A sorghum MYB transcription factor induces 3-deoxyanthocyanidins and enhances resistance against leaf blights in maize

The regulatory pathway of transcription factor MYB36 from Trichoderma asperellum Tas653 resistant to poplar leaf blight pathogen Alternaria alternata Aal004

In fungi, MYB transcription factors (TFs) mainly regulate growth, development, and resistance to stress. However, as major disease-resistance TFs, they have rarely been studied in biocontrol fungi. In this study, MYB36 of Trichoderma asperellum Tas653 (Ta) was shown to respond strongly to the stress caused by Alternaria alternata Aa1004. Compared with wild-type Ta (Ta-Wt), the inhibition rate of the MYB36 knockout strain (Ta-Kn) on Aa1004 decreased by 11.06%; the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities decreased by 82.15 U/g, 0.19 OD470/min/g, and 1631.2 μmol/min/g, respectively. The MYB36 overexpression strain (Ta-Oe) not only enhanced hyperparasitism on Aa1004, caused its hyphae to swell, deform, or even rupture, but also reduced the incidence rate of poplar leaf blight. MYB36 regulates downstream (TFs, detoxification genes, defense genes, and other antifungal-related genes by binding to the cis-acting elements "ACAT" and "ATCG". Zinc finger TFs, as the main antifungal TFs, account for 90% of the total TFs, and Zn37.5 (23.24-) and Zn83.7 (23.18-fold) showed the greatest expression difference when regulated directly by MYB36. The detoxification genes mainly comprised 11 major major facilitator superfamily (MFS) genes, among which MYB36 directly increased the expression levels of three genes by more than 2-3.44-fold. The defense genes mainly encoded cytochrome P450 (P450) and hydrolases. e.g., P45061.3 (2-10.95-), P45060.2 (2-7.07-), and Hyd44.6 (2-2.30-fold). This study revealed the molecular mechanism of MYB36 regulation of the resistance of T. asperellum to A. alternata and provides theoretical guidance for the biocontrol of poplar leaf blight and the anti-disease mechanism of biocontrol fungi.

Maize hydroxycinnamic acids: unveiling their role in stress resilience and human health

Maize production is pivotal in ensuring food security, particularly in developing countries. However, the crop encounters multiple challenges stemming from climatic changes that adversely affect its yield, including biotic and abiotic stresses during production and storage. A promising strategy for enhancing maize resilience to these challenges involves modulating its hydroxycinnamic acid amides (HCAAs) content. HCAAs are secondary metabolites present in plants that are essential in developmental processes, substantially contributing to defense mechanisms against environmental stressors, pests, and pathogens, and exhibiting beneficial effects on human health. This mini-review aims to provide a comprehensive overview of HCAAs in maize, including their biosynthesis, functions, distribution, and health potential applications.

Quantitative trait locus (QTL) analysis and fine-mapping for Fusarium oxysporum disease resistance in Raphanus sativus using GRAS-Di technology

Fusarium wilt is a significant disease in radish, but the genetic mechanisms controlling yellows resistance (YR) are not well understood. This study aimed to identify YR-QTLs and to fine-map one of them using F2:3 populations developed from resistant and susceptible radish parents. In this study, two high-density genetic maps each containing shared co-dominant markers and either female or male dominant markers that spanned 988.6 and 1127.5 cM with average marker densities of 1.40 and 1.53 cM, respectively, were generated using Genotyping by Random Amplicon Sequencing-Direct (GRAS-Di) technology. We identified two YR-QTLs on chromosome R2 and R7, and designated the latter as ForRs1 as the major QTL. Fine mapping narrowed down the ForRs1 locus to a 195 kb region. Among the 16 predicted genes in the delimited region, 4 genes including two receptor-like protein and -kinase genes (RLP/RLK) were identified as prime candidates for ForRs1 based on the nucleotide sequence comparisons between the parents and their predicted functions. This study is the first to use a GRAS-Di for genetic map construction of cruciferous crops and fine map the YR-QTL on the R7 chromosome of radish. These findings will provide groundbreaking insights into radish YR breeding and understanding the genetics of YR mechanism.

Transcriptomic response of Pinus massoniana to infection stress from the pine wood nematode Bursaphelenchus xylophilus

The pinewood nematode (PWN) Bursaphelenchus xylophilus is a forestry quarantine pest and causes an extremely dangerous forest disease that is spreading worldwide. Due to the complex pathogenic factors of pine wood nematode disease, the pathogenesis is still unknown. B. xylophilus ultimately invades a host and causes death. However, little is known about the defence-regulating process of host pine after infection by B. xylophilus at the molecular level. Therefore, we wanted to understand how Pinus massoniana regulates its response to invasion by B. xylophilus. P. massoniana were artificially inoculated with B. xylophilus solution, while those without B. xylophilus solution were used as controls. P. massoniana inoculated with B. xylophilus solution for 0 h, 6 h, 24 h, and 120 h was subjected to high-throughput sequencing to obtain transcriptome data. At various time points (0 h, 6 h, 24 h, 120 h), gene transcription was measured in P. massoniana inoculated with PWN. At different time points, P. massoniana gene transcription differed significantly, with a response to early invasion by PWN. According to Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, P. massoniana response to PWN invasion involves a wide range of genes, including plant hormone signal transformation, flavonoid biosynthesis, amino sugar and nucleoside sugar metabolism, and MAPK signalling pathways. Among them, inoculation for 120 hours had the greatest impact on differential genes. Subsequently, weighted gene coexpression network analysis (WGCNA) was used to analyse transcriptional regulation of P. massoniana after PWN infection. The results showed that the core gene module of P. massoniana responding to PWN was "MEmagenta", enriched in oxidative phosphorylation, amino sugar and nucleotide sugar metabolism, and the MAPK signalling pathway. MYB family transcription factors with the highest number of changes between infected and healthy pine trees accounted for 20.4% of the total differentially expressed transcription factors. To conclude, this study contributes to our understanding of the molecular mechanism of initial PWN infection of P. massoniana. Moreover, it provides some important background information on PWN pathogenic mechanisms.

