivated strawberry Fragaria x ananassa (2n = 8 x = 56). Based on a 113 full-sib progeny from a cross between the variety Capitola and the clone CF1116, we generated two parental maps using Amplified Fragment Length Polymorphism (AFLP) markers. Ninety two percent of the markers (727 out of 789) showed ratios corresponding to simplex markers (the majority being SDRF markers), and 8% (62 out of 789) fitted a multiplex ratio. Linkage maps were first established using SDRF markers in coupling phase. The female map comprised 235 markers distributed among 43 co-segregation groups, giving a map size of 1,604 cM. On the male map, 280 markers were assigned to 43 co-segregation groups, yielding a map size of 1,496 cM. Once the co-segregation groups were established, their association was tested using repulsion-phase markers. In total, taking into account associations representing the same linkage groups, 30 linkage groups were detected on the female side and 28 on the male side. On the female map, 68.3% of the pairwise marker linkages were in coupling versus 31.7% in repulsion phase, and the corresponding figures on the male map were 72.2% and 27.8%, respectively. In addition, both groups linked only in the coupling phase and groups linked in the repulsion phase were characterized. The observations suggest that the meiotic behavior of the F. x ananassa genome is neither fully disomic nor fully polysomic, but rather mixed. The genome may not be as completely diploidized as previously assumed.     

Effects of different amino acids on somatic embryogenesis of strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch.)

This study was conducted to optimize different types and concentrations of amino acids on somatic embryogenesis induction, development and maturation of leaf explants in strawberry cultivars (‘Camarosa’, ‘Paros’ and ‘Kurdistan’). Calli derived from leaf sections were transferred onto MS medium with 1.0 mg/l 2,4-d + 0.5 mg/l BAP supplemented with 0.0, 50, 100, 150 or 200 mg/l concentrations of proline, alanine and glutamine. Stimulation of embryogenesis and embryo development was strictly dependent on the type and concentration of amino acid in the medium. Proline (100 mg/l) was much more effective than glutamine and alanine, on induction and development of somatic embryogenesis in all cultivars. Cultures grown on amino acid-free medium attained lower somatic embryos than cultures grown on amino acid treated medium. Low concentrations (50 mg/l) and high concentrations (200 mg/l) of amino acids tested were inefficient for embryogenesis induction as well as for somatic embryos development.     

Manipulation of cellular energy reveals the relationship between ultraweak luminescence and cellular energy during senescence of strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis>) fruits

The goal of this study was to investigate the ultraweak luminescence (UWL) of strawberry fruits in relation to mitochondrial functions and energy production during strawberry senescence. Fully ripe strawberry fruits and mitochondria isolated from those fruits were treated with either adenosine triphosphate (ATP) or the respiratory chain uncoupler 2,4-dinitrophenol (DNP). The activities of H⁺-ATPase and Ca²⁺-ATPase, the content of ATP, the free radical O₂^? as well as the UWL intensity were measured. Our results showed that activities of H⁺-ATPase and Ca²⁺-ATPase as well as the ATP content gradually decreased during fruit senescence in all three groups. Compared with the control, DNP treatment exacerbated, while ATP treatment reduced the decrease of H⁺-ATPase and Ca²⁺-ATPase activity, the energy charge and UWL intensity. UWL intensity was positively correlated with mitochondrial function and ATP content. Our results strongly suggest that mitochondria are a major source of UWL of strawberry fruits, and that the cellular energy ATP plays important roles in senescence of strawberry fruits, and in UWL formation. Our study provides convincing evidence of the interrelationship between cellular energy and UWL, which helps researchers to better understand the process of senescence in strawberry fruits.     

Positive responses of strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch.) explants to salicylic and iron nanoparticle application under salinity conditions

Mucuna bracteata DC. ex Kurz is an important cover crop in plantations across the tropics. However, low germination rate and poor viability of Mucuna seeds pose significant challenges of using the seeds as starting material. To address these limitations, we have optimized seed germination conditions (such as scarification period, surface sterilization protocols and imbibition period) and in vitro propagation protocols for M. bracteata. We found that seeds treated with sulphuric acid for 30 min, imbibed for 6 h and incubated in dark conditions on a wet cotton roll (10 mL of sterile distilled water) supplemented with 0.1% activated charcoal produced the highest percentage of seed germination (44%) and seed vigor index. In vitro-derived cotyledonary nodes showed the highest number of shoots per explant (5.60) and rooting response (92.9%) when cultured on Murashige and Skoog medium containing 4.44 µM 6-benzylaminopurine and 10.7 µM 1-naphthaleneacetic acid, respectively. Of the 100 rooted plantlets acclimatized, 89.0% survived after 4 weeks of transplanting. Single sequence repeat and flow cytometry analysis were performed to confirm the genetic fidelity of the plants. Our protocol offers, for the first time, a simple and effective seed germination and scalable propagation procedures for M. bracteata. Furthermore, we have also estimated the genome size (1448?±?9 Mb) and DNA content (1.48?±?0.01 pg) for M. bracteata that can be used for future cytogenetic studies on genetic diversity and gene exchange.     

