Members of the germin-like protein family in Brassica napus are candidates for the initiation of an oxidative burst that impedes pathogenesis of Sclerotinia sclerotiorum

Genome-wide Characterization of Small Secreted Peptides in Nicotiana tabacum and Functional Assessment of NtLTP25 in Plant Immunity

Small secreted peptides (SSPs), serving as signaling molecules for intercellular communication, play significant regulatory roles in plant growth, development, pathogen immunity, and responses to abiotic stress. Despite several SSPs, such as PIP, PSK, and PSY having been identified to participate in plant immunity, the majority of SSPs remain understudied, necessitating the exploration and identification of SSPs regulating plant immunity from vast genomic resources. Here we systematically characterized 756 putative SSPs across the genome of Nicotiana tabacum. 173 SSPs were further annotated as established SSPs, such as nsLTP, CAPE, and CEP. Furthermore, we detected the expression of 484 putative SSP genes in five tissues, with 83 SSPs displaying tissue-specific expression. Transcriptomic analysis of tobacco roots under plant defense hormones revealed that 46 SSPs exhibited specific responsiveness to salicylic acid (SA), and such response was antagonistically regulated by methyl jasmonate. It's worth noting that among these 46 SSPs, 16 members belong to nsLTP family, and one of them, NtLTP25, was discovered to enhance tobacco's resistance against Phytophthora nicotianae. Overexpression of NtLTP25 in tobacco enhanced the expression of ICS1, subsequently stimulating the biosynthesis of SA and the expression of NPR1 and pathogenesis-related genes. Concurrently, NtLTP25 overexpression activated genes associated with ROS scavenging, consequently mitigating the accumulation of ROS during the subsequent phases of pathogenesis. These discoveries indicate that these 46 SSPs, especially the 16 nsLTPs, might have a vital role in governing plant immunity that relies on SA signaling. This offers a valuable source for pinpointing SSPs involved in regulating plant immunity.

OsGLP8-7 interacts with OsPRX111 to detoxify excess copper in rice

Lignin is a phenolic biopolymer generated from phenylpropanoid pathway in the secondary cell wall and is required for defense of plants against various stress. Although the fact of stress-induced lignin deposition has been clearly demonstrated, it remains largely elusive how the formation of lignin is promoted under Cu stress. The present study showed that OsGLP8-7, an extracellular glycoprotein of rice (Oryza sativa L.), plays an important function against Cu stress. The loss function of OsGLP8-7 results in Cu sensitivity whereas overexpression of OsGLP8-7 scavenges Cu-induced superoxide anion (O2•-). OsGLP8-7 interacts with apoplastic peroxidase111 (OsPRX111) and elevates OsPRX111 stability when exposed to excess Cu. In OsGLP8-7 overexpressing (OE) lines, the retention of Cu within cell wall limiting Cu uptake into cytoplasm is attributed to the enhanced lignification required for Cu tolerance. Exogenous application of a lignin inhibitor can impair the Cu tolerance of transgenic Arabidopsis lines overexpressing OsGLP8-7. In addition, co-expression of OsGLP8-7 and OsPRX111 genes in tobacco leaves leads to an improved lignin deposition compared to leaves expressing each gene individually or the empty vector. Taken together, our findings provided the convincing evidences that the interaction between OsGLP8-7 and OsPRX111 facilitates effectively lignin polymerization, thereby contributing to Cu tolerance in rice.

Transcriptome-Based Comparative Expression Profiling of Sweet Potato during a Compatible Response with Root-Knot Nematode Meloidogyne incognita Infection

M. incognita, a root-knot nematode (RKN), infects the roots of several important food crops, including sweet potato (Ipomoea batatas Lam.), and severely reduces yields. However, the molecular mechanisms underlying infection remain unclear. Previously, we investigated differential responses to RKN invasion in susceptible and resistant sweet potato cultivars through RNA-seq-based transcriptome analysis. In this study, gene expression similarities and differences were examined in RKN-susceptible sweet potato cultivars during the compatible response to RKN infection. Three susceptible cultivars investigated in previous research were used: Dahomi (DHM), Shinhwangmi (SHM), and Yulmi (YM). Of the three cultivars, YM had the highest number of genes with altered expression in response to infection. YM was also the cultivar with the highest susceptibility to RKN. Comparisons among cultivars identified genes that were regulated in more than one cultivar upon infection. Pairwise comparisons revealed that YM and DHM shared the most regulated genes, whereas YM and SHM shared the lowest number of regulated genes. Five genes were up-regulated, and two were down-regulated, in all three cultivars. Among these, four genes were highly up-regulated in all cultivars: germin-like protein, anthranilate synthase α subunit, isocitrate lyase, and uncharacterized protein. Genes were also identified that were uniquely regulated in each cultivar in response to infection, suggesting that susceptible cultivars respond to infection through shared and cultivar-specific pathways. Our findings expand the understanding of the compatible response to RKN invasion in sweet potato roots and provide useful information for further research on RKN defense mechanisms.

QTL mapping and transcriptome analysis identify novel QTLs and candidate genes in Brassica villosa for quantitative resistance against Sclerotinia sclerotiorum

KEY MESSAGE

Novel QTLs and candidate genes for Sclerotinia-resistance were identified in B. villosa, a wild Brassica species, which represents a new genetic source for improving oilseed rape resistance to SSR. Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is one of the most destructive diseases in oilseed rape growing regions. To date, there is no effective genetic resistance against S. sclerotiorum in the B. napus germplasm and knowledge of the molecular plant-fungal interaction is also limited. To identify new resistance resources, we screened a set of wild Brassica species and identified B. villosa (BRA1896) with a high level of Sclerotinia-resistance. Two segregating F2 populations for Sclerotinia-resistance, generated by interspecific crosses between the resistant B. villosa (BRA1896) and the wild susceptible B. oleracea (BRA1909) were assessed for Sclerotinia-resistance. Genetic mapping using a 15-k Illumina Infinium SNP-array resulted in a high-density genetic map containing 1,118 SNP markers and spanning a total genetic length of 792.2 cM. QTL analysis revealed seven QTLs explaining 3.8% to 16.5% of phenotypic variance. Intriguingly, RNAseq-based transcriptome analysis identified genes and pathways specific to B. villosa, of which a cluster of five genes encoding putative receptor-like kinases (RLKs) and two pathogenesis-related (PR) proteins are co-localized within a QTL on chromosome C07. Furthermore, transcriptomic analysis revealed enhanced ethylene (ET)-activated signaling in the resistant B. villosa, which is associated with a stronger plant immune response, depressed cell death, and enhanced phytoalexin biosynthesis compared to the susceptible B. oleracea. Our data demonstrates that B. villosa represents a novel and unique genetic source for improving oilseed rape resistance against SSR.

Genome-wide analysis of the GLP gene family and overexpression of GLP1-5-1 to promote lignin accumulation during early somatic embryo development in Dimocarpus longan

Longan (Dimocarpus longan Lour.) is an economically important subtropical fruit tree. Its fruit quality and yield are affected by embryo development. As a plant seed germination marker gene, the germin-like protein (GLP) gene plays an important role in embryo development. However, the mechanism underlying the role of the GLP gene in somatic embryos is still unclear. Therefore, we conducted genome-wide identification of the longan GLP (DlGLP) gene and preliminarily verified the function of DlGLP1-5-1. Thirty-five genes were identified as longan GLP genes and divided into 8 subfamilies. Based on transcriptome data and qRT‒PCR results, DlGLP genes exhibited the highest expression levels in the root, and the expression of most DlGLPs was upregulated during the early somatic embryogenesis (SE) in longan and responded to high temperature stress and 2,4-D treatment; eight DlGLP genes were upregulated under MeJA treatment, and four of them were downregulated under ABA treatment. Subcellular localization showed that DlGLP5-8-2 and DlGLP1-5-1 were located in the cytoplasm and extracellular stroma/chloroplast, respectively. Overexpression of DIGLP1-5-1 in the globular embryos (GEs) of longan promoted the accumulation of lignin and decreased the H₂O₂ content by regulating the activities of ROS-related enzymes. The results provide a reference for the functional analysis of DlGLPs and related research on improving lignin accumulation in the agricultural industry through genetic engineering.

Towards Marker-Assisted Breeding for Black Rot Bunch Resistance: Identification of a Major QTL in the Grapevine Cultivar 'Merzling'

Black rot (BR), caused by Guignardia bidwellii, is an emergent fungal disease threatening viticulture and affecting several mildew-tolerant varieties. However, its genetic bases are not fully dissected yet. For this purpose, a segregating population derived from the cross 'Merzling' (hybrid, resistant) × 'Teroldego' (V. vinifera, susceptible) was evaluated for BR resistance at the shoot and bunch level. The progeny was genotyped with the GrapeReSeq Illumina 20K SNPchip, and 7175 SNPs were combined with 194 SSRs to generate a high-density linkage map of 1677 cM. The QTL analysis based on shoot trials confirmed the previously identified Resistance to Guignardia bidwellii (Rgb)1 locus on chromosome 14, which explained up to 29.2% of the phenotypic variance, reducing the genomic interval from 2.4 to 0.7 Mb. Upstream of Rgb1, this study revealed a new QTL explaining up to 79.9% of the variance for bunch resistance, designated Rgb3. The physical region encompassing the two QTLs does not underlie annotated resistance (R)-genes. The Rgb1 locus resulted enriched in genes belonging to phloem dynamics and mitochondrial proton transfer, while Rgb3 presented a cluster of pathogenesis-related Germin-like protein genes, promoters of the programmed cell death. These outcomes suggest a strong involvement of mitochondrial oxidative burst and phloem occlusion in BR resistance mechanisms and provide new molecular tools for grapevine marker-assisted breeding.