Identification of the MYB gene family in Sorghum bicolor and functional analysis of SbMYBAS1 in response to salt stress

Salt stress adversely affects plant growth and development. It is necessary to understand the underlying salt response mechanism to improve salt tolerance in plants. MYB transcription factors can regulate plant responses to salt stress. However, only a few studies have explored the role of MYB TFs in Sorghum bicolor (L.) Moench. So we decided to make a systematic analysis and research on the sorghum MYB family. A total of 210 MYB genes in sorghum were identified in this study. Furthermore, 210 MYB genes were distributed across ten chromosomes, named SbMYB1-SbMYB210. To study the phylogeny of the identified TFs, 210 MYB genes were divided into six subfamilies. We further demonstrated that SbMYB genes have evolved under strong purifying selection. SbMYBAS1 (SbMYB119) was chosen as the study object, which the expression decreased under salt stress conditions. Further study of the SbMYBAS1 showed that SbMYBAS1 is located in the nucleus. Under salt stress conditions, Arabidopsis plants overexpressed SbMYBAS1 showed significantly lower dry/fresh weight and chlorophyll content but significantly higher membrane permeability, MDA content, and Na+/K+ ratio than the wild-type Arabidopsis plants. Yeast two-hybrid screening result showed that SbMYBAS1 might interact with proteins encoded by SORBI_302G184600, SORBI_3009G247900 and SORBI_3004G59600. Results also showed that SbMYBAS1 could regulate the expression of AtGSTU17, AtGSTU16, AtP5CS2, AtUGT88A1, AtUGT85A2, AtOPR2 and AtPCR2 under salt stress conditions. This work laid a foundation for the study of the response mechanism of sorghum MYB gene family to salt stress.

Advances in understanding the mechanism of resistance to anthracnose and induced defence response in tea plants

The tea plant (Camellia sinensis) is susceptible to anthracnose disease that causes considerable crop loss and affects the yield and quality of tea. Multiple Colletotrichum spp. are the causative agents of this disease, which spreads quickly in warm and humid climates. During plant-pathogen interactions, resistant cultivars defend themselves against the hemibiotrophic pathogen by activating defence signalling pathways, whereas the pathogen suppresses plant defences in susceptible varieties. Various fungicides have been used to control this disease on susceptible plants, but these fungicide residues are dangerous to human health and cause fungicide resistance in pathogens. The problem-solving approaches to date are the development of resistant cultivars and ecofriendly biocontrol strategies to achieve sustainable tea cultivation and production. Understanding the infection stages of Colletotrichum, tea plant resistance mechanisms, and induced plant defence against Colletotrichum is essential to support sustainable disease management practices in the field. This review therefore summarizes the current knowledge of the identified causative agent of tea plant anthracnose, the infection strategies and pathogenicity of C. gloeosporioides, anthracnose disease resistance mechanisms, and the caffeine-induced defence response against Colletotrichum infection. The information reported in this review will advance our understanding of host-pathogen interactions and eventually help us to develop new disease control strategies.

Regulation of the regulators: Transcription factors controlling biosynthesis of plant secondary metabolites during biotic stresses and their regulation by miRNAs

Biotic stresses threaten to destabilize global food security and cause major losses to crop yield worldwide. In response to pest and pathogen attacks, plants trigger many adaptive cellular, morphological, physiological, and metabolic changes. One of the crucial stress-induced adaptive responses is the synthesis and accumulation of plant secondary metabolites (PSMs). PSMs mitigate the adverse effects of stress by maintaining the normal physiological and metabolic functioning of the plants, thereby providing stress tolerance. This differential production of PSMs is tightly orchestrated by master regulatory elements, Transcription factors (TFs) express differentially or undergo transcriptional and translational modifications during stress conditions and influence the production of PSMs. Amongst others, microRNAs, a class of small, non-coding RNA molecules that regulate gene expression post-transcriptionally, also play a vital role in controlling the expression of many such TFs. The present review summarizes the role of stress-inducible TFs in synthesizing and accumulating secondary metabolites and also highlights how miRNAs fine-tune the differential expression of various stress-responsive transcription factors during biotic stress.

Evolution and function of red pigmentation in land plants

BACKGROUND

Land plants commonly produce red pigmentation as a response to environmental stressors, both abiotic and biotic. The type of pigment produced varies among different land plant lineages. In the majority of species they are flavonoids, a large branch of the phenylpropanoid pathway. Flavonoids that can confer red colours include 3-hydroxyanthocyanins, 3-deoxyanthocyanins, sphagnorubins and auronidins, which are the predominant red pigments in flowering plants, ferns, mosses and liverworts, respectively. However, some flowering plants have lost the capacity for anthocyanin biosynthesis and produce nitrogen-containing betalain pigments instead. Some terrestrial algal species also produce red pigmentation as an abiotic stress response, and these include both carotenoid and phenolic pigments.

SCOPE

In this review, we examine: which environmental triggers induce red pigmentation in non-reproductive tissues; theories on the functions of stress-induced pigmentation; the evolution of the biosynthetic pathways; and structure-function aspects of different pigment types. We also compare data on stress-induced pigmentation in land plants with those for terrestrial algae, and discuss possible explanations for the lack of red pigmentation in the hornwort lineage of land plants.

CONCLUSIONS

The evidence suggests that pigment biosynthetic pathways have evolved numerous times in land plants to provide compounds that have red colour to screen damaging photosynthetically active radiation but that also have secondary functions that provide specific benefits to the particular land plant lineage.

Linkage QTL Mapping and Genome-Wide Association Study on Resistance in Chickpea to Pythium ultimum

The soilborne oomycete plant pathogen Pythium ultimum causes seed rot and pre-emergence damping-off of chickpea (Cicer arietinum L.). The pathogen has been controlled for several decades using the fungicide metalaxyl as seed treatment but has re-emerged as a severe problem with the detection of metalaxyl-resistant isolates of the pathogen from infested fields in the United States Pacific Northwest. The objective of this study was to identify genetic markers and candidate genes associated with resistance to P. ultimum in an interspecific recombinant inbred line population (CRIL-7) derived from a cross between C. reticulatum (PI 599072) x C. arietinum (FLIP 84-92C) and conduct genome-wide association studies (GWAS) for disease resistance using a chickpea diversity panel consisting of 184 accessions. CRIL-7 was examined using 1029 SNP markers spanning eight linkage groups. A major QTL, “qpsd4-1,” was detected on LG 4 that explained 41.8% of phenotypic variance, and a minor QTL, “qpsd8-1,” was detected on LG8 that explained 4.5% of phenotypic variance. Seven candidate genes were also detected using composite interval mapping including several genes previously associated with disease resistance in other crop species. A total of 302,902 single nucleotide polymorphic (SNP) markers were used to determine population structure and kinship of the diversity panel. Marker–trait associations were established by employing different combinations of principal components (PC) and kinships (K) in the FarmCPU model. Genome-wide association studies detected 11 significant SNPs and seven candidate genes associated with disease resistance. SNP Ca4_1765418, detected by GWAS on chromosome 4, was located within QTL qpsd4-1 that was revealed in the interspecific CRIL-7 population. The present study provides tools to enable MAS for resistance to P. ultimum and identified genomic domains and candidate genes involved in the resistance of chickpea to soilborne diseases.

