Expression data in wheat (T. aestivum L.) near isogenic lines in response to powdery mildew infection
ABSTRACT: We used two wheat genotypes, the susceptible wheat cultivar ‘8866 ’(S) and its near isogenic line with single powdery mildew resistance gene ‘pm30’ (R), to investigate gene expression changes in response to powdery mildew infection by using Wheat Genome Array Overall design: wheat young leveas of near isogenic lines before or 12 hours after powdery mildew infection were selected for RNA extraction and hybridization on Affymetrix microarrays.The leaf samples were harvested from three independent biological replicates, and the leaves without inoculation were regarded as control.
Project description:We used two wheat genotypes, the susceptible wheat cultivar ‘8866 ’(S) and its near isogenic line with single powdery mildew resistance gene ‘pm30’ (R), to investigate gene expression changes in response to powdery mildew infection by using Wheat Genome Array wheat young leveas of near isogenic lines before or 12 hours after powdery mildew infection were selected for RNA extraction and hybridization on Affymetrix microarrays.The leaf samples were harvested from three independent biological replicates, and the leaves without inoculation were regarded as control.
Project description:Previous work has demonstrated that glycerol-3-phosphate (G3P) and oleic acid (18:1) are two important signal molecules associated with plant resistance to fungi. In this article, we provide evidence that a 3% glycerol spray application 1-2 days before powdery mildew infection and subsequent applications once every 4 days was sufficient to stimulate the plant defense responses without causing any significant damage to wheat leaves. We found that G3P and oleic acid levels were markedly induced by powdery mildew infection. In addition, TaGLI1 (encoding a glycerol kinase) and TaSSI2 (encoding a stearoylacyl carrier protein fatty acid desaturase), two genes associated with the glycerol and fatty acid (FA) pathways, respectively, were induced by powdery mildew infection, and their promoter regions contain some fungal response elements. Moreover, exogenous application of glycerol increased the G3P level and decreased the level of oleic acid (18:1). Glycerol application induced the expression of pathogenesis-related (PR) genes (TaPR-1, TaPR-2, TaPR-3, TaPR-4, and TaPR-5), induced the generation of reactive oxygen species (ROS) before powdery mildew infection, and induced salicylic acid (SA) accumulation in wheat leaves. Further, we sprayed glycerol in a wheat field and found that it significantly (p < 0.05) reduced the severity of powdery mildew disease and lessened disease-associated kernel weight loss, all without causing any noticeable degradation in wheat seed quality.
Project description:The present work focused on the characterization of some physiological mechanisms activated upon powdery mildew inoculation of the susceptible barley cultivar Ingrid and its near-isogenic lines (NILs) carrying various resistant genes (Mla, Mlg and mlo). After inoculation with Blumeria graminis f. sp. hordei (Bgh), measurements of leaf reflectance and chlorophyll a fluorescence were performed 3 and 7 day post-inoculation (dpi), while hormone assays were made 7 dpi. Bgh-inoculated resistant genotypes were characterized by lowered leaf reflectance parameters that correlated with carotenoids (CRI) and water content (WBI) in comparison to inoculated Ingrid. The PSII activity (i.e., Fv/Fm, ETo/CSm and P.I.ABS) strongly decreased in susceptible Ingrid leaves when the disease symptoms became visible 7 dpi. In Mla plants with visible hypersensitive spots the PSII activity decreased to a lesser extent. Inoculation resulted in a very slight decrease of photosynthesis at later stage of infection in Mlg plants, whereas in resistant mlo plants the PSII activity did not change. Chlorophyll a fluorescence measurements allowed presymptomatic detection of infection in Ingrid and Mla. Changes in the homeostasis of 22 phytohormones (cytokinins, auxins, gibberellins and the stress hormones JA, SA and ABA) in powdery mildew inoculated barley are discussed in relation to resistance against this biotrophic pathogen.
Project description:At present, most of released wheat cultivars or breeding lines in China are susceptible to powdery mildew (Pm) (caused by Blumeria graminis f. sp. tritici, Bgt), so there is an urgent need to rapidly transfer effective and broad-spectrum Pm resistance genes into elite cultivars/lines. Near-isogenic lines (NILs) with short target gene region are very important in molecular breeding and map-based cloning and can be developed by combining marker-assisted selection and conventional phenotypic identification. However, no Pm gene NILs were reported by using this method in the previous studies. A new broad-spectrum dominant resistance gene Pm2b, derived from the Chinese wheat breeding line KM2939, conferred high resistance to Pm at both the seedling and adult stages. In this study, with the aid of forward and background selection (FS and BS) using molecular markers, the Pm2b gene was introgressed into three elite susceptible commercial cultivars Shimai 15, Shixin 828, and Kenong 199 through the back-crossing procedure. With the appropriate backcrossing generations, selected population sizes and marker number for BS, the homozygous resistant BC3F2:3 NILs of Pm2b gene in the three genetic backgrounds with the highest recipient genome composition of about 99%, confirmed by simple sequence repeat markers and 660K single nucleotide polymorphic array, were developed and evaluated for the powdery mildew resistance and agronomic traits. The different resistance and similar or improved agronomic performance between Pm2b NILs and their corresponding recurrent parents indicated their potential value in the marker-assisted breeding of the Pm2b gene. Moreover, the development of four flanked diagnostic markers (CFD81, BWM25, BWM20, and BWM21) of the Pm2 gene can effectively assist the forward selection and accelerate the transfer and use of this resistance gene.