Genome-wide identification of germin-like proteins in peanut (Arachis hypogea L.) and expression analysis under different abiotic stresses

Peanut is an important food and feed crop, providing oil and protein nutrients. Germins and germin-like proteins (GLPs) are ubiquitously present in plants playing numerous roles in defense, growth and development, and different signaling pathways. However, the GLP members have not been comprehensively studied in peanut at the genome-wide scale. We carried out a genome-wide identification of the GLP genes in peanut genome. GLP members were identified comprehensively, and gene structure, genomic positions, motifs/domains distribution patterns, and phylogenetic history were studied in detail. Promoter Cis-elements, gene duplication, collinearity, miRNAs, protein-protein interactions, and expression were determined. A total of 84 GLPs (AhGLPs ) were found in the genome of cultivated peanut. These GLP genes were clustered into six groups. Segmental duplication events played a key role in the evolution of AhGLPs, and purifying selection pressure was underlying the duplication process. Most AhGLPs possessed a well-maintained gene structure and motif organization within the same group. The promoter regions of AhGLPs contained several key cis-elements responsive to 'phytohormones', 'growth and development', defense, and 'light induction'. Seven microRNAs (miRNAs) from six families were found targeting 25 AhGLPs. Gene Ontology (GO) enrichment analysis showed that AhGLPs are highly enriched in nutrient reservoir activity, aleurone grain, external encapsulating structure, multicellular organismal reproductive process, and response to acid chemicals, indicating their important biological roles. AhGLP14, AhGLP38, AhGLP54, and AhGLP76 were expressed in most tissues, while AhGLP26, AhGLP29, and AhGLP62 showed abundant expression in the pericarp. AhGLP7, AhGLP20, and AhGLP21, etc., showed specifically high expression in embryo, while AhGLP12, AhGLP18, AhGLP40, AhGLP78, and AhGLP82 were highly expressed under different hormones, water, and temperature stress. The qRT-PCR results were in accordance with the transcriptome expression data. In short, these findings provided a foundation for future functional investigations on the AhGLPs for peanut breeding programs.

Genome-Wide Association Studies in Sunflower: Towards Sclerotinia sclerotiorum and Diaporthe/Phomopsis Resistance Breeding

Diseases caused by necrotrophic fungi, such as the cosmopolitan Sclerotinia sclerotiorum and the Diaporthe/Phomopsis complex, are among the most destructive diseases of sunflower worldwide. The lack of complete resistance combined with the inefficiency of chemical control makes assisted breeding the best strategy for disease control. In this work, we present an integrated genome-wide association (GWA) study investigating the response of a diverse panel of sunflower inbred lines to both pathogens. Phenotypic data for Sclerotinia head rot (SHR) consisted of five disease descriptors (disease incidence, DI; disease severity, DS; area under the disease progress curve for DI, AUDPCI, and DS, AUDPCS; and incubation period, IP). Two disease descriptors (DI and DS) were evaluated for two manifestations of Diaporthe/Phomopsis: Phomopsis stem canker (PSC) and Phomopsis head rot (PHR). In addition, a principal component (PC) analysis was used to derive transformed phenotypes as inputs to a univariate GWA (PC-GWA). Genotypic data comprised a panel of 4269 single nucleotide polymorphisms (SNP), generated via genotyping-by-sequencing. The GWA analysis revealed 24 unique marker-trait associations for SHR, 19 unique marker-trait associations for Diaporthe/Phomopsis diseases, and 7 markers associated with PC1 and PC2. No common markers were found for the response to the two pathogens. Nevertheless, epistatic interactions were identified between markers significantly associated with the response to S. sclerotiorum and Diaporthe/Phomopsis. This suggests that, while the main determinants of resistance may differ for the two pathogens, there could be an underlying common genetic basis. The exploration of regions physically close to the associated markers yielded 364 genes, of which 19 were predicted as putative disease resistance genes. This work presents the first simultaneous evaluation of two manifestations of Diaporthe/Phomopsis in sunflower, and undertakes a comprehensive GWA study by integrating PSC, PHR, and SHR data. The multiple regions identified, and their exploration to identify candidate genes, contribute not only to the understanding of the genetic basis of resistance, but also to the development of tools for assisted breeding.

Genome-wide identification and functional analysis of cupin_1 domain-containing members involved in the responses to Sclerotinia sclerotiorum and abiotic stress in Brassica napus

Cupin_1 domain-containing proteins (CDPs) are ubiquitously present in higher plants, which are known to play essential roles in various biological processes. In this study, we carried out genome-wide characterization and systematic investigation of the CDP genes in Brassica napus. A total of 96 BnCDPs, including 71 germin-like proteins (GLPs; proteins with a single cupin_1 domain) and 25 CDP bicupins (proteins with two cupin_1 domains), were identified and clustered into six distinct subfamilies (I-VI) based on the phylogenic analysis, gene structure and motif distribution. Further analysis indicated that whole-genome duplication (WGD) and segmental duplication are main contributors to the species-specific expansion of the BnCDP gene family, and all the duplicated genes subsequently underwent strong purification selection. The promoter region of BnCDPs showed enrichment of cis-regulatory elements associated with development, hormone and stress, as well as transcription factor binding sites, which validates the prediction that BnCDPs are widely involved in plant growth and biotic and abiotic stress responses. The BnCDPs in different subfamilies exhibited obvious differences in expression among 30 developmental tissues/stages of B. napus, implying that BnCDPs may be involved in tissue- and stage-specific developmental processes. Similar trends in expression of most BnCDPs were observed under Sclerotinia sclerotiorum inoculation and four abiotic stresses (dehydration, cold, ABA and salinity), particularly the BnGLPs in subfamily I and III with single cupin_1 domain, revealing that BnCDPs are of great importance in the environmental adaption of B. napus. We then performed a genome-wide association study (GWAS) of 274 B. napus core germplasms on S. sclerotiorum resistance and identified four significantly associated loci harboring five BnGLPs. The expression levels of two candidate genes, BnGLP1.A08 and BnGLP1.C08, were significantly correlated with S. sclerotiorum resistance. Their functional responses to multiple stages of S. sclerotiorum inoculation and four abiotic stresses were further examined through qPCR. Overall, this study provides rich resources for research on the function and evolutionary playground of CDP genes.

Genome-Wide Identification, Characterization, and Expression Analysis Related to Low-Temperature Stress of the CmGLP Gene Family in Cucumis melo L

Germin-like protein (GLP) participates in plant growth and development and plays an important role in plant stress. In the present study, 22 CmGLPs belonging to five classes were identified in the melon genome. Each member of the CmGLPs family contains a typical Cupin_1 domain. We conducted a genome-wide analysis of the melon GLP gene family characterization. CmGLPs were randomly distributed in the melon chromosomes, with the largest number on chromosome 8, having eight family members. Gene duplication events drive the evolution and expansion of the melon GLP gene family. Based on the phylogenetic tree analysis of GLP proteins in melon, rice, Arabidopsis, and cucumber, it was found that the GLP gene families of different species have diverged in evolution. Based on qRT-PCR results, all members of the CmGLP gene family could be expressed in different tissues of melon. Most CmGLP genes were up-regulated after low-temperature stress. The relative expression of CmGLP2-5 increased by 157.13 times at 48 h after low-temperature treatment. This finding suggests that the CmGLP2-5 might play an important role in low-temperature stress in melon. Furthermore, quantitative dual LUC assays indicated that CmMYB23 and CmWRKY33 can bind the promoter fragment of the CmGLP2-5. These results were helpful in understanding the functional succession and evolution of the melon GLP gene family and further revealed the response of CmGLPs to low-temperature stress in melon.

Genetic mapping and genomic prediction of sclerotinia stem rot resistance to rapeseed/canola (Brassica napus L.) at seedling stage

GWAS detected ninety-eight significant SNPs associated with Sclerotinia sclerotiorum resistance. Six statistical models resulted in medium to high predictive ability, depending on trait, indicating potential of genomic prediction for disease resistance breeding. The lack of complete host resistance and a complex resistance inheritance nature between rapeseed/canola and Sclerotinia sclerotiorum often limits the development of functional molecular markers that enable breeding for sclerotinia stem rot (SSR) resistance. However, genomics-assisted selection has the potential to accelerate the breeding for SSR resistance. Therefore, genome-wide association (GWA) mapping and genomic prediction (GP) were performed using a diverse panel of 337 rapeseed/canola genotypes. Three-week-old seedlings were screened using the petiole inoculation technique (PIT). Days to wilt (DW) up to 2 weeks and lesion phenotypes (LP) at 3, 4, and 7 days post-inoculation (dpi) were recorded. A strong correlation (r = - 0.90) between DW and LP_4dpi implied that a single time point scoring at four days could be used as a proxy trait. GWA analyses using single-locus (SL) and multi-locus (ML) models identified a total of 41, and 208 significantly associated SNPs, respectively. Out of these, ninety-eight SNPs were identified by a combination of the SL model and any of the ML models, at least two ML models, or two traits. These SNPs explained 1.25-12.22% of the phenotypic variance and considered as significant, could be associated with SSR resistance. Eighty-three candidate genes with a function in disease resistance were associated with the significant SNPs. Six GP models resulted in moderate to high (0.42-0.67) predictive ability depending on SSR resistance traits. The resistant genotypes and significant SNPs will serve as valuable resources for future SSR resistance breeding. Our results also highlight the potential of genomic selection to improve rapeseed/canola breeding for SSR resistance.

