High salinity is one of the major abiotic stresses that limit crop production. Salicylic acid (SA) has been shown to ameliorate the adverse effects of environmental stress on plants. However, the molecular basis of salicylic acid-mediated salinity tolerance in kenaf is still unclear. To uncover the toxic alleviation effects of SA on kenaf salt stress, the morphological, physiological indexes, and transcriptomic regulating were assayed under NaCl stress with (or without) SA pretreated. The result showed that application of exogenous SA significantly alleviated the repressive effects of kenaf under salt stress, including agronomic traits, antioxidant enzyme systems, and several important pathways and involved differentially expressed genes (DEGs). In addition, some transcription factors (TFs) such as NAC, MYB, bHLH, ERF and enzyme activity-related genes such POD were also significantly changed with exogenous SA application. Virus‑Induced Gene Silencing (VIGS) of a differentially expressed TFs, HcNAC29, reduced salt tolerance in kenaf. Integrating physiological and transcriptomic analyses, a number of important pathways were found to be important for SA-mediated salinity tolerance in kenaf, including phenylpropanoid biosynthesis, flavonoid biosynthesis, plant hormone signaling pathway, and some transcription factors such as NAC. The data presented here may be useful in further elucidating the multiple regulatory roles of SA in plant responses to abiotic stresses.

钙调素是一类钙依赖性调节蛋白,参与植物的生长发育、抗逆胁迫等多种生物学过程。本课题组前期通过蛋白质乙酰化修饰组学研究发现,红麻钙调素蛋白7的乙酰化修饰参与了红麻花粉的发育调控。为研究其参与抗逆性的机制,本研究以红麻保持系P3B双核期的花药为材料,使用PCR法克隆了钙调素基因HcCaM7,最大开放阅读框（open reading frame, ORF）为450 bp,其由149个氨基酸组成,编码相对分子质量16.85 kD的蛋白;亚细胞定位结果显示, HcCaM7蛋白的表达主要定位在细胞质和细胞膜中;利用病毒诱导的基因沉默技术沉默HcCaM7基因,导致红麻沉默植株的生长受到抑制;进一步在体外采用基因密码子扩展技术对发生乙酰化修饰氨基酸位点进行突变,成功获得具有体外乙酰化修饰位点的蛋白HcCaM7mut,并成功诱导表达了无乙酰化修饰的蛋白HcCaM7,结果表明HcCaM7蛋白发生乙酰化修饰后可以显著促进NADK（NAD激酶）活性;用点板法检测含有HcCaM7蛋白和HcCaM7mut蛋白的重组菌在盐(400 mmol L –1 和500 mmol L –1 NaCl)、干旱(400 mmol L –1 和600 mmol L –1 甘露醇)、重金属(30 mmol L –1 和50μmol L –1 CdCl2)及低温胁迫后（利用液氮反复冻融模拟）在LB固体培养基上的存活率发现,含有HcCaM7蛋白的重组菌存活率显著高于空载对照菌,而含有乙酰化修饰的HcCaM7mut蛋白的重组菌存活率进一步提升,表明HcCaM7蛋白能够提高大肠杆菌对非生物胁迫的耐受性,并且乙酰化修饰后效果更佳。因此,HcCaM7基因可以调控红麻生长发育和响应非生物胁迫,乙酰化修饰可以促进HcCaM7蛋白发挥作用。

