Heat Shock Treatment Research Articles

Transcriptomic and physiological responses of a model diatom (Phaeodactylum tricornutum) to heat shock and heat selection

Diatoms are ecologically important phytoplankton as they contribute 40% of the marine primary production and play an essential role in the biogeochemical cycles of many elements. Ocean warming, as a pressing environmental stressor, can profoundly affect the population structure and ecological services of diatoms. However, the molecular mechanisms underpinning cellular and physiological changes of diatoms under heat wave and heat selection conditions remain underexplored. This study revealed the transcriptomic and physiological responses of a model diatom species P. tricornutum to ocean warming at an elevated temperature (25 °C in comparison with 20 °C) under scenarios of heat shock (∼7 days; ∼7 generations) and heat selection (∼175 days; ∼165 generations). While unchanged cell growth and reduced Fv/Fm were recorded in the heat shock treatment, significant reductions in the cell growth rate and Fv/Fm were evident in the heat selection treatment. Contents of Chl-a, carotenoid, total soluble protein, carbon (C), and nitrogen (N) increased significantly in both treatments. Transcriptomics analysis showed that elevated temperature suppressed signaling pathways related to photosynthesis but activated signaling pathways involving in fatty acid metabolism and nitrogen metabolism following the heat selection, associated with elevated substance storage and enlarged cell size. As a result, the increase of both C and N suggest that more energy was likely allocated to growth than division under ocean warming. Notably, P. tricornutum showed a higher resistance to nitrogen limitation condition after acclimating to ocean warming possibly by activation of nitrogen metabolism and uptake. P. tricornutum responded to the projected ocean warming through readjusting energy metabolism.

BCL11B Is Involved in Stress-Induced Differentiation of Keratinocytes and Has A Potential Role in Psoriasis Pathogenesis.

Psoriasis is a common, auto-immune skin disease characterized by abnormal proliferation and differentiation of keratinocytes. Studies revealed the role of stress stimulators in the pathogenesis of psoriasis. Oxidative stress and heat shock are two important stress factors tuning differentiation and proliferation of keratinocytes, regarding to psoriasis disease. BCL11B is a transcription factor with critical role in embryonic keratinocyte differentiation and proliferation. Given this, in keratinocytes we have investigated potential role of BCL11B in stress-induced differentiation. Furthermore, we searched for a potential intercommunication between BCL11B expression and psoriasis-related keratinocyte stress factors. In this experimental study, data sets of psoriatic and healthy skin samples were downloaded in silico and BCL11B was chosen as a potential transcription factor to analyze. Next, a synchronized in vitro model was designed for keratinocyte proliferation and differentiation. Oxidative stress and heat shock treatments were employed on HaCaT keratinocytes in culture, and BCL11B expression level was measured. Cell proliferation rate and differentiation were analyzed by synchronized procedure test. Flow cytometry was done to analyze cell cycle alterations due to the oxidative stress. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) data revealed a significant upregulation of BCL11B expression in keratinocytes, by 24 hours after initiating differentiation. However, it was followed by a significant down-regulation in almost all the experiments, including the synchronized model. Flow cytometer data demonstrated a G1 cell cycle arrest in the treated cells. Results indicated a remarkable role of BCL11B in differentiation and proliferation of HaCaT keratinocytes. This data along with the results of flow cytometer suggested a probable role for BCL11B in stress-induced differentiation, which is similar to what is happening during initiation and progression of normal differentiation.

Transcriptome-wide probing reveals RNA thermometers that regulate translation of glycerol permease genes in Bacillus subtilis.

