Insect chitinases have been proposed as potential targets for pest control. In this work, a novel group IV chitinase gene, MdCht9, from Musca domestica was found to have multiple functions in the physiological activity, including chitin regulation, development and antifungal immunity. The MdCht9 gene was cloned and sequenced, its phylogeny was analysed and its expression was determined in normal and 20E treated larvae. Subsequently, RNA interference (RNAi)-mediated MdCht9 knockdown was performed, followed by biochemical assays, morphological observations and transcriptome analysis. Finally, the recombinant protein MdCht9 (rMdCht9) was purified and tested for anti-microbial activity and enzyme characteristics. The results showed that MdCht9 consists of three domains, highly expressed in a larval salivary gland. RNAi silencing of MdCht9 resulted in significant down-regulation of chitin content and expression of 15 chitin-binding protein (CBP) genes, implying a new insight that MdCht9 might regulate chitin content by influencing the expression of CBPs. In addition, more than half of the lethality and partial wing deformity appeared due to the dsMdCht9 treatment. In addition, the rMdCht9 exhibited anti-microbial activity towards Candida albicans (fungus) but not towards Escherichia coli (G-) or Staphylococcus aureus (G+). Our work expands on previous studies of chitinase while providing a potential target for pest management.

Pollen, as the male gametophyte of plants, plays a critical role in plant sexual reproduction. Investigating pollen-specific promoters not only helps to understand the regulatory mechanisms of pollen development but also provides tissue-specific promoters for plant genetic engineering. Previously, wheat promoter PSG076 was found to confer pollen-specific activity in tobacco. To determine the tissue-specific activity of PSG076 in wheat, a 1.4-kb promoter fragment was fused with the β-glucuronidase (GUS) reporter gene and stably introduced into wheat via particle bombardment. Histochemical analysis in T1 progeny plants showed that the activity of PSG076 promoter was detected specifically in mature pollen and pollen tube. No GUS activity was found in other floral and vegetable tissues. Weak GUS staining was also visible in pollen at 45 days post anthesis (DPA). Further analysis showed that GUS activity was found weakly in middle tricellular pollen grains and increased rapidly as pollen matured. These results indicated that PSG076 promoter has strong activity specifically at late pollen development stage and can be utilized in genetic engineering investigations for creating male sterility in wheat and other plant species for hybrid seed production.

Chitinases are hydrolytic enzymes that play important roles in chitin degradation during the insect development process, and thus are considered as the potential targets for pest management. Here, we identified and characterized the group VII chitinase gene from health pest Musca domestica (MdCht2). We found that MdCht2 was 1932 bp in length with an open reading frame of 1530 bp, which encodes a polypeptide of 509 amino acid residues. Phylogenetic analysis showed that MdCht2 gene was homologs with other closed insects, and belong to the group VII chitinases. Moreover, Real-time PCR analysis indicated that MdCht2 mRNA was highly expressed in pupa stage, as well as in integument and trachea. However, RNAi-mediated knockdown of MdCht2 resulted in high mortality rates and abnormal eclosion. Therefore, we hypothesized that MdCht2 was a crucial gene required for housefly development, which was supported by the transcription level of MdCht2 could be induced by 20hydroxyecdysone (20E), and the dsMdCht2 could resulted in decrease of the chitinase activity and increase of the chitin content. Taken together, our findings suggested that MdCht2 regulated the chitin content via chitinases, thereby leading to abnormal development. Our results provide a potential target for M. domestica management.

Wheat is one of the most important food crops in the world and is considered one of the top targets in crop biotechnology. With the high-quality reference genomes of wheat and its relative species and the recent burst of genomic resources in Triticeae, demands to perform gene functional studies in wheat and genetic improvement have been rapidly increasing, requiring that production of transgenic wheat should become a routine technique. While established for more than 20 years, the particle bombardment-mediated wheat transformation has not become routine yet, with only a handful of labs being proficient in this technique. This could be due to, at least partly, the low transformation efficiency and the technical difficulties. Here, we describe the current version of this method through adaptation and optimization. We report the detailed protocol of producing transgenic wheat by the particle gun, including several critical steps, from the selection of appropriate explants (i.e., immature scutella), the preparation of DNA-coated gold particles, and several established strategies of tissue culture. More importantly, with over 20 years of experience in wheat transformation in our lab, we share the many technical details and recommendations and emphasize that the particle bombardment-mediated approach has fewer limitations in genotype dependency and vector construction when compared with the Agrobacterium-mediated methods. The particle bombardment-mediated method has been successful for over 30 wheat genotypes, from the tetraploid durum wheat to the hexaploid common wheat, from modern elite varieties to landraces. In conclusion, the particle bombardment-mediated wheat transformation has demonstrated its potential and wide applications, and the full set of protocol, experience, and successful reports in many wheat genotypes described here will further its impacts, making it a routine and robust technique in crop research labs worldwide.

