The relative nature of the standards for proof of safety: a review of FDA's safety standards for various consumer products.

Are all food ingredients, dietary supplement ingredients and even foods, required to meet the same safety standards? Are they all equally safe? If so, then why do the various categories have different expressions describing their safety, such as "reasonable certainty of no harm" for food ingredients and "reasonable expectation of no harm" for dietary supplement ingredients? The basis for these different expressions is that they are not standards of safety, but standards of proof of safety. Just as in criminal vs. civil courts, the threshold for proving guilt or fault is different, so too are there differences between various categories of consumer products regulated by the US Food and Drug Administration. This manuscript describes the threshold requirements for each standard, as well as to the identity of the decision makers on what is safe, their credentials as decision makers and the databases mandated for their use.

Understanding bacteriocin heterologous expression: A review.

Bacteriocins are a diverse group of ribosomally synthesised antimicrobial peptides/proteins that play an important role in self-defence. They are widely used as bio-preservatives and effective substitutes for disease eradication. They can be used in conjunction with or as an alternative to antibiotics to minimize the risk of resistance development. There are remarkably few reports indicating resistance to bacteriocins. Although there are many research reports that emphasise heterologous expression of bacteriocin, there are no convincing reports on the significant role that intrinsic and extrinsic factors play in overexpression. A coordinated and cooperative expression system works in concert with multiple genetic elements encoding native proteins, immunoproteins, exporters, transporters and enzymes involved in the post-translational modification of bacteriocins. The simplest way could be to utilise the existing E. coli expression system, which is conventional, widely used for heterologous expression and has been further extended for bacteriocin expression. In this article, we will review the intrinsic and extrinsic factors, advantages, disadvantages and major problems associated with bacteriocin overexpression in E. coli. Finally, we recommend the most effective strategies as well as numerous bacteriocin expression systems from E. coli, Lactococcus, Kluveromyces lactis, Saccharomyces cerevisiae and Pichia pastoris for their suitability for successful overexpression.

Genome-Wide Identification of GRAS Transcription Factors and Their Functional Analysis in Salt Stress Response in Sugar Beet.

GAI-RGA-and-SCR (GRAS) transcription factors can regulate many biological processes such as plant growth and development and stress defense, but there are few related studies in sugar beet. Salt stress can seriously affect the yield and quality of sugar beet (Beta vulgaris). Therefore, this study used bioinformatics methods to identify GRAS transcription factors in sugar beet and analyzed their structural characteristics, evolutionary relationships, regulatory networks and salt stress response patterns. A total of 28 BvGRAS genes were identified in the whole genome of sugar beet, and the sequence composition was relatively conservative. According to the topology of the phylogenetic tree, BvGRAS can be divided into nine subfamilies: LISCL, SHR, PAT1, SCR, SCL3, LAS, SCL4/7, HAM and DELLA. Synteny analysis showed that there were two pairs of fragment replication genes in the BvGRAS gene, indicating that gene replication was not the main source of BvGRAS family members. Regulatory network analysis showed that BvGRAS could participate in the regulation of protein interaction, material transport, redox balance, ion homeostasis, osmotic substance accumulation and plant morphological structure to affect the tolerance of sugar beet to salt stress. Under salt stress, BvGRAS and its target genes showed an up-regulated expression trend. Among them, BvGRAS-15, BvGRAS-19, BvGRAS-20, BvGRAS-21, LOC104892636 and LOC104893770 may be the key genes for sugar beet's salt stress response. In this study, the structural characteristics and biological functions of BvGRAS transcription factors were analyzed, which provided data for the further study of the molecular mechanisms of salt stress and molecular breeding of sugar beet.

Comparison of different derivatisation for amino acids determination of foie gras by high performance liquid chromatography (HPLC).

