Senga Sengana Research Articles

In vitro testing of strawberry resistance to Verticillium dahliae and Phytophthora cactorum

The effects of culture filtrates and homogenates of Verticillium dahliae and Phytophthora cactorum on in vitro growth and development of strawberry shoots of cvs. Elsanta, Real and Senga Sengana were investigated. The filtrates of fungal cultures as well as filtrates of homogenated mycelia did not affect strawberry shoot growth and development, whereas inoculation with mycelia of V. dahliae and P. cactorum resulted in leaf yellowing, growth inhibition, inhibition of root formation, and after several days, the death of infected plants. However, fungal growth on the media that were used was irregular and the infection rate of individual plants was very variable. Mycelial homogenates affected growth and development of strawberry shoots in a similar way to that of an intact mycelium. Because the homogenate was distributed evenly in the culturing medium, the effect was uniform and thus possible to quantitate. It was also possible to differentiate a pathogen’s inoculum potential by adequate dilution of the homogenate. The best effect was obtained with V. dahliae. Fungal homogenate inhibited root formation and shoot growth, caused leaf necrosis and death of the plants after 7–8 weeks. The reaction of the cultivars tested was similar to their sensitivity to verticillium wilt in the field. P. cactorum affected in vitro strawberry shoot growth and development in a similar way to V. dahliae, but the effect was not cultivar-dependent. Preliminary tests showed that the method developed is useful for selection of somaclonal variants resistant/tolerant to infection with these pathogens.

Reactions of strawberry plants to long-term freezing and alternate freezing and thawing

SummaryThe study was conducted in two experiments, one examining the effects of alternate freezing and thawing at –12˚C for 2 h and +6#x02DA;C for 24 h, and the other examining the effects of permanent freezing for 1 or 15 d at+12˚C. In both experiments the plants were grown in the pre-fruiting period at a coastal or a continental location in Norway. The freezing injury increased the higher the stress, indicated by reduced growth, fruit size and yield.It was shown that ‘Korona’ was the most hardy cultivar at a short period of freezing stress and at alternate freezing and thawing, while ‘Senga Sengana’ was more freezing tolerant at long-term permanent freezing than ‘Bounty’ and ‘Korona.’ In general the results indicate that the plants induce freezing tolerance according to some factor of origin, since plants grown in the continental climate were better able to survive long-termpermanent freezing than plants grown in a coastal climate, and plants grown in a coastal climate were better able to survive alternate freezing and thawing than plants grown in a continental climate.

Winter hardiness of micropropagated and conventionally propagated strawberry plants

SummaryEnhanced vigour of micropropagated strawberry (Fragaria X ananassa Duch.) plants has given cause to suspect their winter hardiness to be inferior to that of conventionally propagated plants. This experiment was carried out to examine and compare cold hardiness and overwintering of three types of strawberry plants of cultivars Senga Sengana and Jonsok: 1) micropropagated virus-free elite plants, 2) certified plants (runner plants from elite plants), and 3) ordinary plants (runner plants of conventionally propagated plants from a strawberry farm). A special “double pot”-method was developed and used in planting so that the plants could be lifted for controlled freezing tests during winter. Additionally, winter survival was evaluated in the field during flowering. In controlled freezing tests, strawberry crowns survived -8°C without injury, suffered minor injury at -10°C and severe injury at -12°C. No consistent differences in cold hardiness among the three types of plants were detected during winter. Field evaluation did not reveal any differences in their winter survival, either. Micropropagated plants flowered more freely than did the plants produced through runners.

Sugars and acids of strawberry varieties

The sugar and acid compositions of six strawberry (Fragaria×ananassa Duch.) varieties from 1997 and 1998, grown in different conditions, 26 samples in all, were investigated by GC as trimethylsilyl derivatives. The major sugars were glucose (1.89–4.52 g/100 ml), fructose (2.14–4.14 g/100 ml) and sucrose (0.90–3.87 g/100 ml), the major acids being citric (0.73–1.58 g/100 ml) and malic (0.22–0.69 g/100 ml). Total sugar content (glucose+fructose+sucrose) varied from 5.35 g/100 ml to 10.96 g/100 ml in accordance with soluble solids (°Brix). The correlation between them showed a linear regression y=0.873x-0.420, the percentage of determination of the regression model being 82.1%. Among one variety only, ‘Senga Sengana’, the percentage of the model was 86.9%. No significant differences were found between the strawberries from conventional versus those from organic farms. Contents of sugars and soluble solids were lower in varieties ‘Jonsok’ and ‘Honeoye’ than in ‘Korona’, ‘Bounty’ and ‘Polka’. The concentrations of malic acid were significantly higher in Senga Sengana, Jonsok and Bounty than in other varieties.