几丁质酶是昆虫几丁质降解过程中的重要酶类,在昆虫整个生长发育过程中发挥着重要作用.为筛选及挖掘与防治有害医学昆虫相关的分子靶标,根据家蝇几丁质酶2(Musca domestica chitinase 2,MdCht2)基因序列设计并合成双链RNA(double-stranded RNA,dsRNA),采用微量注射法向家蝇2龄幼虫导入dsRNA,对对照组及干扰组的样本进行转录组测序,筛选差异表达基因,进行GO(gene ontology)功能注释和KEGG(kyoto encyclopedia of genes and genomes)通路富集分析.结果显示,注射dsRNA 24 h后,幼虫MdCht2 mRNA的表达显著下降,提示导入的dsRNA干扰了MdCht2的表达.经转录组测序,与对照组相比,显著差异基因共213条,其中78条基因为上调表达,135条基因为下调表达.随机选取8条显著差异基因通过实时荧光定量PCR(qRT-PCR)进行验证,该结果与转录组结果趋势一致.根据功能注释发现这些差异基因与生长发育、脂类代谢、免疫调控等途径相关.本研究通过RNA干扰和转录组测序技术处理家蝇获得大量差异基因,结果可为后续几丁质酶相关基因的挖掘和鉴定及功能研究提供一定的数据基础.

几丁质酶是昆虫几丁质降解过程中的重要酶类.本研究旨在利用大肠杆菌(Escherichia coli)原核表达系统获得高纯度的MDCht2重组蛋白,并从几丁质酶活性及抗菌活性两方面来初步探讨MDCht2的生物学功能.MDCht2的cDNA序列设计包含酶切位点EcoRⅠ、Hind Ⅲ和6xHis标签的引物,以家蝇3龄幼虫的cDNA为模板进行PCR扩增,以pET28a(+)为载体构建重组质粒,并转化到大肠杆菌Transetta(DE3)中,经IPTG诱导,表达产物用SDS-PAGE凝胶电泳鉴定,利用Ni离子亲和层析技术纯化MDCht2重组蛋白,Western Blot技术及质谱分析鉴定纯化蛋白.以4MU-(GlcNAc)3为底物,测定重组蛋白的酶活性;采用微量液体稀释法分析重组蛋白对金黄色葡萄球菌、大肠杆菌、白假丝酵母菌的抗菌活性.成功克隆MDCht2基因,构建了具有正确序列的原核重组表达质粒,将重组质粒导入Transetta(DE3)中,经镍柱纯化获得带His标签的重组MDCht2蛋白,质谱分析显示重组蛋白与MDCht2蛋白序列一致.酶活分析表明,不同浓度的MD-Cht2重组酶均有几丁质酶活性,呈现一定的量效关系;该重组蛋白的最适pH值为4.0,在pH=8.0时稳定性最好;最适温度为35℃;金属离子和Tris对MDCht2酶活均有抑制作用.抗菌活性结果显示,MDCht2蛋白对金黄色葡萄球菌,大肠杆菌均无抑菌效果,但对白假丝酵母菌有抑制作用,MIC值为225 μg/mL,MBC(Minimum bactericidal concentration)值为450 μg/mL.本研究成功获得了 MDCht 2重组蛋白,体外检测有较强的几丁质酶活性和抗真菌活性,为进一步研究该酶的功能奠定一定基础.