1. In order to compare the difference between different derivatisations for amino acids determination of foie gras via, reversed phase high performance liquid chromatography (HPLC), O-phthalaldehyde and 9-fluorenyl-methyl chloroformate (OPA-FMOC group), phenylisothiocyanate (PITC group) and 6-Aminoquinolyl-N-hydrox-ysuccinimidyl Carbamate (AQC group) were applied to derivatisation reagent in this current experiment. The determination results of automatic amino acid analyser were applied, and 17 amino acids were detected by these three derivatisation methods.2. The running times of OPA-FMOC group, PITC group and AQC group were 18, 45 and 35 min, respectively. There was a large difference between the results of OPA-FMOC group and results from the automatic amino acid analyser, although the difference between the results from PITC and the automatic amino acid analyser was minimal.3. In conclusion, the running time of OPA-FMOC group was shorter than that of PITC group and AQC group; the accuracy of the former was better than the OPA-FMOC group and AQC group for the determination of amino acid of foie gras.

Nature-Derived Gelatin-Based Antifungal Nanotherapeutics for combatting Candida albicans Biofilms.

Infections caused by fungi are emerging global health challenges that are exacerbated by the formation of fungal biofilms. Further challenges arise from environmental contamination with antifungal agents, which promotes environmental acquisition of antifungal resistance. We report the generation of an efficient, sustainable, all-natural antifungal nanotherapeutic based on the integration of an antimicrobial natural essential oil into a gelatin-based nanoemulsion platform. Carvacrol-loaded gelatin nanoemulsions penetrated Candida albicans biofilms, resulting in death of C. albicans cells in biofilms, and displayed selective biofilm elimination without harmful effects on fibroblast cells in a fungal biofilm-mammalian fibroblast co-culture model. Furthermore, the nanoemulsions degraded in the presence of physiologically relevant biomolecules, reducing the potential for environmental pollution and ecotoxicity. Overall, the sustainability, and efficacy of the described gelatin nanoemulsion formulation provides an environmentally friendly strategy for treating biofilm-associated fungal infections, including those caused by drug-resistant fungi.

Genome-wide identification and expression analysis of GRAS gene family in Eucalyptus grandis.

BACKGROUND: The GRAS gene family is a class of plant-specific transcription factors with important roles in many biological processes, such as signal transduction, disease resistance and stress tolerance, plant growth and development. So far, no information available describes the functions of the GRAS genes in Eucalyptus grandis. RESULTS: A total of 82 GRAS genes were identified with amino acid lengths ranging from 267 to 817 aa, and most EgrGRAS genes had one exon. Members of the GRAS gene family of Eucalyptus grandis are divided into 9 subfamilies with different protein structures, while members of the same subfamily have similar gene structures and conserved motifs. Moreover, these EgrGRAS genes expanded primarily due to segmental duplication. In addition, cis-acting element analysis showed that this family of genes was involved involved in the signal transduction of various plant hormones, growth and development, and stress response. The qRT-PCR data indicated that 18 EgrGRAS genes significantly responded to hormonal and abiotic stresses. Among them, the expression of EgrGRAS13, EgrGRAS68 and EgrGRAS55 genes was significantly up-regulated during the treatment period, and it was hypothesised that members of the EgrGRAS family play an important role in stress tolerance. CONCLUSIONS: In this study, the phylogenetic relationship, conserved domains, cis-elements and expression patterns of GRAS gene family of Eucalyptus grandis were analyzed, which filled the gap in the identification of GRAS gene family of Eucalyptus grandis and laid the foundation for analyzing the function of EgrGRAS gene in hormone and stress response.

Is stimulation of browning of human adipose tissue a relevant therapeutic target?

Brown adipose tissue (BAT) and beige adipose tissues are important contributors to cold-induced whole body thermogenesis in rodents. The documentation in humans of cold- and ß-adrenergic receptor agonist-stimulated BAT glucose uptake using positron emission tomography (PET) and of a decrease of this response in individuals with cardiometabolic disorders led to the suggestion that BAT/beige adipose tissues could be relevant targets for prevention and treatment of these conditions. In this brief review, we will critically assess this question by first describing the basic rationale for this affirmation, second by examining the evidence in human studies, and third by discussing the possible means to activate the thermogenic response of these tissues in humans.

Assessment of prognostic factors in pediatric adrenocortical tumors: the modified pediatric S-GRAS score in an international multicenter cohort-a work from the ENSAT-PACT working group.