[目的]研究水杨酸(SA)引发对盐胁迫下红麻生长及生理响应,并揭示SA引发对红麻中逆境相关基因的诱导模式,为红麻耐盐性研究提供理论依据.[方法]以2个不同耐盐性红麻品种(盐抗性材料为CP018,盐感性材料为CP047)为研究对象,将种子引发处理后进行水培试验,分析SA引发对红麻种子萌发及150 mmol·L-1 NaCl胁迫下幼苗农艺性状及生理方面的影响,并通过qRT-PCR技术分析SA引发逆境相关基因的表达模式.[结果]盐抗性品种CP018经过0.2mmol·L-1 SA引发后,能显著提升种子发芽率、发芽势和发芽指数,分别提高34.78％、31.30％和58.07％;盐感性材料CP047也有一定的提高,分别提高7.50％、10.56％和6.23％,但是未达到显著水平.在盐胁迫条件下,经SA引发(S1)与未引发(N1)相比,株高抑制率在盐抗性和盐感性品种中分别显著降低4.07％(CP018)和3.91％(CP047),干重抑制率在2个品种中分别显著降低15.50％(CP018)和15.68％(CP047);鲜重抑制率在盐感性品种CP047中显著降低4.46％,但在盐抗性品种CP018中未达到显著水平.根系扫描分析表明,根长抑制率在盐抗性和盐感性材料中分别显著下降10.74％(CP018)和10.77％(CP047);根表面积抑制率在盐抗性和盐感性品种中分别下降5.09％(CP018)和2.95％(CP047),仅在盐抗性品种CP018中达到显著水平;而根系活力抑制率在盐感性品种CP047中降低46.21％,在盐抗性品种CP018中降低6.56％,仅在盐感性品种CP047中达到显著水平.灰色关联度分析发现根系活力是对影响植株干重最重要的因素.SA引发能降低盐胁迫下红麻叶片的MDA含量,提高POD和SOD酶活性.对12个逆境相关基因的表达量分析结果表明,ACCD、APX2、SOS1、ARR2、PAL、ERF.C3、CHIT和TIFY11表达水平在SA引发处理下均显著上调,而ERF9、ERS1、MYC2和XTH2在2个材料中的表达模式存在差异,其中,XTH22在CP047中显著上调,在盐抗性品种CP018中无显著变化,ERS1和MYC2在盐抗性品种CP018中显著上调,在盐感性品种CP047中却显著下降,而ERF9在2个品种中的趋势则与此相反.[结论]适宜浓度的SA引发可以显著缓解红麻在盐胁迫下的生长,且对不同红麻种质资源的影响程度和方式存在差异,SA可能通过影响生理过程如抗氧化酶系统,并通过诱导特异基因的表达调节红麻植株对非生物胁迫的响应.

Ethylene response factors (ERF) are members of the APETALA2/ERF transcription factor family, and they play an important role in plant growth, development, and response to various environmental stresses. In the present study, an ERF transcription factor HcERF4 was isolated and characterized from kenaf. The protein encoded by the HcERF4 has 233 amino acid residues with a theoretical isoelectric point of 8.89 and a predicted molecular weight of 25.53 kDa. HcERF4 had an over than 86.97% identity to HsERF4 (XP_039019980.1), and shared a closest phylogenetic relationship with Hibiscus syriacus . Subcellular localization analysis shows that HcERF4 is located in the nucleus. Transactivation assays in yeast demonstrated that HcERF4 functions as a transcriptional activator. The expression of HcERF4 was enriched in leaf and root, and can be induced by salt or drought treatments in kenaf. The VIGS-silenced HcERF4 plant showed significantly reduced plant height, stem diameter, fresh weight, and relative water content (RWC) compared with wild type plants under salt or drought stress condition; In addition, the contents of MDA, O 2 − , H 2 O 2 , and free proline is significantly increased, and the activities of SOD and CAT are significantly reduced. The DAB/NBT staining results showed that the H 2 O 2 and O 2 − contents in HcERF4 -silenced plants were consistent with the determination. Based on these results, it is proposed that HcERF4 plays an important role in regulating salt and drought stress in kenaf.

\u3010Objective\u3011<\/strong>To study the growth and physiological response of salicylic acid (SA) priming in kenaf under salt stress, and further reveal the induction pattern of SA priming on the stress-related genes in kenaf, thus provide a theoretical basis for salt tolerance study in kenaf.<\/p><\/sec>\u3010Method\u3011<\/strong>Two different salt-tolerant kenaf cultivars (resistant and sensitive cultivars codenamed CP018 and CP047, respectively) were used as materials. The seeds were tested by SA priming and then subjected to hydroponics experiments to analyze the effect of SA priming on kenaf seed germination and the agronomic and physiological aspects of seedling under 150 mmol\u00B7L-1<\/sup> NaCl stress, and the expression patterns of SA priming stress-related genes were analyzed by qRT-PCR.<\/p><\/sec>\u3010Result\u3011<\/strong>The germination rate, germination potential and germination index of the salt-resistant cult