家蝇(Musca domestica)属于双翅目昆虫,广泛分布于世界各地,目前家蝇抗药现象较为严重.为了筛选及挖掘与防治有害医学昆虫相关的分子靶标,本研究以家蝇幼虫为实验对象,采用RNAi方法沉默家蝇几丁质酶MDCht9基因后,分析幼虫mRNA转录组表达变化,初步探讨MDCht9的功能.研究结果表明,在注射dsRNA 24 h后,幼虫MDCht9 mRNA的表达显著下降85％,提示干扰有一定效果.实验组与对照组相比共筛选出378个基因差异表达显著,其中上调基因162个,下调基因216个,占所有被检测到转录RNA基因的百分比为2.66％.通过GO和KEGG相关生物信息学分析,挖掘出涉及幼虫时期生长发育、蛋白质的消化与吸收、雄虫性成熟、物质代谢等相关通路基因.采用实时荧光定量PCR对差异基因进行验证,与转录组结果一致.本实验通过RNAi方法成功降低MDCht9基因mRNA表达,MDCht9基因参与幼虫时期生长发育、蛋白质的消化与吸收、雄虫性成熟、物质代谢等功能.本研究结果有助于后续生物信息学分析及为家蝇生长发育关键基因的挖掘提供基础数据,为害虫防治提供新的靶标途径.

Background: Candida albicans is associated with high mortality among immunocompromised patients. Resistance to and toxic side effects of antifungal drugs require the development of alternative antifungal agents. AMP-17 is a novel antimicrobial peptide derived from Musca domestica that exerts excellent antifungal effects against the Candida species. In this article, we discuss the potential mechanism of AMP-17 against C. albicans from the perspective of affecting the latter's cell external structure. Methods: Recombinant AMP-17 was prepared by prokaryotic expression system, and its anti-C. albicans activity was detected by microdilution method. Microscopy and scanning electron microscopy were used to examine morphological changes in C. albicans. Cell wall-specific staining method was used to detect the change of cell wall integrity of C. albicans after AMP-17 treatment. AMP-17-induced damage to the C. albicans cell membrane was analyzed by fluorescent probes and glycerol assay kit. The expression of genes related to fungal cell wall and cell-membrane synthesis was detected by qRT-PCR. Results: Morphological observations showed that the growth of C. albicans was significantly inhibited in AMP-17-treated cells; the cells appeared aggregated and dissolved, with severe irregularities in shape. Furthermore, AMP-17 damaged the integrity of C. albicans cell walls. The cell wall integrity rate of AMP-17-treated cells was only 21.7% compared to untreated cells. Moreover, the change of membrane dynamics and permeability suggested that the cell membrane was disrupted by AMP-17 treatment. Genetic analysis showed that after AMP-17 treatment, the cell wall synthesis-related gene FKS2 of C. albicans was up-regulated 3.46-fold, while the cell membrane ergosterol synthesis-related genes ERG1, ERG5, ERG6, and MET6 were down-regulated 5.88-, 17.54-, 13.33-, and 7.14-fold, respectively. Conclusion: AMP-17 treatment disrupted the cell wall integrity and membrane structure of C. albicans and is likely a novel therapeutic option for prevention and control of C. albicans infections.

[背景]AMP-17是从微生物诱导的家蝇转录组数据库筛选到的一条特异性高表达基因,采用原核表达体系获得其重组蛋白并证实了具有显著的抗菌效果,特别是对白色念珠菌具有较强的抗菌活性.[目的]研究抗菌肽AMP-17对白色念珠菌菌丝的抑制作用.[方法]采用微量液体稀释法测定AMP-17对11株白色念珠菌的最小抑菌浓度(minimal inhibitory concentration,MIC);根据对AMP-17的敏感程度选取3株绘制生长曲线;通过光学显微镜观察并计数经AMP-17作用后白色念珠菌芽生孢子生成率及芽管形成率;倒置荧光显微镜观察白色念珠菌酵母相向菌丝相转化及以菌丝相为起点AMP-17促进菌丝相转化为酵母相的情况.[结果]AMP-17对支气管肺泡灌洗液分离株16105的MIC为10 μg/mL,对粪便分离株16214的MIC为40 μg/mL,对其余9株白色念珠菌的MIC均为20 μg/mL;白色念珠菌经不同浓度的AMP-17作用后,各时间点的芽生孢子生成率均显著低于对照组,尤其是40 μg/mL的AMP-17组,芽生孢子生成率仅15％,显著低于阳性药物氟康唑;各实验组芽管形成率显著低于对照组,且芽管形成缓慢,培养6h后芽管形成率仅为6％,形成的芽管长度较短,仅为菌体的1-2倍.镜下观察低浓度的AMP-17即可以完全抑制白色念珠菌菌丝的生长,并且对已经形成的菌丝有一定的生长抑制作用,高浓度的AMP-17则可使已形成的部分菌丝向酵母相转化.[结论]家蝇抗菌肽AMP-17可抑制白色念珠菌菌丝生长.