Genome-wide characterization of the sorghum JAZ gene family and their responses to phytohormone treatments and aphid infestation

Jasmonate ZIM-domain (JAZ) proteins are the key repressors of the jasmonic acid (JA) signal transduction pathway and play a crucial role in stress-related defense, phytohormone crosstalk and modulation of the growth-defense tradeoff. In this study, the sorghum genome was analyzed through genome-wide comparison and domain scan analysis, which led to the identification of 18 sorghum JAZ (SbJAZ) genes. All SbJAZ proteins possess the conserved TIFY and Jas domains and they formed a phylogenetic tree with five clusters related to the orthologs of other plant species. Similarly, evolutionary analysis indicated the duplication events as a major force of expansion of the SbJAZ genes and there was strong neutral and purifying selection going on. In silico analysis of the promoter region of the SbJAZ genes indicates that SbJAZ5, SbJAZ6, SbJAZ13, SbJAZ16 and SbJAZ17 are rich in stress-related cis-elements. In addition, expression profiling of the SbJAZ genes in response to phytohormones treatment (JA, ET, ABA, GA) and sugarcane aphid (SCA) was performed in two recombinant inbred lines (RILs) of sorghum, resistant (RIL 521) and susceptible (RIL 609) to SCA. Taken together, data generated from phytohormone expression and in silico analysis suggests the putative role of SbJAZ9 in JA-ABA crosstalk and SbJAZ16 in JA-ABA and JA-GA crosstalk to regulate certain physiological processes. Notably, upregulation of SbJAZ1, SbJAZ5, SbJAZ13 and SbJAZ16 in resistant RIL during JA treatment and SCA infestation suggests putative functions in stress-related defense and to balance the plant defense to promote growth. Overall, this report provides valuable insight into the organization and functional characterization of the sorghum JAZ gene family.

Identification of QTLs Controlling Resistance to Anthracnose Disease in Water Yam (Dioscorea alata)

Anthracnose disease caused by a fungus Colletotrichum gloeosporioides is the primary cause of yield loss in water yam (Dioscorea alata), the widely cultivated species of yam. Resistance to yam anthracnose disease (YAD) is a prime target in breeding initiatives to develop durable-resistant cultivars for sustainable management of the disease in water yam cultivation. This study aimed at tagging quantitative trait loci (QTL) for anthracnose disease resistance in a bi-parental mapping population of D. alata. Parent genotypes and their recombinant progenies were genotyped using the Genotyping by Sequencing (GBS) platform and phenotyped in two crop cycles for two years. A high-density genetic linkage map was built with 3184 polymorphic Single Nucleotide Polymorphism (NSP) markers well distributed across the genome, covering 1460.94 cM total length. On average, 163 SNP markers were mapped per chromosome with 0.58 genetic distances between SNPs. Four QTL regions related to yam anthracnose disease resistance were identified on three chromosomes. The proportion of phenotypic variance explained by these QTLs ranged from 29.54 to 39.40%. The QTL regions identified showed genes that code for known plant defense responses such as GDSL-like Lipase/Acylhydrolase, Protein kinase domain, and F-box protein. The results from the present study provide valuable insight into the genetic architecture of anthracnose resistance in water yam. The candidate markers identified herewith form a relevant resource to apply marker-assisted selection as an alternative to a conventional labor-intensive screening for anthracnose resistance in water yam.

Dynamic Transcriptome Profiling of Mungbean Genotypes Unveil the Genes Respond to the Infection of Mungbean Yellow Mosaic Virus

Yellow mosaic disease (YMD), incited by mungbean yellow mosaic virus (MYMV), is a primary viral disease that reduces mungbean production in South Asia, especially in India. There is no detailed knowledge regarding the genes and molecular mechanisms conferring resistance of mungbean to MYMV. Therefore, disclosing the genetic and molecular bases related to MYMV resistance helps to develop the mungbean genotypes with MYMV resistance. In this study, transcriptomes of mungbean genotypes, VGGRU-1 (resistant) and VRM (Gg) 1 (susceptible) infected with MYMV were compared to those of uninfected controls. The number of differentially expressed genes (DEGs) in the resistant and susceptible genotypes was 896 and 506, respectively. Among them, 275 DEGs were common between the resistant and susceptible genotypes. Functional annotation of DEGs revealed that the DEGs belonged to the following categories defense and pathogenesis, receptor-like kinases; serine/threonine protein kinases, hormone signaling, transcription factors, and chaperons, and secondary metabolites. Further, we have confirmed the expression pattern of several DEGs by quantitative real-time PCR (qRT-PCR) analysis. Collectively, the information obtained in this study unveils the new insights into characterizing the MYMV resistance and paved the way for breeding MYMV resistant mungbean in the future.

Cyclocarya paliurus Reprograms the Flavonoid Biosynthesis Pathway Against Colletotrichum fructicola

Cyclocarya paliurus is an endemic Chinese tree species with considerable medicinal, timber, and horticultural value. The anthracnose disease of C. paliurus is caused by the fungal pathogen Colletotrichum fructicola, which results in great losses in yield and quality. Here, resistance evaluation of six cultivars of C. paliurus exhibited varying degrees of resistance to C. fructicola infection, where Wufeng was the most resistant and Jinggangshan was the most susceptive. Physiological measurements and histochemical staining assays showed that the Wufeng cultivar exhibits intense reactive oxygen species accumulation and defense capabilities. A multiomics approach using RNA sequencing and metabolome analyses showed that resistance in C. paliurus (Wufeng) is related to early induction of reprogramming of the flavonoid biosynthesis pathway. In vitro antifungal assays revealed that the flavonoid extracts from resistant cultivars strongly inhibited C. fructicola hyphal growth than susceptible cultivars. Relative gene expression analysis further demonstrated the pivotal antifungal role of C. paliurus flavonoids in targeting Colletotrichum appressorium formation. Together, these results represent a novel resistance mechanism of C. paliurus against anthracnose through the reprogramming of flavonoids, which will lay a foundation for breeding anthracnose-resistant varieties and the application of flavonoid extraction of C. paliurus as a natural antifungal treatment.

