Non-thermal plasma enhances growth and salinity tolerance of bok choy (Brassica rapa subsp. chinensis) in hydroponic culture.

In this study, we aimed to examine the growth, physiological and biochemical status, and responses to salinity stress of bok choy (Brassica rapa subsp. chinensis) cultivated in a hydroponic system with a plasma-treated solution. Plasma gas generated using a cylindrical dielectric barrier discharge or air (control) was injected into Hoagland nutrient solution once a week for different durations (0, 5, and 10 min). After 4 weeks, the length of the shoots and roots, number of leaves, and dry weight of bok choy plants significantly increased in individuals grown with Hoagland solution treated with plasma gas for 10 min. An increase in dry weight of individual plants of approximately 80.5% was observed in plants in the plasma-treated group compared to those in a control group. The levels of chlorophyll, total soluble proteins, and nitrogen uptake, and transcription of genes related to salinity stress tolerance-WRKY2, HHP3, and ABI1- were also significantly elevated in bok choy grown with plasma treated Hoagland solution. Moreover, when exposed to 20 mM NaCl, plant length and leaf number were significantly increased, in the group grown with Hoagland solution treated with plasma gas for 10 min. Level of H2O2 was significantly elevated in the treated nutrient solutions. In plants grown with the treated nutrient solution, intracellular NO was highly detected in the cell division and elongation zone of roots. Our findings suggest that plasma treatment of nutrient solutions in hydroponic culture systems may improve the growth, physiological and biochemical status, and tolerance to salinity stress in plants, and a crucial role of H2O2 generated in the treated nutrient solutions may play in this improvement.

Genetic Mapping and Characterization of the Clubroot Resistance Gene BraPb8.3 in Brassica rapa.

Clubroot, a significant soil-borne disease, severely impacts the productivity of cruciferous crops. The identification and development of clubroot resistance (CR) genes are crucial for mitigating this disease. This study investigated the genetic inheritance of clubroot resistance within an F2 progeny derived from the cross of a resistant parent, designated "377", and a susceptible parent, designated "12A". Notably, "377" exhibited robust resistance to the "KEL-23" strain of Plasmodiophora brassicae, the causative agent of clubroot. Genetic analyses suggested that the observed resistance is controlled by a single dominant gene. Through Bulked Segregant Analysis sequencing (BSA-seq) and preliminary gene mapping, we localized the CR gene locus, designated as BraPb8.3, to a 1.30 Mb genomic segment on chromosome A08, flanked by the markers "333" and "sau332-1". Further fine mapping precisely narrowed down the position of BraPb8.3 to a 173.8 kb region between the markers "srt8-65" and "srt8-25", where we identified 22 genes, including Bra020861 with a TIR-NBS-LRR domain and Bra020876 with an LRR domain. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses confirmed that both Bra020861 and Bra020876 exhibit increased expression levels in the resistant parent "377" following inoculation with P. brassicae, thereby underscoring their potential as key genes implicated in BraPb8.3-mediated clubroot resistance. This study not only identifies molecular markers associated with BraPb8.3 but also enriches the genetic resources available for breeding programs aimed at enhancing resistance to clubroot.

Susceptibility of Oilseed Radish (Raphanus sativus subsp. oleiferus) Cultivars and Various Brassica Crops to Plasmodiophora brassicae.

Oilseed radish (OR; Raphanus sativus var. oleiferus) is grown as a cover crop and develops a unique taproot, absorbing nitrogen left by the previous crop. The aim of this project was to investigate the resistance of OR cultivars (cvs.) to Plasmodiophora brassicae, the causal agent of clubroot disease. Twelve market cvs. were compared with cvs. of clubroot-resistant (CR) winter oilseed rape (OSR; Brassica napus) and other selected species of the Brassicaceae family. The study was performed as a replicated bioassay in a growth chamber using a specially composed mixture of field soils holding the natural inoculum of P. brassicae. The results show that the OR cultivars were infected, which implies that OR multiplies the pathogen. The susceptibility of the OR cultivars was not significantly different from that of the CR OSR cultivars Alister and Archimedes, but it was significantly different from that of the OSR cv. Mendel. The disease severity index (DSI) for OR cultivars ranged from 2.3 to 9.3, and disease incidence was 3-17%. The best performance was shown by black radish (Raphanus sativus var. niger) with a DSI of 0.3. For sustainable brassica crop production, we suggest avoiding OR as a cover crop in crop rotations, including OSR or other brassica crops, since there is a risk of increasing inoculum in the soil.