OBJECTIVE: Pediatric adrenocortical carcinoma (pACC) is rare, and prognostic stratification remains challenging. We aimed to confirm the prognostic value of the previously published pediatric scoring system (pS-GRAS) in an international multicenter cohort. DESIGN: Analysis of pS-GRAS items of pACC from 6 countries in collaboration of ENSAT-PACT, GPOH-MET, and IC-PACT. METHODS: We received patient data of the pS-GRAS items including survival information from 9 centers. PS-GRAS score was calculated as a sum of tumor stage (1 = 0; 2-3 = 1; 4 = 2 points), grade (Ki67 index: 0%-9% = 0; 10%-19% = 1; ≥20% = 2 points), resection status (R0 = 0; RX/R1/R2 = 1 point), age (<4 years = 0; ≥4 years = 1 point), and hormone production (androgen production = 0; glucocorticoid-/mixed-/no-hormone production = 1 point) generating 8 scores and 4 groups (1: 0-2, 2: 3-4, 3: 5, 4: 6-7). Primary endpoint was overall survival (OS). RESULTS: We included 268 patients with median age of 4 years. The analysis of the pS-GRAS score showed a significantly favorable prognosis in patients with a lower scoring compared to higher scoring groups (5-year OS: Group 1 98%; group 2 87% [hazard ratio {HR} of death 3.6, 95% CI of HR 1.6-8.2]; group 3 43% [HR of death 2.8, 95% CI 1.9-4.4]; group 4: OS 18% [HR of death 2.1, 95% CI 1.7-2.7]). In the multivariable analysis, age (HR of death 3.5, 95% CI 1.8-7.0), resection status (HR of death 5.5, 95% CI 2.7-11.1), tumor stage (HR of death 1.9, 95% CI of HR 1.2-3.0), and Ki67 index (HR of death 1.7, 95% CI 1.2-2.4) remained strong independent outcome predictors. Especially infants < 4 years showed more often low-risk constellations with a better OS for all tumor stages. CONCLUSION: In an international multicenter study, we confirmed that the pS-GRAS score is strongly associated with overall survival among patients with pACC. Age, resection status, stage, and Ki67 index are important parameters for risk stratification.

Genome-Wide Identification and Expression Analysis of the GRAS Gene Family and Their Responses to Heat Stress in Cymbidium goeringii.

The GRAS gene family, responsible for encoding transcription factors, serves pivotal functions in plant development, growth, and responses to stress. The exploration of the GRAS gene family within the Orchidaceae has been comparatively limited, despite its identification and functional description in various plant species. This study aimed to conduct a thorough examination of the GRAS gene family in Cymbidum goeringii, focusing on its physicochemical attributes, phylogenetic associations, gene structure, cis-acting elements, and expression profiles under heat stress. The results show that a total of 54 CgGRASs were pinpointed from the genome repository and categorized into ten subfamilies via phylogenetic associations. Assessment of gene sequence and structure disclosed the prevalent existence of the VHIID domain in most CgGRASs, with around 57.41% (31/54) CgGRASs lacking introns. The Ka/Ks ratios of all CgGRASs were below one, indicating purifying selection across all CgGRASs. Examination of cis-acting elements unveiled the presence of numerous elements linked to light response, plant hormone signaling, and stress responsiveness. Furthermore, CgGRAS5 contained the highest quantity of cis-acting elements linked to stress response. Experimental results from RT-qPCR demonstrated notable variations in the expression levels of eight CgGRASs after heat stress conditions, particularly within the LAS, HAM, and SCL4/7 subfamilies. In conclusion, this study revealed the expression pattern of CgGRASs under heat stress, providing reference for further exploration into the roles of CgGRAS transcription factors in stress adaptation.

Evaluation of the Genotoxicity of Almond Hull: Implications for Its Use as a Novel Food Ingredient.