Ellagic acid content in berries: Influence of domestic processing and storage

The content of ellagic acid was determined from the berries of the family Rosaceae (strawberry, red raspberry, cloudberry, arctic bramble). Extraction and hydrolysis procedures were optimized and analysis was done with an HPLC method and UV detection. The influence of processing on ellagic acid content was studied in strawberry jam. Strawberries, red raspberries, and strawberry jam were analyzed fresh and after 3, 6, and 9 months of storage in a domestic freezer or refrigerator. Ellagic acid contents after 3 months of storage at −20 °C varied between 31.5 (strawberry ‘Senga Sengana’) and 68.6 mg/100 g f.w. (arctic bramble). Ellagic acid content in strawberry jam (23.8 mg/100 g f.w.) was 80% of that in unprocessed strawberries. The content of ellagic acid in strawberries and red raspberries was reduced by 40% and 30%, respectively, during the 9 months of storage at −20°C. The unprocessed berries studied, together with nuts, make the main contribution to the total dietary intake of ellagic acid in Finland.

MYCORRHIZAL INOCULATION OF MICROPROPAGATED STRAWBERRY - CASE STUDIES ON MINERAL SOIL AND A MINED PEAT BOG

The effects of inoculation of micropropagated strawberries `Senga Sengana' and `Jonsok with arbuscular mycorrhizal fungi at the beginning of weaning were studied in an experiment on mineral soil and mined peat soil, respectively. Despite the same sizes of inoculated and uninoculated plants at the end of weaning, AMF inoculation increased fruit yields especially on mineral soil. The experiment conducted on a mined peat bog showed less pronounced positive effects of AMF. The peat substrate caused slower spread of AMF colonization to newly formed roots. It is concluded that AMF has the potential of being included as a natural part of the micropropagation system.

Winter cover affecting freezing injury in strawberries in a coastal and continental climate

SummaryThe study was conducted in two continental and two coastal experiments on field-grown strawberries on high beds. It was shown that use of winter cover reduced freezing injury in plants without snow cover during winter. Cover positively affected development of flower stalks, increasing the number and the proportion of flower stalks that were large. Also, it reduced injury in flower primordia and thus the number of misshapen fruits, and made the plants produce larger fruits. As a sum, these effects increased the yields up to 9% in the continental and 45% in the coastal fields. The yield differences of the coastal vs. the continental experiments were partly due to more freezing and thawing at the coastal than at the continental fields, and partly influenced by a snow roof to keep the snow off the plants in the continental experiments. Generally, covering with fleece, bubble plastic and brown-paper-laminated bubble plastic gave a better result than straw for winter covering. When straw was used it was essential to remove it in early spring. Using fleece and bubble plastic as winter covers, there was no difference in yield by removal of the cover in the first week of April or May for the cvs ‘Bounty‘ and ‘Senga Sengana‘, but cv. ‘Korona‘ reacted generally positively to prolonging the covering period. Covering from 1 September to 1 November only, had a negative effect on yield compared with no cover, while covering in April only was equal to no covering.

Freeze injury to strawberry plants as evaluated by crown tissue browning, regrowth and yield parameters

The strawberry cvs `Bounty', `Korona' and `Senga Sengana' were frozen for 2 h at −8, −12, −16 or −20°C, at a freeze and thaw rate of 2°C/h. Growth and yield parameters and crown tissue browning were compared with plants stored at 0°C. At −8°C all the plants were severely injured and the fruit yields were reduced to 41, 60 and 66% of uninjured plants respectively for `Senga Sengana', `Bounty' and `Korona'. These yield reductions were reflected in reduced growth and increased crown tissue browning, and there were strong correlations between the different parameters recorded. It is concluded that the limit temperature for severe injury, for a single short term freezing, is between −8 and −12°C for `Bounty' and `Senga Sengana' and a little below −12°C for `Korona'. Plants frozen at −20°C died.