Brassica rapa BrICE1 and BrICE2 Positively Regulate the Cold Tolerance via CBF and ROS Pathways, Balancing Growth and Defense in Transgenic Arabidopsis.

Winter rapeseed (Brassica rapa) has a good chilling and freezing tolerance. inducer of CBF expression 1 (ICE1) plays a crucial role in cold signaling in plants; however, its role in Brassica rapa remains unclear. In this study, we identified 41 ICE1 homologous genes from six widely cultivated Brassica species. These genes exhibited high conservation, with evolutionary complexity between diploid and allotetraploid species. Cold stress induced ICE1 homolog expression, with differences between strongly and weakly cold-tolerant varieties. Two novel ICE1 paralogs, BrICE1 and BrICE2, were cloned from Brassica rapa Longyou 6. Subcellular localization assays showed that they localized to the nucleus, and low temperature did not affect their nuclear localization. The overexpression of BrICE1 and BrICE2 increased cold tolerance in transgenic Arabidopsis and enhanced reactive oxygen species' (ROS) scavenging ability. Furthermore, our data demonstrate that overexpression of BrICE1 and BrICE2 inhibited root growth in Arabidopsis, and low temperatures could induce the degradation of BrICE1 and BrICE2 via the 26S-proteasome pathway. In summary, ICE1 homologous genes exhibit complex evolutionary relationships in Brassica species and are involved in the C-repeat/DREB binding factor (CBF) pathway and ROS scavenging mechanism in response to cold stress; these regulating mechanisms might also be responsible for balancing the development and cold defense of Brassica rapa.

Identification and Functional Exploration of BraGASA Genes Reveal Their Potential Roles in Drought Stress Tolerance and Sexual Reproduction in Brassica rapa L. ssp. pekinensis.

Gibberellic acid-stimulated Arabidopsis sequences (GASAs) are a subset of the gibberellin (GA)-regulated gene family and play crucial roles in various physiological processes. However, the GASA genes in Brassica rapa have not yet been documented. In this study, we identified and characterized 16 GASA genes in Chinese cabbage (Brassica rapa L. ssp. pekinensis). Analysis of the conserved motifs revealed significant conservation within the activation segment of BraGASA genes. This gene family contains numerous promoter elements associated with abiotic stress tolerance, including those for abscisic acid (ABA) and methyl jasmonate (MeJA). Expression profiling revealed the presence of these genes in various tissues, including roots, stems, leaves, flowers, siliques, and callus tissues. When plants were exposed to drought stress, the expression of BraGASA3 decreased notably in drought-sensitive genotypes compared to their wild-type counterparts, highlighting the potentially crucial role of BraGASA3 in drought stress. Additionally, BraGASAs exhibited various functions in sexual reproduction dynamics. The findings contribute to the understanding of the function of BraGASAs and provide valuable insights for further exploration of the GASA gene function of the BraGASA gene in Chinese cabbage.

Brchli1 mutation induces bright yellow leaves by disrupting magnesium chelatase I subunit function in Chinese cabbage (Brassica rapa L. ssp. pekinensis).

