Cell Wall Organization Research Articles

Nickel phytoremediation potential of Plantago major L.: Transcriptome analysis

Plantago major L, a ubiquitous perennial weed thriving in diverse harsh environments, possesses a substantial reservoir of resistance genes, particularly those conferring resistance to heavy metals. Despite its prevalence, the intricate molecular mechanisms underpinning its exceptional ability to endure heavy metal pollution remain largely unexplored. Through transcriptome analysis, this study intended to reveal the mechanisms behind the enrichment of heavy metal Ni (nickel) in P. major and its potential for phytoremediation. In total, 7848 differentially expressed genes (DEGs) exhibited dynamic changes in tissues treated with different Ni concentrations. It was discovered that the root of P. major exhibited a more pronounced and significant response when exposed to higher concentrations of Ni. Furthermore, the upregulated genes associated with adversity stress were significantly observed in response to Ni stress. The majority of pathways related to plant growth and photosynthesis were significantly reduced; however, pathways related to metabolite synthesis, chitin synthesis, and adversity signal transduction were stimulated, and pathways related to root cell wall organization or biogenesis were suppressed. We identified that the rate-limiting enzyme PmHISN1A/B in the histidine synthesis pathway significantly enhanced Ni tolerance of the transgenic Arabidopsis without side effects, which was different to its Arabidopsis homologs. The study uncovered a molecular basis for the Ni tolerance of P. major, a heavy metal remediation plant, and provided potential genetic resources to cultivate novel P. major varieties or breed stress resilience crops.

Transcriptome Analysis Deciphers the Underlying Molecular Mechanism of Peanut Lateral Branch Angle Formation Using Erect Branching Mutant.

Background The growth habit (GH), also named the branching habit, is an important agronomic trait of peanut and mainly determined by the lateral branch angle (LBA). The branching habit is closely related to peanut mechanized farming, pegging, yield, and disease management. Objectives However, the molecular basis underlying peanut LBA needs to be uncovered. Methods In the present study, an erect branching peanut mutant, eg06g, was obtained via 60Co γ-ray-radiating mutagenesis of a spreading-type peanut cultivar, Georgia-06G (G06G). RNA-seq was performed to compare the transcriptome variation of the upper sides and lower sides of the lateral branch of eg06g and G06G. Results In total, 4908 differentially expressed genes (DEGs) and 5833 DEGs were identified between eg06g and G06G from the lower sides and upper sides of the lateral branch, respectively. GO, KEGG, and clustering enrichment analysis indicated that the carbohydrate metabolic process, cell wall organization or biogenesis, and plant hormone signal transduction were mainly enriched in eg06g. Conclusions Further analysis showed that the genes involved in starch biosynthesis were upregulated in eg06g, which contributed to amyloplast sedimentation and gravity perception. Auxin homeostasis and transport-related genes were found to be upregulated in eg06g, which altered the redistribution of auxin in eg06g and in turn triggered apoplastic acidification and activated cell wall modification-related enzymes, leading to tiller angle establishment through the promotion of cell elongation at the lower side of the lateral branch. In addition, cytokinin and GA also demonstrated synergistic action to finely regulate the formation of peanut lateral branch angles. Collectively, our findings provide new insights into the molecular regulation of peanut LBA and present genetic materials for breeding peanut cultivars with ideotypes.

Phenotypic characterization and genetic mapping of the semi-dwarf mutant sdw9 in maize.

In summary, we characterized a maize semi-dwarf mutant, sdw9, and successfully isolated the responsible gene, which encodes a GRAS protein, through a combination of map-based cloning and Re-sequencing (Re-seq). Our findings demonstrate that the candidate gene ZmGRAS42 regulates BR signaling genes, thereby influencing internode development. This regulatory function likely involves processes such as cell division, cell cycle regulation and cell wall synthesis. Favorable variations of ZmGRAS42 identified in this study may hold promise for the development of lodging-resistant maize cultivars suitable for high-density planting, contributing to the improvement of maize breeding programs. Plant height and lateral root angle are crucial determinants of plant architecture in maize (Zea mays) which are closely related to lodging resistance at high planting density. These traits are intricately regulated by various phytohormones. Mutations affecting hormone biosynthesis and signaling often lead to reduced yield alongside diminished plant height, posing challenges in breeding dwarf maize varieties. In this study, the maize mutant sdw9 was characterized, which displays shorter stature and altered lateral root angle compared to WT, while showing potential to increase planting density and improve overall yield despite a slight reduction in single-ear yield. Employing positional cloning coupled with Re-seq techniques, we pinpointed a transposon insertion in the candidate gene ZmGRAS42, which encodes a GRAS transcription factor involved in BR signaling in maize. Transcriptome analysis revealed that ZmGRAS42 orchestrates the expression of several known dwarfing genes such as D8, Br2, and Na2, along with genes associated with cell wall organization, cell division, and cell cycle regulation, notably Cesa4, Cesa7, and Cyc11. Furthermore, identification of favorable ZmGRAS42 haplotypes linked to reduced plant height offers novel avenues for maize breeding strategies. These findings not only hold the potential for enhancing maize lodging resistance but also for optimizing land utilization through high-density planting practices.