Effect of ammonium or nitrate nutrition on net photosynthesis, growth, and activity of the enzymes nitrate reductase and glutamine synthetase in blueberry, raspberry and strawberry

Blueberry, raspberry and strawberry may have evolved strategies for survival due to the different soil conditions available in their natural environment. Since this might be reflected in their response to rhizosphere pH and N form supplied, investigations were carried out in order to compare effects of nitrate and ammonium nutrition (the latter at two different pH regimes) on growth, CO2 gas exchange, and on the activity of key enzymes of the nitrogen metabolism of these plant species. Highbush blueberry (Vaccinium corymbosum L. cv. 13–16–A), raspberry (Rubus idaeus L. cv. Zeva II) and strawberry (Fragaria × ananassa Duch. cv. Senga Sengana) were grown in 10 L black polyethylene pots in quartz sand with and without 1% CaCO3 (w: v), respectively. Nutrient solutions supplied contained nitrate (6 mM) or ammonium (6 mM) as the sole nitrogen source. Compared with strawberries fed with nitrate nitrogen, supply of ammonium nitrogen caused a decrease in net photosynthesis and dry matter production when plants were grown in quartz sand without added CaCO3. In contrast, net photosynthesis and dry matter production increased in blueberries fed with ammonium nitrogen, while dry matter production of raspberries was not affected by the N form supplied. In quartz sand with CaCO3, ammonium nutrition caused less deleterious effects on strawberries, and net photosynthesis in raspberries increased as compared to plants grown in quartz sand without CaCO3 addition. Activity of nitrate reductase (NR) was low in blueberries and could only be detected in the roots of plants supplied with nitrate nitrogen. In contrast, NR activity was high in leaves, but low in roots of raspberry and strawberry plants. Ammonium nutrition caused a decrease in NR level in leaves. Activity of glutamine synthetase (GS) was high in leaves but lower in roots of blueberry, raspberry and strawberry plants. The GS level was not significantly affected by the nitrogen source supplied. The effects of nitrate or ammonium nitrogen on net photosynthesis, growth, and activity of enzymes in blueberry, raspberry and strawberry cultivars appear to reflect their different adaptability to soil pH and N form due to the conditions of their natural environment.

Application of luminescence for quality evaluation of in vitro regenerated strawberry plants

The parameters of chlorophyll a fluorescence induction were measured: Fv/Fm, Sc/Fm, Rfd and coefficient of Ld delayed luminescence decay kinetics, related with a course of primary photosynthesis reactions on leaves of strawberry plants, cultured in vitro by means of the micropropagation methods. Strawberry plants cv. Ananasowa from in vitro cultures in optimal condition show significantly higher values of luminescence parameters indicating better condition of plants of this variety in comparison with the variety Senga Sengana. After temperature lowering, however, these values were more reduced than for plants of Senga Sengana, which can be interpreted as higher susceptibility of this variety to chill. Addition of BAP caused disturbance of primary photosynthesis reactions rate, particularly in lower temperature. Auxin 2,4-D had no effect on the luminescence parameters in comparison with control cultures. Dehydration stress strongly diminished the values of measured parameters for Ananasowa variety what indicates the inhibition of primary photosynthesis reaction in leaves. The old culture of Senga Sengana variety showed higher tolerance on linuron in comparison with the new one.

Influence of pollination modes on yield components in strawberry (Fragaria×ananassa Duch.)

AbstractThe effects of self, wind and open pollination on yield components were investigated in five strawberry genotypes, the cultivars ‘Dukat’, ‘Paula’, ‘Redgauntlet’, ‘Senga Sengana’ and the breeding clone B‐302. Investigations were also conducted to look for additional plant characteristics associated with strawberry yield components after various modes of pollination. Such characteristics would facilitate the indirect selection of highly self‐compatible strawberry genotypes. The greatest effect of self pollination was observed in B‐302 and ‘Redgauntlet’, while the least effect of autogamy was shown m Paula. Conversely, the last cultivar revealed the greatest effect of entomophily, whereas the greatest effect of wind pollination was observed in ‘Dukat’. Relationships between yield components and some flower and pollen characteristics after various pollinations indicated that the degree of self compatibility in strawberry can be predicted from the pollen grain length and the pollen size index. Genotypes producing long pollen grains with large size indices exhibited the greatest effect of autogamy. Anther size, especially length. Which correlated more strongly with yield components than width, could also be used as an index of autogamy in the strawberry. Pollen yield per flower an self compatibility.

Short days and temperature effects on growth and flowering in strawberry (Fragaria × ananassa Duch.)

