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TaMCA1, a regulator of cell death, is important for the interaction between wheat and Puccinia striiformis.

ABSTRACT: Metacaspase orthologs are conserved in fungi, protozoa and plants, however, their roles in plant disease resistance are largely unknown. In this study, we identified a Triticum aestivum metacaspase gene, TaMCA1, with three copies located on chromosomes 1A, 1B and 1D. The TaMCA1 protein contained typical structural features of type I metacaspases domains, including an N-terminal pro-domain. Transient expression analyses indicated that TaMCA1 was localized in cytosol and mitochondria. TaMCA1 exhibited no caspase-1 activity in vitro, but was able to inhibit cell death in tobacco and wheat leaves induced by the mouse Bax gene. In addition, the expression level of TaMCA1 was up-regulated following challenge with the Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaMCA1 via virus-induced gene silencing (VIGS) enhanced plant disease resistance to Pst, and the accumulation of hydrogen peroxide (H2O2). Further study showed that TaMCA1 decreased yeast cell resistance similar to the function of yeast metacaspase, and there was no interaction between TaMCA1 and TaLSD1. Based on these combined results, we speculate that TaMCA1, a regulator of cell death, is important during the compatible interaction of wheat and Pst.

SUBMITTER: Hao Y

PROVIDER: S-EPMC4882554 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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TaMCA1, a regulator of cell death, is important for the interaction between wheat and Puccinia striiformis.

Hao Yingbin Y Wang Xiaojie X Wang Kang K Li Huayi H Duan Xiaoyuan X Tang Chunlei C Kang Zhensheng Z

Scientific reports 20160527

Metacaspase orthologs are conserved in fungi, protozoa and plants, however, their roles in plant disease resistance are largely unknown. In this study, we identified a Triticum aestivum metacaspase gene, TaMCA1, with three copies located on chromosomes 1A, 1B and 1D. The TaMCA1 protein contained typical structural features of type I metacaspases domains, including an N-terminal pro-domain. Transient expression analyses indicated that TaMCA1 was localized in cytosol and mitochondria. TaMCA1 exhib ...[more]

PMID: 27230563

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Project description:Stripe rust [caused by Puccinia striiformis Westend. f. sp. tritici Eriks. (Pst)] is a destructive disease of wheat (Triticum aestivum L.) worldwide. Genetic resistance is the preferred method for control and the Yr5 gene, originally identified in Triticum spelta var. album, represents a major resistance (R) gene that confers all-stage resistance to all currently known races of Pst in the United States. To identify transcripts associated with the Yr5-mediated incompatible interaction and the yr5-compatible interaction, the Wheat GeneChip was used to profile the changes occurring in wheat isolines that differed for the presence of the Yr5 gene after inoculation with Pst. This time-course study (6, 12, 24 and 48 h post-inoculation) identified 115 transcripts that were induced during the R-gene-mediated incompatible interaction, and 73 induced during the compatible interaction. Fifty-four transcripts were induced in both interactions and were considered as basal defence transcripts, whilst 61 transcripts were specific to the incompatible interaction [hypersensitive response (HR)-specific transcripts] and 19 were specific to the compatible interaction (biotrophic interaction-specific transcripts). The temporal pattern of transcript accumulation showed a peak at 24 h after infection that may reflect haustorial penetration by Pst at ~16 h. An additional 12 constitutive transcript differences were attributed to the presence of Yr5 after eliminating those considered as incomplete isogenicity. Annotation of the induced transcripts revealed that the presence of Yr5 resulted in a rapid and amplified resistance response involving signalling pathways and defence-related transcripts known to occur during R-gene-mediated responses, including protein kinase signalling and the production of reactive oxygen species leading to a hypersensitive response. Basal defence also involved substantial induction of many defence-related transcripts but the lack of R-gene signalling resulted in weaker response.

Project description:BACKGROUND: Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat worldwide. To establish compatibility with the host, Pst forms special infection structures to invade the plant with minimal damage to host cells. Although compatible interaction between wheat and Pst has been studied using various approaches, research on molecular mechanisms of the interaction is limited. The aim of this study was to develop an EST database of wheat infected by Pst in order to determine transcription profiles of genes involved in compatible wheat-Pst interaction. RESULTS: Total RNA, extracted from susceptible infected wheat leaves harvested at 3, 5 and 8 days post inoculation (dpi), was used to create a cDNA library, from which 5,793 ESTs with high quality were obtained and clustered into 583 contigs and 2,160 singletons to give a set of 2,743 unisequences (GenBank accessions: GR302385 to GR305127). The BLASTx program was used to search for homologous genes of the unisequences in the GenBank non-redundant protein database. Of the 2,743 unisequences, 52.8% (the largest category) were highly homologous to plant genes; 16.3% to fungal genes and 30% of no-hit. The functional classification of all ESTs was established based on the database entry giving the best E-value using the Bevan's classification categories. About 50% of the ESTs were significantly homologous to genes encoding proteins with known functions; 20% were similar to genes encoding proteins with unknown functions and 30% did not have significant homology to any sequence in the database. The quantitative real-time PCR (qRT-PCR) analysis determined the transcription profiles and their involvement in the wheat-Pst interaction for seven of the gene. CONCLUSION: The cDNA library is useful for identifying the functional genes involved in the wheat-Pst compatible interaction, and established a new database for studying Pst pathogenesis genes and wheat defense genes. The transcription patterns of seven genes were confirmed by the qRT-PCR assay to be differentially expressed in wheat-Pst compatible and incompatible interaction.

