Transgenic Plants Research Articles

The Small Auxin-Up RNA 50 (SAUR50) Gene from Ammopiptanthus nanus Negatively Regulates Drought Tolerance.

Drought stress is a primary abiotic stress that causes significant losses to forestry and agricultural production. Therefore, exploring drought-responsive genes and their regulatory mechanism is crucial for plant molecular breeding for forestry and agriculture production safety. Small auxin-up RNA (SAUR) proteins are essential in plant growth and development but show functional diversity in stress response. In this study, the transcriptome sequencing data of Ammopiptanthus nanus seedlings revealed that the expression of AnSAUR50 was continuously downregulated under drought stress. Hence, the AnSAUR50 gene was cloned and functionally analyzed in drought response. The results showed that the coding sequence of AnSAUR50 was 315 bp in length and encoded 104 amino acids. The AnSAUR50 protein showed high conservation, possessed a SAUR-specific domain, and localized in the nucleus and cell membrane. The heterologous expression of the AnSAUR50 gene enhanced the drought sensitivity of the transgenic Arabidopsis with a lower survival rate, biomass, and higher malondialdehyde content and relative electrolyte leakage. Moreover, transgenic plants showed shorter root lengths and bigger stomatal apertures, resulting in facilitating water loss under drought stress. The study indicates that AnSAUR50 negatively regulates drought tolerance by inhibiting root growth and stomatal closure, which provides insights into the underlying function and regulatory mechanism of SAURs in plant stress response.

EjWRKY6 Is Involved in the ABA-Induced Carotenoid Biosynthesis in Loquat Fruit during Ripening.

The yellow-fleshed loquat is abundant in carotenoids, which determine the fruit's color, provide vitamin A, and offer anti-inflammatory and anti-cancer health benefits. In this research, the impact of abscisic acid (ABA), a plant hormone, on carotenoid metabolism and flesh pigmentation in ripening loquat fruits was determined. Results revealed that ABA treatment enhanced the overall content of carotenoids in loquat fruit, including major components like β-cryptoxanthin, lutein, and β-carotene, linked to the upregulation of most genes in the carotenoid biosynthesis pathway. Furthermore, a transcription factor, EjWRKY6, whose expression was induced by ABA, was identified and was thought to play a role in ABA-induced carotenoid acceleration. Transient overexpression of EjWRKY6 in Nicotiana benthamiana and stable genetic transformation in Nicotiana tabacum with EjWRKY6 indicated that both carotenoid production and genes related to carotenoid biosynthesis could be upregulated in transgenic plants. A dual-luciferase assay proposed a probable transcriptional control between EjWRKY6 and promoters of genes associated with carotenoid production. To sum up, pre-harvest ABA application could lead to carotenoid biosynthesis in loquat fruit through the EjWRKY6-induced carotenoid biosynthesis pathway.

The Abscisic Acid Receptor Gene StPYL8-like from Solanum tuberosum Confers Tolerance to Drought Stress in Transgenic Plants.

Pyrabactin resistance 1-like (PYL) proteins are abscisic acid (ABA) receptors that play a crucial role in the plant's response to adverse environmental conditions. However, as of yet, there is limited research on the role of PYL proteins in potato. In this study, a potato PYL gene, StPYL8-like, was identified through transcriptome analysis under drought stress. Molecular characterization revealed that the StPYL8-like protein possesses a highly conserved PYL family domain. Evolutionary analysis demonstrated that StPYL8-like protein clusters with various PYL proteins are involved in stress responses across different species. Functional assays showed that StPYL8-like robustly responds to different abiotic stresses, including drought and ABA treatment. Furthermore, the transient and stable expressions of StPYL8-like in tobacco enhanced their drought resistance, leading to increased plant height, leaf number, and fresh weight, as well as an improved root system. Transgenic tobacco carrying the StPYL8-like gene exhibited lower malondialdehyde (MDA) levels and higher proline accumulation and antioxidant enzyme activity compared to wild-type plants under drought conditions. Moreover, StPYL8-like upregulated the expression of stress-responsive genes (NtRD29A, NtLEA5, NtP5CS, NtPOD, NtSOD, and NtCAT) in transgenic plants subjected to drought stress. Collectively, these findings highlight the positive regulatory role of the StPYL8-like gene in enhancing potato plants' response to drought stress.

