Identification and characterization of genes differentially expressed in the resistance reaction in wheat infected with Tilletia tritici, the common bunt pathogen

Analysis of microbial communities in wheat, alfalfa, and oat crops after Tilletia laevis Kühn infection

Common bunt caused by Tilletia laevis Kühn is one of the most serious fungal diseases of wheat. The root-microbial associations play key roles in protecting plants against biotic and abiotic factors. Managing these associations offers a platform for improving the sustainability and efficiency of agriculture production. Here, by using high throughput sequencing, we aimed to identify the bacterial and fungal associations in wheat, alfalfa, and oat crops cultivated in different years in the Gansu province of China. Soil samples (0-6 cm below the surface) from infected wheat by T. laevis had significantly more bacterial and fungal richness than control samples as per the Chao1 analysis. We found some dominant fungi and bacterial phyla in infected wheat by T. laevis, such as Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Ascomycota, Basidiomycota, and Mortierello mycota. We also analyzed the chemical and enzymatic properties of soil samples after T. laevis inoculation. The total nitrogen, total kalium (TK), ammonium nitrogen, available kalium, organic carbon, invertase, phosphatase, and catalase were more in T. laevis-infected samples as compared to the control samples, while pH, total phosphorus, nitrate nitrogen, available phosphorus, and urease were more in control samples compared to T. laevis-infected samples. The results of this study will contribute to the control of wheat common bunt by candidate antagonistic microorganisms and adverse properties of soil.

Metabolomic Analysis of Wheat Grains after Tilletia laevis Kühn Infection by Using Ultrahigh-Performance Liquid Chromatography–Q-Exactive Mass Spectrometry

Tilletia laevis causes common bunt disease in wheat, with severe losses of production yield and seed quality. Metabolomics studies provide detailed information about the biochemical changes at the cell and tissue level of the plants. Ultrahigh-performance liquid chromatography–Q-exactive mass spectrometry (UPLC-QE-MS) was used to examine the changes in wheat grains after T. laevis infection. PCA analysis suggested that T. laevis-infected and non-infected samples were scattered separately during the interaction. In total, 224 organic acids and their derivatives, 170 organoheterocyclic compounds, 128 lipids and lipid-like molecules, 85 organic nitrogen compounds, 64 benzenoids, 31 phenylpropanoids and polyketides, 21 nucleosides, nucleotides, their analogues, and 10 alkaloids and derivatives were altered in hyphal-infected grains. According to The Kyoto Encyclopedia of Genes and genomes analysis, the protein digestion and absorption, biosynthesis of amino acids, arginine and proline metabolism, vitamin digestion and absorption, and glycine, serine, and threonine metabolism pathways were activated in wheat crops after T. laevis infection.

ITRAQ-Based Proteomic Analysis of Wheat (Triticum aestivum) Spikes in Response to Tilletia controversa Kühn and Tilletia foetida Kühn Infection, Causal Organisms of Dwarf Bunt and Common Bunt of Wheat

Dwarf bunt and common bunt diseases of wheat are caused by Tilletia controversa Kühn and Tilletia foetida Kühn, respectively, and losses caused by these diseases can reach 70-80% in favourable conditions. T. controversa and T. foetida are fungal pathogens belonging to the Exobasidiomycetes within the basidiomycetous smut fungi (Ustilaginomycotina). In order to illuminate the proteomics differences of wheat spikes after the infection of T. controversa and T. foetida, the isobaric tags for relative and absolute quantification (iTRAQ) technique was used for better clarification. A total of 4553 proteins were differentially detected after T. controversa infection; 4100 were upregulated, and 453 were downregulated. After T. foetida infection, 804 differentially expressed proteins were detected; 447 were upregulated and 357 were downregulated. In-depth data analysis revealed that 44, 50 and 82 proteins after T. controversa and 9, 6 and 16 proteins after T. foetida were differentially expressed, which are antioxidant, plant-pathogen interaction and glutathione proteins, respectively, and 9 proteins showed results consistent with PRM. The top 20 KEGG enrichment pathways were identified after pathogen infection. On the basis of gene ontology, the upregulated proteins were linked with metabolic process, catalytic activity, transferase activity, photosynthetic membrane, extracellular region and oxidoreductase activity. The results expanded our understanding of the proteome in wheat spikes in response to T. controversa and T. foetida infection and provide a basis for further investigation for improving the defense mechanism of the wheat crops.

