Oxidative damage and antioxidative indicators in 48 h germinated rice embryos during the vitrification-cryopreservation procedure

Effects of oxidative stress on the changes of viability of Paeonia lactiflora seeds with different water content before and after cryopreservation

Cryopreservation in liquid nitrogen (LN) is an efficient long - term seed preservation strategy and water content is one of the main factors affecting seed viability after cryopreservation. In this study, Paeonia lactiflora seeds with varying water content were used as materials to determine changes in the antioxidant system before and after cryopreservation. When the water content of P. lactiflora seeds was 15.96 %-10.12 %, the viability of P. lactiflora seeds decreased significantly compared with that of the seeds without cryopreservation, but at the water content of 8.14 %-7.56 % there were no significant differences. However, when the water content of P. lactiflora seeds decreased to 6.01 %-5.19 % the viability was slightly increased compared to the seeds without cryopreservation. The content of superoxide anion (O2-), hydroxyl radical (·OH), hydrogen peroxide (H2O2), malondialdehyde (MDA) and protein carbonyl group (PCO) of seeds with high water content (15.96 %-10.12 %) were significantly increased after cryopreservation. However, superoxide anion (O2-), hydroxyl radical (·OH) and hydrogen peroxide (H2O2) did not change significantly in seeds with low water content (6.01 %-5.19 %) after cryopreservation, while oxidative stress indexes MDA and PCO decreased. These three substances were significantly negatively correlated with seed viability. In terms of antioxidant substances, the contents of catalase (CAT), ascorbic acid (AsA) and glutathione (GSH) decreased and the activities of glutathione reductase (GR) and dehydroascorbate reductase (DHAR) increased during the cryopreserved process of seeds with varying water content. These changes were significantly correlated with ROS content and the changes of MDA and PCO, among which AsA content, GSH content and CAT activity were positively correlated with seed viability. The changes of GR and DHAR activity were negatively correlated with seed viability. In summary, when the water content of the seeds ranged from 8.14 % to 5.19 %, ROS content did not increase significantly after cryopreservation compared with that of before preservation. The changes of MDA and PCO contents before and after cryopreservation, it was inferred that no obvious oxidative damage occurred in seeds, so the viability of seeds did not decrease compared with that of before cryopreservation. Therefore, the optimum water content of P. lactiflora seeds for cryopreservation is 8.14 %-5.19 %.

Variation in phytotoxicity of rice seedlings caused by differential accumulation of azoxystrobin and pyraclostrobin in leaves

The effectiveness of pyraclostrobin (Pyr) and azoxystrobin (Azo) with highly targeting the rice blast is noteworthy, but they have varied toxic levels towards non-target aquatic organisms. Nevertheless, the toxic selectivity and mechanism of non-target plants, specifically rice, remain uncertain. In this study, we investigated the potential phytotoxic effects of Pyr and Azo on rice seedlings, including plant morphology, plant growth, physiological and biochemical changes. The findings revealed that both Pyr and Azo caused toxic effects on rice, resulting in symptoms of chlorosis and inhibited growth. The toxicity of Azo was found to be more severe when applied at the recommended field dose. Disruption of oxidative stress could significantly impact the demonstrated levels of REC, leading to a decrease in photosynthetic pigments and potentially culminating in cell death. Furthermore, the toxic effect of Azo had a greater impact on rice leaves compared to Pyr at treatments of 400, 800, 1600, and 4000 mg/L. However, the in vitro cytotoxicity of Azo on rice leaves was lower than that of Pyr. Therefore, it can be inferred that the mechanism of phytotoxicity of Azo is directly linked to the increased accumulation of the compound on the leaf tips and edges. Additionally, the positive effects observed on plant morphology and growth parameters suggest that the mixed application of plant growth regulators (sodium nitrophenolate aqueous solution of 14 mg/L and diethyl aminoethyl hexanoat of 50 mg/L) can be a promising approach to mitigate the rice phytotoxicity of Azo at 400 and 800 mg/L.