Magnesium chelatase (MgCh) plays a pivotal role in photosynthesis, catalyzing the insertion of magnesium into protoporphyrin IX (Proto IX), a key intermediate in chlorophyll (Chl) biosynthesis. MgCh is a heteromeric complex composed of the MgCh D subunit (CHLD), the MgCh H subunit (CHLH), and the MgCh I subunit (CHLI). The bright yellow leaves (byl) mutant was obtained through ethyl methanesulfonate (EMS) mutagenesis of the 'FT' Chinese cabbage (Brassica rapa L. ssp. pekinensis) doubled haploid line, whose Chl content, net photosynthetic rate (Pn), and non-photochemical quenching coefficient (NPQ) were decreased, and whose chloroplast development was incomplete. byl recovered to a light green phenotype under weak light conditions. Genetic analysis revealed that the bright yellow leaves phenotype of byl was caused by a single recessive nuclear gene. Using Mutmap sequencing and Kompetitive allele-specific PCR (KASP) identification, BraA01g010040.3.5C, encoding the CHLI subunit of MgCh, was identified as the candidate gene and named Brchli1. A nonsynonymous G-to-A mutation in the Brchli1 exon resulted in the substitution of aspartic acid with asparagine. Brchli1-silenced Chinese cabbage displayed bright yellow leaves with decreased Brchli1 expression. Transiently overexpressed Brchli1 in the byl mutant restored the green leaf phenotype and significantly increased relative Brchli1 expression levels. Both BrCHLI1 and its mutated variant were localized in chloroplasts. Yeast two-hybrid and luciferase complementation imaging assays demonstrated that BrCHLI1 interacted with both BrCHLD and itself. BrCHLI1 mutations did not affect its interaction with BrCHLD. Together, Brchli1 mutations impaired the function of MgCh, providing insights into the molecular mechanism of leaf coloration.

Integrated miRNA and mRNA Transcriptome Analysis Reveals Regulatory Mechanisms in the Response of Winter Brassica rapa to Drought Stress.

Drought is a major abiotic stress factor that reduces agricultural productivity. Understanding the molecular regulatory network of drought response in winter rape is of great significance for molecular Brassica rapa. In order to comprehensively analyze the network expression of DEGs and DEMIs in winter rape under drought stress, in this study we used Longyou 7 as the experimental material to identify DEGs and DEMIs related to drought stress by transcriptome and miRNA sequencing. A total of 14-15 key differential mRNA genes related to drought stress and biological stress were screened out under different treatments in the three groups. and 32 differential miRNAs were identified through targeted regulatory relationships, and the mRNA expression of 20 target genes was negatively regulated by the targeting regulatory relationship. It is mainly enriched in starch and sucrose metabolism, carbon metabolism and other pathways. Among them, gra-MIR8731-p3_2ss13GA18GA regulated the expression of multiple mRNAs in the three treatments. miRNA is mainly involved in the drought resistance of Chinese cabbage winter rape by regulating the expression of target genes, such as starch and sucrose metabolism, amino acid biosynthesis, and carbon metabolism. These miRNAs and their target genes play an indispensable role in winter rapeseed drought stress tolerance regulation.

Systematic Analysis of the BrHAT Gene Family and Physiological Characteristics of Brassica rapa L. Treated with Histone Acetylase and Deacetylase Inhibitors under Low Temperature.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Novel multifunctional plant growth-promoting bacteria isolated from the oil palm rhizosphere under long-term organic matter application.

Most agricultural products are presently cultivated on marginal lands with poor soil properties and unfavorable environmental conditions (diseases and abiotic stresses), which can threaten plant growth and yield. Plant growth-promoting bacteria (PGPB) are beneficial bacteria that promote plant growth and biomass and act as biocontrols against diseases and stress. However, most isolated PGPBs have a single function and low survival rates owing to their limited growth behaviors. In this study, we isolated multifunctional PGPB from oil palm rhizosphere, quantitatively measured their activities, and evaluated their effectiveness in Brassica rapa (Komatsuna) cultivation. This is the first study to report the isolation of three multifunctional PGPB strains with ammonium production, phosphate-potassium-silicate solubilization, and indole-3-acetic acid (IAA) production from the oil palm rhizosphere, namely Kosakonia oryzendophytica AJLB38, Enterobacter quasimori AJTS77, and Lelliottia jeotgali AJTS83. Additionally, these strains showed antifungal activity against the oil palm pathogen Ganoderma boninense. These strains grow under high temperature, acidic and alkaline pH, and high salt concentration, which would result in their proliferation in various environmental conditions. The cultivation experiments revealed these strains improved the growth and biomass with half the dosage of chemical fertilizer application, which was not significantly different to the full dosage. Furthermore, the overall plant growth-promoting activities in quantitative assays and overall B. rapa growth in cultivation experiments were statistically correlated, which could contribute to the prediction of plant growth promotion without plant cultivation experiments. Thus, the selected PGPB could be valuable as a biofertilizer to improve soil health and quality and promote agricultural sustainability.