Transcriptomics Analysis of Wheat Tassel Response to Tilletia laevis Kühn, Which Causes Common Bunt of Wheat

Tilletia laevis Kühn [synonym T. foetida (Wallr.) Liro] can lead to a wheat common bunt, which is one of the most serious diseases affecting kernels, a serious reduction in grain yield, and losses can reach up to 80% in favorable environments. To understand how wheat tassels respond to T. laevis, based on an RNA-Seq technology, we analyzed a host transcript accumulation on healthy wheat tassels and on tassels infected by the pathogen. Our results showed that 7,767 out of 15,658 genes were upregulated and 7,891 out of 15,658 genes were downregulated in wheat tassels. Subsequent gene ontology (GO) showed that differentially expressed genes (DEGs) are predominantly involved in biological processes, cellular components, and molecular functions. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that 20 pathways were expressed significantly during the infection of wheat with T. laevis, while biosynthesis of amino acids, carbon metabolism, and starch and sucrose metabolism pathways were more highly expressed. Our findings also demonstrated that genes involved in defense mechanisms and myeloblastosis (MYB) transcription factor families were mostly upregulated, and the RNA-seq results were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on transcriptomics analysis of wheat tassels in response to T. laevis, which will contribute to understanding the interaction of T. laevis and wheat, and may provide higher efficiency control strategies, including developing new methods to increase the resistance of wheat crops to T. laevis-caused wheat common bunt.

Effects of Tilletia foetida on Microbial Communities in the Rhizosphere Soil of Wheat Seeds Coated with Different Concentrations of Jianzhuang

Tilletia foetida (syn. T. laevis) leads to wheat common bunt, a worldwide disease that can lead to 80% yield loss and even total loss of production, together with degrading the quality of grains and flour by producing a rotten fish smell. To explore the potential microbial community that may contribute to the control of soil- and seed-borne pathogens, in this study, we analyzed the effects of the plant pathogenic fungus T. foetida on rhizosphere soil microorganisms in wheat seeds coated with different concentrations of a fungicide (Jianzhuang) used to control the disease. To analyze the bacterial and fungal abundance in T. foetida-infected and mock-infected plants, the microorganisms were sequenced using high-throughput HiSeq 2500 gene sequencing. The results showed that bacterial communities, including Verrucomicrobia, Patescibacteria, Armatimonadetes, Nitrospirae, Fibrobacteres, Chlamydiae, and Hydrogenedentes, and fungal communities, including Basidiomycota and Ciliophora, were more prevalent in the mock group than in the T. foetida-infected group, which may contribute to the control of wheat common bunt. Moreover, cluster and PCoA analysis revealed that replicates of the same samples were clustered together, and these results were also found in the distance index within-group analysis for bacterial and fungal communities in the T. foetida-infected and mock groups.

Molecular cloning, identification of GSTs family in sunflower and their regulatory roles in biotic and abiotic stress

Glutathione-S-transferase (GST) genes exist widely in plants and play major role in metabolic detoxification of exogenous chemical substances and oxidative stress. In this study, 14 sunflower GST genes (HaGSTs) were identified based on the sunflower transcriptome database that we had constructed. Full-length cDNA of 14 HaGTSs were isolated from total RNA by reverse transcription PCR (RT-PCR). Sunflower was received biotic stress (Sclerotinia sclerotiorum) and abiotic stress (NaCl, low-temperature, drought and wound). GST activity was measured by using the universal substrate. The results showed that most of the HaGSTs were up-regulated after NaCl and PEG6000-induced stresses, while a few HaGSTs were up-regulated after S. sclerotiorum, hypothermia and wound-induced stressed, and there was correlation between the changes of GST activity and the expression of HaGSTs, indicating that HaGSTs may play regulatory role in the biotic and abiotic stress responses. 14 HaGSTs from sunflower were identified, and the expression of HaGSTs were tissue-specific and played regulatory roles in both stress and abiotic stress.