Critical Role of Regrowth Conditions in Post-Cryopreservation of In Vitro Plant Germplasm

Cryopreservation is an effective option for the long-term conservation of plant genetic resources, including vegetatively propagated crops and ornamental plants, elite tree genotypes, threatened plant species with non-orthodox seeds or limited seed availability, as well as cell and root cultures useful for biotechnology. With increasing success, an arsenal of cryopreservation methods has been developed and applied to many species and material types. However, severe damage to plant material accumulating during the multi-step cryopreservation procedure often causes reduced survival and low regrowth, even when the optimized protocol is applied. The conditions at the recovery stage play a vital role in supporting material regrowth after cryopreservation and, when optimized, may shift the life-and-death balance toward a positive outcome. In this contribution, we provide an overview of the five main strategies available at the recovery stage to improve post-cryopreservation survival of in vitro plant materials and their further proliferation and development. In particular, we discuss the modification of the recovery medium composition (iron- and ammonium-free), exogenous additives to cope with oxidative stress and absorb toxic chemicals, and the modulation of medium osmotic potential. Special attention is paid to plant growth regulators used at various steps of the recovery process to induce the desired morphological response in cryopreserved tissues. Given studies on electron transport and energy provision in rewarmed materials, we discuss the effects of light-and-dark conditions and light quality. We hope that this summary provides a helpful guideline and a set of references for choosing the recovery conditions for plant species that have not been cryopreserved. We also propose that step-wise recovery may be most effective for materials sensitive to cryopreservation-induced osmotic and chemical stresses.

Transcriptome assessment in 'Red Globe' grapevine zygotic embryos during the cooling and warming phase of the cryopreservation procedure

Cryopreservation has the potential for long-term germplasm storage. The metabolic pathways and gene regulation involved in cryopreservation procedures are still not well documented. Hence, the genetic expression profile was evaluated using RNA-Seq in zygotic embryos of grapevines subjected to cryopreservation by vitrification. Sequencing was performed on the Illumina NextSeq 500. The average alignment of reads was 96% against the reference genome. The expression profiles showed 229 genes differentially expressed (186 repressed and 46 induced). The main biological processes showing upregulated enrichment were related to nucleosome assembly, while downregulated processes were related to organ growth. The most highly repressed processes were associated with the organization of the cell wall and membrane components. The unnamed protein product and 17.3 kDa class II heat shock protein (HSP) were highly induced, while ATPase subunit 1 and expansin-A1 were repressed. The response to the cooling and warming process during cryopreservation probably indicates that the changes occurring in transcription may be related to epigenetics. In addition, the cell exhibits an increase in the reserve of nutrients while seeking to survive modestly using available energy and pausing the plant's development. Additionally, energy containment occurred to cope with the stress caused by the treatment where deactivation of components of the cell membrane was observed, possibly due to changes in fluidity caused by alterations in temperature.

Abscisic acid induces the expression of AsKIN during the recovery period of garlic cryopreservation

Abscisic acid induced the expression of AsKIN during the recovery period of garlic cryopreservation. AsKIN was identified as a gene involved in cold and osmotic stress resistance. Cryopreservation has been proven to be effective in removing viruses from garlic. However, oxidative damage in cryopreservation has a significant impact on the survival after preservation. Abscisic acid (ABA) has been shown to reduce oxidative stress and promote the survival after cryopreservation. However, it is not clear which genes play important roles in this process. In this study, we added ABA to the dehydration step and analyzed the transcriptomic divergences between the ABA-treated group and the control group in three cryogenic steps (dehydration, unloading and recovery). By short time-series expression miner (STEM) analysis and weighted gene co-expression network analysis (WGCNA), the recovery step was identified as the period of significant changes in gene expression levels in cryopreservation. The addition of ABA promoted the upregulated expression of microtubule-related genes in the recovery step. We further identified AsKIN as a hub gene in the recovery step and verified its function. The results showed that overexpression of AsKIN enhanced the tolerance of Arabidopsis to oxidative stress in cryopreservation, influenced the expression of genes in response to cold and osmotic stress and promoted plant growth after stress. The AsKIN gene is likely to be involved in the plant response to cold stress and osmotic stress. These results reveal the molecular mechanisms of ABA in cryopreservation and elucidate the potential biological functions of the kinesin-14 subfamily.

