Percentage Of Spore Germination Research Articles

A hidden herbivory effect on Sphagnum reproduction.

Defence theories provide predictions about trade-offs in the allocation of resources to defence and growth. However, very little is known about how pressure from herbivores influences the allocation of resources during reproduction. Two common peatland bryophyte species, Sphagnum angustifolium and S. capillifolium, were chosen as study species. Vegetative and reproductive shoots of both Sphagnum species were subjected to treatments with and without herbivores in a lab experiment. After 4 weeks of exposure to herbivores in a growth chamber, we measured biomass production, net photosynthesis rate, defence traits (phenolics in leachate and phenolics in extract), nonstructural carbohydrates (soluble sugar and starch), and reproductive traits (capsule number, weight and diameter, and spore germination) of both Sphagnum species. Reproductive shoots had higher constitutive defence than vegetative shoots in S. angustifolium, and a similar pattern was observed in S. capillifolium. With herbivory, reproductive shoots showed stronger induced defence (released more phenolics) than vegetative shoots in S. capillifolium, but not in S. angustifolium. Herbivory had no effect on capsule number, weight, or diameter, but reduced spore germination percentage by more than half in both species. Our study highlights the hidden effects of herbivory on reproduction of Sphagnum and indicates the presence of maternal effects in bryophytes. Ecologists will benefit from examining both quality- and quantity-based traits when attempting to estimate the herbivory effect on plant fitness.

Control of citrus blue and green molds by Actinomycin X2 and its possible antifungal mechanism

Citrus blue and green molds caused by Penicillium digitatum, P. italicum, and P. polonicum, are the major postharvest diseases of citrus fruit. In the present study, Actinomycin X2 (Act-X2), a naturally occurring antibiotic produced by Streptomyces species, was found to show excellent antifungal effect against these three pathogens with a minimum inhibitory concentration (MIC) value of 62.5 μg/mL for them all, which was better than the positive control thiophanate-methyl. Act-X2 significantly reduced the percentage of spore germination, and highly inhibited the mycelial growth of P. italicum, P. digitatum, and P. polonicum with EC50 values being 34.34, 13.76, and 37.48 μg/mL, respectively. In addition, Act-X2 greatly decreased the intracellular protein content while increasing the reactive oxygen species (ROS) level and superoxide anion (O2−) content in the mycelia of pathogens. In vivo test indicated that Act-X2 strongly inhibited the infection of navel oranges by these three Penicillium species, with an inhibition percentage of >50% for them all at the concentration of 10 MIC. Transcriptome analysis suggested that Act-X2 might highly influence the ribosomal functions of P. polonicum, which was supported as well by the molecular docking analysis of Act-X2 with some key functional proteins and RNAs of the ribosome. Furthermore, Act-X2 significantly reduced the decay percentage and improved the firmness, color, and sugar-acid ratio of navel oranges spray-inoculated with P. polonicum during the postharvest storage at 4 °C for 60 d.

Induced Resistance Mechanism of Bacillus velezensis S3-1 Against Pepper Wilt.

In recent years, pepper wilt has emerged as a pivotal constraint on pepper yield augmentation. Bacillus velezensis S3-1, with a wide array of hosts, can be used as both a biocontrol agent and biofertilizer. Nonetheless, the precise mechanisms underpinning its employment in combating pepper wilt remain cloaked in ambiguity. In our study, we found that B. velezensis S3-1 could significantly inhibit Fusarium sp. F1T that caused pepper wilt. S3-1 could effectively inhibit both the growth and germination of F1T conidia, leading to a reduction in the spore germination percentage from 83.2 to 37.1% in vitro experiments. Additionally, leaf detachment experiments revealed that the volatile compounds produced by S3-1 could inhibit the spread of pepper leaf spot area. Moreover, we observed a significant decrease in the content of malondialdehyde (MDA) in pepper treated with S3-1, along with a significant increase in the content of soluble protein, polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) in pepper. Furthermore, RT-PCR analysis showed that the expression of the defense genes CaPR 1 and CaPIN II in pepper after treatment with S3-1 was significantly upregulated, suggesting that S3-1 had the potential to induce systemic resistance in pepper, thereby enhancing its disease resistance. Hence, our findings suggest that S3-1 can be a promising biocontrol agent for managing pepper wilt in modern agriculture.