Development of a qPCR Strategy to Select Bean Genes Involved in Plant Defense Response and Regulated by the Trichoderma velutinum - Rhizoctonia solani Interaction

Bean production is affected by a wide diversity of fungal pathogens, among them Rhizoctonia solani is one of the most important. A strategy to control bean infectious diseases, mainly those caused by fungi, is based on the use of biocontrol agents (BCAs) that can reduce the negative effects of plant pathogens and also can promote positive responses in the plant. Trichoderma is a fungal genus that is able to induce the expression of genes involved in plant defense response and also to promote plant growth, root development and nutrient uptake. In this article, a strategy that combines in silico analysis and real time PCR to detect additional bean defense-related genes, regulated by the presence of Trichoderma velutinum and/or R. solani has been applied. Based in this strategy, from the 48 bean genes initially analyzed, 14 were selected, and only WRKY33, CH5b and hGS showed an up-regulatory response in the presence of T. velutinum. The other genes were or not affected (OSM34) or down-regulated by the presence of this fungus. R. solani infection resulted in a down-regulation of most of the genes analyzed, except PR1, OSM34 and CNGC2 that were not affected, and the presence of both, T. velutinum and R. solani, up-regulates hGS and down-regulates all the other genes analyzed, except CH5b which was not significantly affected. As conclusion, the strategy described in the present work has been shown to be effective to detect genes involved in plant defense, which respond to the presence of a BCA or to a pathogen and also to the presence of both. The selected genes show significant homology with previously described plant defense genes and they are expressed in bean leaves of plants treated with T. velutinum and/or infected with R. solani.

Non-specific lipid transfer proteins in plants: presenting new advances and an integrated functional analysis

Plant non-specific lipid-transfer proteins (nsLTPs) are small, basic proteins present in abundance in higher plants. They are involved in key processes of plant cytology, such as the stablization of membranes, cell wall organization, and signal transduction. nsLTPs are also known to play important roles in resistance to biotic and abiotic stress, and in plant growth and development, such as sexual reproduction, seed development and germination. The structures of plant nsLTPs contain an eight-cysteine residue conserved motif, linked by four disulfide bonds, and an internal hydrophobic cavity, which comprises the lipid-binding site. This structure endows stability and increases the ability to bind and/or carry hydrophobic molecules. There is growing interest in nsLTPs, due to their critical roles, resulting in the need for a comprehensive review of their form and function. Relevant topics include: nsLTP structure and biochemical features, their classification, identification, and characterization across species, sub-cellular localization, lipid binding and transfer ability, expression profiling, functionality, and evolution. We present advances, as well as limitations and trends, relating to the different topics of the nsLTP gene family. This review collates a large body of research pertaining to the role of nsLTPs across the plant kingdom, which has been integrated as an in depth functional analysis of this group of proteins as a whole, and their activities across multiple biochemical pathways, based on a large number of reports. This review will enhance our understanding of nsLTP activity in planta, prompting further work and insights into the roles of this multifaceted protein family in plants.

Molecular cloning and expression of five glutathione S-transferase (GST) genes from Banana (Musa acuminata L. AAA group, cv. Cavendish)

Three tau class MaGSTs responded to abiotic stress, MaGSTF1 and MaGSTL1 responded to signaling molecules, they may play an important role in the growth of banana plantlet. Glutathione S-transferases (GST) are multifunctional detoxification enzymes that participate in a variety of cellular processes, including stress responses. In this study, we report the molecular characteristics of five GST genes (MaGSTU1, MaGSTU2, MaGSTU3, MaGSTF1 and MaGSTL1) cloned from banana (Musa acuminate L. AAA group, cv. Cavendish) using a RACE-PCR-based strategy. The predicted molecular masses of these GSTs range from 23.4 to 27.7 kDa and their pIs are acidic. At the amino acid level, they share high sequence similarity with GSTs in the banana DH-Pahang (AA group) genome. Phylogenetic analysis showed that the deduced amino acid sequences of MaGSTs also have high similarity to GSTs of other plant species. Expression analysis by semi-quantitative RT-PCR revealed that these genes are differentially expressed in various tissues. In addition, their expression is regulated by various stress conditions, including exposure to signaling molecules, cold, salinity, drought and Fusarium oxysporum f specialis(f. Sp) cubense Tropical Race 4 (Foc TR4) infection. The expression of the tau class MaGSTs (MaGSTU1, MaGSTU2 and MaGSTU3) mainly responded to cold, salinity and drought while MaGSTF1 and MaGSTL1 expressions were upregulated by signaling molecules. Our findings suggest that MaGSTs play a key role in both development and abiotic stress responses.