RNA structure regulates bacterial gene expression by several distinct mechanisms via environmental and cellular stimuli, one of which is temperature. While some genome-wide studies have focused on heat shock treatments and the subsequent transcriptomic changes, soil bacteria are less likely to experience such rapid and extreme temperature changes. Though RNA thermometers (RNATs) have been found in 5' untranslated leader regions (5' UTRs) of heat shock and virulence-associated genes, this RNA-controlled mechanism could regulate other genes as well. Using Structure-seq2 and the chemical probe dimethyl sulfate (DMS) at four growth temperatures ranging from 23°C to 42°C, we captured a dynamic response of the Bacillus subtilis transcriptome to temperature. Our transcriptome-wide results show RNA structural changes across all four temperatures and reveal nonmonotonic reactivity trends with increasing temperature. Then, focusing on subregions likely to contain regulatory RNAs, we examined 5' UTRs to identify large, local reactivity changes. This approach led to the discovery of RNATs that control the expression of glpF (glycerol permease) and glpT (glycerol-3-phosphate permease); expression of both genes increased with increased temperature. Results with mutant RNATs indicate that both genes are controlled at the translational level. Increased import of glycerols at high temperatures could provide thermoprotection to proteins.

Screening of Different Media and Heat Shock Treatment Regimens for Enhancing Sporulation in Bacillus licheniformis

Bacillus licheniformis is a spore-producing bacteria. The present study aims to identify maximum sporulation in Bacillus licheniformis through induced heat shock conditions using different solidified media and broth media. Suspensions of Bacillus licheniformis spores were spread-plated on nutrient agar plates before and after heat shock treatments of 60°C, 80°C and 100°C for 30 minutes. The number of spores was determined by the dilution plate count method. The result indicates that the highest spore production for Bacillus licheniformis was observed when the spores were induced in AK (Arret and Kirshbaum) Agar for seven days under a heat shock treatment of 60℃ for 30 minutes. Whereas, in the case of Nutrient Broth media, the spore production was highest after four days at heat shock treatment of 80℃ for 30 minutes. This study will help find the optimal production of spores from Bacillus licheniformis, an industrially beneficial microorganism.

Screening of Different Media and Heat Shock Treatment Regimens for Enhancing Sporulation in Bacillus licheniformis

Screening of Different Media and Heat Shock Treatment Regimens for Enhancing Sporulation in Bacillus licheniformis

Phosphorylated heat shock protein 27improves the bone formation ability of osteoblasts and bone marrow stem cells from patients with adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a scoliotic deformity of unknown etiology that occurs during adolescent development. Abnormal bone metabolism is closely related to AIS, but the cause is uncertain. Recent studies have shown that heat shock protein 27 (HSP27) and its phosphorylation (pHSP27) play important roles in bone metabolism. However, whether HSP27 and pHSP27 are involved in abnormal bone metabolism in AIS is unclear. Osteoblasts (OBs) and bone marrow stem cells (BMSCs) were extracted from the facet joints and bone marrow of AIS patients and controls who underwent posterior spinal fusion surgery. The expression levels of HSP27 and pHSP27, as well as the expression levels of bone formation markers in OBs from AIS patients and controls, were examined by quantitative real-time PCR (qRT-PCR) and Western blotting. The mineralization ability of OBs from AIS patients and controls was analyzed by alizarin red staining after osteogenic differentiation. Heat shock and thiolutin were used to increase the levels of pHSP27 in OBs, and the levels of bone formation markers were also investigated. In addition, the levels of pHSP27 and the bone formation ability of BMSCs from AIS patients and controls were investigated after heat shock treatment. Lower pHSP27 levels and impaired osteogenic differentiation abilities were observed in the OBs of AIS patients than in those of controls. Thiolutin increased HSP27 phosphorylation and increased the mRNA levels of SPP1 and ALPL in OBs from AIS patients. Heat shock treatment increased SPP1 and HSP27 mRNA expression, pHSP27 levels, OCN expression, and mineralization ability of both OBs and BMSCs from AIS patients. Heat shock treatment and thiolutin can increase the levels of pHSP27 and further promote the bone formation of OBs and BMSCs from AIS patients. Therefore, decreased pHSP27 levels may be associated with abnormal bone metabolism in AIS patients.