Application of iron nanoparticles and salicylic acid in in vitro culture of strawberries (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch.) to cope with drought stress

The effects of iron nanoparticles and salicylic acid (SA) on strawberry (Fragaria?×?ananassa Duch.) plants in conditions of drought stress were surveyed under in vitro conditions to find the optimum combination for strawberry tissue culture. Cuttings of the Queen Elisa cultivar were surveyed in a three-way factorial experiment with three replications in 2015. The results showed that drought stress significantly affected all measured parameters of strawberry plantlets under in vitro condition in a negative way. SA compensated for the negative effects of drought stress on strawberry plantlets and improved their growth parameters under in vitro culture. Strawberry plantlets treated with iron nanoparticles were able to cope with stressful conditions better than untreated ones. This study found that iron, a micronutrient in plant growth and in vitro development, greatly influenced the plantlets’ growth parameters and other measured traits. These results indicate that the efficiency of tissue culture and in vitro culture of strawberries could be improved by increased application of iron in the form of nanoparticles. The results might also indicate that the application of iron nanoparticles along with SA can be a useful method for providing higher quantity and quantity in the in vitro culture of strawberries, and could be used for adapting strawberry plants to drought before transplanting them in the field.     

Validation of a PCR test to predict the presence of flavor volatiles mesifurane and γ-decalactone in fruits of cultivated strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis>)

Flavor improvement is currently one of the most important goals for strawberry breeders. At the same time, it is one of the most complex traits to improve, involving the balanced combination of several desired characteristics such as high sweetness, moderate acidity, and the appropriate combination of aroma compounds that are beginning to be delineated in consumer tests. DNA-informed breeding will expedite the selection of complex traits, such as flavor, over traditional phenotypic evaluation, particularly when markers linked to several traits of interests are combined during the breeding process. Natural variation in mesifurane and γ-decalactone, two key volatile compounds providing sweet Sherry and fresh peach-like notes to strawberry fruits, is controlled by the FaOMT and FaFAD1 genes, respectively. In this study, we have optimized a simple PCR test for combined analysis of these genes and determined a prediction accuracy above 91% using a set of 71 diverse strawberry accessions. This high accuracy in predicting the presence of these important volatiles combined with the simplicity of the analytical methodology makes this DNA test an efficient tool for its implementation in current strawberry-breeding programs for the selection of new strawberry cultivars with superior flavor.     

FaGT2: a multifunctional enzyme from strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis>) fruits involved in the metabolism of natural and xenobiotic compounds

Fragaria × ananassa UDP-glucose:cinnamate glucosyltransferase (FaGT2) catalyzes the formation of cinnamic acid and p-coumaric acid glucose esters during strawberry fruit ripening. Here, the ripening and oxidative stress induced enzyme was further characterized by testing a range of structurally different substrates of natural and unnatural origin in vitro and comparing their kinetic parameters to elucidate its additional biological functions. The accepted substrates ranged from derivatives of cinnamic acid and benzoic acid to heterocyclic and aliphatic compounds resulting in the formation of O- and S-glucose esters, as well as O-glucosides. In planta assays confirmed the formation of glucose derivatives after injection of the substrates into strawberry fruits. Common chemical and structural features required for activity were the easy subtraction of a proton from the glucosylation site and the conjugation of the formed anion with π-electrons as best realized in the simplest substrate sorbic acid. In addition to cinnamic acid, the natural compounds anthranilic acid, trans-2-hexenoic acid, nicotinic acid and 2,5-dimethyl-4-hydroxy-3[2H]-furanone were glucosylated in vitro. But FaGT2 was also capable of efficiently converting xenobiotic substances like the herbicide 2,4,5-trichlorophenol and the herbicide analogue 3,5-dichloro-4-hydroxybenzoic acid. The results suggest that FaGT2 is involved in the detoxification of xenobiotics in accordance to its induction by oxidative stress. GenBank Accession number of FaGT2: AY663785.     