Identification, characterization and mapping of differentially expressed genes in a winter wheat cultivar (Centenaire) resistant to Fusarium graminearum infection

Fusarium head blight (FHB), predominantly caused by Fusarium graminearum, is a destructive disease that poses a serious threat to wheat (Triticum aestivum L.) production around the world. A suppression subtractive hybridization (SSH) cDNA library was constructed from F. graminearum infected spikes of a resistant Belgian winter wheat variety Centenaire, exhibiting Type II resistance to FHB. Forty-three differentially expressed transcripts were identified and classified in different categories according to their predicted function, including proteins involved in defense response, signaling, transport of molecules, metabolism and proteins with unknown function. Time-course gene expression analysis between the FHB resistant genotype Centenaire and the susceptible genotype Robigus was carried out on twelve selected genes in order to validate the SSH screening. Real-time quantitative polymerase chain reaction showed that the selected transcripts were differentially expressed between the resistant and the susceptible genotype at three-time points (24, 48 and 72 h) after inoculation with the pathogen, and mostly, the transcripts accumulation rates were higher in the FHB-resistant as compared to the susceptible one. Thirty identified differentially expressed loci were mapped on the corresponding wheat chromosomes either by in silico analysis or by PCR-based mapping strategy, and fifteen of these loci were located within or nearby chromosomal regions known to have quantitative trait loci for FHB resistance in winter wheat cultivars. This work emphasizes the differential gene expression between the FHB-resistant winter wheat Centenaire and the susceptible Robigus and highlights the putative genes and mechanism involved in the disease resistance reaction.

A de novo transcriptome assembly of Lucilia sericata (Diptera: Calliphoridae) with predicted alternative splices, single nucleotide polymorphisms and transcript expression estimates

The blow fly Lucilia sericata (Diptera: Calliphoridae) (Meigen) is a nonmodel organism with no reference genome that is associated with numerous areas of research spanning the ecological, evolutionary, medical, veterinary and forensic sciences. To facilitate scientific discovery in this species, the transcriptome was assembled from more than six billion bases of Illumina and twenty-one million bases of 454 sequence derived from embryonic, larval, pupal, adult and larval salivary gland libraries. The assembly was carried out in a manner that enabled identification of putative single nucleotide polymorphisms (SNPs) and alternative splices, and that provided expression estimates for various life history stages and for salivary tissue. The assembled transcriptome was also used to identify transcribed transposable elements in L. sericata. The results of this study will enable blow fly biologists, dipterists and comparative genomicists to more rapidly develop and test molecular and genetic hypotheses, especially those regarding blow fly development and salivary gland biology.

Control of Common Bunt in Organic Wheat

Common bunt, caused by the seedborne and soilborne pathogens Tilletia caries and T. laevis, has re-emerged as a major disease in organic wheat. In conventional agriculture, common bunt is routinely managed with the use of synthetic chemical seed treatments. For this reason, common bunt is a relatively unimportant disease in conventional agriculture. However, since synthetic chemical inputs are prohibited in organic agriculture, common bunt is a major threat once more in organic wheat and seed production. The challenge today is to manage the disease without the use of chemical seed treatments. This review reports on the management of common bunt under organic farming systems, mainly through host resistance and organic seed treatments. We report the history of screening wheat germplasm for bunt resistance, the search for new sources of resistance, and identification and mapping of bunt resistance genes. Since the pathogen has a gene-for-gene relationship with the host, this review also includes a summary of work on pathogen race identification and virulence patterns of field isolates. Also included are studies on the physiological and molecular basis of host resistance. Alternative seed treatments are discussed, including physical seed treatments, and microbial-based and plant-based treatments acceptable in organic systems. The article concludes with a brief discussion on the current gaps in research on the management of common bunt in organic wheat.

Morphological and molecular analyses of host and nonhost interactions involving barley and wheat and the covered smut pathogen Ustilago hordei