MpPUB9, a U-box E3 ubiquitin ligase, acts as a positive regulator by promoting the turnover of MpEXO70.1 under high salinity in Marchantia polymorpha.

Marchantia polymorpha, occupying a basal position in the monophyletic assemblage of land plants, displays a notable expansion of plant U-box (PUB) proteins compared with those in animals. We elucidated the roles of MpPUB9 in regulating salt stress tolerance in M. polymorpha. MpPUB9 expression was rapidly induced by high salinity and dehydration. MpPUB9 possessed an intact U-box domain in the N-terminus. MpPUB9-Citrine localized to punctate structures and was peripherally associated with microsomal membranes. Phenotypic analyses demonstrate that the hyponastic and epinastic thallus growth phenotypes, which were induced by the overexpression and suppression of MpPUB9, may provoke salt stress-resistant and -susceptible phenotypes, respectively. MpPUB9 was also found to directly interact with the exocyst protein MpEXO70.1, leading to its ubiquitination. Under high-salinity conditions, though the stability of MpPUB9 was dramatically increased, MpEXO70.1 showed slightly faster turnover rates. Transcriptome analyses showed that salt treatment and the overexpression of MpPUB9 co-upregulated the genes related to the modulation of H2O2 and cell wall organization. Overall, our results suggest that MpPUB9 plays a crucial role in the positive regulation of salt stress tolerance, resulting from its interaction with MpEXO70.1 and modulating turnover of the protein under high-salt conditions via the coordination of UPS with autophagy.

Non-additive expression genes play a critical role in leaf vein ratio heterosis in Nicotiana tabacum L.

Heterosis, recognized for improving crop performance, especially in the first filial (F1) generation, remains an area of significant study in the tobacco industry. The low utilization of leaf veins in tobacco contributes to economic inefficiency and resource waste. Despite the positive impacts of heterosis on crop genetics, investigations into leaf-vein ratio heterosis in tobacco have been lacking. Understanding the mechanisms underlying negative heterosis in leaf vein ratio at the molecular level is crucial for advancing low vein ratio leaf breeding research. This study involved 12 hybrid combinations and their parental lines to explore heterosis associated with leaf vein ratios. The hybrids displayed diverse patterns of positive or negative leaf vein ratio heterosis across different developmental stages. Notably, the F1 hybrid (G70 × Qinggeng) consistently exhibited substantial negative heterosis, reaching a maximum of -19.79% 80 days after transplanting. A comparative transcriptome analysis revealed that a significant proportion of differentially expressed genes (DEGs), approximately 39.04% and 23.73%, exhibited dominant and over-dominant expression patterns, respectively. These findings highlight the critical role of non-additive gene expression, particularly the dominance pattern, in governing leaf vein ratio heterosis. The non-additive genes, largely associated with various GO terms such as response to abiotic stimuli, galactose metabolic process, plant-type cell wall organization, auxin-activated signaling pathway, hydrolase activity, and UDP-glycosyltransferase activity, were identified. Furthermore, KEGG enrichment analysis unveiled their involvement in phenylpropanoid biosynthesis, galactose metabolism, plant hormone signal transduction, glutathione metabolism, MAPK signaling pathway, starch, and sucrose metabolism. Among the non-additive genes, we identified some genes related to leaf development, leaf size, leaf senescence, and cell wall extensibility that showed significantly lower expression in F1 than in its parents. These results indicate that the non-additive expression of genes plays a key role in the heterosis of the leaf vein ratio in tobacco. This study marks the first exploration into the molecular mechanisms governing leaf vein ratio heterosis at the transcriptome level. These findings significantly contribute to understanding leaf vein ratios in tobacco breeding strategies.