Characterization of Trichoderma species from forest ecosystems by high-throughput phenotypic microarray

The use of beneficial organisms for the biocontrol of soil-borne pathogens in forestry is still poor explored. In this work, the nutritional demands of 10 previously selected isolates of Trichoderma for the biocontrol of forest soil-borne pathogens have been tested by Phenotype Microarray technology, to investigate about their C-source utilization and exploring the possibility to obtain a microbial consortia (SynCom), an innovative strategy for the biocontrol of plant disease. All Trichoderma isolates tested in this study showed a high spore germination percentage within 3 d and evidenced nutritional preference regardless of the species they belong to, and unrelated to their soil of origin. Results of growth curve analysis and MANOVA test revealed that all isolates assimilate a broad range of substrates, generally preferring complex compounds such as monosaccharides related compounds, nitrogen compounds, carboxylic acids and esters. No evidence of competition for nutritional resources have been observed among isolates of this study. As a result, a combination of different isolates could be proposed to obtain a SynCom useful for the practice of phytopathogen biocontrol in forestry. The addition of i-erythritol, adenosine and turanose to a growth substrate could be suggested as stimulating compounds for the growth of the selected Trichoderma isolates.

Positive effects of biochar application and Rhizophagus irregularis inoculation on mycorrhizal colonization, rice seedlings and phosphorus cycling in paddy soils

Phosphorus (P) is an essential element for plant growth but is often limiting in ecosystems; therefore, improving the P fertilizer use efficiency is important. Biochar and arbuscular mycorrhizal fungi (AMF) may enhance P cycling in paddy soils that contain high total P but low available phosphorus (AP). In this study, the effects of biochar and Rhizophagus irregularis inoculation on the organic and inorganic P contents and phosphatase activity of paddy soil, rice seedling growth, and AMF colonization ability were investigated. Compared with the control, biochar enhanced the percentage spore germination at day 7, hyphal length, most probable number, and mycorrhizal colonization rate of R. irregularis by, on average, 32%, 662%, 70%, and 28%, respectively. Biochar and R. irregularis altered soil P cycling and transformed soil P availability. Biochar and R. irregularis, either individually or in combination, increased the soil AP content by 2%–48%. Rice seedlings treated with biochar and R. irregularis produced greater biomass, and showed improved root morphology and higher nutrient uptake compared with those of the control. The results suggest that combined application of biochar and R. irregularis is beneficial for rice cultivation in paddy soils with high total P but low AP content.

Dry/wet cycling reduces spore germination and viability in six peatland bryophytes.

Dry/wet cycling driven by water level fluctuation in wetlands may strongly influence the destiny of seeds. However, how dry/wet cycling affects spore survival and germinability in peatland bryophytes is poorly understood. Six peatland bryophytes, three hummock- and three hollow-dwelling Sphagnum species, were chosen as study species. We tested the effects of dry (60% air RH)/wet (waterlogging) cycle frequency (once per 12, 8 or 4 days for low, medium or high, respectively) and ratio (3:1, 1:1 or 1:3 dry:wet time per cycle) on spore germinability, viability, dormancy percentage and protonema development. Dry/wet cycling significantly reduced spore germination percentage and viability and slowed protonema development in all Sphagnum species, being more pronounced with higher dry/wet cycling frequencies. The hummock species S. capillifolium and S. fuscum had higher spore germination percentage after the continuous dry treatment, while the hollow species S. angustifolium, S. squarrosum and S. subsecundum showed the opposite response, compared to the continuously wet treatment. Except for S. squarrosum, spore viability was higher after the dry than after the wet treatment. Spore viability and dormancy percentage were higher after a dry/wet ratio of 1:3 than after ratios of 3:1 and 1:1. Our study shows that both germinability and viability of bryophyte spores are reduced by dry/wet cycling (especially when frequent) in peatlands. This emphasizes the need to ensure constant water levels and low frequencies of water level fluctuation, which are relevant in connection with wetland restoration, to promote Sphagnum spore survival and establishment in peatlands after disturbances.