Ustilago hordei interactions on coleoptiles of barley host cultivars Odessa (compatible), Hannchen (incompatible, carrying the Ruh1 resistance gene), and on nonhost Neepawa wheat were studied using light and fluorescent microscopy. Autofluorescence, mainly caused by callose accumulation, was more rapidly expressed in nonhost wheat at 30 to 72 h compared with the incompatible reaction between 72 and 144 h. Microarray results demonstrated that more than half of the 893 differentially regulated genes were observed in Neepawa; of these genes, 45% fell into the defense- and stress-related classes in Neepawa compared with 25 and 37% in Odessa and Hannchen, respectively. Their expression coincided with the early morphological defense responses observed and were associated with the jasmonic acid and ethylene (JA/ET) signaling pathway. Expression patterns in Odessa and Hannchen were similar, involving fewer genes and coinciding with later morphological defense responses of these varieties. Although no visible hypersensitive response was apparent in Hannchen or Neepawa, specific upregulation of hypersensitivity-related proteins was observed, such as beta-VPE at 48 h. Expression levels of the callose synthase gene were closely associated with callose accumulation. Differential responses in defense-gene expression among disease reaction types included upregulation of PR-1.1b and downregulation of a nonspecific lipid transfer protein in the incompatible and compatible interactions, respectively. Transcript levels of EDS1 and PAD4, involved in both basal resistance and R-mediated resistance to avirulent pathogens, were up-regulated during both nonhost and Ruh1-mediated resistance. Application of methyl-jasmonate, salicylic acid and ET to leaves revealed that only PR1.1b is strongly up-regulated by all three compounds, while the majority of the defense-related genes are only slightly up-regulated by these signaling compounds.

Expressional diversity of wheat nsLTP genes: evidence of subfunctionalization via cis-regulatory divergence

Previously, the wheat non-specific lipid transfer proteins (TaLTP), members of a small multigene family, were reported to evidence a complex pattern of expression regulation. In order to assess further the expression diversity of the TaLTP genes, we have attempted to evaluate their expression profiles in responses to abiotic stresses, using semi-quantitative RT-PCR. The expression profiles generated herein revealed that the TaLTP genes in group A evidenced highly similar responses against abiotic stresses, whereas differential expression patterns among genes in each group were also observed. A total of seven promoters were fused to a GUS reporter gene and the recombinants were introduced into Arabidopsis, while three promoters evidenced non-detectible GUS activity. The promoters of TaLTP1, TaLTP7, and TaLTP10 included in group A drove strong expressions during plant development with overlapping patterns, in large part, but also exhibited distinct expression pattern, thereby suggesting subfunctionalization processing over evolutionary time. However, only trace expression in cotyledons, young emerged leaves, and epidermal cell layers of flower ovaries was driven by the promoter of TaLTP3 of group B. These results indicate that their distinct physiological functions appear to be accomplished by a subfunctionalization process involving degenerative mutations in regulatory regions.

An oligo-based microarray offers novel transcriptomic approaches for the analysis of pathogen resistance and fruit quality traits in melon (Cucumis melo L.)

Background

Melon (Cucumis melo) is a horticultural specie of significant nutritional value, which belongs to the Cucurbitaceae family, whose economic importance is second only to the Solanaceae. Its small genome of approx. 450 Mb coupled to the high genetic diversity has prompted the development of genetic tools in the last decade. However, the unprecedented existence of a transcriptomic approaches in melon, highlight the importance of designing new tools for high-throughput analysis of gene expression.

Results

We report the construction of an oligo-based microarray using a total of 17,510 unigenes derived from 33,418 high-quality melon ESTs. This chip is particularly enriched with genes that are expressed in fruit and during interaction with pathogens. Hybridizations for three independent experiments allowed the characterization of global gene expression profiles during fruit ripening, as well as in response to viral and fungal infections in plant cotyledons and roots, respectively. Microarray construction, statistical analyses and validation together with functional-enrichment analysis are presented in this study.

Conclusion

The platform validation and enrichment analyses shown in our study indicate that this oligo-based microarray is amenable for future genetic and functional genomic studies of a wide range of experimental conditions in melon.

Characterization and antifungal properties of wheat nonspecific lipid transfer proteins

This study simultaneously considered the phylogeny, fatty acid binding ability, and fungal toxicity of a large number of monocot nonspecific lipid transfer proteins (ns-LTP). Nine novel full-length wheat ns-LTP1 clones, all possessing coding sequences of 348 bp, isolated from abiotic- and biotic-stressed cDNA libraries from aerial tissues, exhibited highly conserved coding regions with 78 to 99 and 71 to 100% identity at the nucleotide and amino acid levels, respectively. Phylogenetic analyses revealed two major ns-LTP families in wheat. Eight wheat ns-LTP genes from different clades were cloned into the expression vector pPICZalpha and transformed into Pichia pastoris. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and in vitro lipid binding activity assay confirmed that the eight ns-LTP were all successfully expressed and capable of in vitro binding fatty acid molecules. A comparative in vitro study on the toxicity of eight wheat ns-LTP to mycelium growth or spore germination of eight wheat pathogens and three nonwheat pathogens revealed differential toxicities among different ns-LTP. Values indicating 50% inhibition of fungal growth or spore germination of three selected ns-LTP against six fungi ranged from 1 to 7 microM. In vitro lipid-binding activity of ns-LTP was not correlated with their antifungal activity. Using the fluorescent probe SYTOX Green as an indicator of fungal membrane integrity, the in vitro toxicity of wheat ns-LTP was associated with alteration in permeability of fungal membranes.