Differences in transcriptomic responses upon Phytophthora palmivora infection among cultivars reveal potential underlying resistant mechanisms in durian

BackgroundPhytophthora palmivora is a devastating oomycete pathogen in durian, one of the most economically important crops in Southeast Asia. The use of fungicides in Phytophthora management may not be a long-term solution because of emerging chemical resistance issues. It is crucial to develop Phytophthora-resistant durian cultivars, and information regarding the underlying resistance mechanisms is valuable for smart breeding programs.ResultsIn this study, we conducted RNA sequencing (RNA-seq) to investigate early gene expression responses (at 8, 24, and 48 h) after the P. palmivora infection in three durian cultivars, which included one resistant cultivar (Puangmanee; PM) and two susceptible cultivars (Monthong; MT and Kradumthong; KD). We performed co-expression and differential gene expression analyses to capture gene expression patterns and identify the differentially expressed genes. The results showed that genes encoding heat shock proteins (HSPs) were upregulated in all infected durians. The expression levels of genes encoding HSPs, such as ERdj3B, were high only in infected PM. A higher level of P. palmivora resistance in PM appeared to be associated with higher expression levels of various genes encoding defense and chitin response proteins, such as lysM domain receptor-like kinases. MT had a lower resistance level than PM, although it possessed more upregulated genes during P. palmivora infection. Many photosynthetic and defense genes were upregulated in the infected MT, although their expression levels were lower than those in the infected PM. KD, the least resistant cultivar, showed downregulation of genes involved in cell wall organization or biogenesis during P. palmivora infection.ConclusionsOur results showed that the three durian cultivars exhibited significantly different gene expression patterns in response to P. palmivora infection. The upregulation of genes encoding HSPs was common in all studied durians. The high expression of genes encoding chitin response proteins likely contributed to P. palmivora resistance in durians. Durian susceptibility was associated with low basal expression of defense genes and downregulation of several cell wall-related genes. These findings enhance our understanding of durian resistance to Phytophthora infection and could be useful for the development of elite durian cultivars.

Comparative analysis of polysaccharide and cell wall structure in Aspergillus nidulans and Aspergillus fumigatus by solid-state NMR

Invasive aspergillosis poses a significant threat to immunocompromised patients, leading to high mortality rates associated with these infections. Targeting the biosynthesis of cell wall carbohydrates is a promising strategy for antifungal drug development and will be advanced by a molecular-level understanding of the native structures of polysaccharides within their cellular context. Solid-state NMR spectroscopy has recently provided detailed insights into the cell wall organization of Aspergillus fumigatus, but genetic and biochemical evidence highlights species-specific differences among Aspergillus species. In this study, we employed a combination of 13C, 15N, and 1H-detection solid-state NMR, supplemented by Dynamic Nuclear Polarization (DNP), to compare the structural organization of cell wall polymers and their assembly in the cell walls of A. fumigatus and A. nidulans, both of which are key model organisms and human pathogens. The two species exhibited a similar rigid core architecture, consisting of chitin, α-glucan, and β-glucan, which contributed to comparable cell wall properties, including polymer dynamics, water retention, and supramolecular organization. However, differences were observed in the chitin, galactosaminogalactan, protein, and lipid content, as well as in the dynamics of galactomannan and the structure of the glucan matrix.

SUPERMAN Targets PHRAGMOPLAST ORIENTING KINESIN to Negatively Regulate Leaf Cell Division in Poplar

ABSTRACTPlant organs achieve their specific size and shape through the coordination of cell division and cell expansion, processes that are profoundly influenced by environmental cues. Cytokinesis during cell division depends on the position of the cytokinetic wall, but how this process responses to environment fluctuations remains underexplored. Here, we investigated a regulatory module involving C2H2‐type zinc finger protein (C2H2‐ZFP) in leaf morphology during drought stress. A total of 123 C2H2‐ZFP members were identified through a comparative genome survey in Populus alba × P. glandulosa ‘84K’. Among them, PagSUPa, an orthologous gene of Arabidopsis SUPERMAN, was selected due to its responsiveness to drought stress and was further confirmed to play a role in leaf development. Phenotypic characterization and cellular analysis revealed that PagSUPa fine‐tunes the duration of cell proliferation in the adaxial epidermis, thereby influencing leaf morphology by modulating leaf adaxial‐abaxial polarity. Additionally, we found that PagSUPa directly suppresses the expression of PHRAGMOPLAST ORIENTING KINESIN1 (PagPOK1) and PagPOK2, genes encoding proteins involved in phragmoplast orientation and position, which results in impaired cytokinesis and cell wall organization. This study provides novel insights into the regulatory network governed by the SUP gene during leaf development, specifically in relation to cell division.

