REVIEW | doi:10.20944/preprints202103.0595.v1
Subject: Biology, Anatomy & Morphology Keywords: germination, bacterial cell wall, sporulation, germination, morphology
Online: 24 March 2021 (14:56:55 CET)
A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.
ARTICLE | doi:10.20944/preprints201802.0069.v1
Online: 8 February 2018 (15:06:32 CET)
Scarification involves the partial removal of the seed coat on the side of the hilum, opposite the radicle, to speed up germination in acorns. The aim of this study was to determine the influence of scarification on the germination capacity of pedunculate oak acorns, selected and prepared for sowing. The diameter, length and mass of acorns were measured before and after scarification in four batches of acorns harvested from uneven-aged trees (76, 91, 131 and 161 years). The measured parameters were used to determine the correlations between acorn dimensions and mass, and to calculate the dimensional scarification index and the mass scarification index in acorns. Scarified and non-scarified acorns from every batch were germinated on sand and peat substrate for 28 days. The analyzed acorns were characterized by average size and mass. Scarification decreased acorn mass by around 22% and acorn length by around 31% on average. Scarification and the elimination of infected acorns increased germination capacity from around 64% to around 81% on average. Acorns can be divided into size groups before scarification to obtain seed material with varied germination capacity. Larger acorns with higher germination capacity can be used for sowing in container nurseries, whereas smaller acorns with lower germination capacity can be sown in open-field nurseries.
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Fitotoxicity; Seedling development; Germination; Micronuclei; Citotoxicity; Genotoxicity.
Online: 23 September 2022 (02:09:04 CEST)
Brazil is the number-one country in pesticide consumption, and corn is the second most cultivated crop in the country. Chemical control of weeds associated with corn cultivation is performed by application of herbicides with pre- and postemergence action, such as S-metolachlor. Currently, the toxicity of herbicides is a task of great concern. In this regard, the present study aimed to evaluate the effects of an S-metolachlor-based herbicide through bioassays with the plant model Lactuca sativa L. (lettuce) and Zea mays L. (maize). The herbicidal test solutions containing 7.5, 15, 30, 60, 120, 240, 360, 480, 600, and 720 mg L-1 of the active ingredient S-metolachlor were prepared from commercial products. Distilled water was used as a negative control, and aluminum was used as a positive control. Macroscopic analyses (germination and growth) were performed for the two species, and microscopic analyses (chromosomal and nuclear changes) were performed for L. sativa. Negative interference of the S-metolachlor-based herbicide on lettuce was observed for all macroscopic and microscopic parameters tested. In maize, there was no significant interference in germination; however, the herbicide interferes negatively in seedling development. In brief, the herbicide based on S-metolachlor has phytotoxic potential, just as discussed.
Subject: Biology, Anatomy & Morphology Keywords: Arabidopsis; HY2; salt stress; seed germination; proteome; DRPs
Online: 16 July 2021 (13:04:26 CEST)
Phytochromobilin (PΦB) participates in the regulation of plant growth and development as an important synthetase of photoreceptor phytochromes (phy). And Arabidopsis Long Hy-pocotyl 2 (HY2) appropriately works as a key PΦB synthetase. However, whether HY2 takes part in plant stress response signal network remains unknown. Here, we described the func-tion of the HY2 in NaCl signaling. The hy2 mutant was NaCl-insensitive, whereas HY2-overexpressing lines showed NaCl-hypersensitive phenotypes during seed germination. The exogenous NaCl induced the transcription and the protein level of HY2 which positively mediated the expression of downstream stress-related genes of RD29A, RD29B and DREB2A. Further quantitative proteomics showed the patterns of 7,391 proteins under salt stress. HY2 was then found to specifically regulate 215 differentially regulated proteins (DRPs) which, according to GO enrichment analysis, were mainly involved in ion homeostasis, flavonoid biosynthetic & metabolic, hormone response (SA, JA, ABA, ethylene), reactive oxygen spe-cies (ROS) metabolic, photosynthesis and detoxification pathway to respond to salt stress. More importantly, ANNAT1-ANNAT2-ANNAT3-ANNAT4 and GSTU19-GSTF10-RPL5A-RPL5B-AT2G32060, two protein interaction networks specifi-cally-regulated by HY2, jointly participated in the salt stress response. These results direct the pathway of HY2 participating in salt stress, and provide new insights for the plant to re-sist salt stress.