Genome-wide analysis of the rice and Arabidopsis non-specific lipid transfer protein (nsLtp) gene families and identification of wheat nsLtp genes by EST data mining

Background

Plant non-specific lipid transfer proteins (nsLTPs) are encoded by multigene families and possess physiological functions that remain unclear. Our objective was to characterize the complete nsLtp gene family in rice and arabidopsis and to perform wheat EST database mining for nsLtp gene discovery.

Results

In this study, we carried out a genome-wide analysis of nsLtp gene families in Oryza sativa and Arabidopsis thaliana and identified 52 rice nsLtp genes and 49 arabidopsis nsLtp genes. Here we present a complete overview of the genes and deduced protein features. Tandem duplication repeats, which represent 26 out of the 52 rice nsLtp genes and 18 out of the 49 arabidopsis nsLtp genes identified, support the complexity of the nsLtp gene families in these species. Phylogenetic analysis revealed that rice and arabidopsis nsLTPs are clustered in nine different clades. In addition, we performed comparative analysis of rice nsLtp genes and wheat (Triticum aestivum) EST sequences indexed in the UniGene database. We identified 156 putative wheat nsLtp genes, among which 91 were found in the 'Chinese Spring' cultivar. The 122 wheat non-redundant nsLTPs were organized in eight types and 33 subfamilies. Based on the observation that seven of these clades were present in arabidopsis, rice and wheat, we conclude that the major functional diversification within the nsLTP family predated the monocot/dicot divergence. In contrast, there is no type VII nsLTPs in arabidopsis and type IX nsLTPs were only identified in arabidopsis. The reason for the larger number of nsLtp genes in wheat may simply be due to the hexaploid state of wheat but may also reflect extensive duplication of gene clusters as observed on rice chromosomes 11 and 12 and arabidopsis chromosome 5.

Conclusion

Our current study provides fundamental information on the organization of the rice, arabidopsis and wheat nsLtp gene families. The multiplicity of nsLTP types provide new insights on arabidopsis, rice and wheat nsLtp gene families and will strongly support further transcript profiling or functional analyses of nsLtp genes. Until such time as specific physiological functions are defined, it seems relevant to categorize plant nsLTPs on the basis of sequence similarity and/or phylogenetic clustering.

Characterization of a male sterile related gene BcMF15 from Brassica campestris ssp. chinensis

Data from cDNA-AFLP analysis based on the genome-wide transcriptional profiling on the flower buds of the male meiotic cytokinesis (mmc) mutant and its wild-type of Brassica campestris L. ssp. chinensis Makino, syn. B. rapa L. ssp. chinensis, indicated that mutation of the MMC gene resulted in changes in expression of a variety of genes. A transcript-derived fragment specifically accumulated in the wild-type flower buds was isolated, and the corresponding full-length cDNA and DNA was subsequently amplified. Bioinformatical analyses of this gene named BcMF15 (GenBank accession number EF600901) showed that it encoded a protein with 103 amino acids. The BcMF15 had a 88% nucleotide similarity to a lipid transfer protein-like gene. Moreover, sequence prediction indicated that BcMF15 might encode a membrane protein with a signal peptide at the N-terminus. Meanwhile, six domains were predicted in the deduced BcMF15 protein, such as the AAI domain existing in some crucial proteins of pollen development-preferential, signal peptide, transmembrane domain, vWF domain, ZnF_C4 domain, and Tryp_alpha_amyl domain. Spatial and temporal expression patterns analysis by RT-PCR indicated that BcMF15 was exclusively expressed in the fertile line, which indicated this gene is male sterile related. Phylogenetic analysis in Cruciferae revealed that the BcMF15 was relative conservative in evolution. We suppose BcMF15 may be a critical molecule in the transmembrane transportation and signal transduction during microspore development.