Genome-wide identification, molecular evolution, and functional characterization of fructokinase gene family in apple reveal its role in improving salinity tolerance

Fructokinase (FRK) is a regulator of fructose signaling in plants and gateway proteins that catalyze the initial step in fructose metabolism through phosphorylation. Our previous study demonstrated that MdFRK2 protein exhibit not only high affinity for fructose, but also high enzymatic activity due to sorbitol. However, genome-wide identification of the MdFRK gene family and their evolutionary dynamics in apple are yet to be reported. A systematic genome-wide analysis in this study identified a total of nine MdFRK gene members, which could phylogenetically be clustered into seven groups. Chromosomal location and synteny analysis of MdFRKs revealed that their expansion in the apple genome is primarily driven by tandem and segmental duplication events. Divergent expression patterns of MdFRKs were observed in four source-sink tissues and at five different apple fruit developmental stages, which suggested their potential crucial roles in the apple fruit development and sugar accumulation. Reverse transcription-quantitative PCR (RT-qPCR) identified candidate NaCl or drought stress responsive MdFRKs, and transgenic apple plants overexpressing MdFRK2 exhibited considerably enhanced salinity tolerance. Our results will be useful for understanding the functions of MdFRKs in the regulation of apple fruit development and salt stress response.

Overexpression of two DELLA subfamily genes MiSLR1 and MiSLR2 from mango promotes early flowering and enhances abiotic stress tolerance in Arabidopsis

Gibberellic acids (GAs) are a group of endogenous phytohormones that play important roles in plant growth and development. SLENDER RICE (SLR) serves as a vital component of the DELLA gene family, which plays an irreplaceable role in regulating plant flowering and height, as well as stress responses. SLR gene has not been reported in mango, and its function is unknown. In present study, two DELLA subfamily genes MiSLR1 and MiSLR2 were identified from mango. MiSLR1 and MiSLR2 were highly expressed in the stems of the juvenile stage, but were expressed at a low level in flower buds and flowers. Gibberellin treatment could up-regulate the expression of MiSLR1 and MiSLR2 genes, but gibberellin biosynthesis inhibitor prohexadione-calcium (Pro-Ca) and paclobutrazol (PAC) treatments significantly down-regulated the expression of MiSLR1, while MiSLR2 was up-regulated. The expression levels of MiSLR1 and MiSLR2 were up-regulated under both salt and drought treatments. Overexpression of MiSLR1 and MiSLR2 genes significantly resulted early flowering in transgenic Arabidopsis and significantly up-regulated the expression levels of endogenous flower-related genes, such as SUPPRESSOR OF CONSTANS1 (SOC1), APETALA1 (AP1), and FRUITFULL (FUL). Interestingly, MiSLR1 significantly reduced the height of transgenic plants, while MiSLR2 gene increased. Overexpression of MiSLR1 and MiSLR2 increased seed germination rate, root length and survival rate of transgenic plants under salt and drought stress. Physiological and biochemical detection showed that the contents of proline (Pro) and superoxide dismutase (SOD) were significantly increased, while the contents of malondialdehyde (MDA) and H2O2 were significantly decreased. Additionally, protein interaction analysis revealed that MiSLR1 and MiSLR2 interacted with several flowering-related and GA-related proteins. The interaction between MiSLR with MiGF14 and MiSOC1 proteins was found for the first time. Taken together, the data showed that MiSLR1 and MiSLR2 in transgenic Arabidopsis both regulated the flowering time and plant height, while also acting as positive regulators of abiotic stress responses.

