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This article discusses a study that used machine learning to identify and validate plant peroxisome targeting signal type 1 (PTS1) tripeptides. Peroxisomes are organelles in eukaryotic cells that are involved in metabolic pathways. The researchers trained machine learning models using a dataset of functional PTS1 sequences and non-PTS1 sequences, achieving high accuracy and recall rates in predicting peroxisome targeting. They then used the models to predict novel PTS1 tripeptides and confirmed their peroxisome targeting through experimental validation. The study expands our understanding of peroxisomes in plants and has implications for predicting peroxisomal proteins and metabolic pathways in different plant species. However, it is important to consider that the presence of a PTS1 tripeptide does not guarantee peroxisome targeting, as other factors may also influence protein localization. [Extracted from the article]

Cadmium (Cd) is a toxic heavy metal with no known biological function in plants and one of the most toxic substances released into the environment. Crops, such as rice, maize, wheat and tobacco are the major sources of Cd for humans. Cd toxicity inhibits crop growth and development by affecting many central physiological and biochemical processes, and finally it affects human health via the food chain. To adapt to Cd toxicity, crops have evolved a series of detoxification mechanisms. Immediate responses include rapid changes at the transcriptional level with simultaneous changes at the physiological and metabolic levels. However, the long-term responses involve genetic modifications and epigenetic changes. During the last decade, many genes involved in Cd uptake and translocation have been identified, and many of them are transporters. To decrease the accumulation of Cd in cereal grains and tobacco leaves, a number of approaches have been proposed, including physical and chemical methods, developing and planting low accumulation genotypes using transgenic strategies or marker–trait association breeding. In this review, we describe the toxicity of Cd to crops and human body, advances in the molecular mechanisms of Cd accumulation in cereal crops and tobacco, and approaches to decrease Cd accumulation. [ABSTRACT FROM AUTHOR]

Potassium (K+) is mainly absorbed by plants from the soil and is primarily transported within the plant through the xylem. Topping has been reported to cause efflux and loss of K+ in plants; however, its effect on the real-time flow rate and genotypes with varying K+ accumulation ability is still unknown. Therefore, we carried out a pot experiment containing sand culture using two tobacco cultivars EY1 (high K+ accumulating) and Y87 (low K+ accumulating). The results demonstrated the change of K+ flow direction from influx to efflux in the roots of both cultivars due to topping. The percentage ratio of K+ efflux to influx was estimated to be 18.8% in EY-1 and 157.0% in Y87, respectively. We noticed a decline in indole acetic acid (IAA) content due to topping, which activated the expression of K+ efflux channel gene NTORK1 and inhibited the expression of K+ influx channel genes NKT1 and NtKC1. Furthermore, K+ loss from the roots increased due to topping, which led to decreased K+ concentration in entire tobacco plant. Topping had a more serious impact on the K+ efflux rate and K+ loss in Y87. IAA application after topping, in turn, decreased the K+ loss in both the cultivars. We conclude that topping caused a decrease in IAA concentration and K+ losses in tobacco leaves, and these losses can be mitigated by the exogenous application of IAA. [ABSTRACT FROM AUTHOR]

Se is beneficial to plants' growth and it is an essential mineral for animals and humans. However, relatively little is known about the relationship between nano-Se concentrations and plant antioxidant activity. In this work, a pot experiment was carried out using two cultivars of tobacco and increasing nano-Se concentrations. The changes of plant biomass, root growth, chlorophyll content, nutrient accumulation and reactive oxygen species (ROS) content in tobacco leaves after being sprayed with nano-Se were studied. The results indicated that the growth of tobacco can be promoted by applying nano-Se in an appropriate concentration. In addition, our research proves that there is cultivars variation in the response of tobacco to increased concentrations of nano-Se. The biomass, root growth characteristics, chlorophyll content and N accumulation of E'yan 1 were increased significantly and were the highest at 5.0 mg L−1 of nano-Se. On the other hand, the above mentioned indicators for K326 reached the maximum value at 2.5 mg L−1 and decreased at 5.0 mg L−1 of nano-Se. The antioxidant enzymes activity were increased by the application of nano-Se, however cultivars variation was detected. The application of nano-Se reduced the amount of thiobarbituric acid reactive substances (TBARS) and ROS at 5.0 mg L−1 for both cultivars. This study confirms that nano-Se affects positively the growth and oxidative status of tobacco plants. However, this study points out that more research is needed to understand the interaction phenomena observed here between tobacco cultivars and concentrations specifically for the anti-oxidant status of the plant. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is the primary limiting factor of crop production on acid soils. Tibetan wild barley germplasm is a valuable source of potential genes for breeding barley with acid and Al tolerance. We performed microRNA and RNA sequencing using wild (XZ16, Al-tolerant; XZ61, Al-sensitive) and cultivated (Dayton, Al-tolerant) barley. A novel homeobox-leucine zipper transcription factor, HvHOX9 , was identified as a target gene of miR166b and functionally characterized. HvHOX9 was up-regulated by Al stress in XZ16 (but unchanged in XZ61 and Dayton) and was significantly induced only in root tip. Phylogenetic analysis showed that HvHOX9 is most closely related to wheat TaHOX9 and orthologues of HvHOX9 are present in the closest algal relatives of Zygnematophyceae. Barley stripe mosaic virus-induced gene silencing of HvHOX9 in XZ16 led to significantly increased Al sensitivity but did not affect its sensitivity to other metals and low pH. Disruption of HvHOX9 did not change Al concentration in the root cell sap, but led to more Al accumulation in root cell wall after Al exposure. Silencing of HvHOX 9 decreased H+ influx after Al exposure. Our findings suggest that miR166b /HvHOX9 play a critical role in Al tolerance by decreasing root cell wall Al binding and increasing apoplastic pH for Al detoxification in the root. [ABSTRACT FROM AUTHOR]