Early responses to salt stress in quinoa genotypes with opposite behavior

Soil salinity is among the major abiotic stresses that plants must cope with, mainly in arid and semiarid regions. The tolerance to high salinity is an important agronomic trait to sustain food production. Quinoa is a halophytic annual pseudo-cereal species with high nutritional value that can secrete salt out of young leaves in external non-glandular cells called epidermal bladder cells (EBC). Previous work showed high salt tolerance, but low EBC density was associated with an improved response in the early phases of salinity stress, mediated by tissue-tolerance traits mainly in roots. We compared the transcript profiling of two quinoa genotypes with contrasting salt tolerance patterning to identify the candidate genes involved in the differentially early response among genotypes. The transcriptome profiling, supported by in vitro physiological analyses, provided insights into the early-stage molecular mechanisms, both at the shoot and root level, based on the sensitive/tolerance traits. Results showed the presence of numerous differentially expressed genes among genotypes, tissues, and treatments, with genes involved in hormonal and stress response upregulated mainly in the sensitive genotype, suggesting that tolerance may be correlated to restricted changes in gene expression, at least after a short salt stress. These data, showing constitutive differences between the two genotypes, represent a solid basis for further studies to characterize the salt tolerance traits. Additionally, new information provided by this work might be useful for the development of plant breeding or genome engineering programs in quinoa.

Salicylic acid: A key regulator of redox signalling and plant immunity

In plants, the reactive oxygen species (ROS) formed during normal conditions are essential in regulating several processes, like stomatal physiology, pathogen immunity and developmental signaling. However, biotic and abiotic stresses can cause ROS over-accumulation leading to oxidative stress. Therefore, a suitable equilibrium is vital for redox homeostasis in plants, and there have been major advances in this research arena. Salicylic acid (SA) is known as a chief regulator of ROS; however, the underlying mechanisms remain largely unexplored. SA plays an important role in establishing the hypersensitive response (HR) and systemic acquired resistance (SAR). This is underpinned by a robust and complex network of SA with Non-Expressor of Pathogenesis Related protein-1 (NPR1), ROS, calcium ions (Ca²⁺), nitric oxide (NO) and mitogen-activated protein kinase (MAPK) cascades. In this review, we summarize the recent advances in the regulation of ROS and antioxidant defense system signalling by SA at the physiological and molecular levels. Understanding the molecular mechanisms of how SA controls redox homeostasis would provide a fundamental framework to develop approaches that will improve plant growth and fitness, in order to meet the increasing global demand for food and bioenergy.

Identification and functional analysis of a pollen fertility-associated gene GhGLP4 of Gossypium hirsutum L

KEY MESSAGE

Cotton male fertility-associated gene GhGLP4, encoding a germin-like protein, is essential for anthers development by keeping ROS homeostasis through reducing H2O2 level. Utilization of heterosis is an important way to increase cotton yield and improve fiber quality in hybrid cotton development programs. Male sterility is used in the development of cotton hybrids to reduce the cost of hybrid seed production by eliminating the process of emasculation. From the transcriptome analysis of genic male sterile mutant (ms1) and its background C312 of G. hirsutum, a gene encoding germin-like protein (GhGLP4) was found significantly down-regulated in different developmental stages of ms1 anthers. To explore the gene function in cotton fertility, GhGLP4 was further studied and interfered by virus-induced gene silencing. In the GhGLP4 interfered cotton lines, the expression level of GhGLP4 was significantly decreased in the stamens, and the down-regulation of GhGLP4 resulted in pollen sac closure, stigma exertion, filament shortening, decrease in the number of anthers and complete male sterility. The expression levels of respiratory burst oxidase homologs (Rboh, NADPH oxidase) were significantly altered. Further investigation showed that the SOD activity decreased while the H2O2 content increased in the atypical stamens. These results indicated that GhGLP4 gene affected the cotton anther development through maintenance of ROS homeostasis by H2O2 reduction.

Lignin Composition and Timing of Cell Wall Lignification Are Involved in Brassica napus Resistance to Stem Rot Caused by Sclerotinia sclerotiorum

Sclerotinia stem rot (SSR) is an economically and globally significant disease in oilseed rape (Brassica napus) caused by the necrotrophic ascomycete Sclerotinia sclerotiorum. This study explored the role of cell wall reinforcement by lignin as a relevant factor for effective plant defense against attack by this pathogen. Expression of key genes in the phenylpropanoid pathway and the induced synthesis of lignin in infected stem tissues were investigated in a study comparing a susceptible ('Loras') and a moderately resistant cultivar ('Zhongyou 821' [ZY821]). Data revealed an earlier and more rapid defense activation in ZY821 through upregulation of transcript levels of genes related to key steps in the phenylpropanoid pathway associated with increased lignin deposition in the resistant B. napus genotype. Expression level of BnCAD5, encoding a cinnamyl alcohol dehydrogenase, responsible for conversion of monolignol to lignin, was more rapidly upregulated in ZY821 than 'Loras'. The similar expression pattern of BnCAD5 and the gene BnF5H, encoding for ferulate-5-hydroxylase, which catalyzes the synthesis of syringyl (S) lignin precursors, suggests that BnCAD5 is involved in S lignin formation. Histological observations confirmed these results, showing an earlier increase of S lignin deposition in the infected resistant genotype. Deposition of guaiacyl lignin was detected in both genotypes and is thus considered a component of basal, cultivar-independent defense response of B. napus to stem rot. The results indicate the importance of cell wall modification for quantitative stem rot resistance by responses in the phenylpropanoid metabolism generating distinct lignin types on different temporal scales.

Enhanced thermo-tolerance in transgenic potato (Solanum tuberosum L.) overexpressing hydrogen peroxide-producing germin-like protein (GLP)

Germins and germin-like proteins (GLPs) were reported to participate in plant response to biotic and abiotic stresses involving hydrogen peroxide (H₂O₂) production, but their role in mitigating heat stress is poorly understood. Here, we investigated the ability of a Solanum tuberosum L. GLP (StGLP) gene isolated from the yeast cDNA library generated from heat-stressed potato plants and characterized its role in generating innate and/or acquired thermo-tolerance to potato via genetic transformation. The transgenic plants exhibited enhanced tolerance to gradual heat stress (GHS) compared with sudden heat shock (SHS) in terms of maximal cell viability, minimal ion leakage and reduced chlorophyll breakdown. Further, three StGLP transgenic lines (G9, G12 and G15) exhibited enhanced production of H₂O₂, which was either reduced or blocked by inhibitors of H₂O₂ under normal and heat stress conditions. This tolerance was mediated by up-regulation of antioxidant enzymes (catalase, ascorbate peroxidase and glutathione reductase) and other heat stress-responsive genes (StHSP70, StHSP20 and StHSP90) in transgenic potato plants. These results demonstrate that H₂O₂ produced by over-expression of StGLP in transgenic potato plants triggered the reactive oxygen species (ROS) scavenging signaling pathways controlling antioxidant and heat stress-responsive genes in these plants imparting tolerance to heat stress.

Subtilase activity in intrusive cells mediates haustorium maturation in parasitic plants

Parasitic plants that infect crops are devastating to agriculture throughout the world. These parasites develop a unique inducible organ called the haustorium that connects the vascular systems of the parasite and host to establish a flow of water and nutrients. Upon contact with the host, the haustorial epidermal cells at the interface with the host differentiate into specific cells called intrusive cells that grow endophytically toward the host vasculature. Following this, some of the intrusive cells re-differentiate to form a xylem bridge (XB) that connects the vasculatures of the parasite and host. Despite the prominent role of intrusive cells in host infection, the molecular mechanisms mediating parasitism in the intrusive cells remain poorly understood. In this study, we investigated differential gene expression in the intrusive cells of the facultative parasite Phtheirospermum japonicum in the family Orobanchaceae by RNA-sequencing of laser-microdissected haustoria. We then used promoter analyses to identify genes that are specifically induced in intrusive cells, and promoter fusions with genes encoding fluorescent proteins to develop intrusive cell-specific markers. Four of the identified intrusive cell-specific genes encode subtilisin-like serine proteases (SBTs), whose biological functions in parasitic plants are unknown. Expression of SBT inhibitors in intrusive cells inhibited both intrusive cell and XB development and reduced auxin response levels adjacent to the area of XB development. Therefore, we propose that subtilase activity plays an important role in haustorium development in P. japonicum.

Local Duplication of TIR-NBS-LRR Gene Marks Clubroot Resistance in Brassica napus cv. Tosca

Clubroot, caused by Plasmodiophora brassicae infection, is a disease of growing importance in cruciferous crops, including oilseed rape (Brassica napus). The affected plants exhibit prominent galling of the roots that impairs their capacity for water and nutrient uptake, which leads to growth retardation, wilting, premature ripening, or death. Due to the scarcity of effective means of protection against the pathogen, breeding of resistant varieties remains a crucial component of disease control measures. The key aspect of the breeding process is the identification of genetic factors associated with variable response to the pathogen exposure. Although numerous clubroot resistance loci have been described in Brassica crops, continuous updates on the sources of resistance are necessary. Many of the resistance genes are pathotype-specific, moreover, resistance breakdowns have been reported. In this study, we characterize the clubroot resistance locus in the winter oilseed rape cultivar "Tosca." In a series of greenhouse experiments, we evaluate the disease severity of P. brassicae-challenged "Tosca"-derived population of doubled haploids, which we genotype with Brassica 60 K array and a selection of SSR/SCAR markers. We then construct a genetic map and narrow down the resistance locus to the 0.4 cM fragment on the A03 chromosome, corresponding to the region previously described as Crr3. Using Oxford Nanopore long-read genome resequencing and RNA-seq we review the composition of the locus and describe a duplication of TIR-NBS-LRR gene. Further, we explore the transcriptomic differences of the local genes between the clubroot resistant and susceptible, inoculated and control DH lines. We conclude that the duplicated TNL gene is a promising candidate for the resistance factor. This study provides valuable resources for clubroot resistance breeding programs and lays a foundation for further functional studies on clubroot resistance.