Inheritance and ecological effects of exogenous genes from transgenic Brassica napus to Brassica juncea hybrids

●With the rapid development of new breeding techniques, the ecological impacts of transgenic plants receive wide concern again, particularly for potential gene flow from transgenic crops to their relatives. The transgene insertion position, number of gene copies, and flanking sequence of exogenous genes integrated into the recipient genome affect the genetic stability and fitness of offspring.●We employed hybrids F1 and F2, six backcross generations BC1-BC6 and BC1F1 from transgenic Brassica napus with Bacillus thuringiensis (Bt) cry1Ac gene and its wild relative B. juncea through hand pollination. We detected exogenous gene copies, mRNA transcription, and protein expression by ddPCR, qRT-PCR and ELISA, and the fitness of hybrid and backcross generations.●Exogenous genes followed Mendelian segregation expectations in hybrid and backcrossed generations, with stable gene copies, mRNA transcription and protein concentration of exogenous genes in offspring. Exogenous gene copies had no significant effects on plant fitness, but had positive effects on mRNA transcription and protein concentration that varied with growth stages in hybrid and backcross generations.●Our study demonstrated inheritance and ecological effects of exogenous genes from transgenic plants to wild relatives, which will help ecological risk management of biotechnological plants released in the nature.

Integrating Genomics and Phenomics in Agricultural Breeding: A Comprehensive Review

One of the key roles of plant breeders is to improve crop productivity through development of varieties with desirable traits to feed the growing population. The merger of genomics and phenomics - where genomics refer to the study of an organism’s entire DNA sequence and phenomonics is the full explanation of observable characteristics has given a new face to breeding strategies. This paper provides information about this technique from beginning up to now, which implicates high-throughput phenotyping, genomic selection, artificial intelligence platform for crop improvement. It seems that coronal genomics and phenotypical imaging results in transgenic or super climate-resilient plants, therefore improving yield under sustainable conditions. Despite its bright future there are certain issues like data standardization, ethical concerns, and resource restraints that need considering. Development later on gets people thinking about technical fields such as inter-disciplinary researches as well as policy supports that have ability to bring these powerful technologies into assurance of food security together with sustainable agriculture initially collaboration doesn’t need manufacturing centres of technology including genome and phenome data can help breeders achieve wrists precisions in crops development which will result in having robust agricultural systems able to overcome environmental stressors.

Apple vacuolar sugar transporters regulated by MdDREB2A enhance drought resistance by promoting accumulation of soluble sugars and activating ABA signaling

Abstract Soluble sugars are not only an important contributor to fruit quality, but also serve as the osmotic regulators in response to abiotic stresses. Early drought stress promotes sugar accumulation, while specific sugar transporters govern the cellular distribution of the sugars. Here, we show that apple plantlets accumulate soluble sugars in leaf tissues under drought stress. Transcriptional profiling of stressed and control plantlets revealed differential expression of several plasma membrane- or vacuolar membrane-localized sugar transporter genes. Among these, four previously identified vacuolar sugar transporter (VST) genes (MdERDL6–1, MdERDL6–2, MdTST1 and MdTST2) showed higher expression under drought, suggesting their roles in response to drought stress. Promoter cis-elements analyses, yeast one-hybrid and dual-luciferase tests confirmed that the drought-induced transcription factor MdDREB2A could promote the expression of MdERDL6–1/−2 and MdTST1/2 by binding to their promoter regions. Moreover, overexpressing of each of these four MdVSTs alone in transgenic apple or Arabidopsis plants accumulated more soluble sugars and abscisic acid, and enhanced drought resistance. Furthermore, apple plants overexpressing MdERDL6–1 also showed reduced water potential, facilitated stomatal closure and reactive oxygen species scavenging under drought condition compared to control plants. Overall, our results suggest a potential strategy to enhance drought resistance and sugar accumulation in fruits through manipulating the genes involved in vacuolar sugar transport.

