Mycorrhizal Switching and the Role of Fungal Abundance in Seed Germination in a Fully Mycoheterotrophic Orchid, Gastrodia confusoides

Mycorrhizal associations are essential for orchid germination and seedling establishment, and thus may constrain the distribution and abundance of orchids under natural conditions. Previous studies have shown that germination and seedling establishment in several orchids often decline with increasing distance from adult plants, resulting in non-random spatial patterns of seedling establishment. In contrast, individuals of the fully mycoheterotrophic orchid Gastrodia confusoides often tend to have random aboveground spatial patterns of distribution within bamboo forests. Since G. confusoides is parasitic on litter-decaying fungi, its random spatial patterns of distribution may be due to highly scattered patterns of litter-decaying fungi within bamboo forests. To test this hypothesis, we first identified the main mycorrhizal fungi associating with developing seeds and adult plants at a bamboo forest site in Taiwan using Miseq high-throughput DNA sequencing. Next, we combined seed germination experiments with quantitative PCR (qPCR) analyses to investigate to what extent the abundance of mycorrhizal fungi affected spatial patterns of seed germination. Our results show that seed germination and subsequent growth to an adult stage in G. confusoides required a distinct switch in mycorrhizal partners, in which protocorms associated with a single Mycena OTU, while adults mainly associated with an OTU from the genus Gymnopus. A strong, positive relationship was observed between germination and Mycena abundance in the litter, but not between germination and Gymnopus abundance. Fungal abundance was not significantly related to the distance from the adult plants, and consequently germination was also not significantly related to the distance from adult plants. Our results provide the first evidence that the abundance of litter-decaying fungi varies randomly within the bamboo forest and independently from G. confusoides adults.

Wheat germination and highly diluted agitated gibberellic acid (10e-30) - a multi researcher study

Grains of winter wheat (Triticum aestivum L., Capo variety) were observed under the influence of highly diluted gibberellic acid (10-30) prepared by stepwise dilution and agitation according to a protocol derived from homeopathy (“G30x”). Adequate control was used (water prepared according to the homeopathic protocol “W30x” and/or untreated water “W0”). Two sets of multicenter experiments were performed, 4 in 2009-2010 and 4 in 2011, involving altogether 6 researchers, 6 laboratories and 4,000 grains per treatment group. Data were found to be homogeneous within the control groups as well as within the verum groups. When the 2009-2010 experiments were pooled, mean germination rates after 24 hours were (85.9 + 2.6) for the control group and (82.1 + 5.7) for G30x (mean + SD at the level of experiments in %) (N = 2,000 per group). Verum germination rate was 4.4% lower than (i.e. equal to 96.6% of) (4.4 + 96.6 = 101) the control germination rate (100%). The difference is statistically significant (p < 0.001) and the effect size (d) is large (> 0.8). Observations at other points in time between 0 and 40 hours of germination yielded similar results. Practically no difference was found between W30x and W0 groups (p > 0.05). When the 2011 experiments were pooled, the mean germination rates after 24 hours were (73 + 12) for the control group and (73 + 14) for G30x (N = 2,000 per group), i.e. there was practically no difference between the groups (p > 0.05). We interpret the data from 2009-2010 on wheat germination within 40 hours as being in line with our previous findings on wheat stalk growth after one week, i.e. as confirmation that gibberellic acid 30x can influence, i.e. slow down, wheat development. Various possible reasons for the absence of any difference between groups in the 2011 experiments, including seasonal variance, are discussed and it is suggested to perform wheat germination experiments in the very beginning of autumn season only.

Germination Characteristics Is More Associated With Phylogeny-Related Traits of Species in a Salinized Grassland of Northeastern China

Knowing the determinants of seed germination helps us understand plant adaptive strategies to the environment and predict population and community regeneration under climate change. However, multiple factors, including plant and seed traits that influence germination and their relative importance, have received little attention. Here, seed germination experiments were conducted on newly collected seeds for 89 herbaceous species from salinized Songnen grassland. We tested the effects of multiple phylogeny-related plant traits and seed morphological and physiological traits on germination percentage and initial germination time and their relative contribution to shaping germination variation. We found that biennials had higher germination percentages and rates than annuals and perennials. Species with brown seeds had higher germination percentages than those with yellow and black seeds. Eudicots germinated faster than monocots, and seeds with morphophysiological dormancy required more time to initiate germination than those with other kinds of dormancy. Phylogeny-related factors explained more of the variation in germination than seed traits. Seed mass and volume of the large-seeded, but not small-seeded group species were positively correlated with germination percentage. Our findings provide important information for understanding germination variation across species and local adaptation for species in the salinized Songnen grassland.