The Flavonoid Biosynthesis Network in Plants

Flavonoids are an important class of secondary metabolites widely found in plants, contributing to plant growth and development and having prominent applications in food and medicine. The biosynthesis of flavonoids has long been the focus of intense research in plant biology. Flavonoids are derived from the phenylpropanoid metabolic pathway, and have a basic structure that comprises a C15 benzene ring structure of C6-C3-C6. Over recent decades, a considerable number of studies have been directed at elucidating the mechanisms involved in flavonoid biosynthesis in plants. In this review, we systematically summarize the flavonoid biosynthetic pathway. We further assemble an exhaustive map of flavonoid biosynthesis in plants comprising eight branches (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, proanthocyanidin, and anthocyanin biosynthesis) and four important intermediate metabolites (chalcone, flavanone, dihydroflavonol, and leucoanthocyanidin). This review affords a comprehensive overview of the current knowledge regarding flavonoid biosynthesis, and provides the theoretical basis for further elucidating the pathways involved in the biosynthesis of flavonoids, which will aid in better understanding their functions and potential uses.

Anthocyanins: From Mechanisms of Regulation in Plants to Health Benefits in Foods

Anthocyanins represent the major red, purple, and blue pigments in many flowers, fruits, vegetables, and cereals. They are also recognized as important health-promoting components in the human diet with protective effects against many chronic diseases, including cardiovascular diseases, obesity, and cancer. Anthocyanin biosynthesis has been studied extensively, and both biosynthetic and key regulatory genes have been isolated in many plant species. Here, we will provide an overview of recent progress in understanding the anthocyanin biosynthetic pathway in plants, focusing on the transcription factors controlling activation or repression of anthocyanin accumulation in cereals and fruits of different plant species, with special emphasis on the differences in molecular mechanisms between monocot and dicot plants. Recently, new insight into the transcriptional regulation of the anthocyanin biosynthesis, including positive and negative feedback control as well as epigenetic and post-translational regulation of MYB-bHLH-WD40 complexes, has been gained. We will consider how knowledge of regulatory mechanisms has helped to produce anthocyanin-enriched foods through conventional breeding and metabolic engineering. Additionally, we will briefly discuss the biological activities of anthocyanins as components of the human diet and recent findings demonstrating the important health benefits of anthocyanin-rich foods against chronic diseases.

The Sorghum Grain Mold Disease Complex: Pathogens, Host Responses, and the Bioactive Metabolites at Play

Grain mold is a major concern in sorghum [Sorghum bicolor (L.) Moench] production systems, threatening grain quality, safety, and nutritional value as both human food and livestock feed. The crop's nutritional value, environmental resilience, and economic promise poise sorghum for increased acreage, especially in light of the growing pressures of climate change on global food systems. In order to fully take advantage of this potential, sorghum improvement efforts and production systems must be proactive in managing the sorghum grain mold disease complex, which not only jeopardizes agricultural productivity and profitability, but is also the culprit of harmful mycotoxins that warrant substantial public health concern. The robust scholarly literature from the 1980s to the early 2000s yielded valuable insights and key comprehensive reviews of the grain mold disease complex. Nevertheless, there remains a substantial gap in understanding the complex multi-organismal dynamics that underpin the plant-pathogen interactions involved - a gap that must be filled in order to deliver improved germplasm that is not only capable of withstanding the pressures of climate change, but also wields robust resistance to disease and mycotoxin accumulation. The present review seeks to provide an updated perspective of the sorghum grain mold disease complex, bolstered by recent advances in the understanding of the genetic and the biochemical interactions among the fungal pathogens, their corresponding mycotoxins, and the sorghum host. Critical components of the sorghum grain mold disease complex are summarized in narrative format to consolidate a collection of important concepts: (1) the current state of sorghum grain mold in research and production systems; (2) overview of the individual pathogens that contribute to the grain mold complex; (3) the mycotoxin-producing potential of these pathogens on sorghum and other substrates; and (4) a systems biology approach to the understanding of host responses.

Pre-harvest sprouting in cereals: genetic and biochemical mechanisms

With the growth of the global population and the increasing frequency of natural disasters, crop yields must be steadily increased to enhance human adaptability to risks. Pre-harvest sprouting (PHS), a term mainly used to describe the phenomenon in which grains germinate on the mother plant directly before harvest, is a serious global problem for agricultural production. After domestication, the dormancy level of cultivated crops was generally lower than that of their wild ancestors. Although the shortened dormancy period likely improved the industrial performance of cereals such as wheat, barley, rice, and maize, the excessive germination rate has caused frequent PHS in areas with higher rainfall, resulting in great economic losses. Here, we systematically review the causes of PHS and its consequences, the major indicators and methods for PHS assessment, and emphasize the biological significance of PHS in crop production. Wheat quantitative trait loci functioning in the control of PHS are also comprehensively summarized in a meta-analysis. Finally, we use Arabidopsis as a model plant to develop more complete PHS regulatory networks for wheat. The integration of this information is conducive to the development of custom-made cultivated lines suitable for different demands and regions, and is of great significance for improving crop yields and economic benefits.

Genome-wide association analysis reveals seed protein loci as determinants of variations in grain mold resistance in sorghum

GWAS analysis revealed variations at loci harboring seed storage, late embryogenesis abundant protein, and a tannin biosynthesis gene associated with sorghum grain mold resistance. Grain mold is the most important disease of sorghum [Sorghum bicolor (L.) Moench]. It starts at the early stages of grain development due to concurrent infection by multiple fungal species. The genetic architecture of resistance to grain mold is poorly understood. Using a diverse set of 635 Ethiopian sorghum accessions, we conducted a multi-stage disease rating for resistance to grain mold under natural infestation in the field. Through genome-wide association analyses with 173,666 SNPs and multiple models, two novel loci were identified that were consistently associated with grain mold resistance across environments. Sequence variation at new loci containing sorghum KAFIRIN gene encoding a seed storage protein affecting seed texture and LATE EMBRYOGENESIS ABUNDANT 3 (LEA3) gene encoding a protein that accumulates in seeds, previously implicated in stress tolerance, were significantly associated with grain mold resistance. The KAFIRIN and LEA3 loci were also significant factors in grain mold resistance in accessions with non-pigmented grains. Moreover, we consistently detected the known SNP (S4_62316425) in TAN1 gene, a regulator of tannin accumulation in sorghum grain to be significantly associated with grain mold resistance. Identification of loci associated with new mechanisms of resistance provides fresh insight into genetic control of the trait, while the highly resistant accessions can serve as sources of resistance genes for breeding. Overall, our association data suggest the critical role of loci harboring seed protein genes and implicate grain chemical and physical properties in sorghum grain mold resistance.