Selenium can mitigate cadmium toxicity in plants. However, the mechanism of this alleviation has not been fully understood. In the present study, the role of Se in inducing tolerance to Cd stress in cucumber was elucidated. Results showed that Se significantly alleviated Cd-induced growth inhibition, reduced Cd concentration, increased SPAD value and improved photosynthetic performance. Through proteomic analysis by two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry, 26 protein spots were identified, which were significantly influenced by Cd stress and/or Se application. Among these proteins, the abundance of 21 spots (10 in leaves and 11 in roots) were repressed in Cd-treated and up-accumulated or no-changed in Cd+Se-treated cucumber. These altered proteins were involved in the response to stress, metabolism, photosynthesis and storage, they were including glutathione S-transferase F8, heat shock protein STI-like, peroxidase, ascorbate oxidase, fructose-bisphosphate aldolase 2, NiR, Rieske type ion sulfur subunit and PsbP domain-containing protein 6. Furthermore, we identified five proteins with an increase in relative abundance after Cd treatment, they were involved in the functional groups active in response to stress and transport. The present study provided novel insights into Se-mediated tolerance of cucumber seedlings against Cd toxicity at the proteome level. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum (Al) toxicity is a major limiting factor for plant production in acid soils. Wild barley germplasm is a treasure trove of useful genes and offers rich sources of genetic variation for crop improvement. Al-stress-hydroponic-experiments were performed, and the physiochemical characteristic of two contrasting Tibetan wild barley genotypes (Al-resistant XZ16 and Al-sensitive XZ61) and Al-resistant cv. Dayton were compared. Ultrastructure of chloroplasts and root cells in XZ16 was less injured than that in Dayton and XZ61. Moreover, XZ16 secreted significantly more malate besides citrate and exhibited less Al uptake and distribution than both of XZ61 and Dayton in response to Al stress, simultaneously maintained higher H+-, Ca2+Mg2+- and total-ATPase activities over XZ61. The protein synthesis inhibitor cycloheximide reduced citrate secretion from XZ16, but not from Dayton. In Tibetan wild barley, our findings highlight the significant correlations between Al tolerance, ATPase activity and citrate secretion, providing some insights into the physiological basis for Al-detoxification. [Copyright &y& Elsevier]

Aluminum (Al) toxicity is a major limiting factor for plant production in acid soils. Wild barley germplasm is rich in genetic diversity and may provide elite genes for crop Al tolerance improvement. The hydroponic-experiments were performed to compare proteomic and transcriptional characteristics of two contrasting Tibetan wild barley genotypes Al- resistant/tolerant XZ16 and Al-sensitive XZ61 as well as Al-resistant cv. Dayton. Results showed that XZ16 had less Al uptake and translocation than XZ61 and Dayton under Al stress. Thirty-five Al-tolerance/resistance-associated proteins were identified and categorized mainly in metabolism, energy, cell growth/division, protein biosynthesis, protein destination/storage, transporter, signal transduction, disease/defense, etc. Among them, 30 were mapped on barley genome, with 16 proteins being exclusively up-regulated by Al stress in XZ16, including 4 proteins (S-adenosylmethionine-synthase 3, ATP synthase beta subunit, triosephosphate isomerase, Bp2A) specifically expressed in XZ16 but not Dayton. The findings highlighted the significance of specific-proteins associated with Al tolerance, and verified Tibetan wild barley as a novel genetic resource for Al tolerance. [ABSTRACT FROM AUTHOR]

