Identification, characterization, and expression analysis of WRKY transcription factors in Cardamine violifolia reveal the key genes involved in regulating selenium accumulation.

BACKGROUND: Cardamine violifolia is a significant Brassicaceae plant known for its high selenium (Se) accumulation capacity, serving as an essential source of Se for both humans and animals. WRKY transcription factors play crucial roles in plant responses to various biotic and abiotic stresses, including cadmium stress, iron deficiency, and Se tolerance. However, the molecular mechanism of CvWRKY in Se accumulation is not completely clear. RESULTS: In this study, 120 WRKYs with conserved domains were identified from C. violifolia and classified into three groups based on phylogenetic relationships, with Group II further subdivided into five subgroups. Gene structure analysis revealed WRKY variations and mutations within the CvWRKYs. Segmental duplication events were identified as the primary driving force behind the expansion of the CvWRKY family, with numerous stress-responsive cis-acting elements found in the promoters of CvWRKYs. Transcriptome analysis of plants treated with exogenous Se and determination of Se levels revealed a strong positive correlation between the expression levels of CvWRKY034 and the Se content. Moreover, CvWRKY021 and CvWRKY099 exhibited high homology with AtWRKY47, a gene involved in regulating Se accumulation in Arabidopsis thaliana. The WRKY domains of CvWRKY021 and AtWRKY47 were highly conserved, and transcriptome data analysis revealed that CvWRKY021 responded to Na2SeO4 induction, showing a positive correlation with the concentration of Na2SeO4 treatment. Under the induction of Na2SeO3, CvWRKY021 and CvWRKY034 were significantly upregulated in the roots but downregulated in the shoots, and the Se content in the roots increased significantly and was mainly concentrated in the roots. CvWRKY021 and CvWRKY034 may be involved in the accumulation of Se in roots. CONCLUSIONS: The results of this study elucidate the evolution of CvWRKYs in the C. violifolia genome and provide valuable resources for further understanding the functional characteristics of WRKYs related to Se hyperaccumulation in C. violifolia.

A CUC1/auxin genetic module links cell polarity to patterned tissue growth and leaf shape diversity in crucifer plants.

How tissue-level information encoded by fields of regulatory gene activity is translated into the patterns of cell polarity and growth that generate the diverse shapes of different species remains poorly understood. Here, we investigate this problem in the case of leaf shape differences between Arabidopsis thaliana, which has simple leaves, and its relative Cardamine hirsuta that has complex leaves divided into leaflets. We show that patterned expression of the transcription factor CUP-SHAPED COTYLEDON1 in C. hirsuta (ChCUC1) is a key determinant of leaf shape differences between the two species. Through inducible genetic perturbations, time-lapse imaging of growth, and computational modeling, we find that ChCUC1 provides instructive input into auxin-based leaf margin patterning. This input arises via transcriptional regulation of multiple auxin homeostasis components, including direct activation of WAG kinases that are known to regulate the polarity of PIN-FORMED auxin transporters. Thus, we have uncovered a mechanism that bridges biological scales by linking spatially distributed and species-specific transcription factor expression to cell-level polarity and growth, to shape diverse leaf forms.

Uniparental silencing of 5S rRNA genes in plant allopolyploids - insights from Cardamine (Brassicaceae).