Almond hull, a substantial byproduct comprising more than half of almond fresh weight, has recently gained attention due to its functionality and sustainability benefits. Despite heightened interest, information regarding its toxicity remains limited. In order to assess its genotoxic potential, we conducted Good Laboratory Practice-compliant in vitro and in vivo studies following Organization for Economic Co-operation and Development (OECD) guidelines. No evidence of toxicity or mutagenicity was observed in a bacterial reverse mutation assay using five tester strains, evaluating almond hull at concentrations up to 5 mg/plate, with or without metabolic activation. Almond hull did not induce chromosome structural damage in a chromosome aberration assay using Chinese hamster ovary cells, nor did it cause any spermatogonial chromosomal aberration in tested male BALB/c mice. To evaluate its ability to induce DNA damage in rodents, a combined micronucleus assay was conducted in KM mice of both sexes. Almond hull was administered at doses of 1250, 2500, and 5000 mg/kg/day via gavage once daily for 2 days. No adverse effects of almond hull were observed in the micronucleus assay. Our results indicate no evidence of the genotoxic potential of almond hull administered up to the maximum concentrations of 5 g/kg, as recommended by OECD guidelines.

Genome-Wide Identification and Characterization of the GRAS Gene Family in Lettuce Revealed That Silencing LsGRAS13 Delayed Bolting.

Lettuce is susceptible to high-temperature stress during cultivation, leading to bolting and affecting yield. Plant-specific transcription factors, known as GRAS proteins, play a crucial role in regulating plant growth, development, and abiotic stress responses. In this study, the entire lettuce LsGRAS gene family was identified. The results show that 59 LsGRAS genes are unevenly distributed across the nine chromosomes. Additionally, all LsGRAS proteins showed 100% nuclear localization based on the predicted subcellular localization and were phylogenetically classified into nine conserved subfamilies. To investigate the expression profiles of these genes in lettuce, we analyzed the transcription levels of all 59 LsGRAS genes in the publicly available RNA-seq data under the high-temperature treatment conducted in the presence of exogenous melatonin. The findings indicate that the transcript levels of the LsGRAS13 gene were higher on days 6, 9, 15, 18, and 27 under the high-temperature (35/30 °C) treatment with melatonin than on the same treatment days without melatonin. The functional studies demonstrate that silencing LsGRAS13 accelerated bolting in lettuce. Furthermore, the paraffin sectioning results showed that flower bud differentiation in LsGRAS13-silenced plants occurred significantly faster than in control plants. In this study, the LsGRAS genes were annotated and analyzed, and the expression pattern of the LsGRAS gene following melatonin treatment under high-temperature conditions was explored. This exploration provides valuable information and identifies candidate genes associated with the response mechanism of lettuce plants high-temperature stress.

A review of the safety evidence on recombinant human lactoferrin for use as a food ingredient.

Published studies on the glycosylation, absorption, distribution, metabolism, excretion, and safety outcomes of orally ingested recombinant human lactoferrin (rhLF) were reviewed in the context of unanswered safety questions, including alloimmunization, allergenicity, and immunotoxicity potential of rhLF during repeated exposure. The primary objective was to summarize current safety data of rhLF produced in transgenic host expression systems. Overall, results from animal and human studies showed that rhLF was well tolerated and safe. Animal data showed no significant toxicity-related outcomes among any safety or tolerability endpoints. The no observed adverse effect levels (NOAEL) were at the highest level tested in both iron-desaturated and -saturated forms of rhLF. Although one study reported outcomes of rhLF on immune parameters, no animal studies directly assessed immunogenicity or immunotoxicity from a safety perspective. Data from human studies were primarily reported as adverse events (AE). They showed no or fewer rhLF-related AE compared to control and no evidence of toxicity, dose-limiting toxicities, or changes in iron status in various subpopulations. However, no human studies evaluated the immunomodulatory potential of rhLF as a measure of safety. Following this review, a roadmap outlining preclinical and clinical studies with relevant safety endpoints was developed to address the unanswered safety questions.

A review of the toxicity of ingredients in e-cigarettes, including those ingredients having the FDA's "Generally Recognized as Safe (GRAS)" regulatory status for use in food.