目的 从家蝇的EST测序数据库中筛选获得家蝇几丁质酶基因8(MDCht8),对其进行分子特性分析,探讨Cht8基因在家蝇不同组织和发育时期的时空表达模式及其在家蝇免疫防御中的功能. 方法 克隆MDCht8基因,借助MEGA 5.0软件采用邻接法构建系统进化树;采用实时荧光定量PCR检测MDCht8基因时空表达模式及微生物诱导后不同时间点(3、6、12、18、24、36、48 h)MDCht8基因表达水平的变化. 结果 MDCht8基因的ORF框全长1512 bp,编码一个含503个氨基酸的蛋白多肽,理论相对分子质量约为56.801 7×103,进化树分析显示该蛋白与果蝇Cht8遗传距离较近.时空表达模式分析显示,MDCht8基因在2龄幼虫和3龄幼虫内表达量较高,家蝇3龄幼虫的各主要组织中以唾液腺和中肠中的表达水平较高.经白色念珠菌和大肠埃希菌诱导后,家蝇MDCht8基因出现明显上调,金黄色葡萄球菌诱导后未表现出明显上调.成功克隆了MDCht8基因,PCR扩增片段为1 512 bp,与预期相符. 结论 初步揭示了MDCht8基因在家蝇不同虫期,不同组织表达量不同,提示几丁质酶基因在家蝇生长发育过程中具有重要作用;MD-Cht8基因在家蝇幼虫受到病原微生物攻击后表达上调,且攻击后的不同时间点表达量不同,提示MDCht8基因编码的几丁质酶参与家蝇的免疫防御过程.

Wheat, a major worldwide staple food crop, is relatively sensitive to a changing environment, including high temperature. The comprehensive mechanism of heat stress response at the molecular level and exploitation of candidate tolerant genes are far from enough. Using transcriptome data, we analyzed the gene expression profiles of wheat under heat stress. A total of 1705 and 17 commonly differential expressed genes (DEGs) were identified in wheat grain and flag leaf, respectively, through transcriptome analysis. Gene Ontology (GO) and pathway enrichment were also applied to illustrate the functions and metabolic pathways of DEGs involved in thermotolerance of wheat grain and flag leaf. Furthermore, our data suggest that there may be a more complex molecular mechanism or tighter regulatory network in flag leaf than in grain under heat stress over time, as less commonly DEGs, more discrete expression profiles of genes (principle component analysis) and less similar pathway response were observed in flag leaf. In addition, we found that transcriptional regulation of zeatin, brassinosteroid and flavonoid biosynthesis pathways may play an important role in wheat’s heat tolerance. The expression changes of some genes were validated using quantitative real-time polymerase chain reaction and three potential genes involved in the flavonoid biosynthesis process were identified.

Abstract Antimicrobial peptides (AMPs) are cationic small peptide chains that have good antimicrobial activity against a variety of bacteria, fungi, and viruses. AMP-17 is a recombinant insect AMP obtained by a prokaryotic expression system. However, the full antifungal activity, physicochemical characteristics, and cytotoxicity of AMP-17 were previously unknown. AMP-17 was shown to have good antifungal activity against five pathogenic fungi, with minimum inhibitory concentrations (MIC) of 9.375–18.75 μg/ml, and minimum fungicidal concentrations (MFC) of 18.75–37.5 μg/ml. Notably, the antifungal activity of AMP-17 against Cryptococcus neoformans was superior to that of other Candida spp. In addition, the hemolytic rate of AMP-17 was only 1.47%, even at the high concentration of 16× MIC. AMP-17 was insensitive to temperature and high salt ion concentration, with temperatures of 98°C and –80°C, and NaCl and MgCl2 concentrations of 50–200 mmol/l, having no significant effect on antifungal activity. However, AMP-17 was sensitive to proteases, trypsin, pepsin, and proteinase K. The elucidation of antifungal activity, physicochemical properties and cytotoxicity of AMP-17 provided an experimental basis for its safety evaluation and application, as well as indicated that AMP-17 might be a promising drug.