Reviving Mung Bean Seeds: The Impact of Hydro Priming and Heat Shock on Germination Rates

Seed germination is a crucial stage of plant growth that can enhance yield by influencing seedling establishment. The speed and success of germination are key factors that determine the final yield of plants. This research aimed to investigate how hydro priming and heat shock affect the germination properties of green mung bean through a factorial experiment conducted in a completely randomized design with three replications at Parwan University's agronomic laboratory in 2022. The experimental treatments consisted of two temperature levels (35 and 25°C) and three moisture levels (8.5%, 10%, and 11.5%), with four categories of treatment: hydro prim, 30°C shock, 40°C shock, and control. Germination percentage, germination speed, seedling length, and dry weight were measured in the experiment. The results indicated that the triple interaction of temperature, moisture, and treatment was significant only for the germination speed trait at a 5% level. The main effect of temperature and the dual interaction of moisture and treatment at a 1% level were significant for stem length and dry weight. Additionally, the dual interaction between temperature, treatment, and temperature moisture level of 1 and 5% were significant for germination percentage, respectively. Moreover, the study found that hydro priming and thermal flushing treatment frequently improved seed storage capacity. Therefore, the study suggests that hydro priming and heat shock treatments can enhance seed germination and vigor, especially for seed lots stored under unfavorable conditions.

Rapidly generating homozygous mutate zebrafish in F0 generation by technical integration of CRISPR/Cas9 and gynogenesis

Gene editing technique has been widely applied for gene function characterization. However, such an approach is often time-consuming to obtain homozygous mutant. In this article, through timing the earlier injection of embryos, the gene editing efficiency is significantly improved, and together with the technique of the UV inactivated sperm and heat shock treatment for blocking the first cleavage, the gene-edited homozygous zebrafish are successfully obtained in F0 generation, rather than in the third or more generations as reported in the existing results. It is concluded that genetic purification of artificial gynogenesis can play critical role in more efficiently preparing the gene-edited homozygous individuals in fish.

Controlled fermentation of heat-shocked, unsalted and inoculated Moroccan Picholine green olives

The present work reports the controlled fermentation of heat-shocked, unsalted and inoculated green olives. The effects of heat-shock (60, 70 and 80 °C three times for 5 min), inoculation with the oleuropeinolytic strain of L. plantarum FSO175 (L.p-FSO175) and the addition of Cell-Free Supernatant of C. pelliculosa L18 (CFS of C.p-L18) on the fermentation process of unsalted green olives were examined. The results showed a drastic reduction in the initial indigenous Enterobacteria, and an improvement in the acidification of heat-shocked olives at 70 and 80 °C, when compared to 60 °C. The inoculation with L.p-FSO175 and addition of CFS of C.p-L18 enhanced the fermentation and preservation of unsalted green olives, indicated by a significant decrease in pH, increase in free acidity and total disappearance of Enterobacteria. The heat-shock treatment at high temperature (80 °C), inoculation with L.p-FSO175 and addition of CFS of C.p-L18 led to the best reduction in bitterness, and favorable color changes (L, a, and b) in fermented olives. This sequential method led to more appreciated sensory characteristics (mainly bitterness and color) of fermented olives, lower spoilage incidence in olives, and reduced fermentation time to 50 days, and therefore may be suitable to control the fermentation of unsalted green olives of the Moroccan picholine variety.

Peribolosporomycetes class. nov.: description of a new heat resistant and osmotolerant basidiomycete lineage, represented by Peribolospora gen. nov., P. kevripleyi sp. nov., and P. baueri sp. nov.

