More Like this

1. In Silico Identification of the Full Complement of Subtilase-Encoding Genes and Characterization of the Role of TaSBT1.7 in Resistance Against Stripe Rust in Wheat

   https://doi.org/10.1094/PHYTO-05-20-0176-R  

   Yang, Yuheng ; Zhang, Fengfeng ; Zhou, Tianyu ; Fang, Anfei ; Yu, Yang ; Bi, Chaowei ; Xiao, Shunyuan ( November 2020 , Phytopathology®)

   null (Ed.)

   Plant subtilases (SBTs) or subtilisin-like proteases comprise a very diverse family of serine peptidases that participates in a broad spectrum of biological functions. Despite increasing evidence for roles of SBTs in plant immunity in recent years, little is known about wheat (Triticum aestivum) SBTs (TaSBTs). Here, we identified 255 TaSBT genes from bread wheat using the latest version 2.0 of the reference genome sequence. The SBT family can be grouped into five clades, from TaSBT1 to TaSBT5, based on a phylogenetic tree constructed with deduced protein sequences. In silico protein-domain analysis revealed the existence of considerable sequence diversification of the TaSBT family which, together with the local clustered gene distribution, suggests that TaSBT genes have undergone extensive functional diversification. Among those TaSBT genes whose expression was altered by biotic factors, TaSBT1.7 was found to be induced in wheat leaves by chitin and flg22 elicitors, as well as six examined pathogens, implying a role for TaSBT1.7 in plant defense. Transient overexpression of TaSBT1.7 in Nicotiana benthamiana leaves resulted in necrotic cell death. Moreover, knocking down TaSBT1.7 in wheat using barley stripe mosaic virus-induced gene silencing compromised the hypersensitive response and resistance against Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe rust. Taken together, this study defined the full complement of wheat SBT genes and provided evidence for a positive role of one particular member, TaSBT1.7, in the incompatible interaction between wheat and a stripe rust pathogen. 

   more » « less
2. JMJ14 encoded H3K4 demethylase modulates immune responses by regulating defence gene expression and pipecolic acid levels

   https://doi.org/10.1111/nph.16270  

   Li, Dan ; Liu, Ruiying ; Singh, Deepjyoti ; Yuan, Xinyu ; Kachroo, Pradeep ; Raina, Ramesh ( November 2019 , New Phytologist)

   Epigenetic modifications have emerged as an important mechanism underlying plant defence against pathogens. We examined the role of JMJ14, a Jumonji (JMJ) domain‐containing H3K4 demethylase,in local and systemic plant immune responses in Arabidopsis.

   The function of JMJ14 in local or systemic defence response was investigated by pathogen growth assays and by analysing expression and H3K4me3 enrichments of key defence genes using qPCR and ChIP‐qPCR. Salicylic acid (SA) and pipecolic acid (Pip) levels were quantified and function of JMJ14 in SA‐ and Pip‐mediated defences was analysed in Col‐0 andjmj14plants.

   jmj14mutants were compromised in both local and systemic defences. JMJ14 positively regulates pathogen‐induced H3K4me3 enrichment and expression of defence genes involved in SA‐ and Pip‐mediated defence pathways. Consequently, loss of JMJ14 results in attenuated defence gene expression and reduced Pip accumulation during establishment of systemic acquired resistance (SAR). Exogenous Pip partially restored SAR injmj14plants, suggesting that JMJ14 regulated Pip biosynthesis and other downstream factors regulate SAR injmj14plants.

   JMJ14 positively modulates defence gene expressions and Pip levels in Arabidopsis.

    

   more » « less
3. Stem rust resistance in wheat is suppressed by a subunit of the mediator complex

   https://doi.org/10.1038/s41467-020-14937-2  

   Hiebert, Colin W. ; Moscou, Matthew J. ; Hewitt, Tim ; Steuernagel, Burkhard ; Hernández-Pinzón, Inma ; Green, Phon ; Pujol, Vincent ; Zhang, Peng ; Rouse, Matthew N. ; Jin, Yue ; et al ( February 2020 , Nature Communications)

   Stem rust is an important disease of wheat that can be controlled using resistance genes. The geneSuSr-D1identified in cultivar ‘Canthatch’ suppresses stem rust resistance.SuSr-D1mutants are resistant to several races of stem rust that are virulent on wild-type plants. Here we identifySuSr-D1by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of stem rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation inmed15b.Dmutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to stem rust. Suppression is a common phenomenon and this study provides novel insight into suppression of rust resistance in wheat.