Phloretin inhibits the growth of Arabidopsis shoots by inducing chloroplast damage and programmed cell death

Phloretin is a key secondary metabolite produced by apple trees. Known for its strong antioxidant properties, this dihydrochalcone has been extensively studied in animals but less so in plants. Recently, we identified phloretin as a phytotoxic allelochemical that inhibits growth in the model plant Arabidopsis by disrupting auxin metabolism and distribution in the roots. In this study, we found that phloretin significantly hinders the growth of Arabidopsis seedlings' aerial parts after a short-term treatment (10 days) and causes their decay after long-term exposure (28 days). These effects result from ultrastructural damage in the mesophyll cells of the leaves, including chloroplast displacement and swelling, lesions, and alterations in thylakoid and cell wall organization. Interestingly, phloretin-treated plants showed a decrease in malondialdehyde levels and antioxidant enzyme activities, while hydrogen peroxide and proline levels remained unchanged. This suggests that phloretin-induced chlorosis and seedling decay are not due to oxidative stress but rather to severe chloroplast structural damage, leading to inefficient photosynthesis, starch degradation, starvation, and activation of micro- and macroautophagic processes for self-preservation. Ultimately, these processes result in programmed cell death. These new insights into the phytotoxic effects of phloretin on Arabidopsis shoots could pave the way for future research into phloretin as a potential multitarget bioherbicide and enhance our understanding of autoallelopathy in apple trees.

Ume6-dependent pathways of morphogenesis and biofilm formation in Candida auris.

Candida auris is a yeast pathogen causing nosocomial outbreaks of candidemia. Its ability to adhere to inert surfaces and to be transmitted from one patient to another via medical devices is of particular concern. Like other Candida spp., C. auris has the ability to transition from the yeast form to pseudohyphae and to build biofilms. Moreover, some isolates have a unique capacity to form aggregates. These morphogenetic changes may impact virulence. In this study, we demonstrated the role of the transcription factor Ume6 in C. auris morphogenesis. Genetic hyperactivation of Ume6 induced filamentation and aggregation. The Ume6-hyperactivated strain (UME6HA) also exhibited increased adhesion to inert surface and formed biofilms of higher biomass compared to the parental strain. Transcriptomic analyses of UME6HA revealed enrichment of genes encoding for adhesins, proteins involved in cell wall organization, sterol biosynthesis, and aspartic protease activities. The three most upregulated genes compared to wild-type were those encoding for the agglutin-like sequence adhesin Als4498, the C. auris-specific adhesin Scf1, and the hypha-specific G1 cyclin-related protein Hgc1. The deletion of these genes in the UME6HA background showed that Ume6 controls filamentation via Hgc1 and aggregation via Als4498 and Scf1. Adhesion to inert surface was essentially triggered by Scf1. However, Als4498 and Hgc1 were also crucial for biofilm formation. Our data show that Ume6 is a universal regulator of C. auris morphogenesis via distinct modulators.IMPORTANCEC. auris represents a public health threat because of its ability to cause difficult-to-treat infections and hospital outbreaks. The morphogenetic plasticity of C. auris, including its ability to filament, to form aggregates or biofilms on inert surfaces, is important to the fungus for interhuman transmission, skin or catheter colonization, tissue invasion, antifungal resistance, and escape of the host immune system. This work deciphered the importance of Ume6 in the control of distinct pathways involved in filamentation, aggregation, adhesion, and biofilm formation of C. auris. A better understanding of the mechanisms of C. auris morphogenesis may help identify novel antifungal targets.

Differential symbiotic compatibilities between rhizobium strains and cultivated and wild soybeans revealed by anatomical and transcriptome analyses.