ARTICLE | doi:10.20944/preprints201909.0303.v1
Subject: Biology, Forestry Keywords: Mediterranean wetland; NaCl salinity; Fraxinus angustifolia; seed germination
Online: 27 September 2019 (03:11:12 CEST)
The effect of salinity on seed germination/emergence in narrow-leaved ash (Fraxinus angustifolia) was studied both under field and laboratory conditions, in order to detect critical values to NaCl exposure. Research Highlights: Novel statistical methods in germination ecology has been applied (i) to determine the effects of chilling length and salinity (up to 150 mM NaCl) on Fraxinus angustifolia subsp. oxycarpa seed emergence, and (ii) to estimate threshold limits treating germination response to salinity as a biomarker. Background and Objectives: Salinity cut values at germination stage had relevant interest for conservation and restoration aims of Mediterranean floodplain forests in coastal areas subjected to salt spray exposure and/or saline water introgression. Results: Salinity linearly decreased germination/emergence both in the field and laboratory tests. Absence of germination was observed at 70 mM NaCl in the field and at 150 mM NaCl for 4-week (but not for 24-week) chilling. At 50 mM NaCl germination percentage was 50% (or 80%) of control for 4-week (or 24- week) chilling. Critical values for salinity were estimated between freshwater and 50 (75) mM NaCl for 4-week (24-week) chilling by Bayesian analysis. After 7-week freshwater recovery, critical cut-off values included all tested salinity levels up to 150 mM NaCl, indicating a marked resumption of seedling emergence. Conclusions: Fraxinus angustifolia is able to germinate at low salinity and to tolerate temporarily moderate salinity conditions for about two months. Prolonged chilling widened salinity tolerance.
ARTICLE | doi:10.20944/preprints201612.0014.v1
Subject: Earth Sciences, Environmental Sciences Keywords: sustainable technology; phytoremediation; germination; Bouteloua dactyloides; Cynodon dactylon
Online: 2 December 2016 (08:55:14 CET)
Mining wastes generate a high environmental impact, and population exposure to metals and metalloids. Phytoremediation is a technology that uses plants to remediate polluted sites, one of its limitations is seed germination in soil with high content of metals and metalloids. B. dactyloides is a native specie from semiarid regions, while C. dactylon is an introduced specie, both are tolerant to drought and low temperatures. Owing, the objective of this research was to evaluate the germination of both species, exposed to a multi-polluted soil with As, Cd, Pb and Zn of a mining site, pondering different pH conditions (from 5.0 to 9.0). The study considered 4 repetitions by type of seed and soil pH. B. dactyloides showed higher germination percentage (83%) with pH 7.8; while the greater germination of C. dactylon was 34 % at pH 6.0. In the soil at pH 5, the germination in both species was not reached, owing that metals are more bioavailable in an acid environment. C. dactylon is less tolerant to As, Cd, Pb and Zn, so it is considered not effective for phytoremediation process. B. dactyloides has a high phytoremediation potential for multi-polluted sites, but further experiments are needed.
ARTICLE | doi:10.20944/preprints202109.0256.v3
Subject: Biology, Plant Sciences Keywords: germination; Leucadendron; seed storage; seed viability estimation; viability loss
Online: 17 November 2021 (13:15:02 CET)
Seed viability is routinely measured on seeds that fail to germinate at the end of an experiment. Together with the number of germinants, this is used to estimate viability of the seeds at start of the experiment (i.e., initial viability) and provides the comparative basis on which germination success is determined. Perusal of the literature shows that sometimes (perhaps often, as the problem has yet to be recognized or reported) prolonged duration in the treatment, especially the control where little germination occurs, can lead to loss of viability. This results in underestimation of initial viability if that treatment is used. I caution against the routine use of end-of-trial germination and viability of ungerminated seeds as an estimate of initial viability in determining germination success of various treatments. I explore ways to deal with the problem but the preference is for estimates of initial viability to be undertaken on a separate sample of seeds concurrently with the experiment as this avoids the risk of seed death during the trial.
REVIEW | doi:10.20944/preprints202001.0243.v1
Subject: Biology, Plant Sciences Keywords: DOF proteins; DELLA proteins; seed germination; seedling development; seed maturation
Online: 21 January 2020 (11:16:52 CET)
The DOF (DNA binding with one finger) family of plant-specific transcription factors (TF) was first identified in maize in 1995. Since then, DOF proteins have been shown to be present in the whole plant kingdom including the unicellular alga Chlamydomonas reinhardtii. The DOF TF family is characterised by a highly conserved DNA binding domain (DOF domain), consisting of a CX2C-X21-CX2C motif which is able to form a zinc finger structure. Early in the study of DOF proteins it became clear their relevance for seed biology. Indeed, the Prolamine Binding Factor (PBF), one of the first DOF proteins characterised, controls the endosperm-specific expression of the zein genes in maize. Subsequently, several DOF proteins from both monocots and dicots have been shown to be primarily involved in seed development, dormancy and germination, as well as in seedling development and other light-mediated processes. In the last two decades the molecular network underlying these processes have been outlined, and the main molecular players and their interactions have been identified. In this review, we will focus on the DOF TFs involved in these molecular networs, and on their interaction with other proteins.