Heat resistance is the ability to survive short, extreme temperature stresses, exceeding the own growth temperature by far. Despite their occurrence in natural substrates and their relevance for the food and healthcare industry, the diversity of fungi with heat resistance abilities is poorly studied. Sampling of boreal forest soils in Canada in combination with a heat-shock treatment (75 °C, 30 min) yielded, among others, four heat resistant, mesophilic fungal isolates. Based on rDNA barcode sequences, the novel isolates were assigned to Basidiomycota. In this study, we use macromorphological and micromorphological observations, cultivation assays and comparative genomics for physiological characterization, interspecific differentiation, and phylogenetic placement of these isolates. A phylogeny of 38 single-copy orthologous genes, an orthology analysis, and septal pore type analysis revealed the isolates as representatives of two new basidiomycetous species of the novel class Peribolosporomycetes, a sister lineage to all other members of Ustilaginomycotina. Further genomic and phenotypic data support two different species (Peribolospora kevripleyi, Peribolospora baueri), which are heat resistant and osmotolerant.

Genome editing in rice mediated by miniature size Cas nuclease SpCas12f.

Cas9 derived from Streptococcus pyogenes (SpCas9) is used widely in genome editing using the CRISPR-Cas system due to its high activity, but is a relatively large molecule (1,368 amino acid (a.a.) residues). Recently, targeted mutagenesis in human cells and maize using Cas12f derived from Syntrophomonas palmitatica (SpCas12f)-a very small Cas of 497 a.a, which is a more suitable size for virus vectors-was reported. However, there are no reports of genome editing using SpCas12f in crops other than maize. In this study, we applied SpCas12f to genome editing in rice-one of the most important staple crops in the world. An expression vector encoding rice codon-optimized SpCas12f and sgRNA for OsTubulin as a target was introduced into rice calli by Agrobacterium-mediated transformation. Molecular analysis of SpCas12f-transformed calli showed that mutations were introduced successfully into the target region. Detailed analysis by amplicon sequencing revealed estimated mutation frequencies (a ratio of the number of mutated calli to that of SpCas12f-transformed calli) of 28.8% and 55.6% in two targets. Most mutation patterns were deletions, but base substitutions and insertions were also confirmed at low frequency. Moreover, off-target mutations by SpCas12f were not found. Furthermore, mutant plants were regenerated successfully from the mutated calli. It was confirmed that the mutations in the regenerated plants were inherited to the next-generation. In the previous report in maize, mutations were introduced by treatment with heat shock at 45°C for 4h per day for 3days; no mutations were introduced under normal growth conditions at 28°C. Surprisingly, however, mutations can be introduced without heat-shock treatment in rice. This might be due to the culture conditions, with relatively higher temperature (30°C or higher) and constant light during callus proliferation. Taken together, we demonstrated that SpCas12f can be used to achieve targeted mutagenesis in rice. SpCas12f is thus a useful tool for genome editing in rice and is suitable for virus vector-mediated genome editing due to its very small size.

Use of Heat-Shock and Edible Coating to Improve the Postharvest Preservation of Blueberries.

The quality of blueberry fruit is easily altered after harvest. We investigated the regulatory mechanism of heat-shock (postharvest treatment) and edible coating (preharvest treatment) on the post-harvest physiological quality of blueberry from the perspective of physiological, biochemical and organoleptic characteristics. In our research, the optimal TKL concentration and the appropriate range of heat-shock temperatures were first screened based on actual application results, and then a combination of heat-shock temperature and TKL coating with significant differences in preservation effects was selected to investigate the effects of different heat-shock temperatures and TKL60 composite coating on post-harvest quality and volatile compound concentration of blueberries under refrigerated conditions. Our results showed that TKL with 60 mg/L thymol can retard the development of the degree of membrane lipid peroxidation and effectively reduce the incidence of fruit decay and the severity of blueberries infected with major pathogens at 25 °C. Meanwhile, heat-shock treatments were effective in maintaining the quality of blueberries, with a certain advantage from 45 °C to 65 °C after 8 d of storage at ambient temperature, but these treated groups were slightly inferior to TKL60 groups for fresh-keeping effect. Remarkably, the combination of heat-shock treatment and edible coating application could extend the shelf life of blueberries by 7-14 d compared to the results obtained with coating alone under low temperature storage. Specifically, heat treatment at 45 °C for 60 min after TKL60 coating (HT2) retarded the decrease in the levels of ascorbic acid, total anthocyanin, total acid and soluble solids. Gas chromatography-mass spectrometry hierarchical clustering analysis showed that this treatment also improved the aroma of the fruit, which maintained a certain similarity with that of fresh blueberries after 14 d. Principal component analysis (PCA) of the results of the evaluations carried out using an electronic nose (E-nose) and electronic tongue (E-tongue) showed that blueberries of the HT2 treated group did not show a large placement change of the PC1 distribution area from that of the fresh and blank control group. Accordingly, the combination of coating with heat-shock treatment can effectively improve the post-harvest quality and aroma compound concentration of blueberries, showing good application potential in storage and preservation of fresh fruits such as blueberries.