Various species of rhizobium establish compatible symbiotic relationships with soybean (Glycine max) leading to the formation of nitrogen-fixing nodules in roots. The formation of functional nodules is mediated through complex developmental and transcriptional reprogramming that involves the activity of thousands of plant genes. However, host transcriptome that differentiate between functional or non-functional nodules remain largely unexplored. In this study, we investigated differential compatibilities between rhizobium strains (Bradyrhizobium diazoefficiens USDA110 Bradyrhizobium sp. strain LVM105) and cultivated and wild soybeans. The nodulation assays revealed that both USDA110 and LVM105 strains effectively nodulate G. soja but only USDA110 can form symbiotic relationships with Williams 82. LVM105 formed pseudonodules on Williams 82 that consist of a central nodule-like mass that are devoid of any rhizobia. RNA-seq data revealed that USDA110 and LVM105 induce distinct transcriptome programing in functional mature nodules formed on G. soja roots, where genes involved in nucleosome assembly, DNA replication, regulation of cell cycle, and defense responses play key roles. Transcriptome comparison also suggested that activation of genes associated with cell wall biogenesis and organization and defense responses together with downregulation of genes involved in the biosynthesis of isoprenoids and antioxidant stress are associated with the formation of non-functional nodules on Williams 82 roots. Moreover, our analysis implies that increased activity of genes involved in oxygen binding, amino acid transport, and nitrate transport differentiates between fully-developed nodules in cultivated versus wild soybeans.

Comparative Analysis of Polysaccharide and Cell Wall Structure in Aspergillus nidulans and Aspergillus fumigatus by Solid-State NMR.

Invasive aspergillosis poses a significant threat to immunocompromised patients, leading to high mortality rates associated with these infections. Targeting the biosynthesis of cell wall carbohydrates is a promising strategy for antifungal drug development and will be advanced by a molecular-level understanding of the native structures of polysaccharides within their cellular context. Solid-state NMR spectroscopy has recently provided detailed insights into the cell wall organization of Aspergillus fumigatus, but genetic and biochemical evidence highlights species-specific differences among Aspergillus species. In this study, we employed a combination of 13C, 15N, and 1H-detection solid-state NMR, supplemented by Dynamic Nuclear Polarization (DNP), to compare the structural organization of cell wall polymers and their assembly in the cell walls of A. fumigatus and A. nidulans, both of which are key model organisms and human pathogens. The two species exhibited a similar rigid core architecture, consisting of chitin, α-glucan, and β-glucan, which contributed to comparable cell wall properties, including polymer dynamics, water retention, and supramolecular organization. However, differences were observed in the chitin, galactosaminogalactan, protein, and lipid content, as well as in the dynamics of galactomannan and the structure of the glucan matrix.

Transcriptome and protein-protein interaction analysis reveals the tolerance of poplar to high boron toxicity regulated by transport and cell wall synthesis pathways

Soil contamination with high levels of boron (B) destroys the balance of the soil ecosystem, reduces crop yields and poses a potential threat to human health and safety. Hyperaccumulator plants such as poplar can be used to mitigate high B soil contamination and its negative effects. Despite having a certain level of understanding of the physiological response of poplars to high boron stress tolerance, the differences in boron accumulation efficiency among different clones and their underlying molecular mechanisms are still unclear. The effects of high B toxicity on growth, B accumulation and physiological parameters were investigated in this research to compare the high B tolerance and high B accumulation abilities of five poplar clones (717, SXY, NL895, 84 K, and T89). Then two poplar clones (SXY and T89) were selected, due to their differences in B content and accumulation under high B toxicity, for transcriptomic and protein-protein interactions (PPI) analysis. The plant biomass and root-to-shoot ratio were reduced, the leaves exhibited symptoms of chlorosis and shrinkage of high B stressed five poplar clones. Boron toxicity significantly decreased the net photosynthetic rates, disturbed the balance of redox, induced the accumulation of H2O2 and malondialdehyde (MDA), and caused the increase in free proline levels in roots and leaves. B accumulation was significantly increased in the high B treated new leaves. The SXY clones showed the highest B accumulation, making it a potential hyperaccumulator for B contaminated soils. The transcriptome analysis of SXY and T89 revealed differential expression of genes involved in cell wall organization, active transmembrane transporter activity, cell wall synthesis, and B transport. The analysis of PPI indicates that these proteins work together in group functions. We identified some key differentially expressed genes (DEGs) related to transport and cell wall degradation. Our findings suggest that poplar is a plant that can tolerate high levels of boron, and it is possible to select poplar clones that accumulate high levels of boron to reduce soil boron pollution. The potential candidate genes, involved in transport and cell wall synthesis, can be focused on to improve poplar tolerance to high B in future breeding programs.