Primary multistep phosphorelay activation comprises both cytokinin and abiotic stress responses: Insights from comparative analysis of Brassica type-A response regulators.

Multistep phosphorelay (MSP) signaling integrates hormonal and environmental signals to control both plant development and adaptive responses. The type-A RESPONSE REGULATORs (RRAs), the downstream members of the MSP cascade and cytokinin primary response genes are supposed to mediate primarily the negative feedback regulation of (cytokinin-induced) MSP signaling. However, the transcriptional data suggest the involvement of RRAs in stress-related responses as well. By employing evolutionary conservation with the well-characterized Arabidopsis thaliana RRAs, we identified 5 and 38 novel putative RRAs in Brassica oleracea and Brassica napus, respectively. Our phylogenetic analysis suggests the existence of gene-specific selective pressure, maintaining the homologs of ARR3, ARR6, and ARR16 as singletons during the evolution of Brassicaceae. We categorized RRAs based on the kinetics of their cytokinin-mediated upregulation and observed both similarities and specificities in this type of response across Brassicaceae species. Using bioinformatic analysis and experimental data demonstrating the cytokinin and abiotic stress responsiveness of A. thaliana-derived TCSv2 reporter, we unveil the mechanistic conservation of cytokinin- and stress-mediated upregulation of RRAs in Brassica rapa and Brassica napus. Notably, we identify partial cytokinin dependency of cold stress-induced RRA transcription, thus corroborating the role of cytokinin signaling in the crop adaptive responses.

Comparison of Root Transcriptomes against Clubroot Disease Pathogens in a Resistant Chinese Cabbage Cultivar (Brassica rapa cv. 'Akimeki').

Clubroot, caused by Plasmodiophora brassicae, is one of the diseases that causes major economic losses in cruciferous crops worldwide. Although prevention strategies, including soil pH adjustment and crop rotation, have been used, the disease's long persistence and devastating impact continuously remain in the soil. CR varieties were developed for clubroot-resistant (CR) Chinese cabbage, and 'Akimeki' is one of the clubroot disease-resistant cultivars. However, recent studies have reported susceptibility to several Korean pathotypes in Akimeki and the destruction of the resistance to P. brassicae in many Brassica species against CR varieties, requiring the understanding of more fine-tuned plant signaling by fungal pathogens. In this study, we focused on the early molecular responses of Akimeki during infection with two P. brassicae strains, Seosan (SS) and Hoengseong2 (HS2), using RNA sequencing (RNA-seq). Among a total of 2358 DEGs, 2037 DEGs were differentially expressed following SS and HS2 infection. Gene ontology (GO) showed that 1524 and 513 genes were up-regulated following SS and HS2 inoculations, respectively. Notably, the genes of defense response and jasmonic acid regulations were enriched in the SS inoculation condition, and the genes of water transport and light intensity response were enriched in the HS2 inoculation condition. Moreover, KEGG pathways revealed that the gene expression set were related to pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) mechanisms. The results will provide valuable information for developing CR cultivars in Brassica plants.

Genome-Wide Identification and Expression Analysis of BrBASS Genes in Brassica rapa Reveals Their Potential Roles in Abiotic Stress Tolerance.

The bile acid sodium symporter (BASS) family plays an important role in transporting substances and coordinating plants' salt tolerance. However, the function of BASS in Brassica rapa has not yet been elucidated. In this study, eight BrBASS genes distributed on five chromosomes were identified that belonged to four subfamilies. Expression profile analysis showed that BrBASS7 was highly expressed in roots, whereas BrBASS4 was highly expressed in flowers. The promoter element analysis also identified several typical homeopathic elements involved in abiotic stress tolerance and stress-related hormonal responses. Notably, under salt stress, the expression of BrBASS2 was significantly upregulated; under osmotic stress, that of BrBASS4 increased and then decreased; and under cold stress, that of BrBASS7 generally declined. The protein-protein interaction analysis revealed that the BrBASS2 homologous gene AtBASS2 interacted with Nhd1 (N-mediated heading date-1) to alleviate salt stress in plants, while the BrBASS4 homologous gene AtBASS3 interacted with BLOS1 (biogenesis of lysosome-related organelles complex 1 subunit 1) via co-regulation with SNX1 (sorting nexin 1) to mitigate an unfavorable growing environment for roots. Further, Bra-miR396 (Bra-microRNA396) targeting BrBASS4 and BrBASS7 played a role in the plant response to osmotic and cold stress conditions, respectively. This research demonstrates that BrBASS2, BrBASS4, and BrBASS7 harbor great potential for regulating abiotic stresses. The findings will help advance the study of the functions of the BrBASS gene family.