While the phenomenon of uniparental silencing of 35S rDNA in interspecific hybrids and allopolyploids is well documented, there is a notable absence of information regarding whether such silencing extends to the 5S RNA component of ribosomes. To address this gap in knowledge, we analyzed the 5S and 35S rDNA expression in Cardamine (Brassicaceae) allopolyploids, namely C. × insueta (2n = 3x = 24, genome composition RRA), C. flexuosa (2n = 4x = 32, AAHH), and C. scutata (2n = 4x = 32, PPAA) which share a common diploid ancestor (AA). We employed high-throughput sequencing of transcriptomes and genomes and phylogenetic analyses of 5S rRNA variants. The genomic organization of rDNA was further scrutinized through clustering and fluorescence in situ hybridization. In the C. × insueta allotriploid, we observed uniparental dominant expression of 5S and 35S rDNA loci. In the C. flexuosa and C. scutata allotetraploids, the expression pattern differed, with the 35S rDNA being expressed from the A subgenome, whereas the 5S rDNA was expressed from the partner subgenome. Both C. flexuosa and C. scutata but not C. × insueta showed copy and locus number changes. We conclude that in stabilized allopolyploids, transcription of ribosomal RNA components occurs from different subgenomes. This phenomenon appears to result in the formation of chimeric ribosomes comprising rRNA molecules derived from distinct parental origins. We speculate that the interplay of epigenetic silencing and rDNA rearrangements introduces an additional layer of variation in multimolecule ribosomal complexes, potentially contributing to the evolutionary success of allopolyploids.

Gene identification, expression analysis, and molecular docking of SAT and OASTL in the metabolic pathway of selenium in Cardamine hupingshanensis.

KEY MESSAGE: Identification of selenium stress-responsive expression and molecular docking of serine acetyltransferase (SAT) and O-acetyl serine (thiol) lyase (OASTL) in Cardamine hupingshanensis. A complex coupled with serine acetyltransferase (SAT) and O-acetyl serine (thiol) lyase (OASTL) is the key enzyme that catalyzes selenocysteine (Sec) synthesis in plants. The functions of SAT and OASTL genes were identified in some plants, but it is still unclear whether SAT and OASTL are involved in the selenium metabolic pathway in Cardamine hupingshanensis. In this study, genome-wide identification and comparative analysis of ChSATs and ChOASTLs were performed. The eight ChSAT genes were divided into three branches, and the thirteen ChOASTL genes were divided into four branches by phylogenetic analysis and sequence alignment, indicating the evolutionary conservation of the gene structure and its association with other plant species. qRT-PCR analysis showed that the ChSAT and ChOASTL genes were differentially expressed in different tissues under various selenium levels, suggesting their important roles in Sec synthesis. The ChSAT1;2 and ChOASTLA1;2 were silenced by the VIGS system to investigate their involvement in selenium metabolites in C. hupingshanensis. The findings contribute to understanding the gene functions of ChSATs and ChOASTLs in the selenium stress and provide a reference for further exploration of the selenium metabolic pathway in plants.

Topological analysis of 3D digital ovules identifies cellular patterns associated with ovule shape diversity.

Tissue morphogenesis remains poorly understood. In plants, a central problem is how the 3D cellular architecture of a developing organ contributes to its final shape. We address this question through a comparative analysis of ovule morphogenesis, taking advantage of the diversity in ovule shape across angiosperms. Here, we provide a 3D digital atlas of Cardamine hirsuta ovule development at single cell resolution and compare it with an equivalent atlas of Arabidopsis thaliana. We introduce nerve-based topological analysis as a tool for unbiased detection of differences in cellular architectures and corroborate identified topological differences between two homologous tissues by comparative morphometrics and visual inspection. We find that differences in topology, cell volume variation and tissue growth patterns in the sheet-like integuments and the bulbous chalaza are associated with differences in ovule curvature. In contrast, the radialized conical ovule primordia and nucelli exhibit similar shapes, despite differences in internal cellular topology and tissue growth patterns. Our results support the notion that the structural organization of a tissue is associated with its susceptibility to shape changes during evolutionary shifts in 3D cellular architecture.

Achromobacter seleniivolatilans sp. nov. and Buttiauxella selenatireducens sp. nov., isolated from the rhizosphere of selenium hyperaccumulator Cardamine hupingshanesis.

