HyPRP1 performs a role in negatively regulating cotton resistance to V. dahliae via the thickening of cell walls and ROS accumulation

A novel role of the cotton calcium sensor CBL3 was involved in Verticillium wilt resistance in cotton

BACKGROUND

Verticillium wilt, causes mainly by the soilborne pathogen Verticillium dahliae, is a devastated vascular disease resulting in huge financial losses in cotton, so research on improving V. dahliae stress tolerance in cotton is the utmost importance. Calcium as the second messenger acts as a crucial role in plant innate immunity. Cytosolic Ca2+during the pathogen infection is a significant increase in plant immune responses. Calcineurin B-like (CBL) proteins are widely known calcium sensors that regulate abiotic stress responses. However, the role of cotton CBLs in response to V. dahliae stress remains unclear.

OBJECTIVE

To discover and utilize the gene to Verticillium wilt resistance and defense response mechanism of cotton.

METHODS

Through screening the gene to Verticillium wilt resistance in cotton, four GhCBL3 copies were obtained from the current common cotton genome sequences. The protein domain and phylogenetic analyses of GhCBL3 were performed using NCBI Blast, DNAMAN, and MotifScan programs. Real-time RT-PCR was used to detect the expression of GhCBL3 gene in cotton seedlings under various stress treatments. The expression construct including GhCBL3 cDNA was transduced into Agrobacterium tumefaciens (GV3101) by heat shock method and transformed into cotton plants by Virus-Induced Gene Silencing (VIGS) method. The results of silencing of GhCBl3 on ROS accumulation and plant disease resistance in cotton plants were assessed.

RESULTS

A member of calcineurin B-like proteins (defined as GhCBL3) in cotton was obtained. The expression of GhCBL3 was significantly induced and raised by various stressors, including dahliae, jasmonic acid (JA) and H2O2 stresses. Knockdown GhCBL3 in cotton by Virus-Induced Gene Silencing analysis enhanced Verticillium wilt tolerance and changed the occurrence of reactive oxygen species. Some disease-resistant genes were increased in GhCBL3-silencing cotton lines.

CONCLUSION

GhCBL3 may function on regulating the Verticillium dahliae stress response of plants.

Unraveling verticillium wilt resistance: insight from the integration of transcriptome and metabolome in wild eggplant

Verticillium wilt, caused by Verticillium dahliae, is a soil-borne disease affecting eggplant. Wild eggplant, recognized as an excellent disease-resistant resource against verticillium wilt, plays a pivotal role in grafting and breeding for disease resistance. However, the underlying resistance mechanisms of wild eggplant remain poorly understood. This study compared two wild eggplant varieties, LC-2 (high resistance) and LC-7 (sensitive) at the phenotypic, transcriptomic, and metabolomic levels to determine the molecular basis of their resistance to verticillium wilt. These two varieties exhibit substantial phenotypic differences in petal color, leaf spines, and fruit traits. Following inoculation with V. dahliae, LC-2 demonstrated significantly higher activities of polyphenol oxidase, superoxide dismutase, peroxidase, phenylalanine ammonia lyase, β-1,3 glucanase, and chitinase than did LC-7. RNA sequencing revealed 4,017 differentially expressed genes (DEGs), with a significant portion implicated in processes associated with disease resistance and growth. These processes encompassed defense responses, cell wall biogenesis, developmental processes, and biosynthesis of spermidine, cinnamic acid, and cutin. A gene co-expression analysis identified 13 transcription factors as hub genes in modules related to plant defense response. Some genes exhibited distinct expression patterns between LC-2 and LC-7, suggesting their crucial roles in responding to infection. Further, metabolome analysis identified 549 differentially accumulated metabolites (DAMs) between LC-2 and LC-7, primarily consisting of compounds such as flavonoids, phenolic acids, lipids, and other metabolites. Integrated transcriptome and metabolome analyses revealed the association of 35 gene-metabolite pairs in modules related to the plant defense response, highlighting the interconnected processes underlying the plant defense response. These findings characterize the molecular basis of LC-2 resistance to verticillium wilt and thus have potential value for future breeding of wilt-resistant eggplant varieties.

CRISPR/Cas9-based genome editing and functional analysis of SlHyPRP1 and SlDEA1 genes of Solanum lycopersicum L. in imparting genetic tolerance to multiple stress factors