Biochar Amendments and Phytoremediation: A Combined Approach for Effective Lead Removal in Shooting Range Soils.

The increasing contamination of soil with heavy metals poses a problem to environmental sustainability. Among these pollutants, lead is particularly concerning due to its persistence in the environment, with harmful effects on human health and ecosystems. Various strategies that combine phytoremediation techniques with soil amendments have emerged to mitigate lead contamination. In this context, biochar has gained significant attention for its potential to enhance soil quality and remediate metal-contaminated environments. This study aims to investigate the combined effect of biochar amendments on the phytoremediation of lead-contaminated shooting range soils. A series of experiments were conducted to determine the impact of the amount and distribution of biochar on lead removal from soil. Soil samples were incubated with biochar for one week, after which two types of seeds (Brassica rapa and Lolium perenne) were planted. Plant and root lengths, as well as the number of germinated seeds, were measured, and a statistical analysis was conducted to determine the influence of the amendments. After one month, the Pb concentration decreased by more than 70%. Our results demonstrate that seed germination and plant growth were significantly better in soil samples where biochar was mixed rather than applied superficially, with the optimal performance observed at a 10% wt. biochar amendment. Additionally, the combined use of biochar and phytoremediation proved highly effective in immobilizing lead and reducing its bioavailability. These findings suggest that the combination of biochar, particularly when mixed at appropriate concentrations, and Brassica rapa significantly improved lead removal efficiency.

Mechanisms of interleukin-10 induction in murine spleen and RAW264 cells by Latilactobacillus curvatus K4G4 isolated from fermented Brassica rapa L.

Lactic acid bacteria (LAB) are commonly used in fermented foods, and some LAB modulate the immune response. We aimed to investigate the mechanism by which LAB isolates from fermented Brassica rapa L. induce the production of anti-inflammatory interleukin (IL)-10 by the murine spleen and RAW264 cells. Spleen cells from BALB/c mice or the mouse macrophage cell line RAW264 were cultured with heat-killed LAB isolated from fermented B. rapa L., and the IL-10 level in the supernatant was measured. Latilactobacillus curvatus K4G4 provided the most potent IL-10 induction among 13 isolates. Cell wall components of K4G4 failed to induce IL-10, while treatment of the bacteria with RNase A under a high salt concentration altered K4G4 induction of IL-10 by spleen cells. In general, a low salt concentration diminished the IL-10 induction by all strains, including K4G4. In addition, chloroquine pretreatment and knock down of toll-like receptor 7 through small interfering RNA suppressed K4G4 induction of IL-10 production by RAW264 cells. Our results suggest that single-stranded RNA from K4G4 is involved, via endosomal toll-like receptor 7, in the induction of IL-10 production by macrophages. K4G4 is a promising candidate probiotic strain that modulates the immune response by inducing IL-10 from macrophages.

Methyl-Sensitive Amplification Polymorphism (MSAP) Analysis Provides Insights into the DNA Methylation Changes Underlying Adaptation to Low Temperature of Brassica rapa L.