Cytoplasmic male sterility (CMS) is widely exploited in hybrid seed production. Kenaf is an important fiber crop with high heterosis. The molecular mechanism of kenaf CMS remains unclear, particularly in terms of DNA methylation. Here, using the anthers of a kenaf CMS line (P3A) and its maintainer line (P3B), comparative physiological, DNA methylation, and transcriptome analyses were performed. The results showed that P3A had considerably lower levels of IAA, ABA, photosynthetic products and ATP contents than P3B. DNA methylome analysis revealed 650 differentially methylated genes (DMGs) with 313 up- and 337 down methylated, and transcriptome analysis revealed 1788 differentially expressed genes (DEGs) with 558 up- and 1230 downregulated genes in P3A compared with P3B. Moreover, 45 genes were characterized as both DEGs and DMGs, including AUX,CYP, BGL3B, SUS6, AGL30 and MYB21. Many DEGs may be regulated by related DMGs based on methylome and transcriptome studies. These DEGs were involved in carbon metabolism, plant hormone signal transduction, the TCA cycle and the MAPK signaling pathway and were shown to be important for CMS in kenaf. These results provide new insights into the epigenetic mechanism of CMS in kenaf and other crops.

DNA甲基化是植物重要的表观遗传修饰方式之一,在响应逆境胁迫中具有重要作用,但是有关镉胁迫下植物DNA甲基化水平变化的报道甚少.本研究以红麻P3A为材料,采用水培法对幼苗进行300μmol L?1的CdCl2处理,测定幼苗农艺性状及镉含量;利用甲基化敏感扩增多态性技术(methylation-sensitive amplification polymorphism,MSAP)分析镉胁迫下根系DNA甲基化水平变化;回收甲基化差异片段并克隆测序,采用qRT-PCR技术对DNA甲基化差异基因的表达量进行分析.结果表明,CdCl2胁迫显著抑制红麻幼苗的株高、茎粗、根长、根表面积以及全鲜重.对照及镉处理下幼苗根系的DNA甲基化率分别为62.78％、68.23％,其中全甲基化率分别为37.50％、36.36％,半甲基化率分别为25.28％、31.87％,表明镉胁迫显著提高红麻幼苗根系的DNA甲基化水平.qRT-PCR分析表明,7个与抗性密切相关的DNA甲基化差异基因也存在表达量的差异,推测DNA甲基化水平变化在响应红麻镉胁迫中发挥重要作用.本结果为深入探索DNA甲基化响应植物镉胁迫的潜在机制提供了理论基础.

Soil salinization is becoming a major threat to the sustainable development of global agriculture. Kenaf is an industrial fiber crop with high tolerance to salt stress and could be used for soil phytoremediation. However, the molecular mechanism of kenaf salt tolerance remains largely unknown. DNA methylation is an important epigenetic modifications phenomena and plays a key role in gene expression regulation under abiotic stress condition. In the present study, the kenaf seedlings were pre-treated or not with 50 mM 5-azacytidine (5-azaC, a DNA methylation inhibitor) and then subjected to different concentrations of NaCl. Results showed that the biomass and antioxidant activities (superoxide dismutase, peroxidase and catalase) of kenaf seedlings pre-treated with 5-azaC were significantly increased, while the contents of superoxide anion (O-2(-)) and malondialdehyde (MDA) were decreased, indicating that 5-azaC pre-treatment could significantly alleviate salt stress injury. Furthermore, the methylation-sensitive amplified polymorphism (MSAP) analysis revealed that DNA methylation level of keanf seedlings pre-treated with 5-azaC significantly decreased. The expression of seven differentially methylated genes responsing to salt stress was significantly changed from real-time fluorescent quantitative (qRT-PCR) analysis. Finally, knocked-down of the L-ascorbate oxidase (L-AAO) gene by virus-induced gene silencing (VIGS) resulted in increased sensitivity of kenaf seedlings under salt stress. Overall, it was suggested that 5-azaC pre-treatment can significantly improve salt tolerance in kenaf by decreasing ROS content, raising anti-oxidant activities, and regulating DNA methylation and expression of stress-responsive genes. (C) 2021 Elsevier Ltd. All rights reserved.