Identification of virulence associated milRNAs and their bidirectional targets in Rhizoctonia solani and maize during infection

BACKGROUND

Anastomosis group 1 IA (AG1-IA) of Rhizoctonia solani is the major agent of banded leaf and sheath blight (BLSB) disease that causes severe yield loss in many worldwide crops. MicroRNAs (miRNAs) are ~ 22 nt non-coding RNAs that negatively regulate gene expression levels by mRNA degradation or translation inhibition. A better understanding of miRNA function during AG1-IA infection can expedite to elucidate the molecular mechanisms of fungi-host interactions.

RESULTS

In this study, we sequenced three small RNA libraries obtained from the mycelium of AG1-IA isolate, non-infected maize sheath and mixed maize sheath 3 days after inoculation. In total, 137 conserved and 34 novel microRNA-like small RNAs (milRNAs) were identified from the pathogen. Among these, one novel and 17 conserved milRNAs were identified as potential virulence-associated (VA) milRNAs. Subsequently, the prediction of target genes for these milRNAs was performed in both AG1-IA and maize, while functional annotation of these targets suggested a link to pathogenesis-related biological processes. Further, expression patterns of these virulence-associated milRNAs demonstrated that theyparticipate in the virulence of AG1-IA. Finally, regulation of one maize targeting gene, GRMZM2G412674 for Rhi-milRNA-9829-5p, was validated by dual-luciferase assay and identified to play a positive role in BLSB resistance in two maize mutants. These results suggest the global differentially expressed milRNAs of R. solani AG1-IA that participate in the regulation of target genes in both AG1-IA and maize to reinforce its pathogenicity.

CONCLUSIONS

Our data have provided a comprehensive overview of the VA-milRNAs of R. solani and identified that they are probably the virulence factors by directly interfered in host targeting genes. These results offer new insights on the molecular mechanisms of R.solani-maize interactions during the process of infection.

GelFAP: Gene Functional Analysis Platform for Gastrodia elata

Gastrodia elata, also named Tianma, is a valuable traditional Chinese herbal medicine. It has numerous important pharmacological roles such as in sedation and lowering blood pressure and as anticonvulsant and anti-aging, and it also has effects on the immune and cardiovascular systems. The whole genome sequencing of G. elata has been completed in recent years, which provides a strong support for the construction of the G. elata gene functional analysis platform. Therefore, in our research, we collected and processed 39 transcriptome data of G. elata and constructed the G. elata gene co-expression networks, then we identified functional modules by the weighted correlation network analysis (WGCNA) package. Furthermore, gene families of G. elata were identified by tools including HMMER, iTAK, PfamScan, and InParanoid. Finally, we constructed a gene functional analysis platform for G. elata . In our platform, we introduced functional analysis tools such as BLAST, gene set enrichment analysis (GSEA), and cis-elements (motif) enrichment analysis tool. In addition, we analyzed the co-expression relationship of genes which might participate in the biosynthesis of gastrodin and predicted 19 mannose-binding lectin antifungal proteins of G. elata. We also introduced the usage of the G. elata gene function analysis platform (GelFAP) by analyzing CYP51G1 and GFAP4 genes. Our platform GelFAP may help researchers to explore the gene function of G. elata and make novel discoveries about key genes involved in the biological processes of gastrodin.

Phylogenomic Analysis of R2R3 MYB Transcription Factors in Sorghum and their Role in Conditioning Biofuel Syndrome

Background

Large scale cultivation of sorghum for food, feed, and biofuel requires concerted efforts for engineering multipurpose cultivars with optimised agronomic traits. Due to their vital role in regulating the biosynthesis of phenylpropanoid-derived compounds, biomass composition, biotic, and abiotic stress response, R2R3-MYB family transcription factors are ideal targets for improving environmental resilience and economic value of sorghum.

Methods

We used diverse computational biology tools to survey the sorghum genome to identify R2R3-MYB transcription factors followed by their structural and phylogenomic analysis. We used in-house generated as well as publicly available high throughput expression data to analyse the R2R3 expression patterns in various sorghum tissue types.

Results

We have identified a total of 134 R2R3-MYB genes from sorghum and developed a framework to predict gene functions. Collating information from the physical location, duplication, structural analysis, orthologous sequences, phylogeny, and expression patterns revealed the role of duplications in clade-wise expansion of the R2R3-MYB family as well as intra-clade functional diversification. Using publicly available and in-house generated RNA sequencing data, we provide MYB candidates for conditioning biofuel syndrome by engineering phenylpropanoid biosynthesis and sugar signalling pathways in sorghum.

Conclusion

The results presented here are pivotal to prioritize MYB genes for functional validation and optimize agronomic traits in sorghum.

Glyceollin Transcription Factor GmMYB29A2 Regulates Soybean Resistance to Phytophthora sojae

Glyceollin isomers I, II, and III are the major pathogen-elicited secondary metabolites (i.e. phytoalexins) of soybean (Glycine max) that, collectively with other 5-deoxyisoflavonoids, provide race-specific resistance to Phytophthora sojae. The NAC-family transcription factor (TF) GmNAC42-1 is an essential regulator of some but not all glyceollin biosynthesis genes, indicating other essential TF(s) of the glyceollin gene regulatory network remain to be identified. Here, we conducted comparative transcriptomics on soybean hairy roots of the variety Williams 82 and imbibing seeds of Harosoy 63 upon treatment with wall glucan elicitor from P. sojae and identified two homologous R2R3-type MYB TF genes, GmMYB29A1 and GmMYB29A2, up-regulated during the times of peak glyceollin biosynthesis. Overexpression and RNA interference silencing of GmMYB29A2 increased and decreased expression of GmNAC42-1, GmMYB29A1, and glyceollin biosynthesis genes and metabolites, respectively, in response to wall glucan elicitor. By contrast, overexpressing or silencing GmMYB29A1 decreased glyceollin I accumulation with marginal or no effects on the expressions of glyceollin synthesis genes, suggesting a preferential role in promoting glyceollin turnover and/or competing biosynthetic pathways. GmMYB29A2 interacted with the promoters of two glyceollin I biosynthesis genes in vitro and in vivo. Silencing GmMYB29A2 in Williams 82, a soybean variety that encodes the resistance gene Rps1k, rendered it compatible with race 1 P. sojae, whereas overexpressing GmMYB29A2 rendered the susceptible Williams variety incompatible. Compatibility and incompatibility coincided with reduced and enhanced accumulations of glyceollin I but not other 5-deoxyisoflavonoids. Thus, GmMYB29A2 is essential for accumulation of glyceollin I and expression of Phytophthora resistance.