Sucrose non-fermenting 1-related protein kinase 2 (SnRK2) family members play crucial roles in plant abiotic stress response. However, the precise mechanism underlying the function of SnRKs has not been thoroughly elucidated in plants. In this research, a novel SnRK2 gene, TaSnRK2.9 was cloned and characterized from common wheat. The expression of TaSnRK2.9 was upregulated by polyethylene glycol (PEG), NaCl, H2O2, abscisic acid (ABA), methyl jasmonate (MeJA), and ethrel treatments. TaSnRK2.9 was mainly expressed in wheat young root, stamen, pistil, and lemma. Overexpressing TaSnRK2.9 in transgenic tobacco enhanced plants' tolerance to drought and salt stresses both in young seedlings and mature plants with improved survival rate, seed germination rate, and root length. Physiological analyses suggest that TaSnRK2.9 improved antioxidant system such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione (GSH) to reduce the H2O2 content under drought or salt stress. Additionally, TaSnRK2.9 overexpression plants had elevated ABA content, implying that the function of TaSnRK2.9 may be ABA-dependent. Moreover, TaSnRK2.9 increased the expression of some ROS-related, ABA-related, and stress-response genes under osmotic or salt treatment. TaSnRK2.9 could interact with NtABF2 in yeast two-hybrid assay, and increased the expression of NtABF2 under mannitol or NaCl treatment in transgenic tobacco plants. In conclusion, overexpression of TaSnRK2.9 in tobacco conferred plants tolerance to drought and salt stresses through enhanced ROS scavenging ability, ABA-dependent signal transduction, and specific SnRK-ABF interaction.

Background: The trihelix gene family is a plant-specific transcription factor family that plays important roles in plant growth, development, and responses to abiotic stresses. However, to date, no systemic characterization of the trihelix genes has yet been conducted in wheat and its close relatives. Results: We identified a total of 94 trihelix genes in wheat, as well as 22 trihelix genes in Triticum urartu, 29 in Aegilops tauschii, and 31 in Brachypodium distachyon. We analyzed the chromosomal locations and orthology relations of the identified trihelix genes, and no trihelix gene was found to be located on chromosome 7A, 7B, or 7D of wheat, thereby reflecting the uneven distributions of wheat trihelix genes. Phylogenetic analysis indicated that the 186 identified trihelix proteins in wheat, rice, B. distachyon, and Arabidopsis were clustered into five major clades. The trihelix genes belonging to the same clades usually shared similar motif compositions and exon/intron structural patterns. Five pairs of tandem duplication genes and three pairs of segmental duplication genes were identified in the wheat trihelix gene family, thereby validating the supposition that more intrachromosomal gene duplication events occur in the genome of wheat than in that of other grass species. The tissue-specific expression and differential expression profiling of the identified genes under cold and drought stresses were analyzed by using RNA-seq data. qRT-PCR was also used to confirm the expression profiles of ten selected wheat trihelix genes under multiple abiotic stresses, and we found that these genes mainly responded to salt and cold stresses. Conclusions; In this study, we identified trihelix genes in wheat and its close relatives and found that gene duplication events are the main driving force for trihelix gene evolution in wheat. Our expression profiling analysis demonstrated that wheat trihelix genes responded to multiple abiotic stresses, especially salt and cold stresses. The results of our study built a basis for further investigation of the functions of wheat trihelix genes and provided candidate genes for stress-resistant wheat breeding programs.

目的:探讨家蝇幼虫经白色念珠菌Candida albican胁迫后,AMP17基因时空表达谱的变化.方法:显微注射法将白色念珠菌导入家蝇幼虫体内,饲养3 h、6 h、12 h、24 h、36 h、48 h后,提取各组整虫RNA,采用实时荧光定量PCR分析AMP17的时间表达情况;选取经胁迫后3 h、12 h、48 h的幼虫,解剖获得体壁、脂肪体、马氏管、中肠、唾液腺、气管、血淋巴,同上分析AMP17的空间表达情况.以注射PBS为对照组,家蝇RPS18为内参基因,设3个生物重复.结果:注射白色念珠菌后,实验组幼虫的AMP17基因表达量较对照组明显上调,高表达一直持续到12 h,24 h明显下降,但48 h表达量又突然大幅度升高.不同组织中实验组与对照组比较,3 h时体壁表达量最高,上调6.59倍(P<0.01),其次是气管上调4.74倍;感染12 h后,体壁表达量依然最高,上调了5.54倍(P<0.01),其次为血淋巴,上调了1.87倍(P<0.05);感染48 h后,体壁表达量上调了10.98倍(P<0.05);唾液腺上调了7.28倍(P<0.05).结论:经白色念珠菌胁迫后,AMP17基因的表达量出现了明显的上调,提示该基因参与了家蝇应对真菌侵染的免疫反应.