Two Gram-stain-negative bacterial strains, R39T and R73T, were isolated from the rhizosphere soil of the selenium hyperaccumulator Cardamine hupingshanesis in China. Strain R39T transformed selenite into elemental and volatile selenium, whereas strain R73T transformed both selenate and selenite into elemental selenium. Phylogenetic and phylogenomic analyses indicated that strain R39T belonged to the genus Achromobacter, while strain R73T belonged to the genus Buttiauxella. Strain R39T (genome size, 6.68 Mb; G+C content, 61.6 mol%) showed the closest relationship to Achromobacter marplatensis LMG 26219T and Achromobacter kerstersii LMG 3441T, with average nucleotide identity (ANI) values of 83.6 and 83.4 %, respectively. Strain R73T (genome size, 5.22 Mb; G+C content, 50.3 mol%) was most closely related to Buttiauxella ferragutiae ATCC 51602T with an ANI value of 86.4 %. Furthermore, strain A111 from the GenBank database was found to cluster with strain R73T within the genus Buttiauxella through phylogenomic analyses. The ANI and digital DNA-DNA hybridization values between strains R73T and A111 were 97.5 and 80.0% respectively, indicating that they belong to the same species. Phenotypic characteristics also differentiated strain R39T and strain R73T from their closely related species. Based on the polyphasic analyses, strain R39T and strain R73T represent novel species of the genera Achromobacter and Buttiauxella, respectively, for which the names Achromobacter seleniivolatilans sp. nov. (type strain R39T=GDMCC 1.3843T=JCM 36009T) and Buttiauxella selenatireducens sp. nov. (type strain R73T=GDMCC 1.3636T=JCM 35850T) are proposed.

Creating an explosion: Form and function in explosive fruit.

Adaptations for seed dispersal are found everywhere in nature. However, only a fraction of this diversity is accessible through the study of model organisms. For example, Arabidopsis seeds are released by dehiscent fruit; and although many genes required for dehiscence have been identified, the genetic basis for the vast majority of seed dispersal strategies remains understudied. Explosive fruit generate mechanical forces to launch seeds over a wide area. Recent work indicates that key innovations required for explosive dispersal lie in localised lignin deposition and precise patterns of microtubule-dependent growth in the fruit valves, rather than dehiscence zone structure. These insights come from comparative approaches, which extend the reach of developmental genetics by developing experimental tools in less well-studied species, such as the Arabidopsis relative, Cardamine hirsuta.

Whole genome identification, molecular docking and expression analysis of enzymes involved in the selenomethionine cycle in Cardamine hupingshanensis.

BACKGROUND: The selenomethionine cycle (SeMTC) is a crucial pathway for the metabolism of selenium. The basic bioinformatics and functions of four enzymes involved in the cycle including S-adenosyl-methionine synthase (MAT), SAM-dependent methyltransferase (MTase), S-adenosyl-homocysteine hydrolase (SAHH) and methionine synthase (MTR), have been extensively reported in many eukaryotes. The identification and functional analyses of SeMTC genes/proteins in Cardamine hupingshanensis and their response to selenium stress have not yet been reported. RESULTS: In this study, 45 genes involved in SeMTC were identified in the C. hupingshanensis genome. Phylogenetic analysis showed that seven genes from ChMAT were clustered into four branches, twenty-seven genes from ChCOMT were clustered into two branches, four genes from ChSAHH were clustered into two branches, and seven genes from ChMTR were clustered into three branches. These genes were resided on 16 chromosomes. Gene structure and homologous protein modeling analysis illustrated that proteins in the same family are relatively conserved and have similar functions. Molecular docking showed that the affinity of SeMTC enzymes for selenium metabolites was higher than that for sulfur metabolites. The key active site residues identified for ChMAT were Ala269 and Lys273, while Leu221/231 and Gly207/249 were determined as the crucial residues for ChCOMT. For ChSAHH, the essential active site residues were found to be Asn87, Asp139 and Thr206/207/208/325. Ile204, Ser111/329/377, Asp70/206/254, and His329/332/380 were identified as the critical active site residues for ChMTR. In addition, the results of the expression levels of four enzymes under selenium stress revealed that ChMAT3-1 genes were upregulated approximately 18-fold, ChCOMT9-1 was upregulated approximately 38.7-fold, ChSAHH1-2 was upregulated approximately 11.6-fold, and ChMTR3-2 genes were upregulated approximately 28-fold. These verified that SeMTC enzymes were involved in response to selenium stress to varying degrees. CONCLUSIONS: The results of this research are instrumental for further functional investigation of SeMTC in C. hupingshanensis. This also lays a solid foundation for deeper investigations into the physiological and biochemical mechanisms underlying selenium metabolism in plants.