Effects of vitrified cryopreservation duration on IVF and neonatal outcomes

Background

In this study, we aimed to evaluate the impact of the duration of cryopreservation storage on embryo viability, implantation competence, pregnancy outcome and neonatal outcomes.

Methods

We retrospectively evaluated the outcomes of patients who underwent IVF with vitrified cryopreserved embryos between January 2004 and August 2019 by following the first frozen embryo transfer cycles within the study period. A total of 31,143 patients met the inclusion criteria and were grouped according to the embryo storage time as follows: Group 1 (n = 20,926),1–90 days; Group 2 (n = 6,472), 91–180 days; Group 3 (n = 2,237), 181–365 days; Group 4 (n = 746), 366–730 days; and Group 5 (n = 762), > 731 days.

Results

The embryo survival rate decreased significantly with longer durations of cryopreservation. The highest and lowest survival rate was recorded in Group 1 and Group 5, respectively (34853/35338; 98.63% vs. 1281/1801; 71.13%; P < 0.01). The human chorionic gonadotropin (HCG) detection and clinical pregnancy rate was highest in Group 1 (57.85% and 55. 26%, respectively; P < 0.01). Short-term cryopreservation (≤ 3 months) is associated with higher rates of clinical pregnancy. There were no significant differences in neonatal birth weight, neonatal height and congenital anomalies among the groups (P > 0. 05).

Conclusion

The prolonged storage time of vitrified embryos negatively affected survival rate and clinical pregnancy rate. It did not have a significant influence on neonatal health. This study provides new findings about the relationship between prolonged storage time of vitrified embryos and clinical outcomes and offers evidence for the safety of using long-stored embryos after vitrification.

Effects of Kiwifruit Rootstocks with Opposite Tolerance on Physiological Responses of Grafting Combinations under Waterlogging Stress

Kiwifruit is commonly sensitive to waterlogging stress, and grafting onto a waterlogging-tolerant rootstock is an efficient strategy for enhancing the waterlogging tolerance of kiwifruit plants. KR5 (Actinidia valvata) is more tolerant to waterlogging than ‘Hayward’ (A. deliciosa) and is a potential resistant rootstock for kiwifruit production. Here, we focused on evaluating the performance of the waterlogging-sensitive kiwifruit scion cultivar ‘Zhongmi 2′ when grafted onto KR5 (referred to as ZM2/KR5) and Hayward (referred to as ZM2/HWD) rootstocks, respectively, under waterlogging stress. The results showed ‘Zhongmi 2′ performed much better when grafted onto KR5 than when grafted onto ‘Hayward’, exhibiting higher photosynthetic efficiency and reduced reactive oxygen species (ROS) damage. Furthermore, the roots of ZM2/KR5 plants showed greater root activity and energy supply, lower ROS damage, and more stable osmotic adjustment ability than the roots of ZM2/HWD plants under waterlogging stress. In addition, we detected the expression of six key genes involved in the kiwifruit waterlogging response mechanism, and these genes were remarkably induced in the ZM2/KR5 roots but not in the ZM2/HWD roots under waterlogging stress. Moreover, principal component analysis (PCA) further demonstrated the differences in the physiological responses of the ZM2/KR5 and ZM2/HWD plants under waterlogging stress. These results demonstrated that the KR5 rootstock can improve the waterlogging tolerance of grafted kiwi plants by regulating physiological and biochemical metabolism and molecular responses.