Spot blotch disease of wheat as influenced by foliar trichome and stomata density

Spot blotch, caused by Bipolaris sorokiniana, is a potent biotic constraint to wheat crop leading to substantial yield abatement in warm humid South Asia (e.g. India, Nepal and Bangladesh) and other major wheat-growing countries such as Canada, the United States, Brazil and Australia. A set of 98 bread wheat genotypes were evaluated over two growing seasons to investigate the relationship among foliar trichome, stomata density, and susceptibility to the spot blotch pathogen. The higher density of trichomes (90-140 mm −2 ) on the adaxial surface of flag leaves entrapped 32-74 mm −2 pathogen spores. It restricted the dew droplets size (0.15–0.3 mm 2 ) on the flag leaves and thus prevented direct contact between the spores and the leaf epidermis. Trichome density was negatively associated with the disease development and spore germination but positively associated with grain size and the number of spores entrapped on trichomes per mm 2 . Conversely, stomata density was positively associated with the development of the disease. Cluster and principal component analyses divided trichome density, the number of spores trapped on trichome per mm 2 , and thousand grain weight into one group and stomata density, the area under disease progress curve, percent spore germination, and dew scale into another group. The results from this study provided a novel insight to breeders where the selection of bread wheat genotypes with high trichome (90-140 mm −2 ) and low stomata density (72-90 mm −2 ) on foliage could enhance spot blotch resistance in wheat. • Spot blotch of wheat reduces up to 30% yield in the Indian subcontinent. • The relationship among foliar trichome, stomata density, and susceptibility to the spot blotch pathogen was studied. • The higher density of trichomes (90-140 mm −2 ) entrapped 32-74 mm −2 spores prevented direct contact between the spores and the leaf epidermis. • This study assists breeders for the selection of bread wheat genotypes with high trichomes and low stomata density on foliage could enhance spot blotch resistance.

In vitro inhibition of Fusarium solani by Trichoderma harzianum and biofertilizer

Cassava root rot causes significant production losses. Difficulties of management, along with the lack of chemical fungicides officially registered by the Ministry of Agriculture, Livestock and Supply (MAPA), require alternative control methods. This study investigated the in vitro antagonistic activity of Trichoderma harzianum as well as a biological fertilizer MICROGEO® on Fusarium solani. The phytophatogenic strains of F. solani, called F1 and F2 were isolated from rotted cassava tubers and T. harzianum, strain ESALQ 1306, from a biological fungicide. Continuous liquid composting of bovine ruminal content, water and MICROGEO® produced the biological fertilizer. Dual culture method was used at the bioassay with T. harzianum. Sterilized (St) and unsterilized (USt) biological fertilizer were tested in different concentrations (% v/v) diluted in the culture media. Colony diameters were measured daily in order to establish the mycelial growth velocity index, inhibition percentage, aside from the sporulation rate and spore germination percentage. The mycelial growth of F. solani isolates was interrupted after hyphae encounter with T. harzianum, due to the occurrence of mycoparasitism, but without influence on the sporulation rate. Sterilized biological fertilizer induced no biocontrol, whereas the unsterilized product (concentration 2.5%) inhibited approximately 64% and 85% of the mycelial growth of isolates F1 and F2, respectively. Moreover, spore germination declined with increasing concentration. In conclusion, T. harzianum and the unsterilized biofertilizer showed in vitro antagonistic activity on F. solani.