CRISPR/Cas is a breakthrough genome editing system because of its precision, target specificity, and efficiency. As a speed breeding system, it is more robust than the conventional breeding and biotechnological approaches for qualitative and quantitative trait improvement. Tomato (Solanum lycopersicum L.) is an economically important crop, but its yield and productivity have been severely impacted due to different abiotic and biotic stresses. The recently identified SlHyPRP1 and SlDEA1 are two potential negative regulatory genes in response to different abiotic (drought and salinity) and biotic stress (bacterial leaf spot and bacterial wilt) conditions in S. lycopersicum L. The present study aimed to evaluate the drought, salinity, bacterial leaf spot, and bacterial wilt tolerance response in S. lycopersicum L. crop through CRISPR/Cas9 genome editing of SlHyPRP1 and SlDEA1 and their functional analysis. The transient single- and dual-gene SlHyPRP1 and SlDEA1 CRISPR-edited plants were phenotypically better responsive to multiple stress factors taken under the study. The CRISPR-edited SlHyPRP1 and SlDEA1 plants showed a higher level of chlorophyll and proline content compared to wild-type (WT) plants under abiotic stress conditions. Reactive oxygen species accumulation and the cell death count per total area of leaves and roots under biotic stress were less in CRISPR-edited SlHyPRP1 and SlDEA1 plants compared to WT plants. The study reveals that the combined loss-of-function of SlHyPRP1 along with SlDEA1 is essential for imparting significant multi-stress tolerance (drought, salinity, bacterial leaf spot, and bacterial wilt) in S. lycopersicum L. The main feature of the study is the detailed genetic characterization of SlDEA1, a poorly studied 8CM family gene in multi-stress tolerance, through the CRISPR/Cas9 gene editing system. The study revealed the key negative regulatory role of SlDEA1 that function together as an anchor gene with SlHyPRP1 in imparting multi-stress tolerance in S. lycopersicum L. It was interesting that the present study also showed that transient CRISPR/Cas9 editing events of SlHyPRP1 and SlDEA1 genes were successfully replicated in stably generated parent-genome-edited line (GEd0) and genome-edited first-generation lines (GEd1) of S. lycopersicum L. With these upshots, the study's key findings demonstrate outstanding value in developing sustainable multi-stress tolerance in S. lycopersicum L. and other crops to cope with climate change.

Identification and characterization of the Bicupin domain family and functional analysis of GhBCD11 in response to verticillium wilt in cotton

Bicupin domain protein (BCD) family, an important component of Cupin domain superfamily, plays important roles in oxalic acid (OA) degradation and stress responses in high plants. However, no studies have been reported on the Cupin domain family in cotton up till now. In our study, a total 110 proteins including Cupin domain were identified from the upland cotton (Gossypium hirsutum). Among them, 17 proteins contained Bicupin domain. Subsequently, we found that V. dahliae produces OA leading to cotton leaf wilting. RT-qPCR analysis of GhBCDs revealed that OA and V. dahliae Vd080 significantly enhanced the expression of GhBCD11. The Virus-induced gene silencing and overexpression analysis showed that GhBCD11 positively regulates plant resistance to V. dahliae. Subcellular localization showed GhBCD11 located on the plasma membrane. The analysis of expression pattern showed that GhBCD11 can be induced via hormone-mediated signal pathway including salicylic acid (SA), ethephon (ET), methyl jasmonate (JA) and abscisic acid (ABA). In addition, we identified an interaction between 60 S ribosomal protein GhRPL12-3 and GhBCD11 by yeast double hybridization. Overall, this is the first study, where we identified Cupin domain family in cotton, clarified the role of GhBCD11 in cotton for resistance to V. dahliae and found an interaction between GhRPL12-3 and GhBCD11.

BrMYB108 confers resistance to Verticillium wilt by activating ROS generation in Brassica rapa

Increasing plant resistance to Verticillium wilt (VW), which causes massive losses of Brassica rapa crops, is a challenge worldwide. However, few causal genes for VW resistance have been identified by forward genetic approaches, resulting in limited application in breeding. We combine a genome-wide association study in a natural population and quantitative trait locus mapping in an F2 population and identify that the MYB transcription factor BrMYB108 regulates plant resistance to VW. A 179 bp insertion in the BrMYB108 promoter alters its expression pattern during Verticillium longisporum (VL) infection. High BrMYB108 expression leads to high VL resistance, which is confirmed by disease resistance tests using BrMYB108 overexpression and loss-of-function mutants. Furthermore, we verify that BrMYB108 confers VL resistance by regulating reactive oxygen species (ROS) generation through binding to the promoters of respiratory burst oxidase genes (Rboh). A loss-of-function mutant of AtRbohF in Arabidopsis shows significant susceptibility to VL. Thus, BrMYB108 and its target ROS genes could be used as targets for genetic engineering for VL resistance of B. rapa.

Genome-wide association study reveals novel SNPs and genes in Gossypium hirsutum underlying Aphis gossypii resistance

A. gossypii resistance showed great variability in G. hirsutum varieties. One hundred and seventy-six SNPs associated with A. gossypii resistance were identified using GWAS. Four candidate resistance genes were functionally validated. Aphis gossypii is an economically important sap-feeding pest and is widely distributed in the world's cotton-producing regions. Identification of cotton genotypes and developing cultivars with improved A. gossypii resistance (AGR) is essential and desirable for sustainable agriculture. In the present study, A. gossypii was offered no choice but to propagate on 200 Gossypium hirsutum accessions. A relative aphid reproduction index (RARI) was used to evaluate the AGR, which showed large variability in cotton accessions and was classified into 6 grades. A significantly positive correlation was found between AGR and Verticillium wilt resistance. A total of 176 SNPs significantly associated with the RARI were identified using GWAS. Of these, 21 SNPs could be repeatedly detected in three replicates. Cleaved amplified polymorphic sequence, a restriction digestion-based genotyping assay, was developed using SNP1 with the highest observed -log10(P-value). Four genes within the 650 kb region of SNP1 were further identified, including GhRem (remorin-like), GhLAF1 (long after far-red light 1), GhCFIm25 (pre-mRNA cleavage factor Im 25 kDa subunit) and GhPMEI (plant invertase/pectin methylesterase inhibitor superfamily protein). The aphid infection could induce their expression and showed a significant difference between resistant and susceptible cotton varieties. Silencing of GhRem, GhLAF1 or GhCFIm25 could significantly increase aphid reproduction on cotton seedlings. Silencing of GhRem significantly reduced callose deposition, which is reasonably believed to be the cause for the higher AGR. Our results provide insights into understanding the genetic regulation of AGR in cotton and suggest candidate germplasms, SNPs and genes for developing cultivars with improved AGR.