Transcription Factors in Plant Stress Responses: Challenges and Potential for Sugarcane Improvement

Increasing vulnerability of crops to a wide range of abiotic and biotic stresses can have a marked influence on the growth and yield of major crops, especially sugarcane (Saccharum spp.). In response to various stresses, plants have evolved a variety of complex defense systems of signal perception and transduction networks. Transcription factors (TFs) that are activated by different pathways of signal transduction and can directly or indirectly combine with cis-acting elements to modulate the transcription efficiency of target genes, which play key regulators for crop genetic improvement. Over the past decade, significant progresses have been made in deciphering the role of plant TFs as key regulators of environmental responses in particular important cereal crops; however, a limited amount of studies have focused on sugarcane. This review summarizes the potential functions of major TF families, such as WRKY, NAC, MYB and AP2/ERF, in regulating gene expression in the response of plants to abiotic and biotic stresses, which provides important clues for the engineering of stress-tolerant cultivars in sugarcane.

Alternative splicing is a Sorghum bicolor defense response to fungal infection

This study provides new insights that alternative splicing participates with transcriptional control in defense responses to Colletotrichum sublineola in sorghum In eukaryotic organisms, alternative splicing (AS) is an important post-transcriptional mechanism to generate multiple transcript isoforms from a single gene. Protein variants translated from splicing isoforms may have altered molecular characteristics in signal transduction and metabolic activities. However, which transcript isoforms will be translated into proteins and the biological functions of the resulting proteoforms are yet to be identified. Sorghum is one of the five major cereal crops, but its production is severely affected by fungal diseases. For example, sorghum anthracnose caused by Colletotrichum sublineola greatly reduces grain yield and biomass production. In this study, next-generation sequencing technology was used to analyze C. sublineola-inoculated sorghum seedlings compared with mock-inoculated control. It was identified that AS regulation may be as important as traditional transcriptional control during defense responses to fungal infection. Moreover, several genes involved in flavonoid and phenylpropanoid biosynthetic pathways were found to undergo multiple AS modifications. Further analysis demonstrated that non-conventional targets of both 5'- and 3'-splice sites were alternatively used in response to C. sublineola infection. Splicing factors were also affected at both transcriptional and post-transcriptional levels. As the first transcriptome report on C. sublineola infected sorghum, our work also suggested that AS plays crucial functions in defense responses to fungal invasion.

Transcription Factors Associated with Abiotic and Biotic Stress Tolerance and Their Potential for Crops Improvement

In field conditions, crops are adversely affected by a wide range of abiotic stresses including drought, cold, salt, and heat, as well as biotic stresses including pests and pathogens. These stresses can have a marked effect on crop yield. The present and future effects of climate change necessitate the improvement of crop stress tolerance. Plants have evolved sophisticated stress response strategies, and genes that encode transcription factors (TFs) that are master regulators of stress-responsive genes are excellent candidates for crop improvement. Related examples in recent studies include TF gene modulation and overexpression approaches in crop species to enhance stress tolerance. However, much remains to be discovered about the diverse plant TFs. Of the >80 TF families, only a few, such as NAC, MYB, WRKY, bZIP, and ERF/DREB, with vital roles in abiotic and biotic stress responses have been intensively studied. Moreover, although significant progress has been made in deciphering the roles of TFs in important cereal crops, fewer TF genes have been elucidated in sorghum. As a model drought-tolerant crop, sorghum research warrants further focus. This review summarizes recent progress on major TF families associated with abiotic and biotic stress tolerance and their potential for crop improvement, particularly in sorghum. Other TF families and non-coding RNAs that regulate gene expression are discussed briefly. Despite the emphasis on sorghum, numerous examples from wheat, rice, maize, and barley are included. Collectively, the aim of this review is to illustrate the potential application of TF genes for stress tolerance improvement and the engineering of resistant crops, with an emphasis on sorghum.

Sorghum 3-Deoxyanthocyanidin Flavonoids Confer Resistance against Corn Leaf Aphid

In this study we examined the role of sorghum flavonoids in providing resistance against corn leaf aphid (CLA) Rhopalosiphum maidis. In sorghum, accumulation of these flavonoids is regulated by a MYB transcription factor, yellow seed1 (y1). Functional y1 alleles accumulate 3-deoxyflavonoids (3-DFs) and 3-deoxyanthocyanidins (3-DAs) whereas null y1 alleles fail to accumulate these compounds. We found that significantly higher numbers of alate CLA adults colonized null y1 plants as compared to functional y1 plants. Controlled cage experiments and pairwise choice assays demonstrated that apterous aphids preferred to feed and reproduce on null y1 plants. These near-isogenic sorghum lines do not differ in their epicuticular wax content and were also devoid of any leaf trichomes. Significantly higher mortality of CLA was observed on artificial aphid diet supplemented with flavonoids obtained from functional y1 plants as compared to null y1 plants or the relevant controls. Our results demonstrate that the proximate mechanism underlying the deleterious effects on aphids is y1-regulated flavonoids which are important defense compounds against CLA.

The NAC family transcription factor GmNAC42-1 regulates biosynthesis of the anticancer and neuroprotective glyceollins in soybean

BACKGROUND

Glyceollins are isoflavonoid-derived pathogen-inducible defense metabolites (phytoalexins) from soybean (Glycine max L. Merr) that have important roles in providing defense against pathogens. They also have impressive anticancer and neuroprotective activities in mammals. Despite their potential usefulness as therapeutics, glyceollins are not economical to synthesize and are biosynthesized only transiently and in low amounts in response to specific stresses. Engineering the regulation of glyceollin biosynthesis may be a promising approach to enhance their bioproduction, yet the transcription factors (TFs) that regulate their biosynthesis have remained elusive. To address this, we first aimed to identify novel abiotic stresses that enhance or suppress the elicitation of glyceollins and then used a comparative transcriptomics approach to search for TF gene candidates that may positively regulate glyceollin biosynthesis.