Efficacy of plant extracts and extracting agents against Colletotrichum gloeosporoides of pawpaw fruits

Pawpaw (Carica papaya L.) is a fruit crop of economic importance in Kenya, where small scale farmers are the major producers. One factor limiting pawpaw production is anthracnose disease caused by Colletotrichum gloeosporoides, whose management on farm still remains a major challenge. The objective of this study was to determine the efficacy of plant extracts and extracting agents for controlling anthracnose disease on pawpaw fruits. In vitro spore germination and in-vivo tests were done using extracts from five plants; Aloe chiliensis, Azadiracta indica, Carissa edulis, Fuerstia africana and Solanum incanum; and extracting agents methanol, chloroform and ethanol against the fungus. A logistic regression model was used to estimate the botanicals’ dose response treatment ranges. The efficacy of the crude extracts was greatest when methanol was used for extraction. The highest inhibition was recorded in pawpaw fruits treated with leaf extracts of F. africana. There were significant differences in effects among treatments by methanolic extracts of the five plants on conidial spore germination percentage. Aloe chilensis (Aloe) showed a higher spore germination of 35.7%; while Azadirachta indica (Neem) resulted in the lowest spore germination of 1.2%. There were significant differences in days to healing of C. papaya fruits infected with anthracnose. Pawpaw infected fruits healed fastest (3.5 days) when treated with the methanolic leaf extracts of F. africana; while A. chiliensis ethanolic leaf extracts resulted in the longest healing time of over 7 days. Although these botanical fungicides present high potentials or controlling anthracnose pathogens of pawpaw fruits, their suitability for application within the socio-economic framework of Kenyan small-scale producers still remains a matter for further investigation.

Chemical characterization and determination of in vivo and in vitro antifungal activity of essential oils from four Eucalyptus species against the Hemileia vastatrix Berk and Br fungus, the agent of coffee leaf rust

Essential oils, also known as volatile oils, are substances produced through the secondary metabolism of plants. In this study, we determined the chemical composition and the in vitro and in vivo antifungal activity of the essential oils from four species of Eucalyptus, Eucalyptus citriodora, Eucalyptus camaldulensis, Eucalyptus grandis and Eucalyptus microcorys, against the Hemileia vastatrix fungus. The essential oils from these four species of Eucalyptus were extracted from their leaves by the hydrodistillation technique using a modified Clevenger apparatus. The chemical characterization was performed by gas chromatography coupled with a mass spectrometer detector and by gas chromatography using a flame ionization detector. The antifungal activities of the essential oils against H. vastatrix were studied by evaluating the percentage of spore germination using the microdilution test for in vitro assays. The curative and preventive effects were evaluated in in vivo tests. The principal constituents of the essential oil from E. citriodora were citronellal, citronellol and isopulegol, while E. camaldulensis produced 1,8-cineole, α-terpineol and α-pinene. 1,8-cineole, α-pinene and α-terpineol were obtained from E. grandis and 1,8-cineole, α-pinene and trans-pinocarveol were the principal components in the essential oil of E. microcorys. In vitro and in vivo antifungal activities against the fungus under study were observed for most of the essential oils, except the essential oil from E. microcorys, for which no preventive antifungal activity was observed. Only the curing of infection by the H. vastatrix fungus was observed with this oil.