Rice OsHsp16.9A interacts with OsHsp101 to confer thermotolerance

Class I small heat shock proteins (CI sHSPs), OsHsp16.9A and OsHsp18.0, share 74% identity in amino acid sequences and accumulate in response to heat shock treatments. Individual rice transformants overexpressing OsHsp16.9A and OsHsp18.0 exhibit distinct thermoprotection/thermotolerance modes. Under high temperature stress, OsHsp16.9A-overexpressing lines showed higher seed germination rate, seedling survival, and pollen germination than wild-type controls, while OsHsp18.0 overexpression provided higher thermoprotection/thermotolerance for seedling survival. To elucidate the functional roles of OsHsp16.9A, mass spectrometry was used to identify OsHsp16.9A-interacting proteins. OsHsp101 was consistently identified in the OsHsp16.9A protein complex in several mass spectrometry analyses of seed proteins from OsHsp16.9A-overexpressing lines. Both OsHsp16.9A and OsHsp101 proteins accumulated during similar developmental stages of rice seeds and formed a heat-stable complex under high temperature treatments in in vitro assays. Co-localization of OsHsp16.9A and OsHsp101 was observed via ratiometric bimolecular fluorescence complementation analyses. Amino acid mutation studies revealed that OsHsp16.9A glutamate residue 74 and amino acid residues 23–36 were essential for OsHsp16.9A–OsHsp101 interaction. Moreover, overexpressing OsHsp16.9A in OsHsp101 knockdown mutants did not increase the seed germination rate under heat stress, which further confirmed the functional roles of OsHsp16.9A–OsHsp101 interaction in conferring thermotolerance to rice plants.

Lipid ROS- and Iron-Dependent Ferroptotic Cell Death in Unicellular Algae Chlamydomonas reinhardtii.

The phenomenon of heat stress leading to ferroptosis-like cell death has recently been observed in bacteria as well as plant cells. Despite recent findings, the evidence of ferroptosis, an iron-dependent cell death remains unknown in microalgae. The present study aimed to investigate if heat shock could induce reactive oxygen species (ROS) and iron-dependent ferroptotic cell death in Chlamydomonas reinhardtii in comparison with RSL3-induced ferroptosis. After RSL3 and heat shock (50 °C) treatments with or without inhibitors, Chlamydomonas cells were evaluated for cell viability and the induction of ferroptotic biomarkers. Both the heat shock and RSL3 treatment were found to trigger ferroptotic cell death, with hallmarks of glutathione-ascorbic acid depletion, GPX5 downregulation, mitochondrial dysfunction, an increase in cytosolic calcium, ROS production, lipid peroxidation, and intracellular iron accumulation via heme oxygenase-1 activation (HO-1). Interestingly, the cells preincubated with ferroptosis inhibitors (ferrostatin-1 and ciclopirox) significantly reduced RSL3- and heat-induced cell death by preventing the accumulation of Fe2+ and lipid ROS. These findings reveal that ferroptotic cell death affects the iron homeostasis and lipid peroxidation metabolism of Chlamydomonas, indicating that cell death pathways are evolutionarily conserved among eukaryotes.