RESULTS

Acidity stress (pH 3.0 medium) and dehydration exerted prolonged (week-long) inductive or suppressive effects on glyceollin biosynthesis, respectively. RNA-seq found that all known biosynthetic genes were oppositely regulated by acidity stress and dehydration, but known isoflavonoid TFs were not. Systemic acquired resistance (SAR) genes were highly enriched in the geneset. We chose to functionally characterize the NAC (NAM/ATAF1/2/CUC2)-family TF GmNAC42-1 that was annotated as an SAR gene and a homolog of the Arabidopsis thaliana (Arabidopsis) indole alkaloid phytoalexin regulator ANAC042. Overexpressing and silencing GmNAC42-1 in elicited soybean hairy roots dramatically enhanced and suppressed the amounts of glyceollin metabolites and biosynthesis gene mRNAs, respectively. Yet, overexpressing GmNAC42-1 in non-elicited hairy roots failed to stimulate the expressions of all biosynthesis genes. Thus, GmNAC42-1 was necessary but not sufficient to activate all biosynthesis genes on its own, suggesting an important role in the glyceollin gene regulatory network (GRN). The GmNAC42-1 protein directly bound the promoters of biosynthesis genes IFS2 and G4DT in the yeast one-hybrid (Y1H) system.

CONCLUSIONS

Acidity stress is a novel elicitor and dehydration is a suppressor of glyceollin biosynthesis. The TF gene GmNAC42-1 is an essential positive regulator of glyceollin biosynthesis. Overexpressing GmNAC42-1 in hairy roots can be used to increase glyceollin yields > 10-fold upon elicitation. Thus, manipulating the expressions of glyceollin TFs is an effective strategy for enhancing the bioproduction of glyceollins in soybean.

Pre-harvest Sprouting and Grain Dormancy in Sorghum bicolor: What Have We Learned?

The possibility of obtaining sorghum grains with quality to match the standards for a diversity of end-uses is frequently hampered by the susceptibility to pre-harvest sprouting (PHS) displayed by many elite genotypes. For these reasons, obtaining resistance to PHS is considered in sorghum breeding programs, particularly when the crop is expected to approach harvest maturity under rainy or damp conditions prevalence. As in other cereals, the primary cause for sprouting susceptibility is a low dormancy prior to crop harvest; in consequence, most research has focused in understanding the mechanisms through which the duration of dormancy is differentially controlled in genotypes with contrasting sprouting behavior. With this aim two tannin-less, red-grained inbred lines were used as a model system: IS9530 (sprouting resistant) and Redland B2 (sprouting susceptible). Redland B2 grains are able to germinate well before reaching physiological maturity (PM) while IS9530 ones can start to germinate at 40-45 days after pollination, well after PM. Results show that the anticipated dormancy loss displayed by Redland B2 grains is related reduced embryo sensitivity to abscisic acid (ABA) and increased levels of GA upon imbibition. In turn, transcriptional data showed that ABA signal transduction is impaired in Redland B2, which appears to have an impact on GA catabolism, thus affecting the overall GA/ABA balance that regulates germination. QTL analyses were conducted to test whether previous candidate genes were located in a dormancy QTL, but also to identify new genes involved in dormancy. These analyses yielded several dormancy QTL and one of them located in chromosome 9 (qGI-9) was consistently detected even across environments. Fine mapping is already in progress to narrow down the number of candidate genes in qGI-9.

Overexpression of SbMyb60 in Sorghum bicolor impacts both primary and secondary metabolism

Few transcription factors have been identified in C₄ grasses that either positively or negatively regulate monolignol biosynthesis. Previously, the overexpression of SbMyb60 in sorghum (Sorghum bicolor) has been shown to induce monolignol biosynthesis, which leads to elevated lignin deposition and altered cell wall composition. To determine how SbMyb60 overexpression impacts other metabolic pathways, RNA-Seq and metabolite profiling were performed on stalks and leaves. 35S::SbMyb60 was associated with the transcriptional activation of genes involved in aromatic amino acid, S-adenosyl methionine (SAM) and folate biosynthetic pathways. The high coexpression values between SbMyb60 and genes assigned to these pathways indicate that SbMyb60 may directly induce their expression. In addition, 35S::SbMyb60 altered the expression of genes involved in nitrogen (N) assimilation and carbon (C) metabolism, which may redirect C and N towards monolignol biosynthesis. Genes linked to UDP-sugar biosynthesis and cellulose synthesis were also induced, which is consistent with the observed increase in cellulose deposition in the internodes of 35S::SbMyb60 plants. However, SbMyb60 showed low coexpression values with these genes and is not likely to be a direct regulator of cell wall polysaccharide biosynthesis. These findings indicate that SbMyb60 can activate pathways beyond monolignol biosynthesis, including those that synthesize the substrates and cofactors required for lignin biosynthesis.

Properties analysis of transcription factor gene TasMYB36 from Trichoderma asperellum CBS433.97 and its heterogeneous transfomation to improve antifungal ability of Populus

The transcription of TasMYB36 in the biocontrol species T. asperellum was upregulated in four different pathogenic fermentation broths, suggesting that TasMYB36 plays an important role in the response to biotic stresses. Seventy-nine MYB transcription factors that were homologous to TasMYB36 from six sequenced Trichoderma genomes were analyzed. They were distributed in fourteen clades in the phylogenetic tree. The 79 MYBs contained 113 DNA binding domains, and their amino acid sequences were conserved and were different to those in plants. The promoters of 79 MYBs contained 1374 cis-regulators related to the stress response, such as GCR1 (17.5%) and GCN4 (15.5%). Subsequently, TasMYB36 was integrated into the genome of Populus davidiana × P. alba var. pyramidalis (PdPap poplar), and after co-culture of the transformants (PdPap-TasMYB36s) with Alternaria alternate, the transcription of genes in the jasmonic acid (JA) and salicylic acid (SA) hormone signaling pathways were upregulated; the POD, SOD and CAT activities were enhanced; and the reactive oxygen content was reduced in PdPap-TasMYB36s. The disease spots area on PdPap-TasMYB36s leaves infected by A. alternate were average 0.63% (PdPap-Con: 24.7%). In summary, TasMYB36 of T. asperellum CBS433.97 is an important defense response gene that upregulates other stress response genes and could improve resistance to biotic stresses.