Effects of selenium-cadmium co-enriched Cardamine hupingshanensis on bone damage in mice.

Selenium (Se) and cadmium (Cd) usually co-existed in soils, especially in areas with Se-rich soils in China. The potential health consequences for the local populations consuming foods rich in Se and Cd are unknown. Cardamine hupingshanensis (HUP) is Se and Cd hyperaccumulator plant that could be an ideal natural product to assess the protective effects of endogenous Se against endogenous Cd-caused bone damage. Male C57BL/6 mice were fed 5.22 mg/kg cadmium chloride (CdCl2) (Cd 3.2 mg/kg body weight (BW)), or HUP solutions containing Cd 3.2 mg/kg BW and Se 0.15, 0.29 or 0.50 mg/kg BW (corresponding to the HUP0, HUP1 and HUP2 groups) interventions. Se-enriched HUP1 and HUP2 significantly decreased Cd-induced femur microstructure damage and regulated serum bone osteoclastic marker levels and osteogenesis-related genes. In addition, endogenous Se significantly decreased kidney fibroblast growth factor 23 (FGF23) protein expression and serum parathyroid hormone (PTH) levels, and raised serum calcitriol (1,25(OH)2D3). Furthermore, Se also regulated gut microbiota involved in skeletal metabolism disorder. In conclusion, endogenous Se, especially with higher doses (the HUP2 group), positively affects bone formation and resorption by mitigating the damaging effects of endogenous Cd via the modulation of renal FGF23 expression, circulating 1,25(OH)2D3 and PTH and gut microbiota composition.

Investigation of selenium and selenium species in Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model.

Inadequate Se intake can enhance vulnerability to certain health risks, with supplementation lessening these risks. This study investigated the bioavailability of Se and Se species in five Se compounds and in Se-rich Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model, which enabled the study of Se transport and uptake. Translocation results showed that SeCys2 and MeSeCys had high translocation rates in C. violifolia leaves (CVLs). The uptake rate of organic Se increased with time, and MeSeCys exhibited a higher uptake rate than that for SeCys2 and SeMet. The translocation mechanisms of SeMet, Se(IV), and Se(VI) were passive transport, whereas those of SeCys2 and MeSeCys were active transport. The bioavailability of organic Se was higher than that of inorganic Se, with a total Se bioavailability in CVLs of 49.11 %. This study would provide a theoretical basis for the application of C. violifolia in the functional food.

Effects of selenoprotein extracts from Cardamine hupingshanensis on growth, selenium metabolism, antioxidant capacity, immunity and intestinal health in largemouth bass Micropterus salmoides.