Project description:Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is a costly global disease that burdens farmers with yield loss and high fungicide expenses. This sophisticated biotrophic parasite infiltrates wheat leaves and develops infection structures inside host cells, appropriating nutrients while suppressing the plant defense response. Development in most eukaryotes is regulated by small RNA molecules, and the success of host-induced gene silencing technology in Puccinia spp. implies the existence of a functional RNAi system. However, some fungi lack this capability, and small RNAs have not yet been reported in rust fungi. The objective of this study was to determine whether P. striiformis carries an endogenous small RNA repertoire.We extracted small RNA from rust-infected wheat flag leaves and performed high-throughput sequencing. Two wheat cultivars were analyzed: one is susceptible; the other displays partial high-temperature adult plant resistance. Fungal-specific reads were identified by mapping to the P. striiformis draft genome and removing reads present in uninfected control libraries. Sequencing and bioinformatics results were verified by RT-PCR. Like other RNAi-equipped fungi, P. striiformis produces large numbers of 20-22 nt sequences with a preference for uracil at the 5' position. Precise post-transcriptional processing and high accumulation of specific sRNA sequences were observed. Some predicted sRNA precursors possess a microRNA-like stem-loop secondary structure; others originate from much longer inverted repeats containing gene sequences. Finally, sRNA-target prediction algorithms were used to obtain a list of putative gene targets in both organisms. Predicted fungal target genes were enriched for kinases and small secreted proteins, while the list of wheat targets included homologs of known plant resistance genes.This work provides an inventory of small RNAs endogenous to an important plant pathogen, enabling further exploration of gene regulation on both sides of the host/parasite interaction. We conclude that small RNAs are likely to play a role in regulating the complex developmental processes involved in stripe rust pathogenicity.

Project description:BackgroundPuccinia striiformis f. sp. tritici is a fungal pathogen causing stripe rust, one of the most important wheat diseases worldwide. The fungus is strictly biotrophic and thus, completely dependent on living host cells for its reproduction, which makes it difficult to study genes of the pathogen. In spite of its economic importance, little is known about the molecular basis of compatible interaction between the pathogen and wheat host. In this study, we identified wheat and P. striiformis genes associated with the infection process by conducting a large-scale transcriptomic analysis using cDNA-AFLP.ResultsOf the total 54,912 transcript derived fragments (TDFs) obtained using cDNA-AFLP with 64 primer pairs, 2,306 (4.2%) displayed altered expression patterns after inoculation, of which 966 showed up-regulated and 1,340 down-regulated. 186 TDFs produced reliable sequences after sequencing of 208 TDFs selected, of which 74 (40%) had known functions through BLAST searching the GenBank database. Majority of the latter group had predicted gene products involved in energy (13%), signal transduction (5.4%), disease/defence (5.9%) and metabolism (5% of the sequenced TDFs). BLAST searching of the wheat stem rust fungus genome database identified 18 TDFs possibly from the stripe rust pathogen, of which 9 were validated of the pathogen origin using PCR-based assays followed by sequencing confirmation. Of the 186 reliable TDFs, 29 homologous to genes known to play a role in disease/defense, signal transduction or uncharacterized genes were further selected for validation of cDNA-AFLP expression patterns using qRT-PCR analyses. Results confirmed the altered expression patterns of 28 (96.5%) genes revealed by the cDNA-AFLP technique.ConclusionThe results show that cDNA-AFLP is a reliable technique for studying expression patterns of genes involved in the wheat-stripe rust interactions. Genes involved in compatible interactions between wheat and the stripe rust pathogen were identified and their expression patterns were determined. The present study should be helpful in elucidating the molecular basis of the infection process, and identifying genes that can be targeted for inhibiting the growth and reproduction of the pathogen. Moreover, this study can also be used to elucidate the defence responses of the genes that were of plant origin.

Dataset Information

TaMCA1, a regulator of cell death, is important for the interaction between wheat and Puccinia striiformis.

Publications

TaMCA1, a regulator of cell death, is important for the interaction between wheat and Puccinia striiformis.

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