Objective: To optimize the prokaryotic expression conditions of AMPs17 recombinant protein and analyze the antifungal activity of recombinant protein. Methods: Compare different induction temperatures (25℃, 28℃, 30℃, 32℃, 34℃), isopropylthio-β-D galactoside (IPTG) induced concentration (0. 025 mmol/L, 0. 05 mmol/L, 0. 1 mmol/L, 0. 3 mmol/L, 0. 5 mmol/L, 0. 8 mmol/L, 1. 0 mmol/L) and induction time (12 h, 15 h, 18 h, 21 h, 24 h) on the expression of AMPs17 recombinant protein, screening the optimal expression conditions of AMPs17 recombinant protein. The recombinant protein was purified by nickel ion metal chelator affinity chromatography column, and the expression results were analyzed by SDS-PAGE electrophoresis and ImageJ image analysis system. The recombinant protein of AMPs17 was identified by Western blot and the purity of the recombinant protein was analyzed by high performance liquid chromatography (HPLC). The antifungal activity was detected by a micro liquid dilution method and a colony counting method. Results: The results showed that the expression of AMPs17 recombinant protein was the highest and the most stable when induced at32℃ and IPTG concentration of 0. 05 mmol/L for 15 h. The HPLC analysis showed that the purity of AMPs17 recombinant protein reached 90％. In addition, AMPs17 recombinant protein can effectively inhibit the growth of Candida albicans. Conclusion: The induction and expression conditions of antibacterial peptide AMPs17 were optimized, and proteins with high expression, stability and antifungal activity were obtained, which provided certain experimental basis for the follow-up antibacterial mechanism and application research.

目的 从家蝇的基因组库中筛选几丁质酶2 (MDCht2)基因,进行cDNA克隆及分子特性分析,对其时空表达模式进行初步探索. 方法 从家蝇基因组数据库中筛选MDCht2基因,以该基因的cDNA为模板进行PCR扩增,采用生物信息学相关软件对MDCht2基因及其编码蛋白质的基本理化性质、信号肽、蛋白质结构等进行分析,预测蛋白质功能.取家蝇不同生活史时期(卵,1龄幼虫,2龄幼虫,3龄幼虫,蛹,雌雄成虫)及3龄幼虫不同组织(体壁,气管,马氏管,唾液腺,脂肪体,肠道)标本,采用实时荧光定量PCR检测MDCht2基因表达情况. 结果 MDCht2基因cDNA全长1 932 bp,ORF框全长1 530 bp,编码509个氨基酸,理论相对分子质量为57.8×103,pI 5.67,属于亲水性的酸性蛋白,有信号肽,功能结构域位于第37～385位氨基酸间,无几丁质结合域.二级结构分析显示存在无规则卷曲(Cc),α螺旋(Hh),β折叠(Ee)3种类型.PCR扩增得到MDCht2基因长为1 530 bp的序列片段.实时荧光定量PCR检测家蝇MDCht2基因在蛹期的表达量较卵期上调6.477 01倍(P＜0.01),3龄幼虫表达量上调2.655 25倍(P＜0.01),1龄幼虫的表达量上调2.475 01倍(P＜0.05),表达水平排列顺序为蛹＞3龄幼虫＞1龄幼虫＞2龄幼虫＞卵＞雄成虫＞雌成虫.以体壁为参照,MDCht2基因家蝇气管中的表达量较高,气管中的表达量较体壁1.81.816 51倍(P＜0.01),表达水平为气管＞体壁＞唾液腺＞脂肪体＞肠道＞马氏管. 结论 成功克隆了家蝇的MDCht2基因并初步探索了其时空表达模式,即MDCht2基因在蛹期及气管组织高表达,为MDCht2的功能研究奠定了基础.