Abstract: Greenhouse pot experiments were conducted to investigate genotypic differences in response to individual and combined stresses of drought and salinity between Tibetan wild barley genotypes (XZ5, drought-tolerant; XZ16, salinity/aluminum tolerant) and cv. CM72 (salinity-tolerant). Either drought (D) or salinity (S) alone and in combination (D + S) stresses significantly decreased plant growth, chlorophyll content, net photosynthetic rate (Pn), maximal photochemical efficiency of PSII (Fv/Fm), water potential and osmotic potential, with the largest suppression under combined stress, and two wild genotypes showing more tolerance than CM72. Water use efficiency (WUE) increased significantly in XZ5 and XZ16 after D + S, but no significant change in CM72. XZ5 and XZ16 showed 30.9% and 12.1% higher K+ level and 30.5% and 24.1% lower Na+/K+ ratio in plants, compared with CM72, with increased metal nutrients as Ca, Fe and Mn under D + S. The peak accumulation in proline and glycine-beatine was recorded in combined stress with larger accumulation in two wild genotypes. Moreover, larger increases in the level of ASA and GSH, and the activities of Ca2+Mg2+-ATPase, and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), guaiacol peroxidase (POD) and glutathione reductase (GR) under D + S vs control were observed in XZ5 and XZ16 than CM72, with less accumulation of H2O2 and malondialdehyde. These results suggest that high tolerance to D + S stress of XZ5 and XZ16 is closely related to lower Na+/K+ ratio and enhanced Ca2+Mg2+-ATPase, proline, glycine-beatine and WUE, and improved capacity of antioxidative performance to scavenge reactive oxygen species and thus suppressed level of lipid peroxidation. [Copyright &y& Elsevier]

Deciphering the mechanism of Cd accumulation in crops is imperative for minimizing soil-to-plant transfer of Cd to improve safe food production. Hydroponic experiments were performed examining Cd accumulation, growth performance and protein characteristics of two rice genotypes, Xiushui817 and Zheda821, with low and high grain Cd accumulation, respectively, under Cd stress and in the presence of Si. Xiushui817 had lower root-to-shoot Cd translocation and was more sensitive to Cd stress than Zheda821. Si reduced the shoot Cd content in both genotypes but more efficacy in Zheda821. Tandem mass tags (TMT)-based proteomic analysis identified 25 proteins associated with low grain Cd accumulation, including vacuolar H+-pyrophosphatase 1 (OVP1) that was up-regulated after Si addition in Zheda821. The sequence comparison of OVP1 showed one nucleotide difference in Xiushui817 relative to Zheda821 resulting in one amino acid. Overexpression of OVP1 reduced shoot Cd concentration and improved the growth of rice compared with WT under both control and Cd treatment. The results highlight the significant roles of OVP1 in both Cd accumulation and the Si-induced Cd reduction in rice. Our findings provide valuable insights into the molecular mechanism of low Cd accumulation and Si-induced decrease in Cd accumulation in rice. OVP1 could be used for transgenic overexpression in rice or other cereals for safe food production. • The first report proteomic study of grain low Cd accumulation in rice. • Identified 25 proteins, including OVP associated with Si induced Cd decrease. • Overexpression of OVP reduced shoot Cd level and improved rice growth. • Novel genetic resource of grain low Cd accumulation in rice was verified. [ABSTRACT FROM AUTHOR]

We report the complete genome of Priestia filamentosa H146 isolated from tobacco leaves. H146 contained a circular chromosome and five circular plasmids. A total of 4,669 genes were predicted, of which 4,372 genes were in the chromosome and other genes were located on plasmids. The genome sequence data provide an important basis for studying Priestia filamentosa ., Competing Interests: The authors declare no conflict of interest.