DNA甲基化在植物响应生物和非生物胁迫中起重要作用,但是有关铅胁迫下植物DNA甲基化水平变化的研究报道甚少.本研究以红麻P3A为材料,采用水培法对幼苗进行不同浓度(0、200、400、600μmol L-1)PbCl2处理,测定幼苗农艺性状、根系ROS含量和抗氧化酶活性等变化情况;利用甲基化敏感扩增多态性技术(methylation-sensitive amplification polymorphism,MSAP)分析600μmol L-1铅胁迫条件下根系DNA甲基化水平变化,回收差异甲基化片段并克隆测序,采用qRT-PCR技术对DNA甲基化差异基因进行表达分析.结果表明,不同浓度PbCl2胁迫均显著抑制幼苗的茎粗、根长和根表面积,且400μmol L-1及以上浓度PbCl2胁迫显著抑制红麻幼苗的株高和全鲜重.随着铅浓度的提高,红麻幼苗根系的铅含量显著升高,O2?和MDA含量显著增加,SOD活性显著升高,POD活性呈先降低后升高,CAT活性呈先升高后降低的趋势.对照及600μmol L-1 PbCl2处理下的幼苗根系DNA甲基化率分别为71.13％、62.20％,其中全甲基化率分别为50.52％、37.80％,半甲基化率分别为20.62％、24.40％,即铅胁迫显著降低了红麻幼苗根系的DNA甲基化率和全甲基化率,提高了根系的半甲基化率.qRT-PCR分析表明,7个与抗性密切相关的DNA甲基化差异基因也存在表达量差异,推测DNA甲基化水平变化在响应红麻铅胁迫中发挥重要作用.本结果为深入探索DNA甲基化响应植物非生物胁迫的潜在机制,以及生产上利用红麻改良土壤铅污染提供了理论基础.

DNA methylation regulates key biological processes in plants. In this study, kenaf seedlings were pretreated with the DNA methylation inhibitor 5-azacytidine (5-azaC) (at concentrations of 0, 100, 200, 400, and 600 μM), and the results showed that pretreatment with 200 μM 5-azaC promoted flowering most effectively. To elucidate the underlying mechanism, phytohormone, adenosine triphosphate (ATP), and starch contents were determined, and genome-wide DNA methylation and transcriptome analyses were performed on anthers pretreated with 200 μM 5-azaC (5-azaC200) or with no 5-azaC (control conditions; 5-azaC0). Biochemical analysis revealed that 5-azaC pretreatment significantly reduced indoleacetic acid (IAA) and gibberellic acid (GA) contents and significantly increased abscisic acid (ABA) and ATP contents. The starch contents significantly increased in response to 200 and 600 μM 5-azaC. Further genome-wide DNA methylation analysis revealed 451 differentially methylated genes (DMGs) with 209 up- and 242 downregulated genes. Transcriptome analysis showed 3,986 differentially expressed genes (DEGs), with 2,171 up- and 1,815 downregulated genes. Integrated genome-wide DNA methylation and transcriptome analyses revealed 72 genes that were both differentially methylated and differentially expressed. These genes, which included ARFs, PP2C, starch synthase, FLC, PIF1, AGL80, and WRKY32, are involved mainly in plant hormone signal transduction, starch and sucrose metabolism, and flowering regulation and may be involved in early flowering. This study serves as a reference and theoretical basis for kenaf production and provides insights into the effects of DNA methylation on plant growth and development.

Numbers of critical genes and pathways were found from the levels of transcriptome and metabolome, which were useful information for understanding of kenaf CMS mechanism. Cytoplasmic male sterility (CMS) is a maternally inherited trait in higher plants that leads to the inability to produce or release functional pollen. However, there is lack of comprehensive studies to reveal the molecular basis of CMS occurrence in kenaf. Herein, we performed transcriptome and UPLC-MS-based metabolome analyses in the anthers of a CMS (UG93A) and its maintainer (UG93B) to sort out essential genes and metabolites responding to CMS in kenaf. Transcriptome characterized 7769 differentially expressed genes (DEGs) between these two materials, and pathway enrichment analysis indicated that these DEGs were involved mainly in pentose and glucuronate interconversions, starch and sucrose metabolism, taurine and hypotaurine metabolism. In the metabolome assay, a total of 116 significantly different metabolites (SDMs) were identified between the CMS and its maintainer line, and these SDMs were involved in eight KEGG pathways, including flavone and flavonol biosynthesis, glycerophospholipid metabolism, flavonoid biosynthesis, glycosylphosphatidylinositol-anchor biosynthesi. Integrated analyses of transcriptome and metabolome showed that 50 genes had strong correlation coefficient values (R2 > 0.9) with ten metabolites enriched in six pathways; notably, most genes and metabolites of flavonoid biosynthesis pathways and flavone and flavonol biosynthesis pathways involved in flavonoids biosynthetic pathways were downregulated in CMS compared to those in maintainer. Taken together, the decreased accumulation of flavonoids resulted from the compromised biosynthesis pathways coupled with energy deficiency in the anthers may contribute largely to CMS in UG93A of kenaf.