Efficient Production of Doubled Haploids as Isogenic Line Founders via Double Heat Shock Treatment in Willow Gudgeon (Gnathopogon caerulescens)

Doubled haploids (DHs) are essential founders for breeding via isogenic line production. We determined the optimal timing of the first and second (HST1 and HST2) double heat shock treatment for DH production in the willow gudgeon (Gnathopogon caerulescens). Gynogenesis was induced by fertilisation with UV-irradiated sperm (20 mJ/cm2). Each HST was performed at 40.5°C for 1 min. In experiment I, HST1 was applied 23–31 min after the induction of gynogenetic development (incubated at 20°C). HST2 was performed 15 min after HST1 treatment. When HST1 was started 25–26 min after activation, normally hatched larvae appeared relatively frequently (35.6–100%), and most were DHs. In experiment II, HST1 was started 26 min after activation, and HST2 was started 10–25 min after HST1. Starting HST2 10 min after HST1 resulted in 33% more normally hatched larvae than starting 22.5–25 min after. DHs were prevalent among hatched larvae (45.1% and 20.8%, respectively) when performing HST2 10–12.5 min after HST1. Under appropriate HST1 and HST2 timing, gynogens were at the zygote stage, early prophase, and prophase or early prometaphase of the first cell cycle. These results establish the appropriate timing of HST1 and HST2 for the induction of willow gudgeon DHs.

Prussian Blue Nanoparticle-Entrapped GelMA Gels Laden with Mesenchymal Stem Cells as Prospective Biomaterials for Pelvic Floor Tissue Repair.

Pelvic organ prolapse (POP) seriously affects elderly patients' quality of life, and new repair materials are urgently needed. To solve this problem, we synthesized methacrylated gelatin (GelMA) hydrogels and incorporated photothermally active Prussian blue nanoparticles (PBNPs) to synthesize PBNP@GelMA. Then, MSCs were encapsulated in the PBNP@GelMA and exposed to a 1.0 W/cm2 of 808 nm laser for 10 min to perform heat shock pretreatment for the implantation of mesenchymal stem cells (MSCs). Next, we tested the repair efficacy of scaffold-cell complexes both in vitro and in vivo. Our results reveal that the heat shock treatment induced by PBNP@GelMA improved the viability of MSCs, and the underlying mechanism may be related to HSP70. Furthermore, 2 weeks after implantation in the SD rat model, the collagen content increased in the MSC implantation group and PBNP@GelMA implantation group. However, the muscle regeneration at the implanting position was mostly enhanced after the implantation of the heat-shock-pretreated MSCs, which illustrates that heat shock treatment can further promote the MSC-mediated muscle regeneration. Therefore, manipulating the cell environment and providing proper heat stimulus by using PBNP@GelMA with NIR is a novel strategy to enhance the regenerative potential of MSCs and to promote pelvic tissue repair.

A method to enrich polypeptidyl-tRNAs to capture snapshots of translation in the cell.

Life depends on proteins, which all exist in nascent states when the growing polypeptide chain is covalently attached to a tRNA within the ribosome. Although the nascent chains, i.e. polypeptidyl-tRNAs (pep-tRNAs), are considered as merely transient intermediates during protein synthesis, recent advances have revealed that they are directly involved in a variety of cell functions, such as gene expression control. An increasing appreciation for fine-tuning at translational levels demands a general method to handle the pep-tRNAs on a large scale. Here, we developed a method termed peptidyl-tRNAenrichment using organic extraction and silica adsorption (PETEOS), and then identify their polypeptide moieties by mass spectrometry. As a proof-of-concept experiment using Escherichia coli, we identified ∼800 proteins derived from the pep-tRNAs, which were markedly biased towards the N-termini in the proteins, reflecting that PETEOS captured the intermediate pep-tRNA population during translation. Furthermore, we observed the changes in the pep-tRNA set in response to heat shock or antibiotic treatments. In summary, PETEOS will complement conventional methods to investigate nascent chains in the cell.

Tracking of thermal microbial shock proteins and genomic variation of Bacillus cereus due to some abiotic stresses.