Dual catalytic potential of isoeugenol synthase in Asarum sieboldii Miq. (AsIGS): Unveiling isoeugenol preference in vitro and eugenol production in vivo, with insights into hydrogen bonding influence

Asarum sieboldii Miq. is an important medicinal plant valued for its diverse health benefits in the pharmaceutical industry. In the present study, we isolated and characterized isoeugenol synthase from A. sieboldii (AsIGS), an essential enzyme involved in the biosynthesis of volatile phenylpropenes. We hoped to elucidate the secondary metabolic network of eugenol in A. sieboldii plants, which constructed the prerequisite for quality improvement of the well-known TCM Asari Radix et Rhizoma. Bioinformatics analysis revealed high similarity between the DNA sequences of AsIGS and isoeugenol synthase genes from other plants, and that the association of the candidate protein AsIGS with the PIP reductase family. Moreover, the AsIGS protein displayed a molecular weight of about 34.96 kDa, with a theoretical isoelectric point of 6.01 and an average hydrophobicity of −0.092, indicating the protein’s partial acidity, stability, and hydrophilic nature. Phylogenetic analysis showed that AsIGS had a close relationship with isoeugenol synthases and fewer eugenol synthases found in other species. Alphafold2 predicted the structure of the AsIGS protein, and CB-Dock2 predicted the binding sites of the ASIGS-NADPH-coniferyl acetate ternary complex. In vitro enzymatic assay results demonstrated that the optimal temperature of the AsIGS-involved catalysis for coniferyl acetate was 30 °C, and several kinetics parameters were Km (12.21 mM), Vmax (27.9 U/mg), kcat (76.26 s-1), and kcat/Km (6.49 s-1·mM-1). Furthermore, it was also determined that the AsIGS protein had varying performance at different pH levels. While the candidate protein converted coniferyl acetate into both isoeugenol and eugenol at pH 5.5, it just catalyzed the production of isoeugenol at pH 6.5. However, isoeugenol has never been detected in A. sieboldii. Altering AsIGS expression in transgenic plants impacted only eugenol contents. Compared with wild type, overexpression of AsIGS increased eugenol content by 23.3 %, while RNAi-induced down-regulation of AsIGS decreased it by 25.3 %. Taken together, these results confirmed that the AsIGS gene was involved in the biosynthesis of eugenol in A. sieboldii with a dual catalytic potential.

Improving photosynthetic efficiency of rice via over-expressing a ferredoxin-like protein gene from Methanothermobacter thermautotrophicus.

Ferredoxins (Fds) are crucial in various essential plant metabolic processes, including photosynthesis, fermentation and aerobic nitrogen fixation, due to their role in electron transport rate (ETR). However, the full scope of ferredoxin's function across prokaryotes and eukaryotic plants remains less understood. This study investigated the effect of MtFd from Methanothermobacter thermoautotrophicus on rice photosynthetic efficiency. We found that MtFd was localized in the chloroplasts of rice protoplasts. Transgenic analysis showed that MtFd significantly enhanced the photosynthetic capacity compared to the wild-type plants. This enhancement was evident through increased ETR, NADPH content and net photosynthetic rates, as well as decreased non-photochemical quenching (NPQ). Despite similar biomass to wild type plants, MtFd transgenic plants exhibited a marked increase in grain size and the 1000-grian weight. The elevated ETR and surplus free electrons in transgenic plants result in a considerable rise in cellular ROS content, which in turn enhances the enzymatic activity of the antioxidant system. In summary, our findings suggest that introducing the Fd protein from M. thermoautotrophicus into transgenic rice improves photosynthetic efficiency by accelerating ETR, which triggers the cellular oxidative stress response.

Dissecting the molecular basis of the ultra-large grain formation in rice.