INTRODUCTION: Some firms and marketers of electronic cigarettes (e-cigarettes; a type of electronic nicotine delivery system (ENDS)) and refill liquids (e-liquids) have made claims about the safety of ingredients used in their products based on the term "GRAS or Generally Recognized As Safe" (GRAS). However, GRAS is a provision within the definition of a food additive under section 201(s) (21 U.S.C. 321(s)) of the U.S. Federal Food Drug and Cosmetic Act (FD&C Act). Food additives and GRAS substances are by the FD&C Act definition intended for use in food, thus safety is based on oral consumption; the term GRAS cannot serve as an indicator of the toxicity of e-cigarette ingredients when aerosolized and inhaled (i.e., vaped). There is no legal or scientific support for labeling e-cigarette product ingredients as "GRAS". This review discusses our concerns with the GRAS provision being applied to e-cigarette products and provides examples of chemical compounds that have been used as food ingredients but have been shown to lead to adverse health effects when inhaled. The review provides scientific insight into the toxicological evaluation of e-liquid ingredients and their aerosols to help determine the potential respiratory risks associated with their use in e-cigarettes. IMPLICATIONS: The rise in prevalence of e-cigarette use and emerging evidence of adverse effects, particularly on lung health, warrant assessing all aspects of e-cigarette toxicity. One development is manufacturers' stated or implied claims of the safety of using e-cigarette products containing ingredients determined to be "Generally Recognized As Safe" (GRAS) for use in food. Such claims, typically placed on e-cigarette product labels and used in marketing, are unfounded, as pointed out by the United States Food and Drug Administration (FDA)1 and the Flavor and Extract Manufacturers Association (FEMA)2. Assessment of inhalation health risks of all ingredients used in e-liquids, including those claimed to be GRAS, is warranted.

A dual regulatory role of the arbuscular mycorrhizal master regulator RAM1 in tomato.

The REQUIRED FOR ARBUSCULAR MYCORRHIZATION1 (RAM1) transcription factor from the GRAS family is well-known by its role as a master regulator of the arbuscular mycorrhizal (AM) symbiosis in dicot and monocot species, being essential in the transcriptional reprograming for the development and functionality of the arbuscules. In tomato, SlGRAS27 is the putative ortholog of RAM1 (here named SlRAM1), but has not yet been characterized. A reduced colonization of the root and an impaired arbuscule formation were observed in the SlRAM1 silenced plants, confirming the functional conservation of the RAM1 ortholog in tomato . However, unexpectedly, SlRAM1 overexpressing (UBIL:SlRAM1) plants also showed a decreased mycorrhizal colonization. Analysis of non-mycorrhizal UBIL:SlRAM1 roots revealed an overall regulation of AM-related genes and a reduction of strigolactone biosynthesis. Moreover, the external application of the strigolactone analogue GR244DO almost completely reversed the negative effects of SlRAM1 overexpression on the frequency of mycorrhization. However, it only partially recovered the pattern of arbuscule distribution observed in control plants. Our results strongly suggest that SlRAM1 has a dual regulatory role during mycorrhization and, apart from its recognized action as a positive regulator of arbuscule development, SlRAM1 is also involved in different mechanisms for the negative regulation of mycorrhization, including the repression of strigolactone biosynthesis.

Effectiveness of Several GRAS Salts against Fungal Rot of Fruit after Harvest and Assessment of the Phytotoxicity of Sodium Metabisufite in Treated Fruit.

This study evaluates the efficacy of the salts sodium metabisulfite (SMB), ammonium bicarbonate, sodium bicarbonate, and potassium dihydrogen orthophosphate first in vitro against the main postharvest fruit rot fungi, Alternaria alternata, Botrytis cinerea, Penicillium italicum, and Penicillium digitatum. Results showed that 0.2% SMB completely inhibited the mycelium growth of the fungal species. Ammonium bicarbonate and sodium bicarbonate were less effective at 0.2% in inhibiting mycelial growth, ranging from 57.6% to 77.6%. The least effective was potassium dihydrogen orthophosphate. Experiments were also performed in vivo on wounded apples inoculated with the most pathogenic fungus, B. cinerea, and treated with SMB at concentrations of 0.2, 0.5, 1, 2, and 3%, both preventively and curatively. Results based on the decay size showed that SMB, when used as a preventive treatment, had a reduced efficacy, even with the highest concentration. However, this salt proved to be very effective at 0.5% in curative treatment since the decay was completely blocked. Our results suggest that the appropriate concentration of SMB for post-harvest treatment is 0.5% as a curative treatment. On the other hand, the 1% dose induced the onset of phytotoxicity around the wound. To assess the extent of the phytotoxicity reaction, higher concentrations of 1-4% SMB were applied to wounded fruit. Apples and oranges were inoculated or not with B. cinerea and P. digitatum, respectively. Doses of 1-4% induced phytotoxicity in the form of a discolored ring surrounding the wound on the epidermis of the fruit; this phytotoxicity enlarged as the concentration of SMB increased. The phytotoxic features were similar on apples and oranges. The methodological procedure made it possible to carry out a quantitative assessment of SMB phytotoxicity. This method is proposed as an easy-to-use technique for quantitatively estimating the phytotoxicity of antifungal compounds on post-harvest fruit.