Bacillus cereus is considered the most potent bacterial strain in terms of the increment in induced proteins during thermal treatment at 52 °C for 90 min. Protein production in food-born microorganism (Bacillus cereus) recovered from contaminated food was investigated in response to heat shock treatment. Bacterial tolerance towards pH, salinity, and temperature at various levels was also investigated. Heat-shock proteins (HSPs) produced when exposed to 52 °C for up to 60 minutes led to significant differences (30%) above the untreated control (37 °C), and the maximum difference was recorded at 52°C at 90 minutes. ISSR detected a higher number of bands/primer than RAPD (13.7 vs. 12.7, respectively), and more polymorphic bands (10.7 vs. 8.4 bands/primer, respectively). The untreated bacterial strain did not grow at pH levels lower than 3, whereas the thermally treated strain grew significantly at pH two. A consistent increase in HSPs was observed, with a gradual increase in salinity of less than 16%. Surprisingly, the gradual increase in temperature did not induce tolerance against higher temperatures. However, a significant growth rate was noticed in response to heat-shocked treatments. The untreated Bacillus cereus demonstrated antibiotic resistance to gentamycin and clindamycin (1.54 and 1.65 cm, respectively), much lower than the corresponding inhibition areas with preheat-treated test pathogen which were recorded (2.37 and 2.49 cm, respectively).

Biological studies of Puccinia lantanae, a potential biocontrol agent of “Lippia” (Phyla nodiflora var. minor)

Phyla nodiflora var. minor (syn. P. canescens (Kunth) Greene) known as “lippia” is an invasive weed with considerable impact on agricultural systems and conservation areas in Australia. The rust fungus Puccinia lantanae Farl. has been proposed as a potential biocontrol agent of Lantana camara. As it was previously found in Lippia s.l. in Argentina, we aim to study: (i) its geographical distribution in Argentina, Bolivia, and Chile; (ii) teliospore germination and basidiospore formation under different incubation temperatures; (iii) the effect of teliospore age on germination capacity; (iv) the effect of heat shock on teliospore germination and basidiospore formation; and (v) the pathogenicity of the rust fungus on P. nodiflora. Field surveys were conducted in Argentina, Bolivia, and Chile. In vitro experimental assays of germination and pathogenicity were performed. The rust was found in four provinces of Argentina (Jujuy, Salta, Formosa, and Entre Rios) and was not found in Bolivia and Chile. Puccinia lantanae showed the maximum values of teliospore germination and basidiospore formation at 20°C. The effect of aging and heat shock treatments significantly reduced teliospore germination. Pathogenicity tests showed that P. nodiflora var. minor, reptans, and nodiflora were infected with the “Formosa” isolate. The isolates “Salta” and “Entre Rios” infected var. minor and reptans, being potential candidates for biocontrol.

Effects of the repair treatment on improving the heat resistance of Lactiplantibacillus plantarum LIP-1

To improve the heat resistance of lactobacilli during spray-drying, we first investigated the effect of heat shock and repair treatment on the heat resistance of Lactiplantibacillus plantarum LIP-1, and the specific cell repair mechanism. Compared with control group, the reduction of the strain after the heat treatment (75 °C for 40 s) decreased from 1.05 to 0.36 log CFU/mL (initial cell counts 9.30 log CFU/mL) by heat shock (44 °C for 10 min). The residuals of the strain after heat-treated increased by 0.90 log CFU/mL by heat shock firstly, and then the repair treatment (30 °C for 10 min).During recovery period, the relative content of unsaturated long-chain fatty acids (C18:1n9 & C18:2n6) induced by heat shock proteins increased by 7.0%, and the amount of DnaK protein anchored on the cell membrane increased by 0.17 pg/mL. Cell membrane damage caused by heat shock was reduced and strain heat resistance was improved. Industrial relevanceOur research found that the repair treatment after heat shock reduced cell membrane damage caused by heat shock, which is a very promising technology for improving the heat resistance of L. plantarum LIP-1. This technology is also expected to be widely used in the preparation of LAB powders by spray-drying technology.