Analysis of the Treatment of Synthetic Bathing Waters and Their Effects on Seedlings

Synthetically produced bathing waters and their effect on seedlings were analysed in our research. The artificially produced bath waters were treated in different ways. Primarily, simple filtration was performed through a layer of silica sand. During the tests, the obtained greywater was investigated before and after the treatment with the help of various water quality parameters. Irrigation was set as the goal of recycling, and germination experiments were performed on mustard seeds. In these experiments, the synthetically generated treated and untreated bath water was used as irrigation water. Considering the results obtained during the germination, it can be said that the treatment is necessary in any case. Based on the results, it was shown that the filtration was not sufficient, so coagulation was used as an additional treatment method, for which we determined the optimal amount of treatment agent as a starting step.

Nanoscale cluster structure of O2 gas-filled nanobubbles in O2 gas-supersaturated alkaline solution

There exists a close parallelism between gas-filled nanobubble solutions and ultra-high dilutions. Both these solutions contain Brownian nano-sized bubbles. We have studied aggregation kinetics of O2 gas-filled Brownian nanobubbles and their nanoscale cluster structure in 0.1M NaCO3 with NanoSight Particle Tracking Ananlysis (NTA) and transmission electron microscopy (TEM). A number of discrete peaks in a NTA size distribution of O2 nanobubbles in 0.1M NaCO3 eight days later after production are closely related to the existence of stable nanobubble clusters composed of 6-9nm nanobubbles that are inferred from the internal void size observed with TEM. Recent reports on 1HNMR of nanobubble water and its biological effects of wheat germination by Ohshita’s group may correlate with Demangeat`s NMR studies and germination experiments performed by many groups since the first publication by Lily Kolisco in 1923. Demangeat’s has recently published a review on the essential role of succussion that can cause nanobubble formation.

Interactions between ShPP2-1, an F-box family gene, and ACR11A regulate cold tolerance of tomato

There is a critical need to identify germplasm resources and genes that promote cold tolerance of tomato because global tomato production is threatened by cold stress. We found that the expression of an F-box gene family member named ShPP2-1 from Solanum habrochaites is cold inducible and studied its contribution to cold tolerance. Overexpression of ShPP2-1 in cultivated tomato (AC) reduced cold tolerance by intensifying damage to cell membranes. To explore the underlying molecular mechanism, we conducted a yeast two-hybrid library screen and found that a protein containing ACT domain repeats named ACR11A interacts with PP2-1. Overexpression of SlACR11A in AC enhanced the cold tolerance of seedlings and germinating seeds. Cold tolerance decreased in tomato plants that overexpressed both of these genes. Additionally, we performed seed germination experiments in the cold with 177 tomato accessions and identified two alleles of SlACR11A that differ in one single-nucleotide polymorphism. We found that one of these alleles, SlACR11AG, is significantly enriched in cold-tolerant tomato plants. Taken together, our findings indicate that the combination of low expression levels of PP2-1 and high expression levels of ACR11A can promote cold tolerance. These genes may therefore serve as direct targets for both genetic engineering and improvement projects that aim to enhance the cold tolerance of tomato.

Spartina Alterniflora Raised Soil Sulfide Content by Regulating Sulfur Cycle-Associated Bacteria in the Jiuduansha Wetland of China

Purpose The Spartina alterniflora invasion across the southeast coast in China significantly reduced vegetation diversity and generated associated ecological problems. Sulfur (S) is a vital nutrient, while sulfide is phytotoxic and the impact of S. alterniflora invasion on soil S cycle remains unclear. Therefore, this study aims to investigate the impacts of S. alterniflora invasion on the S cycle and associated soil microbial communities.Methods Both field investigation and lab-scale experiments were conducted, analyzing soil sulfide and sulfate contents, soil properties over four seasons in the Jiuduansha Wetland of Shanghai, China, the high-throughput sequencing of soil microbial communities, S cycle-related functional genes and seed germination experiments. Results The contents of sulfide, soil organic carbon (SOC), and total nitrogen (TN) in the bulk soil of S. alterniflora invaded area were higher than those in the native species S. mariqueter habitat and bare mudflat soils. Spartina alterniflora invasion increased the abundance of the Nitrospiraceae and Desulfarculaceae families and reduced that of Hydrogenophilaceae. The relative abundance of the S reduction functional genes (dsrA + dsrB) in the soil was increased after S. alterniflora invasion, while that of the S oxidation functional genes (yedZ + soxY) in the soil was reduced. Seed germination experiments with different sodium sulfide concentrations (Na2S) revealed that the phytotoxicity of sulfide caused more lethal damage to S. mariqueter than to S. alterniflora.Conclusion The S. alterniflora invasion significantly increased SOC and TN contents and reduced the abundance of sulfur-oxidizing functional genes, which led to the accumulation of soil sulfide.