Establishing a Virus-Induced Gene Silencing System in Lycoris chinensis

Lycoris is an important plant with both medicinal and ornamental values. However, it does not have an efficient genetic transformation system, which makes it difficult to study gene function of the genus. Virus-induced gene silencing (VIGS) is an effective technique for studying gene functions in plants. In this study, we develop an efficient virus-induced gene-silencing (VIGS) system using the leaf tip needle injection method. The widely used TRV vector is constructed, and the Cloroplastos Alterados 1 (CLA1) and Phytoene Desaturase (PDS) genes are selected as visual indicators in the VIGS system. As a result, it is observed that leaves infected with TRV-LcCLA1 and TRV-LcPDS both show a yellowing phenotype (loss of green), and the chlorosis range of TRV-LcCLA1 was larger and deeper than that of TRV-LcPDS. qRT-PCR results show that the expression levels of LcCLA1 and LcPDS are significantly reduced, and the silencing efficiency of LcCLA1 is higher than that of LcPDS. These results indicate that the VIGS system of L. chinensis was preliminarily established, and LcCLA1 is more suitable as a gene-silencing indicator. For the monocotyledonous plant leaves with a waxy surface, the leaf tip injection method greatly improves the infiltration efficiency. The newly established VIGS system will contribute to gene functional research in Lycoris species.

Ca2+-responsive phospholipid-binding BONZAI genes confer a novel role for cotton resistance to Verticillium wilt

Verticillium wilt which produced by the soil-borne fungus Verticillium dahliae is an important biotic threat that limits cotton (Gossypium hirsutum) growth and agricultural productivity. It is very essential to explore new genes for the generation of V. dahliae resistance or tolerance cotton varieties. Ca²⁺ signaling as a secondary messenger is involved in pathogen stress response. Despite Ca²⁺-responsive phospholipid-binding BONZAI (BON) genes have intensively been investigated in Arabidopsis, their function has not still been characterized in cotton. Here, we showed that three copies of GhBON1, two copies of GhBON2 and GhBON3 were found from the genome sequences of upland cotton. The expression of GhBON1 was inducible to V. dahliae. Knocking down of GhBON1, GhBON2 and GhBON3 using virus induced gene silencing (VIGS) each increased up-regulation of defense responses in cotton. These GhBON1, GhBON2 and GhBON3-silenced plants enhanced resistance to V. dahliae accompanied by higher burst of hydrogen peroxide and decreased cell death and had more effect on the up-regulation of defense response genes. Further analysis revealed that GhBON1 could interacts with BAK1-interacting receptor-like kinase 1 (GhBIR1) and pathogen-associated molecular pattern (PAMP) receptor regulator BAK1 (GhBAK1) at plasma membrane. Our study further reveals that plant Ca²⁺ -responsive phospholipid-binding BONZAI genes negatively regulate Verticillium wilt with the conserved function in response to disease resistance or plant immunity.

CRISPR-Cas9-based precise engineering of SlHyPRP1 protein towards multi-stress tolerance in tomato

Recently, CRISPR-Cas9-based genome editing has been widely used for plant breeding. In our previous report, a tomato gene encoding hybrid proline-rich protein 1 (HyPRP1), a negative regulator of salt stress responses, has been edited using a CRISPR-Cas9 multiplexing approach that resulted in precise eliminations of its functional domains, proline-rich domain (PRD) and eight cysteine-motif (8CM). We subsequently demonstrated that eliminating the PRD domain of HyPRP1 in tomatoes conferred the highest level of salinity tolerance. In this study, we characterized the edited lines under several abiotic and biotic stresses to examine the possibility of multiple stress tolerance. Our data reveal that the 8CM removal variants of HK and the KO alleles of both HK and 15T01 cultivars exhibited moderate heat stress tolerance. Similarly, plants carrying either the domains of the PRD removal variant (PR1v1) or 8CM removal variants (PR2v2 and PR2v3) showed better germination under osmosis stress (up to 200 mM mannitol) compared to the WT control. Moreover, the PR1v1 line continuously grew after 5 days of water cutoff. When the edited lines were challenged with pathogenic bacteria of Pseudomonas syringae pv. tomato (Pto) DC3000, the growth of the bacterium was significantly reduced by 2.0- to 2.5-fold compared to that in WT plants. However, the edited alleles enhanced susceptibility against Fusarium oxysporum f. sp. lycopersici, which causes fusarium wilt. CRISPR-Cas9-based precise domain editing of the SlHyPRP1 gene generated multi-stress-tolerant alleles that could be used as genetic materials for tomato breeding.