ARTICLE | doi:10.20944/preprints202101.0165.v1
Subject: Biology, Anatomy & Morphology Keywords: base temperature; base water potential; predictive weed emergence model; weed germination
Online: 8 January 2021 (14:12:28 CET)
The efficacy of weed management depends on the correct control timing according to the seedling emergence dynamics. Since soil temperature and soil moisture are two main factors that determine weed germination, the hydrothermal time model can be used to predict their emergence. The aim of this study was to estimate the base temperature (Tb) and base water potential (Ψb) for germination of Chenopodium album, Amaranthus retroflexus, Setaria pumila and Panicum capillare collected from fields in continental Croatia and then to compare these values with those of Italian populations embedded in the AlertInf model. Germination tests were performed at seven constant temperatures (ranging from 4 to 27°C) and eight water potentials (0.00 to - 1.00 MPa). Estimated Tb and Ψb were 3.4°C, -1.38 MPa for C. album, 13.9°C, -0.36 MPa for A. retroflexus, 6.6°C, -0.71 MPa for S. pumila and 11.0°C, -0.87 MPa for P. capillare, respectively. According to the criterion of overlap of the 95% confidence intervals, only Tb of C. album, and Ψb of A. retroflexus were similar between Croatian and Italian populations. Further field experiments should be conducted in the Croatian field to monitor weed emergence patterns of C. album and to calibrate the AlerInf equation parameters.
ARTICLE | doi:10.3390/sci1010032
Subject: Keywords: germination; heteromorphism; imbibition; seed color; seedling growth; sodium chloride; <i>Trifolium pratense</i>
Online: 21 June 2019 (00:00:00 CEST)
The seeds of red clover are heteromorphic and two color morphs can be visually recognized, light purple and yellow, resulting from heterozygosity and recessive homozygosity at two loci. Here, we report the responses of seed imbibition, seed germination, and early seedling growth of the two morphs to distilled water, sodium chloride, and complete nutrient solution. The sensitivity of red clover seeds to treatments increased with the stage of development in what seems to be a cumulative process. No differences were found in seed imbibition between morphs or between treatments. In seedling growth, on the contrary, treatments were always effective, but differences between morphs were only observed in seeds that were treated with nutrient solution, whereas in the intermediate stage of seed germination, the effects by treatments were observed together with the appearance of differences between morphs in distilled water and in the treatment by sodium chloride solution. Simultaneously, the superior performance of the yellow morph that was found in germination, which appears to be a trait stable across cultivars of red clover seeds, turned into a superior performance of the light purple morph in seedling growth.
ARTICLE | doi:10.20944/preprints201802.0160.v3
Subject: Biology, Agricultural Sciences & Agronomy Keywords: wild chili pepper; domestication; seed germination; capsaicinoids content; halopriming; gibberellic acid
Online: 26 March 2018 (08:51:45 CEST)
The effects of different priming techniques were evaluated to improve the dormancy and germination of wild seeds of “Piquín” chili pepper. Three experiments were designed for pre-sowing treatment of seeds: a) chemical seeds digestion; b) halopriming (with K+ or NH4+ of NO3-, SO42- or Cl-) at different priming times (24, 48 or 72 h) and osmotic potential (-5, -10 or -15 atm) and c) previously selected halopriming (KNO3 and NH4NO3) + Gibberellic acid (GA3, at 100 or 200 ppm) were tested. Digestion treatments did show a negative effect on seed germination. Recommended values of osmotic potential (Ψs), to improve Piquín chili seed germination, must be between -10 and -15 atm (-1.0 and -1.5 MPa) and the priming time must be between 48 and 72 hours. Priming techniques can considerably reduce Capsaicinoids content on seeds, improve dormancy, seed germination performance, and increase the rate and uniformity of seedling establishment. KNO3 and secondly GA3 treatments may improve rapid and uniform germination and seedling emergence. The results provide basic information to develop guidelines for commercial establishment of Piquín pepper crops.