Melatonin in cryopreservation media improves transplantation efficiency of frozen-thawed spermatogonial stem cells into testes of azoospermic mice

Background

Cryostorage of spermatogonial stem cells (SSCs) is an appropriate procedure for long-term storage of SSCs for fertility preservation. However, it causes damage to cellular structures through overproduction of ROS and oxidative stress. In this study, we examined the protective effect of melatonin as a potent antioxidant in the basic freezing medium to establish an optimal cryopreservation method for SSCs.

Methods

SSCs were obtained from the testes of neonatal male mice aged 3–6 days. Then, 100 μM melatonin was added to the basic freezing medium containing DMSO for cryopreservation of SSCs. Viability, apoptosis-related markers (BAX and BCL2), and intracellular ROS generation level were measured in frozen–thawed SSCs before transplantation using the MTT assay, immunocytochemistry, and flow cytometry, respectively. In addition, Western blotting and immunofluorescence were used to evaluate the expression of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins in frozen–thawed SSCs after transplantation into recipient testes.

Results

The data showed that adding melatonin to the cryopreservation medium markedly increased the viability and reduced intracellular ROS generation and apoptosis (by decreasing BAX and increasing BCL2) in the frozen–thawed SSCs (p < 0.05). The expression levels of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins and resumption of spermatogenesis from frozen–thawed SSCs followed the same pattern after transplantation.

Conclusions

The results of this study revealed that adding melatonin as an antioxidant to the cryopreservation medium containing DMSO could be a promising strategy for cryopreservation of SSCs to maintain fertility in prepubertal male children who suffer from cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03029-1.

Ascorbic acid addition during dehydration improves garlic shoot tip cryopreservation but does not affect viral load

Cryopreservation is known be an effective method for virus elimination in garlic. However, oxidative damage during the cryopreservation seriously affects the survival of garlic after cryopreservation. Ascorbic acid (AsA) can reduce oxidative damage and improve regrowth following cryopreservation, and its effect may be influenced by the step during which it is added. In this study, AsA was added at the osmoprotection (O) and dehydration (DE) steps of cryopreservation. By observing the dynamic changes in cell viability and reactive oxygen species (ROS) components with different AsA treatments, AsA has been linked to the reduced accumulation of ROS in the shoot tips. Increased gene expression levels of antioxidant enzymes also explained the ROS scavenging effect of AsA. The correlation analysis between cell viability, ROS, membrane lipid peroxidation-related indicators and antioxidant-related indicators showed that membrane lipid peroxidation caused by excess ROS was the main factor affecting cell viability. Ascorbic acid added during dehydration minimized the accumulation of ROS from dehydration to dilution and alleviated the oxidative damage during cryopreservation. Thus, the survival and regrowth of the garlic was significantly improved after cryopreservation. Dehydration was found to be the suitable step for the addition of AsA during garlic cryopreservation. We further evaluated the virus elimination effect under optimal AsA treatment. However, there was no significant difference in virus content in regenerated plants when compared with the control.

ROS-induced oxidative stress in plant cryopreservation: occurrence and alleviation

Reactive oxygen species (ROS)-induced oxidative stress results in low success or even total failure of cryopreservation. Better understanding of how the plant establishes resistance/tolerance to ROS-induced oxidative stress facilitates developments of robust cryopreservation procedures. Cryopreservation provides a safe and efficient strategy for long-term preservation of plant genetic resources. ROS-induced oxidative stress caused damage to cells and reduced the ability of the plant to survive following cryopreservation, eventually resulting in low success or even total failure. This paper provides updated and comprehensive information obtained in the past decade, including the following: (1) ROS generations and adaptive responses of antioxidant systems during cryopreservation; (2) expressions of oxidative stress-associated genes and proteins during cryopreservation; (3) ROS-triggered programmed cell death (PCD) during cryopreservation; and (4) exogenous applications of enzymatic and non-enzymatic antioxidants in improving success of cryopreservation. Prospects for further studies are proposed. The goal of the present study was to facilitate better understanding of the mechanisms by which the plant establishes resistance/tolerance to oxidative stress during cryopreservation and promote further studies toward the developments of robust cryopreservation procedures and wider application of plant cryobiotechnology.