In vitro spore germination and phytoremediation of Hg and Pb using gametophytes of Pityrogramma calomelanos

Few pteridophytes have proven the capacity to accumulate and remediate heavy metals from contaminated soils. Pityrogramma calomelanos, a non-seasonal fast-growing, a cosmopolitan fern, is a good indicator of environmental conditions, was used in the present study. The life cycle of ferns alternates with haploid gametophyte and diploid sporophyte. The present study was undertaken to access the effect of mercury, in form of mercury (II) chloride [(HgCl2)] and lead as lead nitrate [Pb(NO3)2] in developmental studies using in vitro spore germination. Periodic recording of the germination, protonemal growth, rhizoid formation and differentiation of sex organs in different concentrations of heavy metals were conducted for a period of 6 weeks. It was found that the percentage of spore germination and the number of protonemal cells reduced significantly causing developmental defects in the presence of HgCl2 as compared to Pb(NO3)2 (p < 0.0001). A significant decrease in the number of archegonial count and chlorophyll content was observed in different concentrations of the heavy metals tested. Gametophytes of P. calomelanos recorded lead uptake of 646.51 ± 0.93 mg/kg in treatments of 25 ppm of lead and high mercury accumulation up to 1,885 ± 1.98 mg/kg at 10 ppm of mercury, indicating successful uptake of heavy metals. Novelty statement: Pityrogramma calomelanos is gaining interest amongst pteridologists upon proving its exclusive capacity of phytoremediation. It is superior in comparison to the most popular, patented fern Pteris vittata. Our study demonstrates the effective use of the promising fern in its simplest, nonvascular form of gametophytes as a phytoremediation agent in controlled conditions.

Evaluation of high dilutions extract of pyroligneous on the development of Colletotrichum gloeosporioides

The aim of this research was to evaluate the fungitoxicity of high dilutions of tectonic (Tectona grandis) extract in mycelial growth, sporulation and germination of the fungus Colletotrichum gloeosporioides. In a completely randomized design with six dynamizations of the pyroligneous extract (3, 9, 15, 21, 27 and 33 CH) and three controls (distilled water, mother tincture, 30% hydroalcoholic solution) with four replicates each. All treatments were diluted to 0.1% in BDA medium. Mycelial growth rate index, relative percentage of mycelial development (PRD%), inhibition of sporulation and spore germination (%) were evaluated. The treatments did not differ among them for mycelial growth, percentage of spore germination and IVCM. The PRD and sporulation variables varied according to the dynamization, with a maximum reduction of 7% in PRD (33 CH) and a 70% increase in sporulation (3 and 21 CH). The dynamized pirolenous extract did not present expressive fungitoxicity in the growth, sporulation and germination of C. gloeosporioides.

Phyllachora maydis Ascospore Release and Germination from Overwintered Corn Residue

Tar spot of corn, caused by Phyllachora maydis, has been reported in several upper Midwest states in the United States. This has led to expanded efforts to more thoroughly understand the biology of P. maydis and the epidemiology of tar spot. This study determined the potential for P. maydis ascospore release and germination from overwintered P. maydis-infected corn residues from various locations in the upper Midwest. Corn residue samples collected in the spring of 2019 from 12 fields in four states were examined. Ascospore release and germination were observed in all residue samples collected. The mean total number of ascospores released per milliliter of water ranged from 3.6 × 103 to 4.8 × 106 after 4-h incubation and 3.7 × 103 to 4.4 × 106 after 24-h incubation. The mean percent spore germination ranged from 0.7 to 24.1% after 4-h incubation and 2.4 to 24.9% after 24-h incubation. There was a significant inverse relationship between total numbers of ascospores released and the percent germination of the ascospores. Samples from Illinois consistently yielded the greatest total ascospore release but were also consistently among the samples with the lowest percent ascospore germination. Samples from Wisconsin and Indiana were among the lowest for total ascospore numbers but were among the highest for total ascospore germination. These findings provide evidence that P. maydis can overwinter in multiple areas of the upper Midwest. Future research should focus on reducing infested corn residue to reduce initial infection by P. maydis.