This study aimed to assess the impact of dietary selenoprotein extracts from Cardamine hupingshanensis (SePCH) on the growth, hematological parameters, selenium metabolism, immune responses, antioxidant capacities, inflammatory reactions and intestinal barrier functions in juvenile largemouth bass (Micropterus salmoides). The base diet was supplemented with four different concentrations of SePCH: 0.00, 0.30, 0.60 and 1.20 g/Kg (actual selenium contents: 0.37, 0.59, 0.84 and 1.30 mg/kg). These concentrations were used to formulate four isonitrogenous and isoenergetic diets for juvenile largemouth bass during a 60-day culture period. Adequate dietary SePCH (0.60 and 1.20 g/Kg) significantly increased weight gain and daily growth rate compared to the control groups (0.00 g/Kg). Furthermore, 0.60 and 1.20 g/Kg SePCH significantly enhanced amounts of white blood cells, red blood cells, platelets, lymphocytes and monocytes, and levels of hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin in the hemocytes. In addition, 0.60 and 1.20 g/Kg SePCH increased the mRNA expression levels of selenocysteine lyase, selenophosphate synthase 1, 15 kDa selenoprotein, selenoprotein T2, selenoprotein H, selenoprotein P and selenoprotein K in the fish liver and intestine compared to the controls. Adequate SePCH not only significantly elevated the activities of antioxidant enzymes (Total superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase), the levels of total antioxidant capacity and glutathione, while increased mRNA transcription levels of NF-E2-related factor 2, Cu/Zn-superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase. However, adequate SePCH significantly decreased levels of malondialdehyde and H2O2 and the mRNA expression levels of kelch-like ECH-associated protein 1a and kelch-like ECH-associated protein 1b in the fish liver and intestine compared to the controls. Meanwhile, adequate SePCH markedly enhanced the levels of immune factors (alkaline phosphatase, acid phosphatase, lysozyme, complement component 3, complement component 4 and immunoglobulin M) and innate immune-related genes (lysozyme, hepcidin, liver-expressed antimicrobial peptide 2, complement component 3 and complement component 4) in the fish liver and intestine compared to the controls. Adequate SePCH reduced the levels of pro-inflammatory cytokines (tumour necrosis factor-α, interleukin 8, interleukin 1ß and interferon γ), while increasing transforming growth factor ß1 levels at both transcriptional and protein levels in the liver and intestine. The mRNA expression levels of mitogen-activated protein kinase 13 (MAPK 13), MAPK14 and nuclear factor kappa B p65 were significantly reduced in the liver and intestine of fish fed with 0.60 and 1.20 g/Kg SePCH compared to the controls. Histological sections also demonstrated that 0.60 and 1.20 g/Kg SePCH significantly increased intestinal villus height and villus width compared to the controls. Furthermore, the mRNA expression levels of tight junction proteins (zonula occludens-1, zonula occludens-3, Claudin-1, Claudin-3, Claudin-5, Claudin-11, Claudin-23 and Claudin-34) and Mucin-17 were significantly upregulated in the intestinal epithelial cells of 0.60 and 1.20 g/Kg SePCH groups compared to the controls. In conclusion, these results found that 0.60 and 1.20 g/Kg dietary SePCH can not only improve growth, hematological parameters, selenium metabolism, antioxidant capacities, enhance immune responses and intestinal functions, but also alleviate inflammatory responses. This information can serve as a useful reference for formulating feeds for largemouth bass.

Selenium-Enriched Cardamine violifolia Alleviates LPS-Induced Hepatic Damage and Inflammation by Suppressing TLR4/NODs-Necroptosis Signal Axes in Piglets.

Selenium-enriched Cardamine violifolia (SEC), a cruciferous plant, exerts excellent antioxidant and anti-inflammatory capacity, but its effect on hepatic function is unclear. This study investigated the effect and potential mechanism of SEC on hepatic injury induced by lipopolysaccharide (LPS). Twenty-four weaned piglets were randomly allotted to treatment with SEC (0.3 mg/kg Se) and/or LPS (100 µg/kg). After 28 days of the trial, pigs were injected with LPS to induce hepatic injury. These results indicated that SEC supplementation attenuated LPS-induced hepatic morphological injury and reduced aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities in plasma. SEC also inhibited the expression of pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α) after the LPS challenge. In addition, SEC improved hepatic antioxidant capacity via enhancing glutathione peroxidase (GSH-Px) activity and decreasing malondialdehyde (MDA) concentration. Moreover, SEC downregulated the mRNA expression of hepatic myeloid differentiation factor 88 (MyD88) and nucleotide-binding oligomerization domain proteins 1 (NOD1) and its adaptor molecule receptor interacting protein kinase 2 (RIPK2). SEC also alleviated LPS-induced hepatic necroptosis by inhibiting RIPK1, RIPK3, and mixed-lineage kinase domain-like (MLKL) expression. These data suggest that SEC potentially mitigates LPS-induced hepatic injury via inhibiting Toll-like receptor 4 (TLR4)/NOD2 and necroptosis signaling pathways in weaned piglets.