Insights to Gossypium defense response against Verticillium dahliae: the Cotton Cancer

The soil-borne pathogen Verticillium dahliae, also referred as "The Cotton Cancer," is responsible for causing Verticillium wilt in cotton crops, a destructive disease with a global impact. To infect cotton plants, the pathogen employs multiple virulence mechanisms such as releasing enzymes that degrade cell walls, activating genes that contribute to virulence, and using protein effectors. Conversely, cotton plants have developed numerous defense mechanisms to combat the impact of V. dahliae. These include strengthening the cell wall by producing lignin and depositing callose, discharging reactive oxygen species, and amassing hormones related to defense. Despite the efforts to develop resistant cultivars, there is still no permanent solution to Verticillium wilt due to a limited understanding of the underlying molecular mechanisms that drive both resistance and pathogenesis is currently prevalent. To address this challenge, cutting-edge technologies such as clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9), host-induced gene silencing (HIGS), and gene delivery via nano-carriers could be employed as effective alternatives to control the disease. This article intends to present an overview of V. dahliae virulence mechanisms and discuss the different cotton defense mechanisms against Verticillium wilt, including morphophysiological and biochemical responses and signaling pathways including jasmonic acid (JA), salicylic acid (SA), ethylene (ET), and strigolactones (SLs). Additionally, the article highlights the significance of microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs) in gene expression regulation, as well as the different methods employed to identify and functionally validate genes to achieve resistance against this disease. Gaining a more profound understanding of these mechanisms could potentially result in the creation of more efficient strategies for combating Verticillium wilt in cotton crops.

Changes in the Histology of Walnut (Juglans regia L.) Infected with Phomopsis capsici and Transcriptome and Metabolome Analysis

Phomopsis capsici (P. capsici) causes branch blight of walnuts, which leads to significant economic loss. The molecular mechanism behind the response of walnuts remains unknown. Paraffin sectioning and transcriptome and metabolome analyses were performed to explore the changes in tissue structure, gene expression, and metabolic processes in walnut after infection with P. capsici. We found that P. capsici caused serious damage to xylem vessels during the infestation of walnut branches, destroying the structure and function of the vessels and creating obstacles to the transport of nutrients and water to the branches. The transcriptome results showed that differentially expressed genes (DEGs) were mainly annotated in carbon metabolism and ribosomes. Further metabolome analyses verified the specific induction of carbohydrate and amino acid biosynthesis by P. capsici. Finally, association analysis was performed for DEGs and differentially expressed metabolites (DEMs), which focused on the synthesis and metabolic pathways of amino acids, carbon metabolism, and secondary metabolites and cofactors. Three significant metabolites were identified: succinic semialdehyde acid, fumaric acid, and phosphoenolpyruvic acid. In conclusion, this study provides data reference on the pathogenesis of walnut branch blight and direction for breeding walnut to enhance its disease resistance.

Analysis of PAT1 subfamily members in the GRAS family of upland cotton and functional characterization of GhSCL13-2A in Verticillium dahliae resistance

GhSCL13-2A, a member of the PAT1 subfamily in the GRAS family, positively regulates cotton resistance to Verticillium dahliae by mediating the jasmonic acid and salicylic acid signaling pathways and accumulation of reactive oxygen species. Verticillium wilt (VW) is a devastating disease of upland cotton (Gossypium hirsutum) that is primarily caused by the soil-borne fungus Verticillium dahliae. Scarecrow-like (SCL) proteins are known to be involved in plant abiotic and biotic stress responses, but their roles in cotton defense responses are still unclear. In this study, a total of 25 GhPAT1 subfamily members in the GRAS family were identified in upland cotton. Gene organization and protein domain analysis showed that GhPAT1 members were highly conserved. GhPAT1 genes were widely expressed in various tissues and at multiple developmental stages, and they were responsive to jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) signals. Furthermore, GhSCL13-2A was induced by V. dahliae infection. V. dahliae resistance was enhanced in Arabidopsis thaliana by ectopic overexpression of GhSCL13-2A, whereas cotton GhSCL13-2A knockdowns showed increased susceptibility. Levels of reactive oxygen species (ROS) and JA were also increased and SA content was decreased in GhSCL13-2A knockdowns. At the gene expression level, PR genes and SA signaling marker genes were down-regulated and JA signaling marker genes were upregulated in GhSCL13-2A knockdowns. GhSCL13-2A was shown to be localized to the cell membrane and the nucleus. Yeast two-hybrid and luciferase complementation assays indicated that GhSCL13-2A interacted with GhERF5. In Arabidopsis, V. dahliae resistance was enhanced by GhERF5 overexpression; in cotton, resistance was reduced in GhERF5 knockdowns. This study revealed a positive role of GhSCL13-2A in V. dahliae resistance, establishing it as a strong candidate gene for future breeding of V. dahliae-resistant cotton cultivars.