Magic-angle spinning NMR spectral editing of polysaccharides in whole cells using the DREAM scheme

Most bacterial, plant and fungal cells possess at their surface a protective layer called the cell wall, conferring strength, plasticity and rigidity to withstand the osmotic pressure. This molecular barrier is crucial for pathogenic microorganisms, as it protects the cell from the local environment and often constitutes the first structural component encountered in the host-pathogen interaction. In pathogenic molds and yeasts, the cell wall constitutes the main target for the development of clinically-relevant antifungal drugs. In the past decade, solid-state NMR has emerged as a powerful analytical technique to investigate the molecular organization of microbial cell walls in the context of intact cells. 13C NMR chemical shift is an exquisite source of information to identify the polysaccharides present in the cell wall, and two-dimensional 13C–13C correlation experiments provide an efficient tool to rapidly access the polysaccharide composition in whole cells. Here we investigate the use of the adiabatic DREAM (for dipolar recoupling enhancement through amplitude modulation) recoupling scheme to improve solid-state NMR analysis of polysaccharides in intact cells. We demonstrate the advantages of two-dimensional 13C–13C experiments using the DREAM recoupling scheme. We report the spectral editing of polysaccharide signals by varying the radio-frequency carrier position. We provide practical considerations for the implementation of DREAM experiments to characterize polysaccharides in whole cells. We demonstrate the approach on intact fungal cells of Neurospora crassa and Aspergillus fumigatus, a model and a pathogenic filamentous fungus, respectively. The approach could be envisioned to efficiently reduce the spectral crowding of more complex cell surfaces, such as cell wall and peptidoglycan in bacteria.

Candida tropicalis PMT2 Is a Dispensable Gene for Viability but Required for Proper Interaction with the Host.

Candidemia is an opportunistic mycosis with high morbidity and mortality rates. Even though Candida albicans is the main causative agent, other Candida species, such as Candida tropicalis, are relevant etiological agents of candidiasis and candidemia. Compared with C. albicans, there is currently limited information about C. tropicalis' biological aspects, including those related to the cell wall and the interaction with the host. Currently, it is known that its cell wall contains O-linked mannans, and the contribution of these structures to cell fitness has previously been addressed using cells subjected to chemical treatments or in mutants where O-linked mannans and other wall components are affected. Here, we generated a C. tropicalis pmt2∆ null mutant, which was affected in the first step of the O-linked mannosylation pathway. The null mutant was viable, contrasting with C. albicans where this gene is essential. The phenotypical characterization showed that O-linked mannans were required for filamentation; proper cell wall integrity and organization; biofilm formation; protein secretion; and adhesion to extracellular matrix components, in particular to fibronectin; and type I and type II collagen. When interacting with human innate immune cells, it was found that this cell wall structure is dispensable for cytokine production, but mutant cells were more phagocytosed by monocyte-derived macrophages. Furthermore, the null mutant cells showed virulence attenuation in Galleria mellonella larvae. Thus, O-linked mannans are minor components of the cell wall that are involved in different aspects of C. tropicalis' biology.

In situ imaging of LPMO action on plant tissues

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that oxidatively cleave recalcitrant polysaccharides such as cellulose. Several studies have reported LPMO action in synergy with other carbohydrate-active enzymes (CAZymes) for the degradation of lignocellulosic biomass but direct LPMO action at the plant tissue level remains challenging to investigate. Here, we have developed a MALDI-MS imaging workflow to detect oxidised oligosaccharides released by a cellulose-active LPMO at cellular level on maize tissues. Using this workflow, we imaged LPMO action and gained insight into the spatial variation and relative abundance of oxidised and non-oxidised oligosaccharides. We reveal a targeted action of the LPMO related to the composition and organisation of plant cell walls.

Deciphering the antiochratoxigenic activity of plant extracts and Debaryomyces hansenii against Penicillium nordicum in a “chorizo”-based medium by proteomic analysis

Penicillium nordicum is the main ochratoxin A (OTA)-producing species on the surface of dry-fermented sausages, such as the “chorizo”. New antifungal strategies are being developed using biocontrol agents (BCAs), such as plant extracts and native microorganisms. This work aimed to evaluate the antiochratoxigenic capacity and the causative modes of action of BCAs (rosemary essential oil (REO), acorn shell extract and the yeast Debaryomyces hansenii (Dh)) in a “chorizo”-based medium (Ch-DS). BCAs were inoculated on Ch-DS together with P. nordicum and incubated at 12 °C for 15 days to collect mycelia for OTA analyses and comparative proteomics. Both REO and Dh alone decreased OTA accumulation up to 99% and affected the abundance of P. nordicum proteins linked to cell wall organisation, synthesis of OTA-related metabolites and ergosterol synthesis. It is worth highlighting the increased abundance of an amidase by REO, matching with the decrease in OTA. The use of REO and Dh as BCAs could be an effective strategy to reduce the OTA hazard in the meat industry. Based on their not fully coincident modes of action, their combined application could be of interest in “chorizo” to maximise their potential against ochratoxigenic strains.