Compatible and Incompatible Interactions in Wheat Involving the Bt-10 Gene for Resistance to Tilletia tritici, the Common Bunt Pathogen

ABSTRACT The infection of wheat lines Neepawa (susceptible), and its sib BW553 that is nearly isogenic for the Bt-10 resistance gene by differentially virulent races T1 and T27 of common bunt (Tilletia tritici), was followed for 21 days following seeding (dfs) using fluorescence and confocal microscopy. Spore germination was nonsynchronous and all spore stages including germination were observed 5 to 21 dfs. Initial host perception of pathogen invasion, based on autofluorescence in epidermal cells adjacent to the appressoria, was similar in both compatible and incompatible interactions, and occurred as early as 5 to 6 dfs. The total number of sites on a 1-cm segment of coleoptile adjacent to the seed that exhibited autofluorescence was similar in both the compatible and incompatible interactions and rose to a maximum of 35 to 40 per 1 cm length of coleoptile following 17 dfs, although new infection events were observed as late as 21 dfs. In the compatible interaction, the autofluorescence became more diffuse 10 to 12 dfs, emanating in all directions in association with fungal spread. In the incompatible interaction, autofluorescence remained restricted to a small area surrounding the penetration site. Two different reaction zones that extended further in tissues surrounding the penetration point in the incompatible interaction compared with the compatible interaction were identified. The accumulation of callose around invading fungal hyphae was observed during both the compatible and incompatible interactions from 8 to 21 dfs. While callose accumulation was more extensive and widespread in the incompatible interaction, it was clearly present in compatible interactions, particularly in treatments involving BW553. These results were confirmed by expression of callose synthase transcripts that were more abundant in BW553 than in Neepawa and were upregulated during pathogen infection in both compatible and incompatible interactions.

The Triticum aestivum non-specific lipid transfer protein (TaLtp) gene family: comparative promoter activity of six TaLtp genes in transgenic rice

Plant non-specific lipid transfer proteins (nsLTPs) are encoded by a multigene family and support physiological functions, which remain unclear. We adapted an efficient ligation-mediated polymerase chain reaction (LM-PCR) procedure that enabled isolation of 22 novel Triticum aestivum nsLtp (TaLtp) genes encoding types 1 and 2 nsLTPs. A phylogenetic tree clustered the wheat nsLTPs into ten subfamilies comprising 1-7 members. We also studied the activity of four type 1 and two type 2 TaLtp gene promoters in transgenic rice using the 1-Glucuronidase reporter gene. The activities of the six promoters displayed both overlapping and distinct features in rice. In vegetative organs, these promoters were active in leaves and root vascular tissues while no beta-Glucuronidase (GUS) activity was detected in stems. In flowers, the GUS activity driven by the TaLtp7.2a, TaLtp9.1a, TaLtp9.2d, and TaLtp9.3e gene promoters was associated with vascular tissues in glumes and in the extremities of anther filaments whereas only the TaLtp9.4a gene promoter was active in anther epidermal cells. In developing grains, GUS activity and GUS immunolocalization data evidenced complex patterns of activity of the TaLtp7.1a, TaLtp9.2d, and TaLtp9.4a gene promoters in embryo scutellum and in the grain epicarp cell layer. In contrast, GUS activity driven by TaLtp7.2a, TaLtp9.1a, and TaLtp9.3e promoters was restricted to the vascular bundle of the embryo scutellum. This diversity of TaLtp gene promoter activity supports the hypothesis that the encoded TaLTPs possess distinct functions in planta.

Transcriptional response of Choristoneura fumiferana to sublethal exposure of Cry1Ab protoxin from Bacillus thuringiensis

Bacillus thuringiensis is a microbial control agent active against Choristoneura fumiferana, a lepidopteran defoliator of North American forests. Although the B. thuringiensis insecticidal crystal protoxins have a relatively narrow host range, there is concern about their impact on non-target species where intoxication effects may not be overt. Larval toxicity effects can be assessed at the molecular level by determining altered transcriptional profiles in response to sublethal protoxin exposure in sensitive insects. Subtraction hybridization libraries were created using two larval populations, control and protoxin-fed and were characterized by sequencing 1091 clones. Differential mRNA expression of selected clones, as measured by quantitative polymerase chain reaction, identified a number of metabolic and stress-related genes that were either transcriptionally enhanced or repressed after protoxin exposure.