Multicopper oxidases GbAO and GbSKS are involved in the Verticillium dahliae resistance in Gossypium barbadense

Ascorbate oxidase (AO) and skewed5 (SKU5)-similar (SKS) proteins belong to the multicopper oxidase (MCO) family and play important roles in plants in response to environmental stress via modulation of oxidoreduction homeostasis. Currently, reports on the response of Gossypium barbadense MCO to Verticillium wilt (VW) caused by Verticillium dahliae are still limited. Herein, RNA sequencing of two G. barbadense cultivars of VW-resistant XH21 and VW-susceptible XH7 under V. dahliae treatment, combined with physiological and genetic analysis, was performed to analyze the function and mechanism of multicopper oxidases GbAO and GbSKS involved in V. dahliae resistance. The identified differentially expressed genes are mainly involved in the regulation of oxidoreduction reaction, and extracellular components and signaling. Interestingly, ascorbate oxidase family members were discovered as the most significantly upregulated genes after V. dahliae treatment, including GbAO3A/D, GbSKS3A/D, and GbSKS16A/D. H₂O₂ and Asc contents, especially reductive Asc in both XH21 and XH7, were shown to be increased. Silenced expression of respective GbAO3A/D, GbSKS3A/D, and GbSKS16A/D in virus-induced gene silencing (VIGS) cotton plants significantly decreased the resistance to V. dahliae, coupled with the reduced contents of pectin and lignin. Our results indicate that AO might be involved in cotton VW resistance via the regulation of cell wall components.

Stress responsive OsHyPRP16 promoter driven early expression of resistance gene Pi54 potentiate the resistance against Magnaporthe oryzae in transgenic rice

The rice Hybrid Proline Rich Protein (HyPRP) encoding gene, OsHyPRP16 expression exhibit early upregulation in response to Magnaporthe oryzae inoculation. Here, we functionally characterized the OsHyPRP16 promoter through deletion analysis in transgenic Arabidopsis using GUS (β-glucuronidase) reporter assay. The promoter fragments, sequentially deleted from the 5' end could induce differential GUS activity in response to stresses induced by different hormones and abiotic stress conditions. In addition, a strong GUS induction was observed in M. oryzae inoculated transgenic Arabidopsis. Based on the insilico and stress-inducibility of D1 promoter fragment against various phytohormones and rice blast fungus, and with no basal activity under control conditions, we rationally selected D1 promoter fragment to drive the expression of a major rice blast resistance gene; Pi54 in the genetic background of blast susceptible TP309 rice line. The D1 promoter fragment was able to induce the expression of Pi54 at immediate-early stages of M. oryzae infection in transgenic rice. The transgenic plants with Pi54 under the control of D1 promoter fragment displayed complete resistance against M. oryzae infection as compared to control plants. The present study suggests that the D1 fragment of OsHyPRP16 promoter is a valuable tool for breeding and development of rice lines with early-inducible and pathogen-responsive enhanced disease resistance.

Defense Mechanisms of Cotton Fusarium and Verticillium Wilt and Comparison of Pathogenic Response in Cotton and Humans

Cotton is an important economic crop. Fusarium and Verticillium are the primary pathogenic fungi that threaten both the quality and sustainable production of cotton. As an opportunistic pathogen, Fusarium causes various human diseases, including fungal keratitis, which is the most common. Therefore, there is an urgent need to study and clarify the resistance mechanisms of cotton and humans toward Fusarium in order to mitigate, or eliminate, its harm. Herein, we first discuss the resistance and susceptibility mechanisms of cotton to Fusarium and Verticillium wilt and classify associated genes based on their functions. We then outline the characteristics and pathogenicity of Fusarium and describe the multiple roles of human neutrophils in limiting hyphal growth. Finally, we comprehensively compare the similarities and differences between animal and plant resistance to Fusarium and put forward new insights into novel strategies for cotton disease resistance breeding and treatment of Fusarium infection in humans.

Identification and analysis of proline-rich proteins and hybrid proline-rich proteins super family genes from Sorghum bicolor and their expression patterns to abiotic stress and zinc stimuli

Systematic genome-wide analysis of Sorghum bicolor revealed the identification of a total of 48 homologous genes comprising 21 proline-rich proteins (PRPs) and 27 hybrid proline-rich proteins (HyPRPs). Comprehensive scrutiny of these gene homologs was conducted for gene structure, phylogenetic investigations, chromosome mapping, and subcellular localization of proteins. Promoter analysis uncovered the regions rich with phosphorous- (BIHD), ammonium-, sulfur-responsive (SURE), and iron starvation-responsive (IRO2) along with biotic, abiotic, and development-specific cis-elements. Further, PRPs exhibit more methylation and acetylation sites in comparison with HyPRPs. miRNAs have been predicted which might play a role in cleavage and translation inhibition. Several of the SbPRP genes were stimulated in a tissue-specific manner under drought, salt, heat, and cold stresses. Additionally, exposure of plants to abscisic acid (ABA) and zinc (Zn) also triggered PRP genes in a tissue-dependent way. Among them, SbPRP17 has been found upregulated markedly in all tissues irrespective of the stress imposed. The expressions of SbHyPRPs, especially SbHyPRP2, SbHyPRP6, and SbHyPRP17 were activated under all stresses in all three tissues. On the other hand, SbHyPRP8 (root only) and SbHyPRP12 (all three tissues) were highly responsive to cold stress and ABA while SbHyPRP26 was induced by drought and Zn in the stem. Taken together, this study indicates the critical roles that SbPRPs and SbHyPRPs play during diverse abiotic stress conditions and notably the plausible roles that these genes play upon exposure to zinc, the crucial micronutrient in plants.