[目的]对MDCht9基因进行生物信息学分析,构建原核表达载体,获得重组蛋白,并测其酶学活性.[方法]构建邻位连接树研究MDCht9基因的分类归属及其与黑腹果蝇、冈比亚按蚊和致倦库蚊几丁质酶的进化关系,采用生物信息学软件,分析MDCht9基因及编码蛋白的理化性质,信号肽、二级结构等,预测蛋白质的功能;根据其cDNA序列设计引物,PCR扩增,以pET28(+)为载体构建重组质粒,并转化到大肠杆菌BL21 (DE3)中,异丙硫代-β-D半乳糖苷(IPTG)进行诱导,表达产物用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳鉴定,质谱鉴定纯化蛋白.几丁质酶活测定:以4MU-(GlcNAc)3为底物,测定重组蛋白的酶学活性.[结果]系统发育树表明MDCht9基因与果蝇Cht9基因同源性最高,其ORF全长1 401 bp,编码466个氨基酸,理论分子量为50 827.2 Da,等电点为6.97,属于亲水性蛋白.MDCht9基因编码蛋白的第1-22氨基酸为信号肽,剪切位点位于第22与第23位氨基酸之间.MDCht9蛋白的功能结构域位于第24-357位氨基酸间,是18家族几丁质糖基水解酶的催化域,第413-466位氨基酸之间的序列为几丁质结合区域.MDCht9蛋白的二级结构及三级结构显示有3种类型:以无规则卷曲为主(Cc),其次为α-螺旋(Hh)和β折叠(Ee).构建了具有正确序列的MDCht9重组表达质粒,重组蛋白在大肠杆菌BL21 (DE3)中表达;通过亲和层析柱纯化的重组蛋白质谱鉴定,与MDCht9序列一致,提示MDCht9重组蛋白获取成功.酶学活性表明不同浓度的MDCht9重组蛋白均有几丁质酶活性,而且呈现一定的量效关系,0.18 mg/mL重组蛋白的4 MU生成量为53.63 U,0.045 mg/mL重组蛋白的4 MU生成量为9.97 U.[结论]采用原核表达系统成功获得MDCht9的重组蛋白,且重组蛋白有较强的酶活性,为进一步研究其功能奠定了基础.

CBL-interacting protein kinases are involved in plant responses to abiotic stresses, including salt stress. However, the negative regulating mechanism of this gene family in response to salinity is less reported. In this study, we evaluated the role of TaCIPK25 in regulating salt response in wheat. Under conditions of high salinity, TaCIPK25 expression was markedly down-regulated in roots. Overexpression of TaCIPK25 resulted in hypersensitivity to Na + and superfluous accumulation of Na + in transgenic wheat lines. TaCIPK25 expression did not decline in transgenic wheat and remained at an even higher level than that in wild-type wheat controls under high-salinity treatment. Furthermore, transmembrane Na + /H + exchange was impaired in the root cells of transgenic wheat. These results suggested that TaCIPK25 negatively regulated salt response in wheat. Additionally, yeast-one-hybrid, β-glucuronidase activity and DNA-protein-interaction-enzyme-linked-immunosorbent assays showed that the transcription factor TaWRKY9 bound W-box in the TaCIPK25 promoter region. Quantitative real-time polymerase chain reaction assays showed concomitantly inverted expression patterns of TaCIPK25 and TaWRKY9 in wheat roots under salt treatment, ABA application and inhibition of endogenous ABA condition. Overall, based on our results, in a salt stress condition, the negative salt response in wheat involved TaCIPK25 with the expression regulated by TaWRKY9.

PSG076基因是从奥地利小麦品种‘Ferdinand’中分离的花粉特异性表达基因,功能未知.为获得可用于小麦基因工程的花粉特异性启动子,采用优化的反向PCR法分离PSG076启动子,获得了起始密码子上游约1.4 kb的启动子序列.生物信息学分析显示,该启动子除含有与花粉特异性表达相关的调控元件AGAAA和GTGA外,还含有花粉特异性表达相关的数量元件AGGTCA和AAATGA,推测其为活性较强的花粉特异性启动子.实验中对反向PCR方法的优化可提高扩增侧翼未知序列的效率,特别适用于启动子序列的扩增.