Quantitative trait loci and underlying candidate genes controlling agronomical and fruit quality traits in octoploid strawberry <Emphasis Type="Italic">(Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis>)

Breeding for fruit quality traits in strawberry (Fragaria × ananassa, 2n = 8x = 56) is complex due to the polygenic nature of these traits and the octoploid constitution of this species. In order to improve the efficiency of genotype selection, the identification of quantitative trait loci (QTL) and associated molecular markers will constitute a valuable tool for breeding programs. However, the implementation of these markers in breeding programs depends upon the complexity and stability of QTLs across different environments. In this work, the genetic control of 17 agronomical and fruit quality traits was investigated in strawberry using a F₁ population derived from an intraspecific cross between two contrasting selection lines, ‘232’ and ‘1392’. QTL analyses were performed over three successive years based on the separate parental linkage maps and a pseudo-testcross strategy. The integrated strawberry genetic map consists of 338 molecular markers covering 37 linkage groups, thus exceeding the 28 chromosomes. 33 QTLs were identified for 14 of the 17 studied traits and approximately 37% of them were stable over time. For each trait, 1–5 QTLs were identified with individual effects ranging between 9.2 and 30.5% of the phenotypic variation, indicating that all analysed traits are complex and quantitatively inherited. Many QTLs controlling correlated traits were co-located in homoeology group V, indicating linkage or pleiotropic effects of loci. Candidate genes for several QTLs controlling yield, anthocyanins, firmness and l-ascorbic acid are proposed based on both their co-localization and predicted function. We also report conserved QTLs among strawberry and other Rosaceae based on their syntenic location.     

A reliable multiplexed microsatellite set for genotyping <Emphasis Type="Italic">Fragaria</Emphasis> and its use in a survey of 60 <Emphasis Type="Italic">F</Emphasis>. × <Emphasis Type="Italic">ananassa</Emphasis> cultivars

We have identified a reliable set of multiplexed microsatellite (SSR) markers for the genotyping of strawberry cultivars and their octoploid progenitors. Over 100 SSRs were screened in two F. × ananassa genotypes and from these, 32 that showed promise for genotyping were selected for further analysis. These SSRs were used to screen a set of 16 strawberry cultivars and a set of fingerprints were produced. Those SSRs that produced reliable, reproducible and easy to interpret fingerprints, that could also distinguish readily between the 16 strawberry cultivars screened, and which could be conveniently included in three multiplex reactions, were selected to form the genotyping set. The genotyping set, consisting of 10 previously-reported SSRs was used to fingerprint a total of 56 cultivated strawberry, and four octoploid Fragaria species accessions. The SSRs used could reliably distinguish between all 60 genotypes surveyed, including sibling cultivars derived from the same parental lines. The primers could be combined for multiplex PCR and represent a useful and convenient genotyping set for Fragaria that will permit fingerprinting data to be shared between laboratories.     

Comparison of suitability of RAPD and ISSR techniques for determination of strawberry (<Emphasis Type="Italic">Fragaria ×</Emphasis><Emphasis Type="Italic">ananassa</Emphasis> Duch.) relationship

Two PCR-based techniques, RAPD and ISSR, were utilized for determination of genetic relationship of 24 strawberry cultivars used in breeding program at the Research Institute of Pomology and Floriculture in Poland. Polymorphism of investigated genotypes was observed in reactions with 23 out of 48 tested RAPD primes and 41 from 90 tested ISSR primers. Relationship, determined on the base of polymorphic products analysis and showed in the form of dendrograms (UPGMA percent method), was generally similar for both techniques, although similarity values based on ISSR data were higher than those based on RAPD. The parallel use of two data sets seems to allow for precise estimation of cultivars relationship and diminishing mistakes connected with methods' technical limitations.     

<Emphasis Type="Italic">Carex</Emphasis> × <Emphasis Type="Italic">involuta</Emphasis> and <Emphasis Type="Italic">Carex juncella</Emphasis> in the flora of Slovakia

The paper brings information on an isolated occurrence and morphological characters of Carex × involuta and C. juncella populations in the Vel’ká Fatra Mts. Their presence has been known neither from the territory of Slovakia nor from the whole Western Carpathians till now.     