Comparative Proteomic Analysis Reveals the Ascorbate Peroxidase-Mediated Plant Resistance to Verticillium dahliae in Gossypium barbadense

In previous research on the resistance of cotton to Verticillium wilt (VW), Gossypium hirsutum and G. barbadense were usually used as the susceptible and resistant cotton species, despite their different genetic backgrounds. Herein, we present data independent acquisition (DIA)-based comparative proteomic analysis of two G. barbadense cultivars differing in VW tolerance, susceptible XH7 and resistant XH21. A total of 4,118 proteins were identified, and 885 of them were differentially abundant proteins (DAPs). Eight co-expressed modules were identified through weighted gene co-expression network analysis. GO enrichment analysis of the module that significantly correlated with V. dahliae infection time revealed that oxidoreductase and peroxidase were the most significantly enriched GO terms. The last-step rate-limiting enzyme for ascorbate acid (AsA) biosynthesis was further uncovered in the significantly enriched GO terms of the 184 XH21-specific DAPs. Additionally, the expression of ascorbate peroxidase (APX) members showed quick accumulation after inoculation. Compared to XH7, XH21 contained consistently higher AsA contents and rapidly increased levels of APX expression, suggesting their potential importance for the resistance to V. dahliae. Silencing GbAPX1/12 in both XH7 and XH 21 resulted in a dramatic reduction in VW resistance. Our data indicate that APX-mediated oxidoreductive metabolism is important for VW resistance in cotton.

Identification and expression analysis of arabinogalactan protein genes in cotton reveal the function of GhAGP15 in Verticillium dahliae resistance

Verticillium wilt, primarily caused by the fungal pathogen Verticillium dahliae, is a serious disease in cotton. Arabinogalactan proteins (AGPs), a class of hydroxyproline-rich glycoproteins, have been widely implicated in plant growth and environmental adaptation. The purpose of this study is to identify and characterize AGP members in cotton plants and explore their roles in responding to environmental stressors. In total, 65 GhAGP members were identified in upland cotton (Gossypium hirsutum), along with 43, 35, and 37 AGP members that were also identified in G. barbadense, G. arboreum, and G. raimondii, respectively. According to gene structure and protein domains analysis, GhAGP genes in upland cotton are highly conserved. Meanwhile, tandem duplication events have occurred frequently throughout cotton's evolutionary history. Expression analysis showed that GhAGP genes were widely expressed during growth and development and in response to abiotic stressors. Many cis-elements related to hormonal responses and environmental stressors were detected in GhAGP promoter regions. GhAGP genes participate in responding to cold, drought, and salt stress, and were sensitive to ET signaling. Furthermore, the expression level of GhAGP15 was elevated during V. dahliae infection and resistance against V. dahliae in upland cotton was significantly weakened by silencing GhAGP15 using a virus-induced gene silencing (VIGS) approach. Our results further suggest that the function of GhAGP15 in V. dahliae resistance might be involved in regulation of the JA, SA, and reactive oxygen species (ROS) pathways. The comprehensive analysis of AGP genes in cotton performed in this study provides a basic framework for further functional research of these genes.

Analysis of the PRA1 Genes in Cotton Identifies the Role of GhPRA1.B1-1A in Verticillium dahliae Resistance

Verticillium wilt in cotton (Gossypium hirsutum) is primarily caused by Verticillium dahliae. Previous data suggest that prenylated RAB acceptors (PRAs) play essential roles in environmental plant adaptation, although the potential roles of PRA1 in cotton are unclear. Therefore, in this study, PRA1 family members were identified in G. hirsutum, and their roles in biotic and abiotic stresses were analyzed. Thirty-seven GhPRA1 family members were identified in upland cotton, which were divided into eight groups. Gene structure and domain analyses revealed that the sequences of GhPRA1 members in each group were highly conserved. Many environmental stress-related and hormone-response cis-acting elements were identified in the GhPRA1 promoter regions, indicating that they may respond to biotic and abiotic stresses. Expression analysis revealed that GhPRA1 members were widely expressed in upland cotton. The GhPRA1 genes responded to abiotic stress: drought, cold, salt, and heat stress. GhPRA1.B1-1A expression increased after V. dahliae infection. Furthermore, the functional role of GhPRA1.B1-1A was confirmed by overexpression in Arabidopsis thaliana, which enhanced the resistance to V. dahliae. In contrast, V. dahliae resistance was significantly weakened via virus-induced gene silencing of GhPRA1.B1-1A in upland cotton. Simultaneously, reactive oxygen species accumulation; the H2O2, salicylic acid, and jasmonic acid contents; and callose deposition were significantly decreased in cotton plants with GhPRA1.B1-1A silencing. These findings contribute to a better understanding of the biological roles of GhPRA1 proteins and provide candidate genes for cotton breeders for breeding V. dahliae-resistant cultivars.