Sclerotinia Stem Rot Resistance in Rapeseed: Recent Progress and Future Prospects

Sclerotinia stem rot (SSR) of rapeseed (Brassica napus), caused by the soil-borne fungus Sclerotinia sclerotiorum, is one of the main diseases seriously affecting the yield and oil quality of infected rapeseed crops. The complexity of the inheritance of resistance and of the interaction mechanisms between rapeseed and S. sclerotiorum limits resistance gene identification and molecular breeding. In this review, the latest progress of research into resistance to SSR in B. napus is summarized from the following three directions: the pathogenesis mechanisms of S. sclerotiorum, the resistance mechanisms of B. napus toward S. sclerotiorum, and rapeseed breeding for resistance to SSR. This review aims to provide a theoretical basis and useful reference for analyzing the mechanism of the interaction between B. napus and S. sclerotiorum, searching for gene loci associated with the resistance response, and for achieving disease-resistance genetic manipulation and molecular design breeding in rapeseed.

Genome-Wide Identification and Expression Profiling of Germin-Like Proteins Reveal Their Role in Regulating Abiotic Stress Response in Potato

Germin and germin-like proteins (GLPs) perform a significant role in plants against biotic and abiotic stress. To understand the role of GLPs in potato, a comprehensive genome-wide analysis was performed in the potato genome. This study identified a total of 70 StGLPs genes in the potato genome, distributed among 11 chromosomes. Phylogenetic analysis exhibited that StGLPs were categorized into six groups with high bootstrap values. StGLPs gene structure and motifs analysis showed a relatively well-maintained intron-exon and motif formation within the cognate group. Additionally, several cis-elements in the promoter regions of GLPs were hormones, and stress-responsive and different families of miRNAs target StGLPs. Gene duplication under selection pressure also exhibited positive and purifying selections in StGLPs. In our results, the StGLP5 gene showed the highest expression in response to salt stress among all expressed StGLPs. Totally 19 StGLPs genes were expressed in response to heat stress. Moreover, three genes, StGLP30, StGLP17, and StGLP14, exhibited a relatively higher expression level in the potato after heat treatment. In total, 22 genes expressed in response to abscisic acid (ABA) treatment indicated that ABA performed an essential role in the plant defense or tolerance mechanism to environmental stress. RNA-Seq data validated by RT-qPCR also confirm that the StGLP5 gene showed maximum expression among selected genes under salt stress. Concisely, our results provide a platform for further functional exploration of the StGLPs against salt and heat stress conditions.

Molecular evidence for the involvement of cotton GhGLP2, in enhanced resistance to Verticillium and Fusarium Wilts and oxidative stress

Germin-like proteins (GLPs) are a diverse and ubiquitous family of plant glycoproteins belonging to the cupin super family; they play considerable roles in plant responses against various abiotic and biotic stresses. Here, we provide evidence that GLP2 protein from cotton (Gossypium hirsutum) functions in plant defense responses against Verticillium dahliae, Fusarium oxysporum and oxidative stress. Purified recombinant GhGLP2 exhibits superoxide dismutase (SOD) activity and inhibits spore germination of pathogens. Virus-induced silencing of GhGLP2 in cotton results in increased susceptibility to pathogens, plants exhibited severe wilt on leaves, enhanced vascular browning and suppressed callose deposition. Transgenic Arabidopsis (Arabidopsis thaliana) plants overexpressing GhGLP2 showed significant resistance to V. dahliae and F. oxysporum, with reduced mycelia growth, increased callose deposition and cell wall lignification at infection sites on leaves. The enhanced tolerance of GhGLP2-transgenic Arabidopsis to oxidative stress was investigated by methyl viologen and ammonium persulfate treatments, along with increased H₂O₂ production. Further, the expression of several defense-related genes (PDF1.2, LOX2, and VSP1) or oxidative stress-related genes (RbohD, RbohF) was triggered by GhGLP2. Thus, our results confirmed the involvement of GhGLP2 in plant defense response against Verticillium and Fusarium wilt pathogens and stress conditions.

ROS Homeostasis in Abiotic Stress Tolerance in Plants

Climate change-induced abiotic stress results in crop yield and production losses. These stresses result in changes at the physiological and molecular level that affect the development and growth of the plant. Reactive oxygen species (ROS) is formed at high levels due to abiotic stress within different organelles, leading to cellular damage. Plants have evolved mechanisms to control the production and scavenging of ROS through enzymatic and non-enzymatic antioxidative processes. However, ROS has a dual function in abiotic stresses where, at high levels, they are toxic to cells while the same molecule can function as a signal transducer that activates a local and systemic plant defense response against stress. The effects, perception, signaling, and activation of ROS and their antioxidative responses are elaborated in this review. This review aims to provide a purview of processes involved in ROS homeostasis in plants and to identify genes that are triggered in response to abiotic-induced oxidative stress. This review articulates the importance of these genes and pathways in understanding the mechanism of resistance in plants and the importance of this information in breeding and genetically developing crops for resistance against abiotic stress in plants.

Unveiling the genetic basis of Sclerotinia head rot resistance in sunflower

BACKGROUND

Sclerotinia sclerotiorum is a necrotrophic fungus that causes Sclerotinia head rot (SHR) in sunflower, with epidemics leading to severe yield losses. In this work, we present an association mapping (AM) approach to investigate the genetic basis of natural resistance to SHR in cultivated sunflower, the fourth most widely grown oilseed crop in the world.

RESULTS

Our association mapping population (AMP), which comprises 135 inbred breeding lines (ILs), was genotyped using 27 candidate genes, a panel of 9 Simple Sequence Repeat (SSR) markers previously associated with SHR resistance via bi-parental mapping, and a set of 384 SNPs located in genes with molecular functions related to stress responses. Moreover, given the complexity of the trait, we evaluated four disease descriptors (i.e, disease incidence, disease severity, area under the disease progress curve for disease incidence, and incubation period). As a result, this work constitutes the most exhaustive AM study of disease resistance in sunflower performed to date. Mixed linear models accounting for population structure and kinship relatedness were used for the statistical analysis of phenotype-genotype associations, allowing the identification of 13 markers associated with disease reduction. The number of favourable alleles was negatively correlated to disease incidence, disease severity and area under the disease progress curve for disease incidence, whereas it was positevily correlated to the incubation period.

CONCLUSIONS

Four of the markers identified here as associated with SHR resistance (HA1848, HaCOI_1, G33 and G34) validate previous research, while other four novel markers (SNP117, SNP136, SNP44, SNP128) were consistently associated with SHR resistance, emerging as promising candidates for marker-assisted breeding. From the germplasm point of view, the five ILs carrying the largest combination of resistance alleles provide a valuable resource for sunflower breeding programs worldwide.

Fine mapping QSc.VR4, an effective and stable scald resistance locus in barley (Hordeum vulgare L.), to a 0.38-Mb region enriched with LRR-RLK and GLP genes

An effective and stable quantitative resistance locus, QSc.VR4, was fine mapped, characterized and physically anchored to the short arm of 4H, conferring adult plant resistance to the fungus Rhynchosporium commune in barley. Scald caused by Rhynchosporium commune is one of the most destructive barley diseases worldwide. Accumulation of adult plant resistance (APR) governed by multiple resistance alleles is predicted to be effective and long-lasting against a broad spectrum of pathotypes. However, the molecular mechanisms that control APR remain poorly understood. Here, quantitative trait loci (QTL) analysis of APR and fine mapping were performed on five barley populations derived from a common parent Vlamingh, which expresses APR to scald. Two QTLs, designated QSc.VR4 and QSc.BR7, were detected from a cross between Vlamingh and Buloke. Our data confirmed that QSc.VR4 is an effective and stable APR locus, residing on the short arm of chromosome 4H, and QSc.BR7 derived from Buloke may be an allele of reported Rrs2. High-resolution fine mapping revealed that QSc.VR4 is located in a 0.38 Mb genomic region between InDel markers 4H2282169 and 4H2665106. The gene annotation analysis and sequence comparison suggested that a gene cluster containing two adjacent multigene families encoding leucine-rich repeat receptor kinase-like proteins (LRR-RLKs) and germin-like proteins (GLPs), respectively, is likely contributing to scald resistance. Adult plant resistance (APR) governed by QSc.VR4 may confer partial levels of resistance to the fungus Rhynchosporium commune and, furthermore, be an important resource for gene pyramiding that may contribute broad-based and more durable resistance.