Effects of the fungus Pestalotiopsis maculans (Ascomycota: Amphisphaeriales) on the gametophytic development of the fern Lygodium venustum (Lygodiaceae)

Lygodium sp. is a climbing fern that occurs in open forests, settling frequently in areas with disturbed vegetation. In Argentina, Lygodium venustum inhabits in the protected area "Moconá" Provincial Park, in few and small populations. In-vitro cultivation of spores is a strategy for ex-situ conservation of species with reduced or threatened populations. Usually, fern spores need to be surface sterilized before sowing, to avoid the development of unwanted microorganisms. As part of our project focused on the conservation of native fern species in Argentina, the aim of this work was to evaluate a propagation protocol for L. venustum through in-vitro cultivation of spores, employing a standard procedure of disinfection, to investigate its effect on spore germination and the subsequent gametophyte as well as its response by the inoculation with a fungus. A batch of spores was previously treated with 10% (v/v) solution of NaOCl during 2 min and then sown in Dyer agar medium supplemented with 1% Nystatin (T1). The petri dishes were incubated in a growth chamber under white illumination (28μmol m-2 s-1) with a photoperiod of 12 hr and a temperature of 22±2°C. Another set of spores without previous disinfection was sown on Dyer agar medium and under the same conditions and used as a control (T0). Spore germination and gametophyte and sporophyte development were monitored through periodical observations under stereoscopic and light microscopes. As during cultures of non-disinfected spores a fungus developed in association with L. venustum gametophytes, its conidia were morphologically characterized as well as those obtained from the black spots present on the sporophyte leaves. A conidial suspension was applied to 20 days-old gametophytes obtained in axenic conditions to evaluate the appearance of any symptom. In both treatments (T1 and T0), spores germinated at 7 days after sowing. The pattern of spore germination followed the Anemia-type, unlike the Vittaria-type found by other researchers. Untreated spores showed a higher mean percentage of germination than those treated (86 and 72 % in 30 days, respectively). In T0 gametophytes grew in association with a fungus, whose conidia had the morphological characteristics of Pestalotiopsis maculans, as occurred with the conidia obtained from the black spots of L. venustum leaves. The association of P. maculans with L. venustum is reported here for the first time. The gametophytes developed in T0 and those inoculated with P. maculans became necrotic and died before producing gametangia, suggesting a pathogenic role of the fungus. The elevated percentage of spore germination registered in T0 could also indicate some effect of P. maculans or its metabolites in the promotion of spore germination. Gametophytes developed in T1 became bisexual or unisexual male, which points to the presence of some antheridiogen that induces the production of antheridia on smaller or slower-growing gametophytes. The sporophytes arose after 4 months of spore sown in T1, pointing out the methodology employed here suitable for the ex-situ conservation of L. venustum.

Effects of cobalt on spore germination, gametophyte growth and development, and juvenile sporophyte growth of Saccharina japonica (Phaeophyceae)

Cobalt (Co), an essential element that is toxic in excess amounts, is a major component of wastewater that has accidentally been released from nuclear power plants. However, the effects of Co in seawater on the life cycle of macroalgae have seldom been investigated. Here, we tested the effects of different Co concentrations (1, 10, 50, 100, 200, 500, and 1000 μg L−1) on spore germination, gametophyte growth and development, and juvenile sporophyte growth of the brown alga Saccharina japonica. Sterilized natural seawater with a known Co concentration was used as the control. The spore germination percentage in the 1000 μg L−1 group was significantly reduced after 1 and 2 days of exposure. The gametophyte growth in the 1 μg L−1 group was significantly accelerated, while that of the ≥ 50 μg L−1 groups was significantly inhibited after 9 days of exposure. The relative growth rate and maximum quantum yield (Fv/Fm) of photosystem II of the juvenile sporophytes in the 1 μg L−1 group were significantly higher, while those of the ≥ 10 μg L−1 groups were significantly lower after 2 weeks of exposure. By culturing the sporophytes in the control medium, Fv/Fm values recovered from Co stress within 4 days. These results highlight the potentially severe impact of accidentally released Co from nuclear power plants on the life cycle of S. japonica. Further studies should focus on the toxic mechanism of Co in S. japonica and the phytoremediation potential of seaweeds to alleviate Co pollution.