Summary‘Korona’, ‘Elsanta’, ‘Bounty’ and ‘Senga Sengana’ strawberry (Fragaria × ananassa Duch.) plants, were placed at constant temperatures of 9, 15 or 21°C and daylengths of 8 h (short day) or 24 h (long day). The plants were given different numbers of short-day (SD) cycles, and flowering and growth were studied. ‘Korona’ and ‘Elsanta’ were responsive to both short-day treatment and temperature, with optimum flowering at 15°C and 24 SD. ‘Bounty’ was more responsive to temperature, inducing flowers independently of the number of SD cycles at 9°C and 15°C. In ‘Senga Sengana’ flowering was induced independently of temperature and the number of SD cycles, indicating that it had a stronger dependence on other environmental effects. The effect of the number of short-day cycles and the temperature on vegetative growth variâtes such as the number of stolons and daughter plants, the length of flower trusses and petiole length were also studied.

Peroxidase Isoenzymes in Strawberry Roots Infected with Binucleate Rhizoctonia spp. and their Implication in Disease Resistance

AbstractInfection of strawberry plants with binucleate Rhizoctonia spp. results in an increase in peroxidase activity and the appearance of new isoforms of the enzyme. In healthy and diseased roots of two different strawberry genotypes seven peroxidase isoenzymes were found. In healthy strawberry cv. Senga Sengana, which was moderately resistant to infection, four isoenzymes (1, 2, 5, and 6) were found. Moreover the activity of these isoenzymes was increased and three new isoenzymes (3, 4, and 7) were found in infected roots. In the strawberry hybrid 3/2/86/88/R, which is very susceptible to infection, only isoenzyme 2 was present in the roots of healthy plants. Following infection, the activity of isoenzyme 2 was increased and five new isoenzymes (1, 4, 5, 6, and 7) were detectable. The results obtained indicate that strawberry resistance to binucleate Rhizoctonia may be correlated with peroxidase isoenzyme profile with particular reference to isoform 3, which is only present in infected roots of the moderately resistant cv., Senga Sengana.

Identification of RAPD markers linked to a Phytophthora fragariae resistance gene (Rpf1) in the cultivated strawberry

Bulked segregant analysis (BSA) was used to identify seven random amplified polymorphic DNA (RAPD) markers linked to the Rpf 1 gene. Rpf 1 confers resistance to Phytophthora fragariae var. fragariae, the causal agent of red stele root rot in Fragaria spp. The bulked DNAs represented subsets of a F1 population obtained from the cross Md683×Senga Sengana which consisted of 60 plants and segregated in a 1:1 ratio for resistance or susceptibility to race 2.3.4 isolate NS2 of P. fragariae. Seven markers were shown to be linked to Rpf 1 and were generated from four primers; five of these markers were in coupling phase and two in repulsion phase with respect to the gene. A linkage map of this resistance gene region was generated using JoinMap 2.0TM. The manner in which Rpf 1 and the linked markers co-segregated indicated that they are inherited in a disomic fashion. These markers could enable gene pyramiding and marker-assisted selection of resistance genes in strawberry breeding programmes.

Electron microscopy and molecular identification of phytoplasmas associated with strawberry green petals in the Czech Republic

The presence of phytoplasma inFragaria ananassa x Duch cv Senga Sengana showing strawberry green petals symptoms was observed by electron microscopy of phloem tissue. No phytoplasmas were found in asymptomatic strawberry plants used as controls. Nucleic acids extracted from these plants were used in nested-PCR assays with primers amplifying 16S rRNA sequences specifie for phytoplasmas. Bands of 1.2 kb were obtained and the subsequent nested-PCR with specific primers and RFLP analyses allowed to classify the detected phytoplasmas in the aster yellows group (16SrI). They belonged to the subgroup I-C of which type strain is clover phyllody phytoplasma.