Project description:BACKGROUND: MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition. MiRNAs can have large-scale regulatory effects on development and stress response in plants. RESULTS: To test whether miRNAs play roles in regulating response to powdery mildew infection and heat stress in wheat, by using Solexa high-throughput sequencing we cloned the small RNA from wheat leaves infected by preponderant physiological strain Erysiphe graminis f. sp. tritici (Egt) or by heat stress treatment. A total of 153 miRNAs were identified, which belong to 51 known and 81 novel miRNA families. We found that 24 and 12 miRNAs were responsive to powdery mildew infection and heat stress, respectively. We further predicted that 149 target genes were potentially regulated by the novel wheat miRNA. CONCLUSIONS: Our results indicated that diverse set of wheat miRNAs were responsive to powdery mildew infection and heat stress and could function in wheat responses to both biotic and abiotic stresses.
Project description:Powdery mildew resistance gene Pm21, located on the chromosome 6V short arm of Haynaldia villosa and transferred to wheat as a 6VS·6AL translocation (T6VS·6AL), confers durable and broad-spectrum resistance to wheat powdery mildew. Pm21 has become a key gene resource for powdery mildew resistance breeding all over the world. In China, 12 wheat varieties containing Pm21 have been planted on more than 3.4 million hectares since 2002. Pm21 has been intractable to molecular genetic mapping because the 6VS does not pair and recombine with the 6AS. Moreover, all known accessions of H. villosa are immune to powdery mildew fungus. Pm21 is still defined by cytogenetics as a locus. In the present study, a putative serine and threonine protein kinase gene Stpk-V was cloned and characterized with an integrative strategy of molecular and cytogenetic techniques. Stpk-V is located on the Pm21 locus. The results of a single cell transient expression assay showed that Stpk-V could decrease the haustorium index dramatically. After the Stpk-V was transformed into a susceptible wheat variety Yangmai158, the characterized transgenic plants showed high and broad-spectrum powdery mildew resistance similar to T6VS·6AL. Silencing of the Stpk-V by virus-induced gene silencing in both T6VS·6AL and H. villosa resulted in their increased susceptibility. Stpk-V could be induced by Bgt and exogenous H(2)O(2), but it also mediated the increase of endogenous H(2)O(2), leading to cell death and plant resistance when the plant was attacked by Bgt.
Project description:In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici) and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM) mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew) became more favourable for another pest (aphids).
Project description:Since many fungal pathogens develop resistance to fungicides, novel and low-cost alternative methods to improve plant health and fitness need to be developed. An approach to improve productivity in crops is to stimulate the plant's own defence mechanisms via priming. Therefore, we investigated if a fermentation-based elicitor could prime plant defences against powdery mildew in wheat by inducing the expression of endogenous defence-related genes. Wheat seedlings were spray-treated with a fermentation-based elicitor 8 days prior to inoculation with powdery mildew. Disease assays showed a significantly reduced number of powdery mildew pustules were formed on wheat treated with the mixed elicitor. In vitro sensitivity assays tested the ability of powdery mildew conidia to germinate on agar amended with the fermentation-based product and concluded that fungal germination and differentiation were also inhibited. Tissue samples were taken at time points pertaining to different developmental stages of powdery mildew infection. Significantly higher expression of PR genes (PR1, PR4, PR5, and PR9) was observed in the microbial fermentation mixture-treated plants compared with untreated plants. These genes are often associated with the elicitation of plant defence responses to specific biotrophic pathogens, such as powdery mildew, suggesting an elicitor-mediated response in the wheat plants tested. The product components were assessed, and the components were found to act synergistically in the microbial fermentation mixture. Therefore, this fermentation-based elicitor provides an effective method for powdery mildew control.
Project description:Powdery mildew, caused by the biotrophic fungal pathogen Blumeria graminis f. sp. tritici, is a major limitation for wheat yield. However, the molecular mechanisms underlying wheat resistance against powdery mildew remain largely unclear. In this study, we report the role of JASMONATE-ZIM domain protein TaJAZ1 in regulating bread wheat resistance against powdery mildew. We generated transgenic bread wheat lines over-expressing the truncated TaJAZ1 without the Jas motif, which showed increased TaPR1/2 gene expression and reactive oxygen species accumulation, leading to enhanced resistance against powdery mildew. Simultaneously, we identified a Jasmonic acid (JA)-induced bHLH transcription factor TaMYC4 in bread wheat. We demonstrated that TaJAZ1 directly interacts with TaMYC4 to repress its transcriptional activity. Meanwhile, we show that the ZIM domain of TaJAZ1 interacts with the C terminus of TaNINJA, whereas the N-terminal EAR motif of TaNINJA interacts with the transcriptional co-repressor TaTPL. Collectively, our work pinpoints TaJAZ1 as a favorable gene to enhance bread wheat resistance toward powdery mildew, and provides a molecular framework for JA signaling in bread wheat.
Project description:To test whether non-coding RNAs play roles in regulating response to powdery mildew infection and heat stress in wheat, by using Solexa high-throughput sequencing and computational analysis and experimental approach we cloned the small RNAs and identified 125 putative long npcRNAs from wheat leaves infected by preponderant physiological strain Erysiphe graminis f. sp. tritici (Egt) or by heat stress treatment. Among long non-coding RNAs, some were precursors of small RNAs such as microRNAs and siRNAs, two long npcRNAs were identified as signal recognition particle (SRP) 7S RNA variants, and three were characterized as U3 snoRNAs. Wheat long npcRNAs showed tissue dependent expression patterns and were responsive to powdery mildew infection and heat stress. Overall design: Examination non-coding RNAs of 2 near isogenic lines 8866 (Susceptible) and Pm30 (Resistant) in response to powdery milew and two genotypes CK (insensitive) and TAM107 (insensitive) to heat. CK and TAM107 represent the same material in different treatments (no heat stress or 1hour after heat stress).