The Feasibility of Antioxidants Avoiding Oxidative Damages from Reactive Oxygen Species in Cryopreservation

Cryopreservation prolongs the storage time of cells and plays an important role in modern biology, agriculture, plant science and medicine. During cryopreservation, cells may suffer many damages, such as osmotic dehydration, large ice puncture and oxidative damages from reactive oxygen species (ROS). Classic cryoprotectants (CPAs) are failing to dispose of ROS, while antioxidants can turn ROS into harmless materials and regulate oxidative stress. The combination of antioxidants and CPAs can improve the efficiency of cryopreservation while negative results may occur by misuse of antioxidants. This paper discussed the feasibility of antioxidants in cryopreservation.

Selenium mitigates salt-induced oxidative stress in durum wheat (Triticum durum Desf.) seedlings by modulating chlorophyll fluorescence, osmolyte accumulation, and antioxidant system

Hydroponic experiments were conducted to investigate the effects of different concentrations of sodium selenate (Na₂SeO₄) and sodium selenite (Na₂SeO₃) on durum wheat seed germination and seedling growth under salt stress. The treatments used were 0 and 50 mM NaCl solutions, each supplemented with Na₂SeO₄ or Na₂SeO₃ at 0, 0.1, 1, 2, 4, 8, or 10 μM. Salt alone significantly inhibited seed germination and reduced seedling growth. Addition of low concentrations (0.1-4 μM) of Na₂SeO₄ or Na₂SeO₃ mitigated the adverse effects of salt stress on seed germination, biomass accumulation, and other physiological attributes. Among them, 1 μM Na₂SeO₄ was most effective at restoring seed germination rate, germination energy, and germination index, significantly increasing these parameters by about 12.35, 24.17, and 11.42%, respectively, compared to salt-stress conditions. Adding low concentrations of Na₂SeO₄ or Na₂SeO₃ to the salt solution also had positive effects on chlorophyll fluorescence indices, decreased the concentrations of free proline and malondialdehyde, as well as electrolyte leakage, and increased catalase, superoxide dismutase, and peroxidase activities in roots and shoots. However, high concentrations (8-10 μM) of Na₂SeO₄ or Na₂SeO₃ disrupted seed germination and seedling growth, with damage caused by Na₂SeO₃ being more severe than that by Na₂SeO₄. It is thus clear that exogenous selenium can improve the adaptability of processing wheat to salt stress and maintain higher photosynthetic rate by decreasing the accumulation of reactive oxygen species and alleviating the degree of membrane lipid peroxidation. Na₂SeO₄ was more effective than Na₂SeO₃ at all given concentrations.

Single-wall carbon nanotubes improve cell survival rate and reduce oxidative injury in cryopreservation of Agapanthus praecox embryogenic callus

BACKGROUND

Cryopreservation is the best way for long-term in vitro preservation of plant germplasm resources. The preliminary studies found that reactive oxygen species (ROS) induced oxidative stress and ice-induced membrane damage are the fundamental causes of cell death in cryopreserved samples. How to improve plant cryopreservation survival rate is an important scientific issue in the cryobiology field.

RESULTS

This study found that the survival rate was significantly improved by adding single-wall carbon nanotubes (SWCNTs) to plant vitrification solution (PVS) in cryopreservation of Agapanthus praecox embryogenic callus (EC), and analyzed the oxidative response of cells during the control and SWCNTs-added cryopreservation protocol. The SWCNTs entered EC at the step of dehydration and mainly located around the cell wall and in the vesicles, and most of SWCNTs moved out of EC during the dilution step. Combination with physiological index and gene quantitative expression results, SWCNTs affect the ROS signal transduction and antioxidant system response during plant cryopreservation. The EC treated by SWCNTs had higher antioxidant levels, like POD, CAT, and GSH than the control group EC. The EC mainly depended on the AsA-GSH and GPX cycle to scavenge H₂O₂ in the control cryopreservation, but depended on CAT in the SWCNTs-added cryopreservation which lead to low levels of H₂O₂ and MDA. The elevated antioxidant level in dehydration by adding SWCNTs enhanced cells resistance to injury during cryopreservation. The ROS signals of EC were balanced and stable in the SWCNTs-added cryopreservation.