Soil cadmium (Cd) contamination has become a massive environmental problem. Kenaf is an industrial fiber crop with high tolerance to heavy metals and could be potentially used for soil phytoremediation. However, the molecular mechanism of Cd in kenaf tolerance remains largely unknown. In the present study, using two contrasting Cd sensitive kenaf (GH and YJ), the key factors accounting for differential Cd tolerance were investigated. GH has a stronger Cd transport and accumulation ability than YJ. In addition, physiological index investigation on malondialdehyde (MDA) contents and antioxidant enzyme (SOD, POD, and CAT) activities showed GH has a stronger detoxification capacity than YJ. Furthermore, the cell ultrastructure of GH is more stable than that of YJ under Cd stress. Transcriptome analysis revealed 2221 (689 up and 1532 down) and 3321 (2451 up and 870 down) genes were differentially expressed in GH and YJ, respectively. More DEGs (differentially expressed genes) were characterized as up-regulated in GH, indicating GH is inclined to activate gene expression to cope with cadmium stress. GO and KEGG analyses indicate that DEGs were assigned and enriched in different pathways. Plenty of critical Cd-induced DEGs such as SOD2, PODs, MT1, DTXs, NRT1, ABCs, CES, AP2/ERF, MYBs, NACs, and WRKYs were identified. The DEGs involved pathways, including antioxidant, heavy metal transport or detoxification, substance transport, plant hormone and calcium signals, ultrastructural component, and a wide range of transcription factors were suggested to play crucial roles in kenaf Cd tolerance, and accounting for the difference in Cd stress sensitivities.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">为明确不同浓度磷胁迫对大豆幼苗生长及基因组DNA甲基化水平的影响,采用甲基化敏感扩增多态性（MSAP）和实时荧光定量PCR（qRT-PCR）技术分析大豆材料‘CP016’的幼苗在不同浓度磷胁迫下根系DNA甲基化水平和相关基因的表达量变化。结果表明:1)随着磷浓度的逐渐增加,大豆幼苗的株高、鲜重、根长和根表面积呈先升高后降低的趋势,无磷和高磷胁迫（1 000μmol/L）均显著抑制大豆的生长,低磷胁迫（100μmol/L）促进地上部生长,极低磷胁迫（10μmol/L）促进根系生长;2)随着磷浓度的逐渐增加,大豆幼苗根系中的POD和CAT活性呈先降低后升高的趋势,SOD活性、淀粉和蔗糖含量呈先升高后降低的趋势;3)MSAP分析表明,随着磷浓度的增加,大豆幼苗根系DNA甲基化率和全甲基化率逐渐升高。具体来说,在无磷、正常供磷和高磷处理下,大豆幼苗根系的DNA甲基化率分别为43.04%、48.52%和51.05%;4)qRT-PCR分析结果表明,无磷胁迫下,调控大豆幼苗根系POD活性和淀粉合成相关基因以及甲基化酶基因DRM2的表达量显著升高;调控SOD活性和蔗糖合成相关基因以及去甲基化酶基因ROS1的表达量显著降低。本研究表明,无磷和高磷胁迫显著抑制大豆的生长,并使其抗氧化酶系统紊乱,淀粉和蔗糖含量降低,但适度的低磷胁迫可以促进大豆幼苗的生长。无磷和高磷胁迫分别降低和提高大豆幼苗根系的DNA甲基化水平。</span>

Thermal denaturation of tilapia myosin were studied at various pHs (2.0, 6.0, 7.0 and 11.0) by soluble protein content, total sulfhydryl content, surface hydrophobicity, tryptophan fluorescence, alpha-helix content, and SDS-PAGE. The results showed that, under neutral and acid conditions, soluble protein content decreased gradually with thermal processing (40 similar to 90 degrees C, 1 degrees C/min), but no obvious changes was observed at alkaline pH (P>0.05). Comparatively, the degree of thermal denaturation of myosin was pH 7.0 < pH 11.0 < pH 6.0< pH 2.0. At pH 2.0 and 6.0, heat-induced partly unfolding and aggregation of myosin resulted in disruption of the secondary structure and tertiary structure, soluble protein content of myosin decreased significantly at 40 similar to 80 degrees C (P<0.05). In addition, SDS-PAGE analysis showed that at extreme pHs (2.0 and 11.0), thermal treatment resulted in the degradation of myosin. The non-reduction SDS-PAGE analysis indicated that myosin molecules under alkaline conditions were more likely to produce polymer, and the formation of polymer mainly was cross-linking of myosin heavy chain by disulfide bond between each other.