Understanding the response of microbial communities and their potential functions is essential for sustainability of agroecosystems under long-term continuous cropping. However, limited research has focused on investigating the interaction between soil physicochemical factors and microbial community dynamics in agroecosystems under long-term continuous cropping. This study probed into the physicochemical properties, metabolites, and microbial diversity of tobacco rhizosphere soils cropped continuously for 0, 5, and 20 years. The relative abundance of bacterial genera associated with nutrient cycling (e.g., Sphingomonas ) increased while potential plant pathogenic fungi and beneficial microorganisms showed synergistic increases with the duration of continuous cropping. Variations in soil pH, alkeline nitrogen (AN) content, and soil organic carbon (SOC) content drove the shifts in soil microbial composition. Metabolites such as palmitic acid, 3-hydroxypropionic acid, stearic acid, and hippuric acid may play a key role in soil acidification. Those results enhance our ability to predict shifts in soil microbial community structure associated with anthropogenic continuous cropping, which can have long-term implications for crop production., Competing Interests: YH, HC, and BD were employed by Guizhou Tobacco Company Bijie Region Tobacco Company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ding, Dai, He, Liang, Zhai, Zhang, Hu, Cai, Dai, Xu and Zhang.)

The lack of irrigation water in agricultural soils poses a significant constraint on global crop production. In-depth investigation into microRNAs (miRNAs) has been widely used to achieve a comprehensive understanding of plant defense mechanisms. However, there is limited knowledge on the association of miRNAs with drought tolerance in cigar tobacco. In this study, a hydroponic experiment was carried out to identify changes in plant physiological characteristics, miRNA expression and metabolite profile under drought stress, and examine the mitigating effects of selenium (Se) application. The shoot dry weight of drought-stressed plants was approximately half (50.3%) of that in non-stressed (control) conditions. However, plants supplied with Se attained 38.8% greater shoot dry weight as compared to plants with no Se supply under drought stress. Thirteen miRNAs were identified to be associated with drought tolerance. These included 7 known (such as nta-miR156b and nta-miR166a) and 6 novel miRNAs (such as novel-nta-miR156-5p and novel-nta-miR209-5p) with the target genes of squamosa promoter-binding-like protein 4 ( SPL4 ), serine/threonine protein phosphatase 2A ( PPP2A ), cation/calcium exchanger 4-like ( CCX4 ), extensin-1-like ( EXT1 ) and reduced wall acetylation 2 ( RWA2 ). Further investigation revealed that the expression levels of Ext1 and RWA2 were significantly decreased under drought stress but increased with Se addition. Moreover, key metabolites such as catechin and N-acetylneuraminic acid were identified, which may play a role in the regulation of drought tolerance. The integrated analysis of miRNA sequencing and metabolome highlighted the significance of the novel-nta-miR97-5p- LRR-RLK - catechin pathway in regulating drought tolerance. Our findings provide valuable insights into the molecular mechanisms underlying drought tolerance and Se-induced stress alleviation in cigar tobacco., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Dai, Yang, Teng, Wang, Liang, Khan, Yang, Qiao, Zhang and Yang.)

Soil bacterial communities are intricately linked to ecosystem functioning, and understanding how communities assemble in response to environmental change is ecologically significant. Little is known about the assembly processes of bacteria communities across agro-ecosystems, particularly with regard to their environmental adaptation. To gain further insights into the microbial community characteristics of agro-ecosystems soil in the Panxi area of Sichuan Province and explore the key environmental factors driving the assembly process of the microbial community, this study conducted field sampling in major farmland areas of Panxi area and used Illumina MiSeq high-throughput sequencing technology to conduct bacterial sequencing. Soil organic matter (SOM), alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK) and other environmental factors were determined. The membership function method and principal component analysis method were used to evaluate the fertility of the soil. The results revealed minimal differences in alpha diversity index among samples with different comprehensive fertility indices, while NMDS analysis showed that community differences between species were mainly reflected in high fertility and low fertility (R: 0.068, p: 0.011). Proteobacteria, Acidobacteria and Actinobacteria were the main types of microbial communities, accounting for more than 60% of the relative abundance. Proteobacteria accounted for a higher proportion in the high fertility samples, while Acidobacteria and Actinobacteria accounted for a higher proportion in the middle and low fertility samples. Both the neutral theoretical model and zero model analysis showed that the microbial communities in tobacco-planting soil with different comprehensive fertility indices presented a random assembly process. With the increase in environmental distance difference, the diversity of the microbial community in medium and low-fertility soil also increased, but there was no significant change in high-fertility soil. Redundancy analysis showed that pH and SOM were the key factors affecting microbial community composition. The results of this study can provide a theoretical reference for the study of environmental factors and microbial communities in tobacco-growing soil., Competing Interests: TL, HD, ZZ, and YZ were employed by Zhengzhou Tobacco Research Institute of CNTC. YC was employed by Liangshan Branch of Sichuan Tobacco Company. GY was employed by China Tobacco Henan Industrial Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Xu, Liang, Dai, Zhai, Chen, Yin, Zhang and Yue.)