Selenium content, chemical composition and volatile components of essential oil and hydrosol from flowers of Cardamine violifolia.

Cardamine violifolia is a unique selenium hyperaccumulating vegetable in China, but its flowers are commonly wasted in large-scale cultivation. To better utilize this resource, this study explored the selenium content, chemical composition, and volatile organic compounds (VOCs) of hydro-distilling essential oil (EO) and hydrosol from C. violifolia flowers. ICP-MS results indicated that the EO and hydrosol contained selenium reaching 13.66±2.82 mg/kg and 0.0084±0.0013 mg/kg, respectively. GC-MS analysis revealed that organic acids, hydrocarbons, and amines were the main components of EO. Additionally, benzyl nitrile, benzaldehyde, benzyl isothiocyanate, benzyl alcohol, megastigmatrienone, and 2-methoxy-4-vinylphenol also existed in considerable amounts. The hydrosol extract had fewer components, mainly amines. HS-SPME-GC-MS corresponded to the composition analysis and aromatic compounds were the prevalent VOCs, while HS-GC-IMS primarily identified C2-C10 molecular alcohols, aldehydes, ethers, and sulfur-containing compounds. This study first described the chemical composition and VOC profiles of EO and hydrosol from selenium hyperaccumulating plant.

Life-cycle selenium accumulation and its correlations with the rhizobacteria and endophytes in the hyperaccumulating plant Cardamine hupingshanensis.

Cardamine hupingshanensis (C. hupingshanensis) is known for its ability to hyperaccumulate selenium (Se). However, the roles of the rhizobacteria or endophytes in Se hyperaccumulation have not been explored in C. hupingshanensis. Here, in-situ-like pot experiments were conducted to investigate the characteristics of Se accumulation throughout C. hupingshanensis growth stages and its correlations with rhizobacteria and endophytes under varying soil Se levels. Results showed that Se levels in roots, stems and leaves increased from the seedling to bolting stage, but remained relatively stable during the flowering and maturity. Leaves exhibited the highest Se levels (736.48 ± 6.51 mg/kg DW), followed by stems (575.39 ± 27.05 mg/kg DW), and lowest in roots (306.62 ± 65.45 mg/kg DW) under high-Se stress. The Se translocation factors from soils to C. hupingshanensis roots was significantly higher (p < 0.05) in low-Se soils compared to medium- and high-Se soils. Rhizobacterial diversity showed significant positive correlations (p < 0.05) with both total and bioavailable soil Se contents. The levels of soil Se and growth stages of C. hupingshanensis were found to have significant effects (p < 0.03) on the compositions of rhizosphere bacteria and C. hupingshanensis endophytes. Low-abundance bacteria (< 5%), including Gemmatimonadetes, Latescibacteria and Nitrospirae, were identified to potentially increase the bioavailable Se levels in the rhizosphere. The Se accumulation significantly decreased (p < 0.05) in C. hupingshanensis grown in sterilized low- (32.4%), medium- (17%) and high-Se (42%) soils. Endophytes in C. hupingshanensis, such as Firmicutes and Proteobacteria, were likely recruited from the rhizobacteria, as evidenced by the isolated bacterial strains, and played an important role in Se hyperaccumulation, particularly during the flowering stage. This study provides new insights into potential mechanism underlying Se hyperaccumulation in C. hupingshanensis.