MfOfd1 is crucial for stress responses and virulence in the peach brown rot fungus Monilinia fructicola

Monilinia fructicola is the most widely distributed species among the Monilinia genus in the world, and causes blossom blight, twig canker, and fruit rot on Rosaceae fruits. To date, studies on genomics and pathogenicity are limited in M. fructicola. In this study, we identified a redox-related gene, MfOfd1, which was significantly up-regulated at 1 hr after inoculation of M. fructicola on peach fruits. We used the clustered regulatory inter-spaced short palindromic repeats (CRISPR)/Cas9 system combined with homologous recombination to determine the function of the MfOfd1 gene. The results showed that the sporulation of knockdown transformants was reduced by 53% to 83%. The knockdown transformants showed increased sensitivity to H₂ O₂ and decreased virulence on peach fruits compared to the wild-type isolate Bmpc7. It was found that H₂ O₂ could stimulate the expression of MfOfd1 in the wild-type isolate. The transformants were also more sensitive to exogenous osmotic stress, such as glycerol, d-sorbitol, and NaCl, and to dicarboximide fungicides (iprodione and dimethachlon). These results indicate that the MfOfd1 gene plays an important role in M. fructicola in sporulation, oxidative response, osmotic stress tolerance, and virulence.

Proteomic changes may lead to yield alteration in maize under carbon dioxide enriched condition

In the present study, the effect of elevated CO2 on growth, physiology, yield and proteome was studied on two maize (Zea mays L.) varieties grown under Free-air CO2 enrichment. Growth in high CO2 (530 ppm) did not affect either photosynthesis or pigment contents in both varieties. Reduced MDA content, antioxidant and antioxidative enzymes levels were observed in both varieties in response to high CO2. PEHM-5 accumulated more biomass than SMH-3031 under eCO2. PEHM-5 also had more seed starch and total soluble sugar than SMH-3031. However, SMH-3031 had increased number of seed per cob than PEHM-5. Interestingly, thousand seed weight was significantly increased in PEHM-5 only, while it was decreased in SMH-3031 under eCO2. We observed increased seed size in PEHM-5, while the size of the SMH-3031 seeds remained unaltered. Leaf proteomics revealed more abundance of proteins related to Calvin cycle, protein synthesis assembly and degradation, defense and redox homeostasis in PEHM-5 that contributed to better growth and yield in elevated CO2. While in SMH-3031 leaf, proteins related to Calvin cycle, defense and redox homeostasis were less abundant in elevated CO2 resulting in average growth and yield. The results showed a differential response of two maize varieties to eCO2.

An update on the arsenal: mining resistance genes for disease management of Brassica crops in the genomic era

Brassica species include many economically important crops that provide nutrition and health-promoting substances to humans worldwide. However, as with all crops, their production is constantly threatened by emerging viral, bacterial, and fungal diseases, whose incidence has increased in recent years. Traditional methods of control are often costly, present limited effectiveness, and cause environmental damage; instead, the ideal approach is to mine and utilize the resistance genes of the Brassica crop hosts themselves. Fortunately, the development of genomics, molecular genetics, and biological techniques enables us to rapidly discover and apply resistance (R) genes. Herein, the R genes identified in Brassica crops are summarized, including their mapping and cloning, possible molecular mechanisms, and application in resistance breeding. Future perspectives concerning how to accurately discover additional R gene resources and efficiently utilize these genes in the genomic era are also discussed.

Primary Metabolism Is Distinctly Modulated by Plant Resistance Inducers in Coffea arabica Leaves Infected by Hemileia vastatrix

Epidemics of coffee leaf rust (CLR) leads to great yield losses and huge depreciation of coffee marketing values, if no control measures are applied. Societal expectations of a more sustainable coffee production are increasingly imposing the replacement of fungicide treatments by alternative solutions. A protection strategy is to take advantage of the plant immune system by eliciting constitutive defenses. Based on such concept, plant resistance inducers (PRIs) have been developed. The Greenforce CuCa formulation, similarly to acibenzolar-S-methyl (ASM), shows promising results in the control of CLR (Hemileia vastatrix) in Coffea arabica cv. Mundo Novo. The molecular mechanisms of PRIs action are poorly understood. In order to contribute to its elucidation a proteomic, physiological (leaf gas-exchange) and biochemical (enzymatic) analyses were performed. Coffee leaves treated with Greenforce CuCa and ASM and inoculation with H. vastatrix were considered. Proteomics revealed that both PRIs lead to metabolic adjustments but, inducing distinct proteins. These proteins were related with photosynthesis, protein metabolism and stress responses. Greenforce CuCa increased photosynthesis and stomatal conductance, while ASM caused a decrease in these parameters. It was further observed that Greenforce CuCa reinforces the redox homeostasis of the leaf, while ASM seems to affect preferentially the secondary metabolism and the stress-related proteins. So, the PRIs prepare the plant to resist CLR but, inducing different defense mechanisms upon pathogen infection. The existence of a link between the primary metabolism and defense responses was evidenced. The identification of components of the plant primary metabolism, essential for plant growth and development that, simultaneously, participate in the plant defense responses can open new perspectives for plant breeding programs.

GhABP19, a Novel Germin-Like Protein From Gossypium hirsutum, Plays an Important Role in the Regulation of Resistance to Verticillium and Fusarium Wilt Pathogens

Germin-like proteins (GLPs) are water-soluble plant glycoproteins belonging to the cupin superfamily. The important role of GLPs in plant responses against various abiotic and biotic stresses, especially pathogens, is well validated. However, little is known about cotton GLPs in relation to fungal pathogens. Here, a novel GLP gene was isolated from Gossypium hirsutum and designated as GhABP19. The expression of GhABP19 was upregulated in cotton plants inoculated with Verticillium dahliae and Fusarium oxysporum and in response to treatment with jasmonic acid (JA) but was suppressed in response to salicylic acid treatment. A relatively small transient increase in GhABP19 was seen in H2O2 treated samples. The three-dimensional structure prediction of the GhABP19 protein indicated that the protein has three histidine and one glutamate residues responsible for metal ion binding and superoxide dismutase (SOD) activity. Purified recombinant GhABP19 exhibits SOD activity and could inhibit growth of V. dahliae, F. oxysporum, Rhizoctonia solani, Botrytis cinerea, and Valsa mali in vitro. To further verify the role of GhABP19 in fungal resistance, GhABP19-overexpressing Arabidopsis plants and GhABP19-silenced cotton plants were developed. GhABP19-transgenic Arabidopsis lines showed much stronger resistance to V. dahliae and F. oxysporum infection than control (empty vector) plants did. On the contrary, silencing of GhABP19 in cotton conferred enhanced susceptibility to fungal pathogens, which resulted in necrosis and wilt on leaves and vascular discoloration in GhABP19-silenced cotton plants. The H2O2 content and endogenous SOD activity were affected by GhABP19 expression levels in Arabidopsis and cotton plants after inoculation with V. dahliae and F. oxysporum, respectively. Furthermore, GhABP19 overexpression or silencing resulted in activation or suppression of JA-mediated signaling, respectively. Thus, GhABP19 plays important roles in the regulation of resistance to verticillium and fusarium wilt in plants. These modulatory roles were exerted by its SOD activity and ability to activate the JA pathway. All results suggest that GhABP19 was involved in plant disease resistance.

Comparative analysis of Cd-responsive maize and rice transcriptomes highlights Cd co-modulated orthologs

Background

Metal tolerance is often an integrative result of metal uptake and distribution, which are fine-tuned by a network of signaling cascades and metal transporters. Thus, with the goal of advancing the molecular understanding of such metal homeostatic mechanisms, comparative RNAseq-based transcriptome analysis was conducted to dissect differentially expressed genes (DEGs) in maize roots exposed to cadmium (Cd) stress.

Results

To unveil conserved Cd-responsive genes in cereal plants, the obtained 5166 maize DEGs were compared with 2567 Cd-regulated orthologs in rice roots, and this comparison generated 880 universal Cd-responsive orthologs groups composed of 1074 maize DEGs and 981 rice counterparts. More importantly, most of the orthologous DEGs showed coordinated expression pattern between Cd-treated maize and rice, and these include one large orthologs group of pleiotropic drug resistance (PDR)-type ABC transporters, two clusters of amino acid transporters, and 3 blocks of multidrug and toxic compound extrusion (MATE) efflux family transporters, and 3 clusters of heavy metal-associated domain (HMAD) isoprenylated plant proteins (HIPPs), as well as all 4 groups of zinc/iron regulated transporter protein (ZIPs). Additionally, several blocks of tandem maize paralogs, such as germin-like proteins (GLPs), phenylalanine ammonia-lyases (PALs) and several enzymes involved in JA biosynthesis, displayed consistent co-expression pattern under Cd stress.

Out of the 1074 maize DEGs, approximately 30 maize Cd-responsive genes such as ZmHIPP27, stress-responsive NAC transcription factor (ZmSNAC1) and 9-cis-epoxycarotenoid dioxygenase (NCED, vp14) were also common stress-responsive genes reported to be uniformly regulated by multiple abiotic stresses. Moreover, the aforementioned three promising Cd-upregulated genes with rice counterparts were identified to be novel Cd-responsive genes in maize.

Meanwhile, one maize glutamate decarboxylase (ZmGAD1) with Cd co-modulated rice ortholog was selected for further analysis of Cd tolerance via heterologous expression, and the results suggest that ZmGAD1 can confer Cd tolerance in yeast and tobacco leaves.

Conclusions

These novel findings revealed the conserved function of Cd-responsive orthologs and paralogs, which would be valuable for elucidating the genetic basis of the plant response to Cd stress and unraveling Cd tolerance genes.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5109-8) contains supplementary material, which is available to authorized users.