BACKGROUND: DNA methylation can change rapidly to regulate the expression of stress-responsive genes. Previous studies have shown that there are significant differences in the cold resistance of winter rapeseed (Brassica rapa L.) after being domesticated in different selection environments; however, little is known about the epigenetic regulatory mechanisms of its cold resistance formation. METHODS: Four winter rapeseed materials ('CT-2360', 'MXW-1', '2018-FJT', and 'DT-7') domesticated in different environments were selected to analyze the DNA methylation level and pattern changes under low temperature using methylation-sensitive amplified polymorphism technology with 60 primer pairs. RESULTS: A total of 18 pairs of primers with good polymorphism were screened, and 1426 clear bands were amplified, with 594 methylation sites, accounting for 41.65% of the total amplified bands. The total methylation ratios of the four materials were reduced after low-temperature treatment, in which the DNA methylation level of 'CT-2360' was higher than that of the other three materials; the analysis of methylation patterns revealed that the degree of demethylation was higher than that of methylation in 'MXW-1', '2018-FJT', and 'DT-7', which were 22.99%, 19.77%, and 24.35%, respectively, and that the methylation events in 'CT-2360' were predominantly dominant at 22.95%. Fifty-three polymorphic methylated DNA fragments were randomly selected and further analyzed, and twenty-nine of the cloned fragments were homologous to genes with known functions. The candidate genes VQ22 and LOC103871127 verified the existence of different expressive patterns before and after low-temperature treatment. CONCLUSIONS: Our work implies the critical role of DNA methylation in the formation of cold resistance in winter rapeseed. These results provide a comprehensive insight into the adaptation epigenetic regulatory mechanism of Brassica rapa L. to low temperature, and the identified differentially methylated genes can also be used as important genetic resources for the multilateral breeding of winter-resistant varieties.

A Physiological and Molecular Docking Insight on Quercetin Mediated Salinity Stress Tolerance in Chinese Flowering Cabbage and Increase in Glucosinolate Contents.

The present study was performed to investigate the negative impact of salinity on the growth of Chinese flowering cabbage (Brassica rapa ssp. chinensis var. parachinensis) and the ameliorative effects of quercetin dihydrate on the plant along with the elucidation of underlying mechanisms. The tolerable NaCl stress level was initially screened for the Chinese flowering cabbage plants during a preliminary pot trial by exposing the plants to salinity levels (0, 50, 100, 150, 200, 250, 300, 350, and 400 mM) and 250 mM was adopted for further experimentation based on the findings. The greenhouse experiment was performed by adopting a completely randomized design using three different doses of quercetin dihydrate (50, 100, 150 µM) applied as a foliar treatment. The findings showed that the exposure salinity significantly reduced shoot length (46.5%), root length (21.2%), and dry biomass (32.1%) of Chinese flowering cabbage plants. Whereas, quercetin dihydrate applied at concentrations of 100, and 150 µM significantly diminished the effect of salinity stress by increasing shoot length (36.8- and 71.3%), root length (36.57- and 56.19%), dry biomass production (51.4- and 78.6%), Chl a (69.8- and 95.7%), Chl b (35.2- and 87.2%), and carotenoid contents (21.4- and 40.3%), respectively, compared to the plants cultivated in salinized conditions. The data of physiological parameters showed a significant effect of quercetin dihydrate on the activities of peroxidase, superoxide dismutase, and catalase enzymes. Interestingly, quercetin dihydrate increased the production of medicinally important glucosinolate compounds in Chinese flowering cabbage plants. Molecular docking analysis showed a strong affinity of quercetin dihydrate with three different stress-related proteins of B. rapa plants. Based on the findings, it could be concluded that quercetin dihydrate can increase the growth of Chinese flowering cabbage under both salinity and normal conditions, along with an increase in the medicinal quality of the plants. Further investigations are recommended as future perspectives using other abiotic stresses to declare quercetin dihydrate as an effective remedy to rescue plant growth under prevailing stress conditions.

Uncovering genes involved in pollinator-driven mating system shifts and selfing syndrome evolution in Brassica rapa.

Shifts in pollinator occurrence and their pollen transport effectiveness drive the evolution of mating systems in flowering plants. Understanding the genomic basis of these changes is essential for predicting the persistence of a species under environmental changes. We investigated the genomic changes in Brassica rapa over nine generations of pollination by hoverflies associated with rapid morphological evolution toward the selfing syndrome. We combined a genotyping-by-sequencing (GBS) approach with a genome-wide association study (GWAS) to identify candidate genes, and assessed their functional role in the observed morphological changes by studying mutations of orthologous genes in the model plant Arabidopsis thaliana. We found 31 candidate genes involved in a wide range of functions from DNA/RNA binding to transport. Our functional assessment of orthologous genes in A. thaliana revealed that two of the identified genes in B. rapa are involved in regulating the size of floral organs. We found a protein kinase superfamily protein involved in petal width, an important trait in plant attractiveness to pollinators. Moreover, we found a histone lysine methyltransferase (HKMT) associated with stamen length. Altogether, our study shows that hoverfly pollination leads to rapid evolution toward the selfing syndrome mediated by polygenic changes.