A novel selenite-tolerant rhizosphere bacterium Wautersiella enshiensis sp. nov., isolated from Chinese selenium hyperaccumulator, Cardamine hupingshanensis.

Selenium (Se) is a dietary essential trace element for humans with various physiological functions and it could also be accumulated by some plant species, like Astragalus bisulcatus, Stanleya pinnata, and Cardamine hupinshanensis. A novel Gram-stain-negative, facultatively anaerobic, selenite-tolerant bacterium, designated strain YLX-1T , was isolated from the rhizosphere of a Se hyperaccumulating plant, Cardamine hupingshanensis in Enshi, China. Phylogenetic analysis based on 16 S rRNA gene sequences indicated that strain YLX-1T is a potential new species in the genus Wautersiella. Strain YLX-1T could grow in the temperature range of 4-37°C (optimally at 28°C) and in the pH range of 5-9 (optimum pH 7), which also could tolerate Se up to 6000 mg Se/L via producing extracellular red nano-Se with 100-300 nm size. However, it could predominantly accumulate selenocystine (SeCys2 ) in the cell under lower Se stress (1.5 mg Se/L). These results would help broaden our knowledge about the Se accumulation and transformation mechanism involved in rhizosphere bacteria like strain YLX-1T in C. hupingshanensis. Based on polyphasic data, we propose the creation of the new species Wautersiella enshiensis sp. nov., strain YLX-1T ( = CCTCC M 2013671) which will be promising to produce nano-Se as fertilizer, food additives or medicine.

Interspersed expression of CUP-SHAPED COTYLEDON2 and REDUCED COMPLEXITY shapes Cardamine hirsuta complex leaf form.

How genetically regulated growth shapes organ form is a key problem in developmental biology. Here, we investigate this problem using the leaflet-bearing complex leaves of Cardamine hirsuta as a model. Leaflet development requires the action of two growth-repressing transcription factors: REDUCED COMPLEXITY (RCO), a homeodomain protein, and CUP-SHAPED COTYLEDON2 (CUC2), a NAC-domain protein. However, how their respective growth-repressive actions are integrated in space and time to generate complex leaf forms remains unknown. By using live imaging, we show that CUC2 and RCO are expressed in an interspersed fashion along the leaf margin, creating a distinctive striped pattern. We find that this pattern is functionally important because forcing RCO expression in the CUC2 domain disrupts auxin-based marginal patterning and can abolish leaflet formation. By combining genetic perturbations with time-lapse imaging and cellular growth quantifications, we provide evidence that RCO-mediated growth repression occurs after auxin-based leaflet patterning and in association with the repression of cell proliferation. Additionally, through the use of genetic mosaics, we show that RCO is sufficient to repress both cellular growth and proliferation in a cell-autonomous manner. This mechanism of growth repression is different to that of CUC2, which occurs in proliferating cells. Our findings clarify how the two growth repressors RCO and CUC2 coordinate to subdivide developing leaf primordia into distinct leaflets and generate the complex leaf form. They also indicate different relationships between growth repression and cell proliferation in the patterning and post-patterning stages of organogenesis.

Pan-European study of genotypes and phenotypes in the Arabidopsis relative Cardamine hirsuta reveals how adaptation, demography, and development shape diversity patterns.

We study natural DNA polymorphisms and associated phenotypes in the Arabidopsis relative Cardamine hirsuta. We observed strong genetic differentiation among several ancestry groups and broader distribution of Iberian relict strains in European C. hirsuta compared to Arabidopsis. We found synchronization between vegetative and reproductive development and a pervasive role for heterochronic pathways in shaping C. hirsuta natural variation. A single, fast-cycling ChFRIGIDA allele evolved adaptively allowing range expansion from glacial refugia, unlike Arabidopsis where multiple FRIGIDA haplotypes were involved. The Azores islands, where Arabidopsis is scarce, are a hotspot for C. hirsuta diversity. We identified a quantitative trait locus (QTL) in the heterochronic SPL9 transcription factor as a determinant of an Azorean morphotype. This QTL shows evidence for positive selection, and its distribution mirrors a climate gradient that broadly shaped the Azorean flora. Overall, we establish a framework to explore how the interplay of adaptation, demography, and development shaped diversity patterns of 2 related plant species.