CRISPR/Cas9-Mediated Multiplex Genome Editing of the BnWRKY11 and BnWRKY70 Genes in Brassica napus L

Targeted genome editing is a desirable means of basic science and crop improvement. The clustered, regularly interspaced, palindromic repeat (CRISPR)/Cas9 (CRISPR-associated 9) system is currently the simplest and most commonly used system in targeted genomic editing in plants. Single and multiplex genome editing in plants can be achieved under this system. In Arabidopsis, AtWRKY11 and AtWRKY70 genes were involved in JA- and SA-induced resistance to pathogens, in rapeseed (Brassica napus L.), BnWRKY11 and BnWRKY70 genes were found to be differently expressed after inoculated with the pathogenic fungus, Sclerotinia sclerotiorum (Lib.) de Bary. In this study, two Cas9/sgRNA constructs targeting two copies of BnWRKY11 and four copies of BnWRKY70 were designed to generate BnWRKY11 and BnWRKY70 mutants respectively. As a result, twenty-two BnWRKY11 and eight BnWRKY70 independent transformants (T₀) were obtained, with the mutation ratios of 54.5% (12/22) and 50% (4/8) in BnWRKY11 and BnWRKY70 transformants respectively. Eight and two plants with two copies of mutated BnWRKY11 and BnWRKY70 were obtained respectively. In T₁ generation of each plant examined, new mutations on target genes were detected with high efficiency. The vast majority of BnWRKY70 mutants showed editing in three copies of BnWRKY70 in examined T₁ plants. BnWRKY70 mutants exhibited enhanced resistance to Sclerotinia, while BnWRKY11 mutants showed no significant difference in Sclerotinia resistance when compared to non-transgenic plants. In addition, plants that overexpressed BnWRKY70 showed increased sensitivity when compared to non-transgenic plants. Altogether, our results demonstrated that BnWRKY70 may function as a regulating factor to negatively control the Sclerotinia resistance and CRISPR/Cas9 system could be used to generate germplasm in B. napus with high resistance against Sclerotinia.

Integrated mRNA, sRNA, and degradome sequencing reveal oilseed rape complex responses to Sclerotinia sclerotiorum (Lib.) infection

Sclerotinia stem rot (SSR), caused by the fungal pathogen Sclerotinia sclerotiorum, is a devastating disease resulting in yield losses and decreases in seed quality in oilseed rape (Brassica napus) worldwide. However, the molecular mechanisms underlying the response of oilseed rape to S. sclerotiorum infection at the transcriptional and post-transcriptional levels are poorly understood. Here, we used an integrated omics approach (transcriptome, sRNAome, and degradome sequencing) on the Illumina platform to compare the RNA expression and post-transcriptional profiles of oilseed rape plants inoculated or not with S. sclerotiorum. In total, 7,065 differentially expressed genes (DEGs) compared with the mock-inoculated control at 48 hours post inoculation were identified. These DEGs were associated with protein kinases, signal transduction, transcription factors, hormones, pathogenesis-related proteins, secondary metabolism, and transport. In the sRNA-Seq analysis, 77 known and 176 novel miRNAs were identified; however, only 10 known and 41 novel miRNAs were differentially expressed between the samples inoculated or not with S. sclerotiorum. Degradome sequencing predicted 80 cleavage sites with 64 miRNAs. Integrated mRNA, sRNA and degradome sequencing analysis reveal oilseed rape complex responses to S. sclerotiorum infection. This study provides a global view of miRNA and mRNA expression profiles in oilseed rape following S. sclerotiorum infection.

Overexpression of germin-like protein GmGLP10 enhances resistance to Sclerotinia sclerotiorum in transgenic tobacco

Germin-like proteins (GLPs) are ubiquitous water-soluble glycoproteins that are located in the extracellular matrix. These proteins have been reported to play vital roles in diverse biological processes. In the present study, a GLP in soybean (Glycine max L. Merr.), GmGLP10, was characterized. Sequence analysis revealed that the GmGLP10 gene (GenBank Accession Number EU916258) encodes a 213-amino acid (aa) protein, which contains a N-terminal signal peptide at 1-22 aa and is highly homologous to the members of the GER2 subfamily. GmGLP10 was highly expressed in the leaves, but very faint in the roots. The expression of GmGLP10 was induced by methyl jasmonate (MeJA), ethylene (ET), salicylic acid (SA), oxalate acid (OA), and the infection of Sclerotinia sclerotiorum. Overexpression of GmGLP10 in transgenic tobacco significantly enhanced tolerance to OA and S. sclerotiorum infection. Moreover, higher levels of H2O2 and the upregulated expression of a set of plant defense-related genes and HR (hypersensitive response)-associated genes were detected in the transgenic plants. These results suggest that GmGLP10 functions as a positive regulator of resistance to S. sclerotiorum.

Genome-wide analyses of direct target genes of four rice NAC-domain transcription factors involved in drought tolerance

BACKGROUND

Plant stress responses and mechanisms determining tolerance are controlled by diverse sets of genes. Transcription factors (TFs) have been implicated in conferring drought tolerance under drought stress conditions, and the identification of their target genes can elucidate molecular regulatory networks that orchestrate tolerance mechanisms.

RESULTS

We generated transgenic rice plants overexpressing the 4 rice TFs, OsNAC5, 6, 9, and 10, under the control of the root-specific RCc3 promoter. We showed that they were tolerant to drought stress with reduced loss of grain yield under drought conditions compared with wild type plants. To understand the molecular mechanisms underlying this tolerance, we here performed chromatin immunoprecipitation (ChIP)-Seq and RNA-Seq analyses to identify the direct target genes of the OsNAC proteins using the RCc3:6MYC-OsNAC expressing roots. A total of 475 binding loci for the 4 OsNAC proteins were identified by cross-referencing their binding to promoter regions and the expression levels of the corresponding genes. The binding loci were distributed among the promoter regions of 391 target genes that were directly up-regulated by one of the OsNAC proteins in four RCc3:6MYC-OsNAC transgenic lines. Based on gene ontology (GO) analysis, the direct target genes were related to transmembrane/transporter activity, vesicle, plant hormones, carbohydrate metabolism, and TFs. The direct targets of each OsNAC range from 4.0-8.7% of the total number of up-regulated genes found in the RNA-Seq data sets. Thus, each OsNAC up-regulates a set of direct target genes that alter root system architecture in the RCc3:OsNAC plants to confer drought tolerance. Our results provide a valuable resource for functional dissection of the molecular mechanisms of drought tolerance.

CONCLUSIONS

Many of the target genes, including transmembrane/transporter, vesicle related, auxin/hormone related, carbohydrate metabolic processes, and transcription factor genes, that are up-regulated by OsNACs act as the cellular components which would alter the root architectures of RCc3:OsNACs for drought tolerance.

Proteome Profiling of Paulownia Seedlings Infected with Phytoplasma

Phytoplasma is an insect-transmitted pathogen that causes witches' broom disease in many plants. Paulownia witches' broom is one of the most destructive diseases threatening Paulownia production. The molecular mechanisms associated with this disease have been investigated by transcriptome sequencing, but changes in protein abundance have not been investigated with isobaric tags for relative and absolute quantitation. Previous results have shown that methyl methane sulfonate (MMS) can help Paulownia seedlings recover from the symptoms of witches' broom and reinstate a healthy morphology. In this study, a transcriptomic-assisted proteomic technique was used to analyze the protein changes in phytoplasma-infected Paulownia tomentosa seedlings, phytoplasma-infected seedlings treated with 20 and 60 mg·L^-1 MMS, and healthy seedlings. A total of 2,051 proteins were obtained, 879 of which were found to be differentially abundant in pairwise comparisons between the sample groups. Among the differentially abundant proteins, 43 were related to Paulownia witches' broom disease and many of them were annotated to be involved in photosynthesis, expression of dwarf symptom, energy production, and cell signal pathways.

Narrow-Leafed Lupin (Lupinus angustifolius) β1- and β6-Conglutin Proteins Exhibit Antifungal Activity, Protecting Plants against Necrotrophic Pathogen Induced Damage from Sclerotinia sclerotiorum and Phytophthora nicotianae

Vicilins (7S globulins) are seed storage proteins and constitute the main protein family in legume seeds, particularly in narrow-leafed lupin (Lupinus angustifolius L.; NLL), where seven vicilin genes, called β1- to β7-conglutin have been identified. Vicilins are involved in germination processes supplying amino acids for seedling growth and plant development, as well as in some cases roles in plant defense and protection against pathogens. The roles of NLL β-conglutins in plant defense are unknown. Here the potential role of five NLL β-conglutin family members in protection against necrotrophic fungal pathogens was investigated and it was demonstrated that recombinant purified 6xHis-tagged β1- and β6-conglutin proteins exhibited the strongest in vitro growth inhibitory activity against a range of necrotrophic fungal pathogens compared to β2, β3, and β4 conglutins. To examine activity in vivo, two representative necrotrophic pathogens, the fungus Sclerotinia sclerotiorum and oomycete Phytophthora nicotianae were used. Transient expression of β1- and β6-conglutin proteins in Nicotiana benthamiana leaves demonstrated in vivo growth suppression of both of these pathogens, resulting in low percentages of hyphal growth and elongation in comparison to control treated leaves. Cellular studies using β1- and β6-GFP fusion proteins showed these conglutins localized to the cell surface including plasmodesmata. Analysis of cellular death following S. sclerotiorum or P. nicotianae revealed both β1- and β6-conglutins suppressed pathogen induced cell death in planta and prevented pathogen induced suppression of the plant oxidative burst as determined by protein oxidation in infected compared to mock-inoculated leaves.