The effect of end of day far-red light on regulating flowering of short-day strawberry (<Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch. сv. Paros) in a long-day situation

The effects of manipulation of phytochrome state and plant age were tested on flowering strawberry (Fragaria × ananassa Duch. cv. Paros) using end of day far red light (EOD-FR) under undesirable environmental conditions (high temperature and long day). The first and second experiments examined the effects of EOD-FR on flower induction, level of phytochrome and carbohydrates (starch, sucrose, fructose, and glucose), which were variable along with acid invertase enzyme. In the first experiment, there was no flower emergence, but in the second experiment, induction occurred in plants exposed to 6 h of EOD-FR for 32 cycles. The third experiment tested the effect of far red light (6 h + 32 d) on plants of 8, 10, and 12 weeks of age, and induction occurred in 12-week-old plants. The results of experiments II and III indicated that in the induced plants, the amount of phytochrome (Pr) increased. Furthermore, a higher level of sucrose was observed in induced plants, but the level of starch was lower. Nevertheless, amounts of glucose, fructose, and invertase enzyme did not change significantly, although they did show a slight increase in induced plants. These results provide evidence that a light-quality pathway exists that acts on regulation of flowering time in short-day strawberry cultivation.     

An innovative approach to <Emphasis Type="Italic">ex vitro</Emphasis> rooting and acclimatization of <Emphasis Type="Italic">Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa</Emphasis> Duch. microshoots using а biogenic silica- and green-tea-catechin-based mechanocomposite

A new approach for rapid ex vitro rooting and acclimatization of Fragaria × ananassa micropropagated plantlets of two cultivars (“Alpha” and “Festivalnaya”) has been developed using a mechanocomposite based on biogenic silica and green-tea catechins. Two different mechanocomposite treatments were studied: dipping the cut ends of microshoots in the mechanocomposite powder (the dry dip method) and single watering with solutions at concentrations of 0.3, 1.0, and 3.0 g L^?1. These variants were compared with pulse treatment of microplants with 30 mg L^?1 indole-3-acetic acid (IAA) for 4 h and a control group of microshoots that were moistened with hormone-free ¼-strength MS medium. The frequencies of ex vitro rooting at the end of the acclimatization period (30 d) varied from 24.8 to 99.7%. The dry dip treatment was best (rooting frequency about 100%) with up to 7.15?±?0.54-cm root length, and 6.10?±?0.31 roots per plantlet. Moreover, this study showed that the growth-stimulating effect of this mechanocomposite treatment on root formation resulted in increased rosette height, leaf number, leaf area, and dry weight of aerial parts. Histological analysis of the leaf blades revealed decreased mesophyll thickness of microshoots treated with the mechanocomposite (up to 88.77?±?2.95 vs. 111.51?±?3.56 μm for the control). Morphometric analysis of scanning electron microscopy data showed that mechanocomposite treatments led to increased stomata density and stomata length. These structural changes led to normalization of the water regime and indicated successful acclimatization. The combination of ex vitro rooting and acclimatization reduced the procedure time by 4 wk, and may be used for commercial strawberry micropropagation.     

Expressed sequence tags (ESTs) and simple sequence repeat (SSR) markers from octoploid strawberry <Emphasis Type="Italic">(Fragaria</Emphasis> × <Emphasis Type="Italic">ananassa)</Emphasis>

Background  

Cultivated strawberry (Fragaria × ananassa) represents one of the most valued fruit crops in the United States. Despite its economic importance, the octoploid genome presents a formidable barrier to efficient study of genome structure and molecular mechanisms that underlie agriculturally-relevant traits. Many potentially fruitful research avenues, especially large-scale gene expression surveys and development of molecular genetic markers have been limited by a lack of sequence information in public databases. As a first step to remedy this discrepancy a cDNA library has been developed from salicylate-treated, whole-plant tissues and over 1800 expressed sequence tags (EST's) have been sequenced and analyzed.     

Adventitious shoot regeneration from seven commercial strawberry cultivars (<Emphasis Type="Italic">Fragaria </Emphasis>×<Emphasis Type="Italic"> ananassa</Emphasis> Duch.) using a range of explant types

The parameters for optimal regeneration of seven commercial strawberry cultivars were tested using a range of explants and culture conditions. Efficient levels of regeneration--those needed to carry out transformation experiments--with the cultivars Calypso, Pegasus, Bolero, Tango and Emily were achieved with leaf discs, petioles, roots and stipules. Regeneration from cv. Elsanta proved to be difficult from all explant material, although unpollinated ovaries proved to be a promising explant source, with 12% of the explants regenerating shoots. In cv. Eros, regeneration occurred only from root tissue. A comparison of the genetic background suggests that there is a strong genetic component amongst the different cultivars determining their regeneration capacity. The development of these regeneration systems provides a means to use almost the whole stock plant for the efficient genetic transformation of commercial strawberry varieties.