ARTICLE | doi:10.20944/preprints202208.0455.v1
Subject: Life Sciences, Biotechnology Keywords: Shock waves; Acoustic cavitation; Gene expression; Aspergillus niger; Cell permeabilization; Fungal germination
Online: 26 August 2022 (09:34:23 CEST)
Shock waves, as used in medicine, can induce cell permeabilization, genetically transforming filamentous fungi; however, little is known on the interaction of shock waves with the cell wall. Because of this, the selection of parameters has been empirical. We studied the influence of shock waves on the germination of Aspergillus niger, to understand their effect on the modulation of four genes related to the growth of conidia. Parameters were varied in the range reported in protocols for genetic transformation. Vials containing conidia in suspension were exposed to either 50, 100 or 200 single-pulse or tandem shock waves, with different peak pressures (approximately 42, 66 and 83 MPa). In the tandem mode, three delays were tested. To equalize the total energy, the number of tandem “events” was halved compared to the number of single-pulse shock waves. Our results demonstrate that shock waves do not generate severe cellular effects on the viability and germination of A. niger conidia. Nevertheless, increase in the aggressiveness of the treatment induced a modification in the four genes tested. Scanning electron microscopy revealed significant changes to the cell wall of the conidia. Under optimized conditions, shock waves could be used for several biotechnological applications, surpassing conventional techniques.
REVIEW | doi:10.20944/preprints202012.0274.v1
Subject: Biology, Anatomy & Morphology Keywords: seed dormancy; germination; light-mediated process; abiotic stress; epigenetic control; translational control
Online: 11 December 2020 (10:30:09 CET)
The transition from a dormant to a germinating seed represents a crucial developmental switch in the life cycle of a plant. Subsequent transition from a germinating seed to an autotrophic organism also requires a robust and multi-layered control. Seed germination and seedling growth are multistep processes, involving both internal and external signals, which lead to a fine-tuning control network.
REVIEW | doi:10.20944/preprints202011.0734.v1
Subject: Biology, Anatomy & Morphology Keywords: abscisic acid; after-ripening; desiccation tolerance; dormancy; germination; gibberellins; LAFL; longevity; seeds
Online: 30 November 2020 (14:41:46 CET)
Desiccation tolerance appeared as the key adaptation feature of photoautotrophic organisms for survival in terrestrial habitats. During the further evolution, vascular plants developed complex anatomy structures and molecular mechanisms to maintain the hydrated state of cell environment, which essentially increased their ability to sustain water deficit and dehydration. However, the role of the genes encoding the mechanisms behind this adaptive feature in the higher vascular plants is restricted to the dehydration protection of spores, seeds and pollen, whereas the mature vegetative stages became sensitive to desiccation. During maturation, orthodox seeds lose up to 95% of their water and successfully enter dormancy. This feature allows seeds maintaining their viability even under strongly fluctuating environmental conditions. The mechanisms behind the desiccation tolerance are activated at the late seed maturation stage and are associated with the accumulation of late embryogenesis abundant proteins (LEA proteins), small heat shock proteins (sHSP), non-reducing oligosaccharides, and antioxidants of different chemical nature. The main regulators of maturation and desiccation tolerance onset are abscisic acid and protein DOG1, which control the network of transcription factors, among which are LEC1, LEC2, FUS3, ABI3, ABI5, AGL67, PLATZ1, PLATZ2. This network is complemented by epigenetic regulation of gene expression by methylation of DNA, post-translational modifications of histones and chromatin remodeling impact on seed desiccation tolerance and longevity. Moreover, orthodox seeds are able to maintain desiccation tolerance during germination up to the stage of radicle protrusion. This time point is critical in the process of seed development, as the seeds lose desiccation tolerance at this moment.
REVIEW | doi:10.20944/preprints201911.0382.v1
Subject: Biology, Plant Sciences Keywords: abscisic acid; abiotic-stresses signaling; ubiquitination; seed-germination; e3 ubiquitin ligase; stomatal-regulation
Online: 30 November 2019 (09:20:52 CET)
Plants are immobile, and, to overcome harsh environmental conditions, such as drought, salt, and cold, they have evolved complex signaling pathways. Abscisic acid (ABA), an isoprenoid phytohormone, is a critical signaling mediator that regulates diverse biological processes in various organisms. Significant progress has been made in the determination and characterization of key ABA-mediated molecular factors involved in different stress responses, including stomatal closure and developmental processes, such as seed germination and bud dormancy. Since ABA-signaling is a complex signaling network that integrates with other signaling pathways, the dissection of its intricate regulatory network is necessary to understand the function of essential regulatory genes involved in ABA signaling. In the present review, we focus on two aspects of ABA signaling. First, the perception of the stress signal (abiotic and biotic) and the response network of ABA-signaling components that transduce the signal to the downstream pathway to respond to stress tolerance, regulation of stomata, and ABA signaling component ubiquitination. Second, ABA-signaling in plant development processes, such as lateral root growth regulation, seed germination, and flowering time regulation. Examining such diverse signal integration dynamics could enhance our understanding of the underlying genetic, biochemical, and molecular mechanisms of ABA signaling networks in plants.