Proteomic and physiological approach reveals drought-induced changes in rapeseeds: Water-saver and water-spender strategy

The cultivar-dependent differences in Brassica napus L. seed yield are significantly affected by drought stress. Here, the response of leaf proteome to long-term drought (28days) was studied in cultivars (cvs): Californium (C), Cadeli (D), Navajo (N), and Viking (V). Analysis of twenty-four 2-D DIGE gels revealed 134 spots quantitatively changed at least 2-fold; from these, 79 proteins were significantly identified by MALDI-TOF/TOF. According to the differences in water use, the cultivars may be assigned to two categories: water-savers or water-spenders. In the water-savers group (cvs C+D), proteins related to nitrogen assimilation, ATP and redox homeostasis were increased under stress, while in the water-spenders category (cvs N+V), carbohydrate/energy, photosynthesis, stress related and rRNA processing proteins were increased upon stress. Taking all data together, we indicated cv C as a drought-adaptable water-saver, cv D as a medium-adaptable water-saver, cv N as a drought-adaptable water-spender, and cv V as a low-adaptable drought sensitive water-spender rapeseed. Proteomic data help to evaluate the impact of drought and the extent of genotype-based adaptability and contribute to the understanding of their plasticity. These results provide new insights into the provenience-based drought acclimation/adaptation strategy of contrasting winter rapeseeds and link data at gasometric, biochemical, and proteome level.

SIGNIFICANCE

Soil moisture deficit is a real problem for every crop. The data in this study demonstrates for the first time that in stem-prolongation phase cultivars respond to progressive drought in different ways and at different levels. Analysis of physiological and proteomic data showed two different water regime-related strategies: water-savers and spenders. However, not only water uptake rate itself, but also individual protein abundances, gasometric and biochemical parameters together with final biomass accumulation after stress explained genotype-based responses. Interestingly, under a mixed climate profile, both water-use patterns (savers or spenders) can be appropriate for drought adaptation. These data suggest, than complete "acclimation image" of rapeseeds in stem-prolongation phase under drought could be reached only if these characteristics are taken, explained and understood together.

Contrasting Regulation of NO and ROS in Potato Defense-Associated Metabolism in Response to Pathogens of Different Lifestyles

Our research provides new insights into how the low and steady-state levels of nitric oxide (NO) and reactive oxygen species (ROS) in potato leaves are altered after the challenge with the hemibiotroph Phytophthora infestans or the necrotroph Botrytis cinerea, with the subsequent rapid and invader-dependent modification of defense responses with opposite effects. Mainly in the avirulent (avr) P. infestans–potato system, NO well balanced with the superoxide level was tuned with a battery of SA-dependent defense genes, leading to the establishment of the hypersensitive response (HR) successfully arresting the pathogen. Relatively high levels of S-nitrosoglutathione and S-nitrosothiols concentrated in the main vein of potato leaves indicated the mobile function of these compounds as a reservoir of NO bioactivity. In contrast, low-level production of NO and ROS during virulent (vr) P. infestans-potato interactions might be crucial in the delayed up-regulation of PR-1 and PR-3 genes and compromised resistance to the hemibiotrophic pathogen. In turn, B. cinerea triggered huge NO overproduction and governed inhibition of superoxide production by blunting NADPH oxidase. Nevertheless, a relatively high level of H₂O₂ was found owing to the germin-like activity in cooperation with NO-mediated HR-like cell death in potato genotypes favorable to the necrotrophic pathogen. Moreover, B. cinerea not only provoked cell death, but also modulated the host redox milieu by boosting protein nitration, which attenuated SA production but not SA-dependent defense gene expression. Finally, based on obtained data the organismal cost of having machinery for HR in plant resistance to biotrophs is also discussed, while emphasizing new efforts to identify other components of the NO/ROS cell death pathway and improve plant protection against pathogens of different lifestyles.

Genome-Wide Characterization and Expression Analysis of the Germin-Like Protein Family in Rice and Arabidopsis

Previous studies have shown that germin-like proteins (GLPs) are present ubiquitously in rice and Arabidopsis. However, the understanding regarding their role in development and abiotic/biotic stress resistance remains limited. In the present study, we report genome-wide identification, characterisation, subcellular localization, enzyme activity, and expression analysis of the GLP gene family in rice and Arabidopsis to study their functions. In total, 43 and 32 GLPs in the rice and Arabidopsis genome were identified based on a systematic analysis, respectively. The GLP genes were clustered into six clades based on phylogenetic analysis, and many stress and developmental-related cis-elements were detected in promoters of GLP genes. In addition, subcellular location and superoxide dismutase (SOD) analysis demonstrated that the random selected OsGLP genes on chromosomes 8 and 4 of rice were expressed in the cell wall with SOD activity. Overall, our results showed that tandem duplication events, especially the clusters of tandem duplication genes on chromosome 8 in rice, play a major role in expansion of the GLP family and thus increase our understanding of the role of the GLP family in abiotic/biotic stress and development.

Transcriptomic comparison between Brassica oleracea and rice (Oryza sativa) reveals diverse modulations on cell death in response to Sclerotinia sclerotiorum

Sclerotinia stem rot caused by Sclerotinia sclerotiorum is a devastating disease of Brassica crops, but not in rice. The leaves of a rice line, a partial resistant (R) and a susceptible (S) Brassica oleracea pool that bulked from a resistance-segregating F2 population were employed for transcriptome sequencing before and after inoculation by S. sclerotiorum for 6 and 12 h. Distinct transcriptome profiles were revealed between B. oleracea and rice in response to S. sclerotiorum. Enrichment analyses of GO and KEGG indicated an enhancement of antioxidant activity in the R B. oleracea and rice, and histochemical staining exhibited obvious lighter reactive oxygen species (ROS) accumulation and cell death in rice and the R B. oleracea as compared to that in the S B. oleracea. Significant enhancement of Ca(2+) signalling, a positive regulator of ROS and cell death, were detected in S B. oleracea after inoculation, while it was significantly repressed in the R B. oleracea group. Obvious difference was detected between two B. oleracea groups for WRKY transcription factors, particularly for those regulating cell death. These findings suggest diverse modulations on cell death in host in response to S. sclerotiorum. Our study provides useful insight into the resistant mechanism to S. sclerotiorum.

Protein Dynamics in the Plant Extracellular Space

The extracellular space (ECS or apoplast) is the plant cell compartment external to the plasma membrane, which includes the cell walls, the intercellular space and the apoplastic fluid (APF). The present review is focused on APF proteomics papers and intends to draw information on the metabolic processes occurring in the ECS under abiotic and biotic stresses, as well as under non-challenged conditions. The large majority of the proteins detected are involved in "cell wall organization and biogenesis", "response to stimulus" and "protein metabolism". It becomes apparent that some proteins are always detected, irrespective of the experimental conditions, although with different relative contribution. This fact suggests that non-challenged plants have intrinsic constitutive metabolic processes of stress/defense in the ECS. In addition to the multiple functions ascribed to the ECS proteins, should be considered the interactions established between themselves and with the plasma membrane and its components. These interactions are crucial in connecting exterior and interior of the cell, and even simple protein actions in the ECS can have profound effects on plant performance. The proteins of the ECS are permanently contributing to the high dynamic nature of this plant compartment, which seems fundamental to plant development and adaptation to the environmental conditions.

Reactive oxygen species, essential molecules, during plant-pathogen interactions

Reactive oxygen species (ROS) are continually generated as a consequence of the normal metabolism in aerobic organisms. Accumulation and release of ROS into cell take place in response to a wide variety of adverse environmental conditions including salt, temperature, cold stresses and pathogen attack, among others. In plants, peroxidases class III, NADPH oxidase (NOX) locates in cell wall and plasma membrane, respectively, may be mainly enzymatic systems involving ROS generation. It is well documented that ROS play a dual role into cells, acting as important signal transduction molecules and as toxic molecules with strong oxidant power, however some aspects related to its function during plant-pathogen interactions remain unclear. This review focuses on the principal enzymatic systems involving ROS generation addressing the role of ROS as signal molecules during plant-pathogen interactions. We described how the chloroplasts, mitochondria and peroxisomes perceive the external stimuli as pathogen invasion, and trigger resistance response using ROS as signal molecule.

De novo Transcriptome Analysis of Rhizoctonia solani AG1 IA Strain Early Invasion in Zoysia japonica Root

Zoysia japonica brown spot was caused by necrotrophic fungus Rhizoctonia solani invasion, which led to severe financial loss in city lawn and golf ground maintenance. However, little was known about the molecular mechanism of R. solani pathogenicity in Z. japonica. In this study we examined early stage interaction between R. solani AG1 IA strain and Z. japonica cultivar “Zenith” root by cell ultra-structure analysis, pathogenesis-related proteins assay and transcriptome analysis to explore molecular clues for AG1 IA strain pathogenicity in Z. japonica. No obvious cell structure damage was found in infected roots and most pathogenesis-related protein activities showedg a downward trend especially in 36 h post inoculation, which exhibits AG1 IA strain stealthy invasion characteristic. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database classification, most DEGs in infected “Zenith” roots dynamically changed especially in three aspects, signal transduction, gene translation, and protein synthesis. Total 3422 unigenes of “Zenith” root were predicted into 14 kinds of resistance (R) gene class. Potential fungal resistance related unigenes of “Zenith” root were involved in ligin biosynthesis, phytoalexin synthesis, oxidative burst, wax biosynthesis, while two down-regulated unigenes encoding leucine-rich repeat receptor protein kinase and subtilisin-like protease might be important for host-derived signal perception to AG1 IA strain invasion. According to Pathogen Host Interaction (PHI) database annotation, 1508 unigenes of AG1 IA strain were predicted and classified into 37 known pathogen species, in addition, unigenes encoding virulence, signaling, host stress tolerance, and potential effector were also predicted. This research uncovered transcriptional profiling during the early phase interaction between R. solani AG1 IA strain and Z. japonica, and will greatly help identify key pathogenicity of AG1 IA strain.