The shape of rice grains not only determines the thousand-grain weight but also correlates closely with the grain quality. Here we identified an ultra-large grain accession (ULG) with a thousand-grain weight exceeding 60 g. The integrated analysis of QTL, BSA, de novo genome assembled, transcription sequencing, and gene editing was conducted to dissect the molecular basis of the ULG formation. The ULG pyramided advantageous alleles from at least four known grain-shaping genes, OsLG3, OsMADS1, GS3, GL3.1, and one novel locus, qULG2-b, which encoded a leucine-rich repeat receptor-like kinase. The collective impacts of OsLG3, OsMADS1, GS3, and GL3.1 on grain size were confirmed in transgenic plants and near-isogenic lines. The transcriptome analysis identified 112 genes cooperatively regulated by these four genes that were prominently involved in photosynthesis and carbon metabolism. By leveraging the pleiotropy of these genes, we enhanced the grain yield, appearance, and stress tolerance of rice var. SN265. Beyond showcasing the pyramiding of multiple grain size regulation genes that can produce ULG, our study provides a theoretical framework and valuable genomic resources for improving rice variety by leveraging the pleiotropy of grain size regulated genes.

Heterologous expression of coffee HB12 confers tolerance to water deficit in transgenic plants through an ABA-independent route

Drought is one of the major abiotic stresses affecting plant growth, with serious negative consequences for crop yields worldwide. Among these crops, coffee is severely injured by water deficiency. Despite its economic importance, very little is known about the molecular mechanisms governing coffee responses to water deficit. In the present work, a total of 288 members of the homeobox (HB) gene family were identified in the genome of the Coffea Arabica Brazilian Coffee Genome Project database. In silico analysis allowed to determine the expression pattern of 33 HD genes. Among them, three genes (CaZHD4, CaHB1-like2 and CaHB12) were found to be up-regulated by osmotic stress in the database. Expression analyses revealed that CaHB12 is highly up-regulated in the leaves and lateral roots of Coffea arabica plants under moderate and severe water deficit conditions even after 10 days of drought induction. Functional characterization of transgenic Arabidopsis plants constitutively expressing CaHB12 resulted in increased tolerance to water deficit at different developmental stages and increased tolerance to salt stress during seed germination. To gain further insights into genes modulated by the ectopic expression of CaHB12, a RNA-Seq was performed revealing that classical drought-responsive genes were mostly repressed, suggesting that other mechanisms likely contribute to the tolerant phenotype exhibited by CaHB12-expressing plants, such as the pathway signalled by heat shock proteins, reactive oxygen species and heat shock transcription factor signalling pathways. Moreover, to provide further support for the involvement of CaHB12 in drought stress tolerance, three independent soybean transgenic lines overexpressing CaHB12 were employed in this study. Accordingly, at a physiological level, the constitutive expression of CaHB12 promotes the regulation of stomatal conductance and antioxidant activity under drought conditions, suggesting that this gene plays a key role in plant responses to water deprivation and can confer tolerance to drought stress. Our data suggest that CaHB12 is a positive regulator of the stress response in coffee plants and indicate that this gene is a potential candidate for biotechnological approaches.

UDP-glycosyltransferase UGT96C10 functions as a novel detoxification factor for conjugating the activated dinitrotoluene sulfonate in switchgrass.

Dinitrotoluene sulfonates (DNTSes) are highly toxic hazards regulated by the Resource Conservation and Recovery Act (RCRA) in the United States. The trinitrotoluene (TNT) red water formed during the TNT purification process consists mainly of DNTSes. Certain plants, including switchgrass, reed and alfalfa, can detoxify low concentrations of DNTS in TNT red water-contaminated soils. However, the precise mechanism by which these plants detoxify DNTS remains unknown. In order to aid in the development of phytoremediation resources with high DNTS removal rates, we identified and characterized 1-hydroxymethyl-2,4-dinitrobenzene sulfonic acid (HMDNBS) and its glycosylated product HMDNBS O-glucoside as the degradation products of 2,4-DNT-3-SO3Na, the major isoform of DNTS in TNT red water-contaminated soils, in switchgrass via LC-MS/MS- and NMR-based metabolite analyses. Transcriptomic analysis revealed that 15 UDP-glycosyltransferase genes were dramatically upregulated in switchgrass plants following 2,4-DNT-3-SO3Na treatment. We expressed, purified and assayed the activity of recombinant UGT proteins in vitro and identified PvUGT96C10 as the enzyme responsible for the glycosylation of HMDNBS in switchgrass. Overexpression of PvUGT96C10 in switchgrass significantly alleviated 2,4-DNT-3-SO3Na-induced plant growth inhibition. Notably, PvUGT96C10-overexpressing transgenic switchgrass plants removed 83.1% of 2,4-DNT-3-SO3Na in liquid medium after 28 days, representing a 3.2-fold higher removal rate than that of control plants. This work clarifies the DNTS detoxification mechanism in plants for the first time, suggesting that PvUGT96C10 is crucial for DNTS degradation. Our results indicate that PvUGT96C10-overexpressing plants may hold great potential for the phytoremediation of TNT red water-contaminated soils.