OsHyPRP06/R3L1 regulates root system development and salt tolerance via apoplastic ROS homeostasis in rice (Oryza sativa L.)

Plant root morphology is constantly reshaped in response to triggers from the soil environment. Such modifications in root system architecture involve changes in the abundance of reactive oxygen species (ROS) in the apoplast and in cell wall (CW) composition. The hybrid proline-rich proteins (HyPRPs) gene family in higher plants is considered important in the regulation of CW structure. However, the functions of HyPRPs remain to be characterized. We therefore analysed the functions of OsR3L1 (Os04g0554500) in rice. qRT-PCR and GUS staining revealed that OsR3L1 is expressed in roots. While the r3l1 mutants had a defective root system with fewer adventitious roots (ARs) and lateral roots (LRs) than the wild type, lines overexpressing OsR3L1 (R3L1-OE) showed more extensive LR formation but with a shorter root length. The expression of OsR3L1 was initiated by the OsMADS25 transcription factor. Moreover, the abundance of OsR3L1 transcripts was increased by NaCl. The R3L1-OE-3 line exhibited enhanced salt tolerance, whereas the r3l1-2 mutant showed greater salt sensitivity. The addition of H₂ O₂ increased the levels of OsR3L1 transcripts. Data are presented indicating that OsR3L1 modulates H₂ O₂ accumulation in the apoplast. We conclude that OsR3L1 regulates salt tolerance through regulation of peroxidases and apoplastic H₂ O₂ metabolism.

Identification of cell wall-associated kinases as important regulators involved in Gossypium hirsutum resistance to Verticillium dahliae

BACKGROUND

Verticillium wilt, caused by the soil borne fungus Verticillium dahliae, is a major threat to cotton production worldwide. An increasing number of findings indicate that WAK genes participate in plant-pathogen interactions, but their roles in cotton resistance to V. dahliae remain largely unclear.

RESULTS

Here, we carried out a genome-wide analysis of WAK gene family in Gossypium hirsutum that resulted in the identification of 81 putative GhWAKs, which were all predicated to be localized on plasma membrane. In which, GhWAK77 as a representative was further located in tobacco epidermal cells using transient expression of fluorescent fusion proteins. All GhWAKs could be classified into seven groups according to their diverse protein domains, indicating that they might sense different outside signals to trigger intracellular signaling pathways that were response to various environmental stresses. A lot of cis-regulatory elements were predicted in the upstream region of GhWAKs and classified into four main groups including hormones, biotic, abiotic and light. As many as 28 GhWAKs, playing a potential role in the interaction between cotton and V. dahliae, were screened out by RNA-seq and qRT-PCR. To further study the function of GhWAKs in cotton resistance to V. dahliae, VIGS technology was used to silence GhWAKs. At 20 dpi, VIGSed plants exhibited more chlorosis and wilting than the control plants. The disease indices of VIGSed plants were also significantly higher than those of the control. Furthermore, silencing of GhWAKs significantly affected the expression of JA- and SA-related marker genes, increased the spread of V. dahliae in the cotton stems, dramatically compromised V. dahliae-induced accumulation of lignin, H2O2 and NO, but enhanced POD activity.

CONCLUSION

Our study presents a comprehensive analysis on cotton WAK gene family for the first time. Expression analysis and VIGS assay provided direct evidences on GhWAKs participation in the cotton resistance to V. dahliae.

Response of Resistant and Susceptible Bayberry Cultivars to Infection of Twig Blight Pathogen by Histological Observation and Gibberellin Related Genes Expression

Bayberry is an important fruit tree native to the subtropical regions of China. However, a systematic twig blight disease caused by Pestalotiopsis versicolor and P. microspora, resulted in the death of the whole tree of bayberry. The main variety Dongkui is highly sensitive to the twig blight disease, but the variety Zaojia is very highly resistant to the disease. Therefore, it is very necessary to clear the difference between resistant and susceptible varieties in response to the fungal infection. In this paper, we investigated the response of resistant and susceptible bayberry cultivars to infection of twig blight pathogen by histological observation and gibberellin signaling pathway-related genes expression. Microscopic observation revealed the difference in the infection process between resistant and susceptible varieties. The results of frozen scanning electron microscopy showed that the Pestalotiopsis conidia were shrunk, the mycelium was shriveled and did not extend into the cells of resistant cultivars, while the conidia were full and the top was extended, the mycelia was normal and continued to extend to the cells of a susceptible cultivar. Indeed, the medulla cells were almost intact in resistant cultivar, but obviously damaged in susceptible cultivar after inoculation of the main fungal pathogen P. versicolor conidia, which is earlier germinated on sterile glass slide than that of a hard plastic slide. The quantitative real-time PCR results showed a significant difference between resistant and susceptible cultivars in the expression of gibberellin signaling pathway-related genes in leaves and stems of bayberry, which is closely related to infection time, the type of genes and varieties. Overall, this study provides a clue for our understanding of the resistance mechanism of bayberry against the twig blight disease.