Brassica rapa CURLY LEAF is a major H3K27 methyltransferase regulating flowering time.

MAIN CONCLUSION: In Brassica rapa, the epigenetic modifier BraA.CLF orchestrates flowering by modulating H3K27me3 levels at the floral integrator genes FT, SOC1, and SEP3, thereby influencing their expression. CURLY LEAF (CLF) is the catalytic subunit of the plant Polycomb Repressive Complex 2 that mediates the trimethylation of histone H3 lysine 27 (H3K27me3), an epigenetic modification that leads to gene silencing. While the function of CURLY LEAF (CLF) has been extensively studied in Arabidopsis thaliana, its role in Brassica crops is barely known. In this study, we focused on the Brassica rapa homolog of CLF and found that the loss-of-function mutant braA.clf-1 exhibits an accelerated flowering together with pleiotropic phenotypic alterations compared to wild-type plants. In addition, we carried out transcriptomic and H3K27me3 genome-wide analyses to identify the genes regulated by BraA.CLF. Interestingly, we observed that several floral regulatory genes, including the B. rapa homologs of FT, SOC1 and SEP3, show reduced H3K27me3 levels and increased transcript levels compared to wild-type plants, suggesting that they are direct targets of BraA.CLF and key players in regulating flowering time in this crop. In addition, the results obtained will enhance our understanding of the epigenetic mechanisms regulating key developmental traits and will aid to increase crop yield by engineering new Brassica varieties with different flowering time requirements.

Too hot to handle: temperature-induced plasticity influences pollinator behaviour and plant fitness.

Increased temperature can induce plastic changes in many plant traits. However, little is known about how these changes affect plant interactions with insect pollinators and herbivores, and what the consequences for plant fitness and selection are. We grew fast-cycling Brassica rapa plants at two temperatures (ambient and increased temperature) and phenotyped them (floral traits, scent, colour and glucosinolates). We then exposed plants to both pollinators (Bombus terrestris) and pollinating herbivores (Pieris rapae). We measured flower visitation, oviposition of P. rapae, herbivore development and seed output. Plants in the hot environment produced more but smaller flowers, with lower UV reflectance and emitted a different volatile blend with overall lower volatile emission. Moreover, these plants received fewer first-choice visits by bumblebees and butterflies, and fewer flower visits by butterflies. Seed production was lower in hot environment plants, both because of a reduction in flower fertility due to temperature and because of the reduced visitation of pollinators. The selection on plant traits changed in strength and direction between temperatures. Our study highlights an important mechanism by which global warming can change plant-pollinator interactions and negatively impact plant fitness, as well as potentially alter plant evolution through changes in phenotypic selection.

Biodegradation of nitenpyram (neonicotinoid insecticide) by endophytic bacterium, Bacillus thuringiensis strain NIT-2, isolated from neonicotinoid-treated plant samples.

Nitenpyram (neonicotinoid insecticide) is commonly used for crop protection from pests. Currently, due to its widespread use, the nitenpyram accumulation in the environment is anticipated to be high. Hence, the removal of nitenpyram residue from the environment is essential. However, the biodegradation of nitenpyram by endophytes is still unreported. Therefore, we aimed to isolate and identify a bacterial strain capable of degrading nitenpyram. We isolated approximately 300 endophytic strains from Brassica rapa var. perviridis that had been exposed to different neonicotinoid insecticides. After 14 days of incubation, a bacterial strain, NIT-2, with nitenpyram degradation capability (approximately 65%) was found. Via 16S rRNA gene sequencing, the strain was identified as Bacillus thuringiensis. In addition, metabolites, 2-[N-(6-chloro-3-pyridylmethyl)-N-ethyl]amino-2-methyliminoacetic acid, N-(6-chloro-3-pyridilmethyl)-N-ethyl-N-methylformamidine (CPMF), and N-(6-chloro-3-pyridilmethyl)-N-ethylformamide (CPF), were identified during the degradation. Moreover, CPMF and CPF were further degraded 71% and 18%, respectively by NIT-2. Thus, B. thuringiensis strain NIT-2 is the first reported endophytic bacterium capable of degrading nitenpyram.