MdWRKY71 as a positive regulator involved in 5-aminolevulinic acid-induced salt tolerance in apple

5-Aminolevulinic acid (ALA), is a novel plant growth regulator that can enhance plant tolerance against salt stress. However, the molecular mechanism of ALA is not well studied. In this study, ALA improved salt tolerance of apple (Malus × domestica 'Gala') when the detached leaves or cultured calli were used as the materials. The expression of MdWRKY71, a WRKY transcription factor (TF) gene was found to be responsive to NaCl as well as ALA treatment. Functional analysis showed that overexpressing (OE)-MdWRKY71 significantly improved the salt tolerance of the transgenic apple, while RNA interfering (RNAi)-MdWRKY71 reduced the salt tolerance. However, exogenous ALA alleviated the salt damage in the RNAi-MdWRKY71 apple. When MdWRKY71 was transferred into tobacco, the salt tolerance of transgenic plants was enhanced, which was further improved by exogenous ALA. Subsequently, MdWRKY71 bound to the W-box of promoters of MdSOS2, MdNHX1, MdCLC-g, MdSOD1, MdCAT1 and MdAPX1, transcriptionally activating the gene expressions. Since the genes are responsible for Na+ and Cl− transport and antioxidant enzyme activity respectively, it can be concluded that MdWRKY71, a new TF, is involved in ALA-improved salt tolerance by regulating ion homeostasis and redox homeostasis. These results provided new insights into the transcriptional regulatory mechanism of ALA in enhancing apple salt tolerance.

Application of an endogenous pGhαGloA promoter in CRISPR/Cas12a system for efficient genome editing to creat glandless cotton germplasm

The efficient genome editing tool (the CRISPR/Cas12a system) has been used in research on plant functionional genomics and improvement of agronomic traits. In this study, CRISPR/Cas12a system was optimized by using the endogenous pGhαGloA promoter in cotton. Using this system, crRNAs was driven by the Pol II pGhaGloA promoter to construct the pGhRBE3-pGhαGloA-GhPGF vector and carry out genetic transformation. The vector could work efficiently in all positive transgenic plants and the editing efficiency at the crRNA1 target site was up to 93.37%, and the editing efficiency of the crRNA2 target was up to 88.24%, which is significantly higher in editing efficiency of the pGhRBE3 system with Pol III promoter-Ubi 6.7 promoter, this result indicates that the Pol II promoter is more suitable for expressing multiple sgRNA or crRNA than the pol III promoter in cotton. The vector mainly generated the editing type of fragment deletion and the deletion size was in the range of 3-12 bp with the editing sites spanning at the 14th to 29th bases downstream of the protospacer adjacent motif (PAM). All the targeted mutation loci were stably inherited from T0 to T2 generation and three transgene-free lines with target site mutations of GhPGF gene were obtained and these glandless and gossypol-free/(low contents) cotton germplasm will play key role for healthy cottonseeds oil/cake production. Therefore, the CRISPR/Cas12a system driven by the pGhαGloA promoter can efficiently edit target genes in cotton, which provides a powerful tool for cotton functionional genomics and genetic improvement.