Selenium speciation and volatile flavor compound profiles in the edible flowers, stems, and leaves of selenium-hyperaccumulating vegetable Cardamine violifolia.

Cardamine violifolia is a unique selenium (Se)-hyperaccumulating vegetable in China. The total Se content and Se speciation of three edible parts, including flowers, stems, and leaves were detected by HPLC-ICP-MS. Volatile organic compounds (VOCs) greatly impact food flavor. The VOCs of three samples were analyzed by E-nose, HS-GC-IMS, and HS-SPME-GC-MS. The results showed that the total Se content in flowers was significantly higher than that in leaves and was the lowest in stems. Organic Se accounts for more than 98% of the total Se content, primarily selenocystine, followed by methyl selenocysteine. A total of 102 VOCs were identified from C. violifolia, mainly esters, aldehydes, alcohols, and ketones. Flowers contained abundant VOCs, while stems and leaves contained fewer but similar profiles. Moreover, multivariate statistical analysis was applied to investigate the VOC variations and marker VOCs. This work can provide useful knowledge for understanding the Se characteristics and flavor of C. violifolia.

Selenium hyperaccumulator plant Cardamine enshiensis: from discovery to application.

Selenium (Se) is an essential trace element for animals and humans. Se biofortification and Se functional agriculture are emerging strategies to satisfy the needs of people who are deficient in Se. With 200 km2 of Se-excess area, Enshi is known as the "world capital of Se." Cardamine enshiensis (C. enshiensis) is a Se hyperaccumulation plant discovered in the Se mine drainage area of Enshi. It is edible and has been approved by National Health Commission of the People's Republic of China as a new source of food, and the annual output value of the Se-rich industry in Enshi City exceeds 60 billion RMB. This review will mainly focus on the discovery and mechanism underlying Se tolerance and Se hyperaccumulation in C. enshiensis and highlight its potential utilization in Se biofortification agriculture, graziery, and human health.

Selenium-enriched Cardamine violifolia protects against sepsis-induced intestinal injury by regulating mitochondrial fusion in weaned pigs.

Sepsis is a life-threatening organ dysfunction caused by the dysregulated response of the host to an infection, and treatments are limited. Recently, a novel selenium source, selenium-enriched Cardamine violifolia (SEC) has attracted much attention due to its anti-inflammatory and antioxidant properties, but little is known about its role in the treatment of sepsis. Here, we found that SEC alleviated LPS-induced intestinal damage, as indicated by improved intestinal morphology, and increased disaccharidase activity and tight junction protein expression. Moreover, SEC ameliorated the LPS-induced release of pro-inflammatory cytokines, as indicated by decreased IL-6 level in the plasma and jejunum. Moreover, SEC improved intestinal antioxidant functions by regulating oxidative stress indicators and selenoproteins. In vitro, TNF-α-challenged IPEC-1 cells were examined and showed that selenium-enriched peptides, which are the main functional components extracted from Cardamine violifolia (CSP), increased cell viability, decreased lactate dehydrogenase activity and improved cell barrier function. Mechanistically, SEC ameliorated LPS/TNF-α-induced perturbations in mitochondrial dynamics in the jejunum and IPEC-1 cells. Moreover, CSP-mediated cell barrier function is primarily dependent on the mitochondrial fusion protein MFN2 but not MFN1. Taken together, these results indicate that SEC mitigates sepsis-induced intestinal injury, which is associated with modulating mitochondrial fusion.