Physiological and molecular mechanisms of melatonin to alleviate benzoic acid-induced autotoxicity stress in Prunus persica

Autotoxicity stress is well known as a critical factor in the replant problem that hinders the sustainable development of agriculture. Benzoic acid (BA) is identified as a major autotoxin in peach replant problem, and causes serious growth inhibition of peach plants. Melatonin is a multi-functional molecule that plays a key role in alleviating stress-induced damage in plants. However, the functions and the inherent molecular mechanisms of melatonin under autotoxicity stress remains largely elusive. Here, we found that application of melatonin significantly enhanced BA tolerance in peach seedlings. Exogenous melatonin mitigated the negative impact of BA stress on peach root growth. Melatonin pretreatment boosted flavonoid biosynthesis and increased soluble sugar content of peach plants under BA stress. In addition, melatonin also promoted the reactive oxygen species scavenging by enhancing the antioxidant capacity. Consistent with these alterations, transcriptome analysis demonstrated that up-regulations of flavonoid biosynthesis, starch and sucrose metabolism, and antioxidant-related genes were observed when melatonin applied under BA stress. Furthermore, we also observed that an induction in genes involved in xenobiotic transmembrane transport, cell wall organization or biogenesis, and α-linolenic acid metabolism, which might contribute to the melatonin-mediated BA tolerance. Collectively, our findings reveal that melatonin confers BA tolerance of peach seedlings, primarily attributed to increased flavonoid and soluble sugar levels, enhanced antioxidant capacities, and extensive transcriptome reprograming. This opens new avenues for utilizing melatonin to alleviate peach replant problem.

Signatures of adaptation and purifying selection in highland populations of Dasiphora fruticosa.

High mountains harbor a considerable proportion of biodiversity, but we know little about how diverse plants adapt to the harsh environment. Here we finished a high-quality genome assembly for Dasiphora fruticosa, an ecologically important plant distributed in the Qinghai-Tibetan Plateau and lowland of the Northern Hemisphere, and resequenced 592 natural individuals to address how this horticulture plant adapts to highland. Demographic analysis revealed D. fruticosa underwent a bottleneck after Naynayxungla Glaciation. Selective sweep analysis of two pairs of lowland and highland population identified 63 shared genes related to cell wall organization or biogenesis, cellular component organization, and dwarfism, suggesting parallel adaptation to highland habitats. Most importantly, we found that stronger purging of estimated genetic load due to inbreeding in highland populations apparently contributed to their adaptation to the highest mountain. Our results revealed how plants could tolerate the extreme plateau, which could provide potential insights for species conservation and crop breeding.

Genome-wide identification and examination of the wheat glycosyltransferase family 43 regulation during Fusarium graminearum infection

In Arabidopsis and rice, the glycosyltransferase (GT) 43 family is involved in xylan synthesis. However, there have been limited reports on the study of the TaGT43 family in wheat. In this study, 28 TaGT43 family members were identified in wheat (Triticum aestivum L.) and clustered into three major groups based on the similarity of amino acid sequences. The results of the TaGT43 family's conserved motif and gene structure analyses agree with this result. Collinearity analysis revealed segmental duplications mainly promoted TaGT43 family expansion. cis-Acting element analysis revealed that the TaGT43 genes were involved in the light response, phytohormone response, abiotic/biotic stress response, and growth and development. The TaGT43 family showed a tissue-specific expression pattern, primarily expressed in roots and stems. Besides, the transcriptional and expression levels of multiple TaGT43 genes were upregulated during the infection of F. graminearum. According to metabolomics studies, F. graminearum infection affected the phenylpropanoid biosynthesis pathway in wheat, a critical factor in cell wall construction. Furthermore, GO enrichment analysis indicated that the TaGT43 genes play a significant role in cell wall organization. Based on these results, it may be concluded that the TaGT43 family mediates cell wall organization in response to F. graminearum infection.