CONCLUSIONS

The SWCNTs regulated oxidative stress responses of EC during the process and controlled oxidative damages by the maintenance of ROS homeostasis to achieve a high survival rate after cryopreservation. This study is the first to systematically describe the role of carbon nanomaterial in the regulation of plant oxidative stress response, and provided a novel insight into the application of nanomaterials in the field of cryobiology.

Facilitating effects of plant hormones on biomass production and nutrients removal by Tetraselmis cordiformis for advanced sewage treatment and its mechanism

Advanced sewage treatment by microalgae is regarded as a promising method for addressing eutrophication. To improve sewage treatment, three kinds of plant hormones including auxin (indole-3-acetic acid, IAA), cytokinin (Zeatin), and brassinosteroid, were chosen to measure the influence of plant hormones on nitrogen and phosphorus removal by Tetraselmis cordiformis and to analyze their mechanisms, including photosynthesis, nutrient metabolism, and gene transcription. The results indicated that the maximal removal efficiencies of total nitrogen and phosphate by T. cordiformis were elevated by the plant hormones by 184.3% and 53.2%, respectively. The chlorophyll a content was increased by 1.1 times by the plant hormones in comparison with the control. Moreover, after being stimulated by plant hormones, the activities of nitrate reductase (NR) and glutamine synthetase (GS) increased by 90.4% and 82.1%, respectively, in comparison with the control. Supplementation with plant hormones also significantly elevated the mRNA expression level of GS-related gene by 30.9%. This study demonstrated that plant hormones could significantly promote the nutrient removal of microalgae for sewage treatment in artificial laboratory conditions and provided theoretical support for its further practical full-scale application under variable conditions.

Biochemical analyses of Dendrobium Sabin Blue PLBs during cryopreservation by vitrification

Dendrobium Sabin Blue is an important orchid hybrid that has been grown extensively as cut flower, potted plant and is also popular for its deep purplish blue flowers.  The most efficient long term conservation method of this hybrid is through cryopreservation. Cryopreservation involving the vitrification method consists of explants exposure to highly concentrated cryoprotective solution followed by freezing rapidly in liquid nitrogen. However, these treatments involved highly concentrated cryoprotectant that could incur toxicity to the explants. Hence, cryopreservation protocol requires biochemical analyses in understanding the damages or injuries occurred during cryopreservation treatments. In this study, biochemical analyses revealed a general reduction in chlorophyll, carotenoid and porphyrin content to 0.40 µg/g F W (thawing stage), 31.50 µg/g F W unloading stage and 2230.41 µg/g F W (thawing stage), respectively in comparison to the control treatments. In addition, increased level in proline content were obtained at different cryopreservation stages with highest level (5.42 µmole/g F W) recorded at the PVS2 dehydration stage. Fluctuated outcomes were obtained in catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) enzyme activities in PLBs exposed to different cryopreservation stages. Lowest values recorded for CAT enzyme activity were obtained at the dehydration stage (3.94 U/g). Lowest POX enzyme activities were obtained at the dehydration (122.36 U/g) and growth recovery (106.40 U/g) stages. Additionally, lowest APX enzyme activities values were recorded at the thawing (7.47 U/g) and unloading (7.28 U/g) stages. These have contributed to low regeneration of Dendrobium Sabin Blue protocorm like bodies (PLBs) following cryopreservation. Hence, in the future experimental design, exogenous antioxidant could be included in the cryopreservation procedures to improve the existing protocol.