Antimicrobial and Phytotoxic Activity of Origanum heracleoticum and O. majorana Essential Oils Growing in Cilento (Southern Italy).

There is a growing interest in a potential use of essential oils (EOs) as a replacement for traditional pesticides and herbicides. The aims of this study were to: (i) Identify the chemical composition of the two EOs derived from Origanum heracleoticum L. and O. majorana L., (ii) evaluate the in vitro antifungal activity of the EOs against some postharvest phytopathogens (Botrytis cinerea, Penicillium expansum, Aspergillus niger and Monilinia fructicola), (iii) evaluate the in vitro antibacterial activity against Bacillus megaterium, Clavibacter michiganensis, Xanthomonas campestris, Pseudomonas fluorescens and P. syringae pv. phaseolicola, (iv) evaluate the effect of both studied EOs on the spore germination percentage and their minimum inhibitory concentration (MIC) against M. fructicola, and (v) study the possible phytotoxicity of the two EOs and their major constituents, carvacrol for O. heracleoticum and terpinen-4-ol for O. majorana, against tha germination and initial radicle growth of radish, lettuce, garden cress and tomato. The two EOs demonstrated promising in vitro antimicrobial and antifungal activities against all tested microorganisms. EOs showed high inhibition of spore germination percentage at the minimal inhibitory concentration of 500 and 2000 µg/mL, respectively. Moreover, both germination and radical elongation of selected plant species were sensitive to the oils.

Entomopathogenic fungi naturally infecting the eucalypt bronze bug, Thaumastocoris peregrinus (Heteroptera: Thaumastocoridae), in Uruguay

AbstractThaumastocoris peregrinus Carpintero &amp; Dellapé (Heteroptera: Thaumastocoridae) is a sap‐sucking insect that feeds on leaves of Eucalyptus. In Uruguay, it was detected in 2008 causing significant economic losses in Eucalyptus plantations. At present, there is no efficient control for this pest; thus, the use of biological control agents seems to be an environmentally friendly alternative to reduce the damage caused by this insect. The aims of this study were to isolate and identify the species of entomopathogenic fungi that naturally infect T. peregrinus in Uruguay and to characterize and select the most virulent isolates towards this pest. Individuals of T. peregrinus were collected in eight Eucalyptus plantations infested by the pest. The entomopathogenic fungi were isolated and identified by observation of their micromorphological characteristics, and their identity was confirmed by molecular methods. The pathogenicity and virulence against T. peregrinus of the isolated entomopathogenic fungi were evaluated. Isolates causing the highest insect mortality were selected to evaluate the effect of temperature and water activity on conidial viability. Entomopathogenic fungi were found in very low number with the prevalence of less than 3%. Isolates corresponded to Beauveria, Fusarium, Isaria, Lecanicillium, Paecilomyces, Pochonia, Purpureocillium and Simplicillium genera. Two species, B. pseudobassiana and L. muscarium, were first recorded in Uruguay. Among all the tested species, an isolate of B. bassiana (FI 2403) showed the highest virulence followed by an isolate of B. pseudobassiana. The isolate of B. bassiana presented the highest percentage of spore germination at the three temperatures and the highest viability at low water activities. Isolate FI 2403 was selected as a promissory candidate for the development of a commercial formulation against T. peregrinus.