Sugar Utilization-Associated Food-Grade Selection Markers in Lactic Acid Bacteria and Yeast.

This comprehensive review explores the development of food-grade selection markers in lactic acid bacteria and yeast; some of their strains are precisely defined as safe microorganisms and are crucial in the food industry. Lactic acid bacteria, known for their ability to ferment carbohydrates into lactic acid, provide essential nutrients and contribute to immune responses. With its strong fermentation capabilities and rich nutritional profile, yeast finds use in various food products. Genetic engineering in these microorganisms has grown rapidly, enabling the expression of enzymes and secondary products for food production. However, the focus is on ensuring safety, necessitating food-grade selection markers. Traditional antibiotic and heavy metal resistance selection markers pose environmental and health risks, prompting the search for safer alternatives. Complementary selection markers, such as sugar utilization markers, offer a promising solution. These markers use carbohydrates as carbon sources for growth and are associated with the natural metabolism of lactic acid bacteria and yeast. This review discusses the use of specific sugars, such as lactose, melibiose, sucrose, D-xylose, glucosamine, and N-acetylglucosamine, as selection markers, highlighting their advantages and limitations. In summary, this review underscores the importance of food-grade selection markers in genetic engineering and offers insights into their applications, benefits, and challenges, providing valuable information for researchers in the field of food microbiology and biotechnology.

PpSCARECROW1 (PpSCR1) regulates leaf blade and mid-vein development in Physcomitrium patens.

In plants, asymmetric cell divisions result in distinct cell fates forming large and small daughter cells, adding to the cellular diversity in an organ. SCARECROW (SCR), a GRAS domain-containing transcription factor controls asymmetric periclinal cell divisions in flowering plants by governing radial patterning of ground tissue in roots and cell proliferation in leaves. Though SCR homologs are present across land plant lineages, the current understanding of their role in cellular patterning and leaf development is mostly limited to flowering plants. Our phylogenetic analysis identified three SCR homologs in moss Physcomitrium patens, amongst which PpSCR1 showed highest expression in gametophores and its promoter activity was prominent at the mid-vein and the flanking leaf blade cells pointing towards its role in leaf development. Notably, out of the three SCR homologs, only the ppscr1 knock-out lines developed slender leaves with four times narrower leaf blade and three times thicker mid-vein. Detailed histology studies revealed that slender leaf phenotype is either due to the loss of anticlinal cell divisions or failure of periclinal division suppression in the leaf blade. RNA-Seq analyses revealed that genes responsible for cell division and differentiation are expressed differentially in the mutant. PpSCR1 overexpression lines exhibited significantly wider leaf lamina, further reconfirming the role in leaf development. Together, our data suggests that PpSCR1 is involved in the leaf blade and mid-vein development of moss and that its role in the regulation of cell division and proliferation is ancient and conserved among flowering plants and mosses.

Unveiling the Probiotic Potential of Streptococcus thermophilus MCC0200: Insights from In Vitro Studies Corroborated with Genome Analysis.