ARTICLE | doi:10.20944/preprints201808.0493.v1
Subject: Life Sciences, Genetics Keywords: Weed competitive ability; early seed germination and seedling vigor traits; quantitative trait loci (QTLs); single nucleotide polymorphism; direct seeded rice
Online: 29 August 2018 (10:46:02 CEST)
Weed competitive ability (WCA) is a desirable key trait for the improvement of grain yield under direct-seeded rice (DSR) and the aerobic rice ecosystem. The present study targeted screening of 167 introgression lines (ILs) of a Green Super Rice (GSR) IR2-6 population derived from a cross between Weed Tolerant Rice 1 (WTR1) as the recipient parent and Y134 as the donor parent developed at IRRI for weed competitiveness in screen house conditions (SHC). The ILs were phenotyped for WCA traits such as early seed germination (ESG) and early seedling vigor (ESV) in Petri dishes and pot experiment conditions. The results of phenotypic variance revealed ESG-related traits, especially first germination count (1st GC) that positively correlated with second germination count (2nd GC), germination percentage (GP), total dry weight (TDW), total fresh weight (TFW), and vigor index (VI-1), whereas, in ESV, all the traits were positively correlated with each other except for three traits: root dry weight (RDW), 1st GC, and GP-2. The ESG and ESV traits are vital for weed competitiveness. A 6K SNP array was used to study the genetic association for the WCA traits. Forty-four QTLs for WCA traits were mapped on all chromosomes (except on chromosomes 4 and 8) through single marker analysis (SMA). Out of 44 QTLs, 29 were associated with ESG traits and 15 with ESV traits, with LOD scores of 2.93 to 8.03 and 2.93 to 5.04 and explained phenotypic variance ranging from 7.85% to 19.9% and from 7.85% to 13.2%, respectively. However, 31 QTLs were contributed by a negative additive allele from Y134, whereas a positive additive allele was contributed by WTR1 in 13 QTLs. Among them, two QTL hotspot regions were mapped on chromosome 11 (24.7-27.9 Mb) and chromosome 12 (14.8-17.4 Mb). The majority of the QTLs related to WCA traits were grouped into two QTL hotspots: QTL hotspot-I (qAFW11.1, qFC11.1, qFC11.2, qSC11.1, qGP-111.1, qGP-111.2, qTFGS11.1, qVI-111.1, and qVI-111.2) and QTL hotspot-II (qFC12.1, qFC12.2, qSC12.1, qFC12.2, qGP-112.1, qGP-112.2, qTFGS12.1, qTFGS12.2, qVI-112.1, qIV12.2, qFC12.1, and qGC12.2), and a few of them were co-localized on chromosomes 11 and 12. Further, we fine-tuned in the genomic regions of QTL hotspots and identified a total of 13 putative candidate genes on chromosomes 11 and 12 collectively. The present study is the first report on the genetic basis of WCA-related traits and the co-localized QTLs, which could be highly valuable in future breeding programs aiming to improve WCA in rice.
REVIEW | doi:10.20944/preprints201807.0432.v1
Subject: Biology, Plant Sciences Keywords: Seed coat; pericarps; floral bracts; glumes; dead organs enclosing embryos; seed germination; seedling establishment; hydrolytic enzymes; ROS detoxifying enzymes; cell wall modification enzymes; nutrients; phytohormones; nucleases; chitinases; Brassicaceae; Poaceae
Online: 26 July 2018 (09:53:41 CEST)
Plants have evolved a variety of dispersal units whereby the embryo is enclosed by various dead protective layers derived from maternal organs of the reproductive system including seed coats (integuments), pericarps (ovary wall, e.g., indehiscent dry fruits) as well as floral bracts (e.g. glumes) in grasses. Commonly, dead organs enclosing embryos (DOEEs) are assumed to provide a physical shield for embryo protection and means for dispersal in the ecosystem. In this review article, we will highlight recent studies showing that DOEEs of various species across families also have the capability for long-term storage of various substances including active proteins (hydrolases, ROS detoxifying enzymes), nutrients and metabolites that have the potential to support the embryo during storage in the soil and assist in germination and seedling establishment. We discuss a possible role for DOEEs as natural coatings capable of ‘engineering’ the seed microenvironment for the benefit of the embryo, the seedling and the growing plant.