Evaluation of Soil Seed Banks in Different Aged Caragana microphylla Plantation in Desert Steppe Ecosystems

Soil seed bank (SSB) represents potential plant communities, which is essential in the restoration of degraded ecosystems. Consequently, SSB is crucial in the reconstruction and recovery of aboveground plants because they largely determine the process and direction of vegetation restoration. SSB is also important indicators that can be used to evaluate the effects of management on degraded desert steppe. Here, field sampling and soil seed germination experiments were used to investigate the role of SSB in the recovery of degraded desert steppe. Results indicated that (1) the species composition of SSB and ground vegetation significantly differed in different aged Caragana microphylla plantation and control in the Yanchi County. (2) The abundance of SSB was significantly promoted by C. microphylla plantation. The average seed density in Caragana plantation SSB was 11248.75 m−2, which was 17 times than that of SSB in areas without C. microphylla plantation. (3) The ages of C. microphylla plantation were closely related to the composition and density of SSB.

Cyanobacterial Akinete Distribution, Viability, and Cyanotoxin Records in Sediment Archives From the Northern Baltic Sea

Cyanobacteria of the order Nostocales, including Baltic Sea bloom-forming taxa Nodularia spumigena, Aphanizomenon flosaquae, and Dolichospermum spp., produce resting stages, known as akinetes, under unfavorable conditions. These akinetes can persist in the sediment and germinate if favorable conditions return, simultaneously representing past blooms and possibly contributing to future bloom formation. The present study characterized cyanobacterial akinete survival, germination, and potential cyanotoxin production in brackish water sediment archives from coastal and open Gulf of Finland in order to understand recent bloom expansion, akinete persistence, and cyanobacteria life cycles in the northern Baltic Sea. Results showed that cyanobacterial akinetes can persist in and germinate from Northern Baltic Sea sediment up to &gt;40 and &gt;400 years old, at coastal and open-sea locations, respectively. Akinete abundance and viability decreased with age and depth of vertical sediment layers. The detection of potential microcystin and nodularin production from akinetes was minimal and restricted to the surface sediment layers. Phylogenetic analysis of culturable cyanobacteria from the coastal sediment core indicated that most strains likely belonged to the benthic genus Anabaena. Potentially planktonic species of Dolichospermum could only be revived from the near-surface layers of the sediment, corresponding to an estimated age of 1–3 years. Results of germination experiments supported the notion that akinetes do not play an equally significant role in the life cycles of all bloom-forming cyanobacteria in the Baltic Sea. Overall, there was minimal congruence between akinete abundance, cyanotoxin concentration, and the presence of cyanotoxin biosynthetic genes in either sediment core. Further research is recommended to accurately detect and quantify akinetes and cyanotoxin genes from brackish water sediment samples in order to further describe species-specific benthic archives of cyanobacteria.

Increasing fungal abundance in the substrate enhances seed germination in a fully mycoheterotrophic orchid

Mycorrhizal associations are essential for orchid germination and seedling establishment, and thus may constrain the distribution and abundance of orchids under natural conditions. Previous works have shown that germination and seedling establishment in several orchids often decline with increasing distance from adult plants, resulting in nonrandom spatial patterns of seedling establishment. In contrast, individuals of the fully mycoheterotrophic orchid Gastrodia confusoides often tend to have random spatial patterns of distribution within bamboo forests. Since G. confusoides is parasitic on litter-decaying fungi, its random spatial patterns of distribution may be due to highly scattered patterns of litter-decaying fungi within bamboo forests. To test this hypothesis, we first identified the main mycorrhizal fungi associating with developing seeds and adult plants using Miseq high-throughput sequencing. Next, we combined seed germination experiments with quantitative PCR (qPCR) analyses to investigate to what extent the abundance of mycorrhizal fungi affected spatial patterns of seed germination. Our results show that seed germination and subsequent growth to an adult stage in G. confusoides required a distinct switch in mycorrhizal partners, in which protocorms associated with a single Mycena fungus, while adults associated with a fungus from the genus Gymnopus. A strong, positive relationship was observed between germination and Mycena abundance in the litter, but not between germination and Gymnopus abundance. Fungal abundance was not significantly related to the distance from the adult plants, and consequently germination was also not significantly related to the distance from adult plants. Our results provide the first evidence that the spatial distribution and abundance of litter-decaying fungi are distributed randomly within the bamboo forest and independently from G. confusoides adults.