Streptococcus thermophilus is widely used as a starter culture in the dairy industry and has garnered attention as a beneficial bacterium owing to its health-promoting functionalities in humans. In this study, the probiotic potential of S. thermophilus MCC0200 isolated from a dairy product was investigated through a combinatorial approach of in vitro and in silico studies. MCC0200 demonstrated the ability to survive harsh gastrointestinal (GI) transit, adhere to intestinal mucosa and exert health-promoting traits in in vitro studies. These findings were corroborated with in silico evidence, wherein, MCC0200 genome harboured genes associated with tolerance to GI conditions, intestinal adhesion and colonization. Genome mapping also highlighted the ability of MCC0200 to produce compounds advantageous for the host (folate, bacteriocins), to release antioxidant enzymes that can quench the free radicals (superoxide dismutase, NADH peroxidase), and to metabolize food components that can be harmful to sensitive people (lactose). MCC0200 also demonstrated a positive effect on reducing cholesterol levels, proving to be a potential candidate for food and pharmaceutical applications. The absence of transmissible antibiotic resistance genes and virulence genes underscored the generally regarded as safe (GRAS) nature of MCC0200. This study explored the potential of Streptococcus thermophilus for its probable applications as a probiotic beyond the dairy industry.

Comprehensive Analysis of the GRAS Gene Family in Paulownia fortunei and the Response of DELLA Proteins to Paulownia Witches' Broom.

The GRAS (GAI\RGA\SCL) gene family encodes plant-specific transcription factors that play crucial roles in plant growth and development, stress tolerance, and hormone network regulation. Plant dwarfing symptom is mainly regulated by DELLA proteins of the GRAS gene subfamily. In this study, the association between the GRAS gene family and Paulownia witches' broom (PaWB) was investigated. A total of 79 PfGRAS genes were identified using bioinformatics methods and categorized into 11 groups based on amino acid sequences. Tandem duplication and fragment duplication were found to be the main modes of amplification of the PfGRAS gene family. Gene structure analysis showed that more than 72.1% of the PfGRASs had no introns. The genes PfGRAS12/18/58 also contained unique DELLA structural domains; only PfGRAS12, which showed significant response to PaWB phytoplasma infection in stems, showed significant tissue specificity and responded to gibberellin (GA3) in PaWB-infected plants. We found that the internodes were significantly elongated under 100 µmol·L-1 GA3 treatment for 30 days. The subcellular localization analysis indicated that PfGRAS12 is located in the nucleus and cell membrane. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays confirmed that PfGRAS12 interacted with PfJAZ3 in the nucleus. Our results will lay a foundation for further research on the functions of the PfGRAS gene family and for genetic improvement and breeding of PaWB-resistant trees.

Heat Stress-Tolerant Quantitative Trait Loci Identified Using Backcrossed Recombinant Inbred Lines Derived from Intra-Specifically Diverse Aegilops tauschii Accessions.

In the face of climate change, bringing more useful alleles and genes from wild relatives of wheat is crucial to develop climate-resilient varieties. We used two populations of backcrossed recombinant inbred lines (BIL1 and BIL2), developed by crossing and backcrossing two intra-specifically diverse Aegilops tauschii accessions from lineage 1 and lineage 2, respectively, with the common wheat cultivar 'Norin 61'. This study aimed to identify quantitative trait loci (QTLs) associated with heat stress (HS) tolerance. The two BILs were evaluated under heat stress environments in Sudan for phenology, plant height (PH), grain yield (GY), biomass (BIO), harvest index (HI), and thousand-kernel weight (TKW). Grain yield was significantly correlated with BIO and TKW under HS; therefore, the stress tolerance index (STI) was calculated for these traits as well as for GY. A total of 16 heat-tolerant lines were identified based on GY and STI-GY. The QTL analysis performed using inclusive composite interval mapping identified a total of 40 QTLs in BIL1 and 153 QTLs in BIL2 across all environments. We detected 39 QTLs associated with GY-STI, BIO-STI, and TKW-STI in both populations (14 in BIL1 and 25 in BIL2). The QTLs associated with STI were detected on chromosomes 1A, 3A, 5A, 2B, 4B, and all the D-subgenomes. We found that QTLs were detected only under HS for GY on chromosome 5A, TKW on 3B and 5B, PH on 3B and 4B, and grain filling duration on 2B. The higher number of QTLs identified in BIL2 for heat stress tolerance suggests the importance of assessing the effects of intraspecific variation of Ae. tauschii in wheat breeding as it could modulate the heat stress responses/adaptation. Our study provides useful genetic resources for uncovering heat-tolerant QTLs for wheat improvement for heat stress environments.