2,5-Dimethyl-4-hydroxy-3[2H]-furanone [formula omitted] in strawberry fruits

2,5-Dimethyl-4-hydroxy-3[2H]-furanone 6′-O- malonyl-β- d-glucopyranoside was isolated from a glycosidic extract of strawberry fruit ( Fragaria x ananassa, cv. Senga Sengana) by means of countercurrent chromatography and reverse-phase HPLC. Identification was achieved by comparison of chromatographic and 1H, 13C and 2D-NMR, as well as mass spectral data with those of the synthesized reference compound. In ripe strawberry fruit, a 1:1 ratio of the malonylated glucoside to its deacylated glucoconjugate was determined by on-line liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

The viability and storage of strawberry pollen

AbstractInvestigations were carried out in 1990 and 1991 to estimate the pollen viability of five strawberry genotypes and their suitability for storage. Pollen viability was assessed by acetocarmine staining, in vitro germination, and in vivo assays. Pollen was stored in darkness at −18°C for 1 year, and pollen viability was estimated every 4 months during storage.The highest percentage of stained and in vitro germinated pollen grains, respectively, was shown by fresh pollen of cv. ‘Dukat’ (91 and 45%). The lowest values of these characteristics were observed in pollen of cv. ‘Paula’ (48% and 20%, respectively). The best response to storage at −18°C occurred in pollen of the breeding clone ‘B‐302’ and the cv. ‘Redgauntlet’. ‘Paula’ pollen responded least favourably to this. Pollen of the cvs. ‘Dukaf’. ‘Senga Sengana’, and clone ‘B‐302’ after storage for 4 months, still had sufficient capacity for fruit set after cross‐pollinations.

Infection of hairy roots of strawberry (Fragaria x Ananassa Duch.) with arbuscular mycorrhizal fungus

Hairy root cultures of strawberry (Fragaria x ananassa Duch.) were induced with the Agrobacterium rhizogenes strain A4. Cultures were maintained on B50 medium but could also grow on a minimal medium, which did not inhibit the growth of arbuscular mycorrhizal fungi. The growth and nutrient uptake were characterized in shake flasks and in a bioreactor. Spores of the native Finnish arbuscular mycorrhizal fungus Glomus fistulosum V128 were used to infect strawberry (Fragaria x ananassa Duch. 'Senga Sengana') hairy roots in vitro. During cultivation, vegetative spore formation was observed. At the end of the cultivation, hyphae and arbuscules were observed in the stained roots.

Effect of soil application of cadmium contaminated lime on soil cadmium distribution and cadmium concentration in strawberry leaves and fruit

Abstract Heavy metal environmental pollution which occurs as a result of lime contaminated with cadmium (Cd) poses a potential health hazard. This investigation was undertaken to study uptake of Cd by strawberry plants grown in soil amended with three different sources and two different rates of industry waste lime containing 3.4, 14.3, and 60.0 mg Cd/kg, respectively. The effects of Cd applied to the soil were investigated, including its distribution in the soil and effect on Cd concentration in strawberry cv. Senga Sengana (Fragaria anassa) leaves and fruit in response to soil organic matter content and lime rates. Cadmium accumulated mainly in the plough layer, increasing from 0.170 mg Cd/kg (background level) to a maximum of 1.2 mg Cd/kg. Fruit had very high, hazardous Cd concentrations regardless of its content in the soil. This indicates that Cd was easily taken up by strawberry plants and accumulated in upper plant parts, including the fruit. Soil Cd content had no effect on concentration of this e...

Identification of pathogenic races ofPhytophthora fragariae Hickman in Germany

The fungusPhytophthora fragariae Hickman is the causal agent of red stele disease in strawberry (Fragaria × ananassa), this being a major disease in many areas with cool and moist conditions. Success of resistance breeding can be nullified by the appearence of specific races of the fungus capable of overcoming the introduced resistance. In some countries (USA, UK, Japan and Canada) races were identified by using a differential set of strawberry cultivars. The absence of an international standard differential set and the use of different test methods make a comparison of the identified races difficult or even lead to contradictory results for one variety/race combination. The aim of this study was to obtain information about the spectrum of pathogenic races in Germany as a basic contribution to research on resistance breeding against the fungus. The susceptibility of different strawberry cultivars to German isolates ofP. fragariae was evaluated. The inoculation was done by modifying a method described by Milholland et al. (1989). Rootedin vitro plants, four weeks after transferring them to the soil, were used for the investigation. Inoculation was done with a zoospore suspension of defined concentration. Up to now three German isolates, G-1, G-2, and G-3, can be separated by their ability to infect and produce oospores in the roots of the strawberry cultivars ‘Senga Sengana’, either ‘Saladin’, ‘Redgauntlet’ or ‘Climax’ andFragaria chiloensis clone ‘YaquinaB’. These results confirm the existence of pathogenic races ofP. fragariae in Germany and should be taken into consideration for resistance breeding against the fungus.