Correction to: Effects of temperature and salinity on the reproductive phases of Macrocystis pyrifera (L.) C. Agardh (Phaeophyceae) in the Magellan region

The region of Magallanes has the world’s largest sub-Antarctic environments, including the heterogeneous habitats of archipelagos, fjords, channels, and inlets formed by ice advancing and retreating during Quaternary glacial processes. In marine ecosystems, the temperature, salinity, and photoperiod are key parameters which delimit the survival, reproduction and development of the macroalgae and, therefore, the biogeography of numerous sub-Antarctic species. In this research, we compare the reproductive development patterns in spores of Macrocystis pyrifera coming from places with different salinities along longitudinal and latitudinal gradients in Skyring Sound, Otway Sound, the Strait of Magellan (Possession Bay and Puerto del Hambre), and the Beagle Channel (Paula Bay). Laboratory analyses included four salinities and two different temperatures, comparing the percentage of spore germination, sex ratio in females and male gametophytes, and the development of gametogenesis through the proportion of gametophytes and sporophytes, with a factorial experimental design. The best germination percentages were obtained in Puerto del Hambre; the best sex ratio, on the other hand, was in Skyring Sound; finaly, for gametogenesis development, the best results were obtained in Otway Sound and Possession Bay. We prove the temperature and salinity effect over the studied population; moreover, these results demonstrate that at the end of the cycle each population develops more effectively in their local conditions, evidence of a local adaptation in M. pyrifera populations living in contrasting sites in the same region. This is crucial to understand how these populations react to the effect of environmental stressors; furthermore, the selection of appropriate conditions is also an important factor for the future commercial cultivation management of these important macroalgae.

Effects of temperature and salinity on the reproductive phases of Macrocystis pyrifera (L.) C. Agardh (Phaeophyceae) in the Magellan region

The region of Magallanes has the world’s largest sub-Antarctic environments, including the heterogeneous habitats of archipelagos, fjords, channels, and inlets formed by ice advancing and retreating during Quaternary glacial processes. In marine ecosystems, the temperature, salinity, and photoperiod are key parameters which delimit the survival, reproduction and development of the macroalgae and, therefore, the biogeography of numerous sub-Antarctic species. In this research, we compare the reproductive development patterns in spores of Macrocystis pyrifera coming from places with different salinities along longitudinal and latitudinal gradients in Skyring Sound, Otway Sound, the Strait of Magellan (Possession Bay and Puerto del Hambre), and the Beagle Channel (Paula Bay). Laboratory analyses included four salinities and two different temperatures, comparing the percentage of spore germination, sex ratio in females and male gametophytes, and the development of gametogenesis through the proportion of gametophytes and sporophytes, with a factorial experimental design. The best germination percentages were obtained in Puerto del Hambre; the best sex ratio, on the other hand, was in Skyring Sound; finaly, for gametogenesis development, the best results were obtained in Otway Sound and Possession Bay. We prove the temperature and salinity effect over the studied population; moreover, these results demonstrate that at the end of the cycle each population develops more effectively in their local conditions, evidence of a local adaptation in M. pyrifera populations living in contrasting sites in the same region. This is crucial to understand how these populations react to the effect of environmental stressors; furthermore, the selection of appropriate conditions is also an important factor for the future commercial cultivation management of these important macroalgae.

Can fern spores develop hydration memory in response to priming?

Fern spores and seeds initiate germination with fast water uptake, followed by a stationary phase with no appreciable water uptake and biochemical and metabolic processes that precede germination. After that, seed, germination is avoided by dehydration, as part of the priming treatments. After dehydration, seeds maintain their metabolic advances (hydration memory). As a result, rehydrated seeds germinate rapidly. We hypothesized that, as seeds, fern spores may be capable of developing hydration memory. To assess priming, spores of six fern species were exposed to: four or eight days of hydration in water (hydro-priming) or in a soil matrix (matrix-priming); or 1 month of hydration in the soil of the collection site (natural-priming). At the end of the treatments, the spores were dehydrated in the dark and germinated under laboratory conditions. Germination was evaluated using lag-time, germination rate and germination percentage. Priming treatments shortened lag time and/or increased germination rate or germination percentage in relation to the controls. Matrix-priming (8 days) reduced the spore germination percentage in three species. Our results provide evidence that fern spores possess a hydration memory that probably evolved in the soil bank and suggests that hydration-dehydration cycles within the natural soil might provide advantages for successful germination.