Barley as a production platform for oral vaccines in sustainable fish aquaculture

Vaccination is the most effective measure to prevent disease outbreaks in fish aquaculture, with oral vaccine administration emerging as the most practical approach. However, oral vaccines face a notable limitation due to insufficient stimulation of the complex gut-associated lymphoid tissue caused by factors such as vaccine degradation, poor absorption, and recognition by the immune cells. An innovative solution to these limitations lies in the plant-based production of recombinant vaccines. Plant cells enable the production and targeted storage of recombinant vaccines in specific cell organelles which ensure superior protection from degradation and contain natural compounds acting as adjuvants. Our study explores the potential of barley (Hordeum vulgare), a globally significant cereal crop, for producing orally administered subunit vaccines against viral infections affecting economically important fish species in the Salmonidae and Cyprinidae families. Through Agrobacterium-mediated transformation of immature barley embryos, we have generated homozygous T2 generation of transgenic barley expressing recombinant antigens of spring viremia of carp virus and infectious salmon anaemia virus. The expression of these plant-based recombinant vaccines was confirmed by immunodetection, which was supported by fluorescence observation, specifically in the seed endosperm. The antigenicity of transgenic plant material containing recombinant antigens was evaluated using an intubation model of common carp (Cyprinus carpio), revealing a substantial upregulation of the immunoglobulin transcripts in both systemic and mucosal tissues over a period of 28 days following a single dose of transgenic antigens. Collectively, these results underscore the potential of barley-based recombinant vaccines for disease prevention in fish aquaculture.

Molecular cloning and functional characterization in response to saline-alkali stress of the MhZEP gene in Arabidopsis thaliana.

Soil salinization is one of the major environmental factors that restrict plant growth and development. Zeaxanthin epoxidase (ZEP) functions in ABA biosynthesis and the xanthophyll cycle and has a vital role in plant responses to various environmental stresses. It was found by quantitative real-time PCR (qRT-PCR) that MhZEP responded to saline-alkali stress and showed the highest expression at 48h of saline-alkali stress, which was 14.53-fold of 0h. The MhZEP gene was cloned from the apple rootstock begonia (Malus halliana Koehne) and its protein physicochemical properties were analyzed. Subsequently, the functional characterization of MhZEP (ID: 103403091) was further investigated in Arabidopsis thaliana. The MhZEP contained a complete open reading frame with a length of 1998bp, and encoded 665 amino acids with an isoelectric point of 7.18. Phylogenetic tree analysis showed that MhZEP was the most homologous and closely related to Glycine max. Compared with wild-type, transgenic plants grew better under saline-alkali stress and the MhZEP-OE line showed higher chlorophyll content, carotenoid content, enzyme activities (POD, SOD, CAT and APX) and K+ content, whereas they had lower chlorosis and Na+ content than the wild type (WT), which indicated that they had strong resistance to stress. The expression levels of saline-alkali stress-related genes in A. thaliana MhZEP-OE were examined by qRT-PCR, and it was found that the MhZEP improved the tolerance of A. thaliana to saline-alkali stress tolerance by regulating the expression of carotenoid synthesis genes (MhPSY, MhZDS, MhLYCB and MhVDE) and ABA biosynthesis genes (MhNCED5, MhABI1 and MhCYP707A2). And the potassium-sodium ratio in the cytoplasm was increased to maintain ionic homeostasis by modulating the expression of Na+ transporter genes (MhCHX15 and MhSOS1) and K+ transporter genes (MhHKT1;1, MhNHX1 and MhSKOR1). Moreover, the expression of H+-ATPase genes (MhAHA2 and MhAHA8) was increased to reduce the oxidative damage caused by saline-alkali stress. In summary, MhZEP acted as an essential role in plant resistance to saline-alkali stress, which lays the foundation for further studies on its function in apple.