    

   more » « less
4. TaADF4 , an actin‐depolymerizing factor from wheat, is required for resistance to the stripe rust pathogen Puccinia striiformis f. sp. tritici

   https://doi.org/10.1111/tpj.13459  

   Zhang, Bing ; Hua, Yuan ; Wang, Juan ; Huo, Yan ; Shimono, Masaki ; Day, Brad ; Ma, Qing ( February 2017 , The Plant Journal)

   Actin filament assembly in plants is a dynamic process, requiring the activity of more than 75 actin‐binding proteins. Central to the regulation of filament assembly and stability is the activity of a conserved family of actin‐depolymerizing factors (ADFs), whose primarily function is to regulate the severing and depolymerization of actin filaments. In recent years, the activity ofADFproteins has been linked to a variety of cellular processes, including those associated with response to stress. Herein, a wheatADFgene,TaADF4,was identified and characterized.TaADF4encodes a 139‐amino‐acid protein containing five F‐actin‐binding sites and two G‐actin‐binding sites, and interacts with wheat (Triticum aestivum) Actin1 (TaACT1),in planta. Following treatment of wheat, separately, with jasmonic acid, abscisic acid or with the avirulent race,CYR23, of the stripe rust pathogenPuccinia striiformisf. sp.tritici, we observed a rapid induction in accumulation ofTaADF4mRNA. Interestingly, accumulation ofTaADF4mRNAwas diminished in response to inoculation with a virulent race,CYR31. Silencing ofTaADF4resulted in enhanced susceptibility toCYR23, demonstrating a role forTaADF4in defense signaling. Using a pharmacological‐based approach, coupled with an analysis of host response to pathogen infection, we observed that treatment of plants with the actin‐modifying agent latrunculin B enhanced resistance toCYR23, including increased production of reactive oxygen species and enhancement of localized hypersensitive cell death. Taken together, these data support the hypothesis thatTaADF4 positively modulates plant immunity in wheat via the modulation of actin cytoskeletal organization.

    

   more » « less
5. Geographic variation in the genetic basis of resistance to leaf rust between locally adapted ecotypes of the biofuel crop switchgrass ( Panicum virgatum )

   https://doi.org/10.1111/nph.16555  

   VanWallendael, Acer ; Bonnette, Jason ; Juenger, Thomas E. ; Fritschi, Felix B. ; Fay, Philip A. ; Mitchell, Robert B. ; Lloyd‐Reilley, John ; Rouquette, Jr, Francis M. ; Bergstrom, Gary C. ; Lowry, David B. ( April 2020 , New Phytologist)

   Local adaptation is an important process in plant evolution, which can be impacted by differential pathogen pressures along environmental gradients. However, the degree to which pathogen resistance loci vary in effect across space and time is incompletely described.

   To understand how the genetic architecture of resistance varies across time and geographic space, we quantified rust (Pucciniaspp.) severity in switchgrass (Panicum virgatum) plantings at eight locations across the central USA for 3 yr and conducted quantitative trait locus (QTL) mapping for rust progression.

   We mapped several variable QTLs, but two large‐effect QTLs which we have namedPrr1andPrr2were consistently associated with rust severity in multiple sites and years, particularly in northern sites. By contrast, there were numerous small‐effect QTLs at southern sites, indicating a genotype‐by‐environment interaction in rust resistance loci. Interestingly,Prr1andPrr2had a strong epistatic interaction, which also varied in the strength and direction of effect across space.

   Our results suggest that abiotic factors covarying with latitude interact with the genetic loci underlying plant resistance to control rust infection severity. Furthermore, our results indicate that segregating genetic variation in epistatically interacting loci may play a key role in determining response to infection across geographic space.

    

   more » « less