Distinct Mechanisms of Biotic and Chemical Elicitors Enable Additive Elicitation of the Anticancer Phytoalexin Glyceollin I

Phytoalexins are metabolites biosynthesized in plants in response to pathogen, environmental, and chemical stresses that often have potent bioactivities, rendering them promising for use as therapeutics or scaffolds for pharmaceutical development. Glyceollin I is an isoflavonoid phytoalexin from soybean that exhibits potent anticancer activities and is not economical to synthesize. Here, we tested a range of source tissues from soybean, in addition to chemical and biotic elicitors, to understand how to enhance the bioproduction of glyceollin I. Combining the inorganic chemical silver nitrate (AgNO₃) with the wall glucan elicitor (WGE) from the soybean pathogen Phytophthora sojae had an additive effect on the elicitation of soybean seeds, resulting in a yield of up to 745.1 µg gt-1 glyceollin I. The additive elicitation suggested that the biotic and chemical elicitors acted largely by separate mechanisms. WGE caused a major accumulation of phytoalexin gene transcripts, whereas AgNO₃ inhibited and enhanced the degradation of glyceollin I and 6″-O-malonyldaidzin, respectively.

Finger Millet: A "Certain" Crop for an "Uncertain" Future and a Solution to Food Insecurity and Hidden Hunger under Stressful Environments

Crop growth and productivity has largely been vulnerable to various abiotic and biotic stresses that are only set to be compounded due to global climate change. Therefore developing improved varieties and designing newer approaches for crop improvement against stress tolerance have become a priority now-a-days. However, most of the crop improvement strategies are directed toward staple cereals such as rice, wheat, maize etc., whereas attention on minor cereals such as finger millet [Eleusine coracana (L.) Gaertn.] lags far behind. It is an important staple in several semi-arid and tropical regions of the world with excellent nutraceutical properties as well as ensuring food security in these areas even during harsh environment. This review highlights the importance of finger millet as a model nutraceutical crop. Progress and prospects in genetic manipulation for the development of abiotic and biotic stress tolerant varieties is also discussed. Although limited studies have been conducted for genetic improvement of finger millets, its nutritional significance in providing minerals, calories and protein makes it an ideal model for nutrition-agriculture research. Therefore, improved genetic manipulation of finger millets for resistance to both abiotic and biotic stresses, as well as for enhancing nutrient content will be very effective in millet improvement. Key message: Apart from the excellent nutraceutical value of finger millet, its ability to tolerate various abiotic stresses and resist pathogens make it an excellent model for exploring vast genetic and genomic potential of this crop, which provide us a wide choice for developing strategies for making climate resilient staple crops.

Identification of an orthologous clade of peroxidases that respond to feeding by greenbugs (Schizaphis graminum) in C4 grasses

Knowledge of specific peroxidases that respond to aphid herbivory is limited in C4 grasses, but could provide targets for improving defence against these pests. A sorghum (Sorghum bicolor (L.) Moench) peroxidase (SbPrx-1; Sobic.002G416700) has been previously linked to biotic stress responses, and was the starting point for this study. Genomic analyses indicated that SbPrx-1 was part of a clade of five closely related peroxidase genes occurring within a ~30kb region on chromosome 2 of the sorghum genome. Comparison of this ~30-kb region to syntenic regions in switchgrass (Panicum virgatum L.) and foxtail millet (Setaria italica L.) identified similar related clusters of peroxidases. Infestation of a susceptible sorghum cultivar with greenbugs (Shizaphis graminum Rondani) induced three of the five peroxidases. Greenbug infestation of switchgrass and foxtail millet plants showed similar inductions of peroxidases. SbPrx-1 was also induced in response to aphid herbivory in a greenbug-resistant sorghum line, Cargill 607E. These data indicate that this genomic region of C4 grasses could be valuable as a marker to assess potential insect resistance in C4 grasses.

Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in Sorghum bicolor

The phenylpropanoid biosynthetic pathway that generates lignin subunits represents a significant target for altering the abundance and composition of lignin. The global regulators of phenylpropanoid metabolism may include MYB transcription factors, whose expression levels have been correlated with changes in secondary cell wall composition and the levels of several other aromatic compounds, including anthocyanins and flavonoids. While transcription factors correlated with downregulation of the phenylpropanoid biosynthesis pathway have been identified in several grass species, few transcription factors linked to activation of this pathway have been identified in C4 grasses, some of which are being developed as dedicated bioenergy feedstocks. In this study we investigated the role of SbMyb60 in lignin biosynthesis in sorghum (Sorghum bicolor), which is a drought-tolerant, high-yielding biomass crop. Ectopic expression of this transcription factor in sorghum was associated with higher expression levels of genes involved in monolignol biosynthesis, and led to higher abundances of syringyl lignin, significant compositional changes to the lignin polymer and increased lignin concentration in biomass. Moreover, transgenic plants constitutively overexpressing SbMyb60 also displayed ectopic lignification in leaf midribs and elevated concentrations of soluble phenolic compounds in biomass. Results indicate that overexpression of SbMyb60 is associated with activation of monolignol biosynthesis in sorghum. SbMyb60 represents a target for modification of plant cell wall composition, with the potential to improve biomass for renewable uses.

Ternary WD40 Repeat-Containing Protein Complexes: Evolution, Composition and Roles in Plant Immunity

Plants, like mammals, rely on their innate immune system to perceive and discriminate among the majority of their microbial pathogens. Unlike mammals, plants respond to this molecular dialog by unleashing a complex chemical arsenal of defense metabolites to resist or evade pathogen infection. In basal or non-host resistance, plants utilize signal transduction pathways to detect "non-self," "damaged-self," and "altered-self"- associated molecular patterns and translate these "danger" signals into largely inducible chemical defenses. The WD40 repeat (WDR)-containing proteins Gβ and TTG1 are constituents of two independent ternary protein complexes functioning at opposite ends of a plant immune signaling pathway. They are also encoded by single-copy genes that are ubiquitous in higher plants, implying the limited diversity and functional conservation of their respective complexes. In this review, we summarize what is currently known about the evolutionary history of these WDR-containing ternary complexes, their repertoire and combinatorial interactions, and their downstream effectors and pathways in plant defense.