Reactive Oxygen Species Play a Role in the Infection of the Necrotrophic Fungi, Rhizoctonia solani in Wheat

Rhizoctonia solani is a nectrotrophic fungal pathogen that causes billions of dollars of damage to agriculture worldwide and infects a broad host range including wheat, rice, potato and legumes. In this study we identify wheat genes that are differentially expressed in response to the R. solani isolate, AG8, using microarray technology. A significant number of wheat genes identified in this screen were involved in reactive oxygen species (ROS) production and redox regulation. Levels of ROS species were increased in wheat root tissue following R. solani infection as determined by Nitro Blue Tetrazolium (NBT), 3,3'-diaminobenzidine (DAB) and titanium sulphate measurements. Pathogen/ROS related genes from R. solani were also tested for expression patterns upon wheat infection. TmpL, a R. solani gene homologous to a gene associated with ROS regulation in Alternaria brassicicola, and OAH, a R. solani gene homologous to oxaloacetate acetylhydrolase which has been shown to produce oxalic acid in Sclerotinia sclerotiorum, were highly induced in R. solani when infecting wheat. We speculate that the interplay between the wheat and R. solani ROS generating proteins may be important for determining the outcome of the wheat/R. solani interaction.

TMT-based quantitative proteomics analyses reveal novel defense mechanisms of Brassica napus against the devastating necrotrophic pathogen Sclerotinia sclerotiorum

The white mould disease, caused by Sclerotinia sclerotiorum, is one of the most important diseases in the vital oil crop Brassica napus. Nevertheless, the defense mechanisms of B. napus against S. sclerotiorum are poorly understood. In this study, we performed comparative quantitative proteomics analyses to reveal B. napus defense mechanisms against S. sclerotiorum. The proteomes of B. napus leaves inoculated with S. sclerotiorum wild-type strain 1980 and nonpathogenic mutant strain Ep-1PB as well as empty agar plug as the control were analyzed using TMT label-based quantitative analysis technique. A total of 79, 299 and 173 proteins consistently differentially expressed between Ep-1PB- and mock-inoculated leaves, 1980- and mock-inoculated leaves, as well as 1980- and Ep-1PB-inoculated leaves, respectively, were identified. The differential expression of 12 selected proteins was confirmed by qRT-PCR analyses. The Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein-protein interaction prediction analyses revealed that redox homeostasis, lipid signaling, calcium signaling, histone and DNA methylation-mediated transcription regulation and defense-related proteins such as defensin and defensin-like proteins and cyanate lyase, contribute to defense against S. sclerotiorum. Our results provide new insights into molecular mechanisms that may be involved in defense responses of B. napus to S. sclerotiorum.

SIGNIFICANCE

The Sclerotinia white mould disease is one of the most important diseases in the significant oil crop Brassica napus. Nevertheless, the defense mechanisms of B. napus against S. sclerotiorum are still largely unknown to date. In this study, we addressed this issue by performing TMT label-based comparative quantitative analyses of the proteomes of B. napus leaves inoculated with S. sclerotiorum wild-type strain 1980 and nonpathogenic mutant strain Ep-1PB as well as empty agar plug as the control. Through comparative analyses on 79, 299, and 173 proteins that are consistently differentially expressed in between Ep-1PB-inoculated and the control leaves, 1980-inoculated and the control leaves, as well as 1980-inoculated and Ep-1PB-inoculated leaves, respectively, we revealed that redox homeostasis, lipid signaling, calcium signaling, histone and DNA methylation-mediated transcription regulation and defense-related proteins such as defensin and defensin-like proteins as well as cyanate lyase, contribute to B. napus defenses against S. sclerotiorum. Notably, the potential role of lipid signaling, calcium signaling, histone and DNA methylation-mediated transcription regulation and cyanate lyase in B. napus defense against S. sclerotiorum are not reported previously but rather unveiled for the first time in this study. The current study represents the most extensive analysis of the protein profile of B. napus in response to S. sclerotiorum inoculation and includes for the first time the results from comparison between plants inoculated with the wild-type strain and a nonpathogenic mutant strain of S. sclerotiorum. Collectively, our results provide new insights into the molecular mechanisms of interactions between B. napus and S. sclerotiorum.

Proteins involved in biophoton emission and flooding-stress responses in soybean under light and dark conditions

To know the molecular systems basically flooding conditions in soybean, biophoton emission measurements and proteomic analyses were carried out for flooding-stressed roots under light and dark conditions. Photon emission was analyzed using a photon counter. Gel-free quantitative proteomics were performed to identify significant changes proteins using the nano LC-MS along with SIEVE software. Biophoton emissions were significantly increased in both light and dark conditions after flooding stress, but gradually decreased with continued flooding exposure compared to the control plants. Among the 120 significantly identified proteins in the roots of soybean plants, 73 and 19 proteins were decreased and increased in the light condition, respectively, and 4 and 24 proteins were increased and decreased, respectively, in the dark condition. The proteins were mainly functionally grouped into cell organization, protein degradation/synthesis, and glycolysis. The highly abundant lactate/malate dehydrogenase proteins were decreased in flooding-stressed roots exposed to light, whereas the lysine ketoglutarate reductase/saccharopine dehydrogenase bifunctional enzyme was increased in both light and dark conditions. Notably, however, specific enzyme assays revealed that the activities of these enzymes and biophoton emission were sharply increased after 3 days of flooding stress. This finding suggests that the source of biophoton emission in roots might involve the chemical excitation of electron or proton through enzymatic or non-enzymatic oxidation and reduction reactions. Moreover, the lysine ketoglutarate reductase/saccharopine dehydrogenase bifunctional enzyme may play important roles in responses in flooding stress of soybean under the light condition and as a contributing factor to biophoton emission.

Attack modes and defence reactions in pathosystems involving Sclerotinia sclerotiorum, Brassica carinata, B. juncea and B. napus

BACKGROUND AND AIMS

Sclerotinia stem rot (SSR, Sclerotinia sclerotiorum) is a damaging disease of oilseed brassicas world-wide. Host resistance is urgently needed to achieve control, yet the factors that contribute to stem resistance are not well understood. This study investigated the mechanisms of resistance to SSR.

METHODS

Stems of 5-week-old Brassica carinata, B. juncea and B. napus of known resistance were infected via filter paper discs impregnated with S. sclerotiorum mycelium under controlled conditions. Transverse sections of the stem and portions of the stem surface were examined using optical and scanning electron microscopy. The association of anatomical features with the severity of disease (measured by mean lesion length) was determined.

KEY RESULTS

Several distinct resistance mechanisms were recorded for the first time in these Brassica-pathogen interactions, including hypersensitive reactions and lignification within the stem cortex, endodermis and in tissues surrounding the lesions. Genotypes showing a strong lignification response 72 h post-infection (hpi) tended to have smaller lesions. Extensive vascular invasion by S. sclerotiorum was observed only in susceptible genotypes, especially in the vascular fibres and xylem. Mean lesion length was negatively correlated with the number of cell layers in the cortex, suggesting progress of S. sclerotiorum is impeded by more cell layers. Hyphae in the centre of lesions became highly vacuolate 72 hpi, reflecting an ageing process in S. sclerotiorum hyphal networks that was independent of host resistance. The infection process of S. sclerotiorum was analogous in B. carinata and B. napus. Infection cushions of the highly virulent isolate of S. sclerotiorum MBRS-1 were grouped together in dense parallel bundles, while hyphae in the infection cushions of a less aggressive isolate WW-3 were more diffuse, and this was unaffected by host genotype.

CONCLUSIONS

A variety of mechanisms contribute to host resistance against S. sclerotiorum across the three Brassica species. These complex interactions between pathogen and host help to explain variable expressions of resistance often observed in the field.

Emerging Trends in Molecular Interactions between Plants and the Broad Host Range Fungal Pathogens Botrytis cinerea and Sclerotinia sclerotiorum

Fungal plant pathogens are major threats to food security worldwide. Sclerotinia sclerotiorum and Botrytis cinerea are closely related Ascomycete plant pathogens causing mold diseases on hundreds of plant species. There is no genetic source of complete plant resistance to these broad host range pathogens known to date. Instead, natural plant populations show a continuum of resistance levels controlled by multiple genes, a phenotype designated as quantitative disease resistance. Little is known about the molecular mechanisms controlling the interaction between plants and S. sclerotiorum and B. cinerea but significant advances were made on this topic in the last years. This minireview highlights a selection of nine themes that emerged in recent research reports on the molecular bases of plant-S. sclerotiorum and plant-B. cinerea interactions. On the fungal side, this includes progress on understanding the role of oxalic acid, on the study of fungal small secreted proteins. Next, we discuss the exchanges of small RNA between organisms and the control of cell death in plant and fungi during pathogenic interactions. Finally on the plant side, we highlight defense priming by mechanical signals, the characterization of plant Receptor-like proteins and the hormone abscisic acid in the response to B. cinerea and S. sclerotiorum, the role of plant general transcription machinery and plant small bioactive peptides. These represent nine trends we selected as remarkable in our understanding of fungal molecules causing disease and plant mechanisms associated with disease resistance to two devastating broad host range fungi.