Brassinosteroid improves resistance to phosphorus deficiency stress through regulating nutrient balance and reactive oxygen species scavenging in potato

Brassinosteroid (BR) plays a crucial role in plant growth, development and response to abiotic stress. However, the mechanism by which BR regulates the response of potato plants to phosphorus deficiency stress is still largely unknown. In this work, the effects of BR on the growth of potato plants under phosphorus deficient condition were investigated. Exogenous BR application mitigated the growth inhibition caused by phosphorus deficiency stress. Transcriptomic analyses revealed that BR application altered the expression of genes involved in mitogen-activated protein kinase (MAPK) signaling pathway, plant hormone signal transduction, and nitrogen and phosphorus metabolisms under phosphorus deficient condition. Further gene ontology (GO) analysis indicated a significant enrichment of genes associated with reactive oxygen species scavenging process. Ectopic expression of potato brassinosteroid synthesis gene StCYP85A1 in Arabidopsis improved the resistance of transgenic plants to phosphorus deficiency stress, as indicated by the increased germination greening ratio and root growth. Quantitative real time PCR and antioxidant enzyme activity analysis revealed that ectopic expression of StCYP85A1 altered the expression of genes related to nitrogen and phosphorus metabolism, and promoted antioxidant enzyme activity in transgenic plants. These findings indicated that BR improved the tolerance of potato plants to phosphorus deficiency stress by regulating nutrient homeostasis and reactive oxygen species scavenging.

LrHSP17.2 Plays an Important Role in Abiotic Stress Responses by Regulating ROS Scavenging and Stress-Related Genes in Lilium regale.

As an important part of heat shock response module, heat shock proteins (HSP) play an important role in plant defense response against heat stress; however, the involvement of the majority of the HSP family members against other abiotic stresses remains poorly understood. In the present study, LrHSP17.2 was identified and its function against abiotic stress was analyzed. The expression level of LrHSP17.2 was significantly induced by heat. Heterologous transgenes of LrHSP17.2 showed that LrHSP17.2 can increase the activity of catalase, peroxidase, superoxide dismutase to removes excess reactive oxygen species (ROS), maintain the stability of the membrane structure, and regulate genes related to antioxidant enzymes and defense under abiotic stress. In addition, LrHSP17.2 could be regulated by exogenous abscisic acid and melatonin, and the related hormone synthesis genes of transgenic plants were significantly up-regulated under heat stress. Taken together, our results revealed that LrHSP17.2 is involved in regulating abiotic stress responses by regulating ROS scavenging and stress-related genes in Lilium regale.

Revealing cis- and trans-regulatory elements underlying nuclear distribution and function of the Arabidopsis histone H2B.8 variant

The H2B.8 variant has been diverged from other variants by its extended N-terminal region that possesses a conserved domain. We generated transgenic Arabidopsis plants expressing H2B.9 (class I), H2B.5 (class II) and H2B.8 (class III) fused to GFP under the 35 S promoter and studied their nuclear distribution and function. H2B.8-GFP showed peculiar nuclear localization at chromocenters in all cell types examined, while H2B.5-GFP and H2B.9-GFP displayed various patterns often dependent on cell types. H2B variants faithfully assembled onto nucleosomes showing no effect on nuclear organization; H2B.8-GFP appeared as three distinct isoforms in which one isoform appeared to be SUMOylated. Interestingly, transient expression in protoplasts revealed H2B.8 nuclear localization distinct from transgenic plants as it was restricted to the nuclear periphery generating a distinctive ring-like appearance accompanied by nuclear size reduction. This unique appearance was abolished by deletion of the N-terminal conserved domain or when H2B.8-GFP is transiently expressed in ddm1 protoplasts. GFP-TRAP-coupled proteome analysis uncovered H2B.8-partner proteins including H2A.W.12, which characterizes heterochromatin. Thus, our data highlight H2B.8 as a unique variant evolved in angiosperms to control chromatin compaction/aggregation and uncover cis- and trans-regulatory elements underlying its nuclear distribution and function.