Genome-Wide Analysis of Ribosomal Protein GhRPS6 and Its Role in Cotton Verticillium Wilt Resistance

Verticillium wilt is threatening the world’s cotton production. The pathogenic fungus Verticillium dahliae can survive in the soil in the form of microsclerotia for a long time, colonize through the root of cotton, and invade into vascular bundles, causing yellowing and wilting of cotton leaves, and in serious cases, leading to plant death. Breeding resistant varieties is the most economical and effective method to control Verticillium wilt. In previous studies, proteomic analysis was carried out on different cotton varieties inoculated with V. dahliae strain Vd080. It was found that GhRPS6 was phosphorylated after inoculation, and the phosphorylation level in resistant cultivars was 1.5 times than that in susceptible cultivars. In this study, knockdown of GhRPS6 expression results in the reduction of SA and JA content, and suppresses a series of defensive response, enhancing cotton plants susceptibility to V. dahliae. Overexpression in Arabidopsis thaliana transgenic plants was found to be more resistant to V. dahliae. Further, serines at 237 and 240 were mutated to phenylalanine, respectively and jointly. The transgenic Arabidopsis plants demonstrated that seri-237 compromised the plant resistance to V. dahliae. Subcellular localization in Nicotiana benthamiana showed that GhRPS6 was localized in the nucleus. Additionally, the pathogen inoculation and phosphorylation site mutation did not change its localization. These results indicate that GhRPS6 is a potential molecular target for improving resistance to Verticillium wilt in cotton. This lays a foundation for breeding disease-resistant varieties.

Evolution, expression and functional analysis of cultivated allotetraploid cotton DIR genes

BACKGROUND

Dirigent (DIR) proteins mediate regioselectivity and stereoselectivity during lignan biosynthesis and are also involved in lignin, gossypol and pterocarpan biosynthesis. This gene family plays a vital role in enhancing stress resistance and in secondary cell-wall development, but systematical understanding is lacking in cotton.

RESULTS

In this study, 107 GbDIRs and 107 GhDIRs were identified in Gossypium barbadense and Gossypium hirsutum, respectively. Most of these genes have a classical gene structure without intron and encode proteins containing a signal peptide. Phylogenetic analysis showed that cotton DIR genes were classified into four distinct subfamilies (a, b/d, e, and f). Of these groups, DIR-a and DIR-e were evolutionarily conserved, and segmental and tandem duplications contributed equally to their formation. In contrast, DIR-b/d mainly expanded by recent tandem duplications, accompanying with a number of gene clusters. With the rapid evolution, DIR-b/d-III was a Gossypium-specific clade involved in atropselective synthesis of gossypol. RNA-seq data highlighted GhDIRs in response to Verticillium dahliae infection and suggested that DIR gene family could confer Verticillium wilt resistance. We also identified candidate DIR genes related to fiber development in G. barbadense and G. hirsutum and revealed their differential expression. To further determine the involvement of DIR genes in fiber development, we overexpressed a fiber length-related gene GbDIR78 in Arabidopsis and validated its function in trichomes and hypocotyls.

CONCLUSIONS

These findings contribute novel insights towards the evolution of DIR gene family and provide valuable information for further understanding the roles of DIR genes in cotton fiber development as well as in stress responses.

Transcriptome Analysis Revealed GhWOX4 Intercedes Myriad Regulatory Pathways to Modulate Drought Tolerance and Vascular Growth in Cotton

Cotton is a paramount cash crop around the globe. Among all abiotic stresses, drought is a leading cause of cotton growth and yield loss. However, the molecular link between drought stress and vascular growth and development is relatively uncharted. Here, we validated a crucial role of GhWOX4, a transcription factor, modulating drought stress with that of vasculature growth in cotton. Knock-down of GhWOX4 decreased the stem width and severely compromised vascular growth and drought tolerance. Conversely, ectopic expression of GhWOX4 in Arabidopsis enhanced the tolerance to drought stress. Comparative RNAseq analysis revealed auxin responsive protein (AUX/IAA), abscisic acid (ABA), and ethylene were significantly induced. Additionally, MYC-bHLH, WRKY, MYB, homeodomain, and heat-shock transcription factors (HSF) were differentially expressed in control plants as compared to GhWOX4-silenced plants. The promotor zone of GhWOX4 was found congested with plant growth, light, and stress response related cis-elements. differentially expressed genes (DEGs) related to stress, water deprivation, and desiccation response were repressed in drought treated GhWOX4-virus-induced gene silencing (VIGS) plants as compared to control. Gene ontology (GO) functions related to cell proliferation, light response, fluid transport, and flavonoid biosynthesis were over-induced in TRV: 156-0 h/TRV: 156-1 h (control) in comparison to TRV: VIGS-0 h/TRV: VIGS-1 h (GhWOX4-silenced) plants. This study improves our context for elucidating the pivotal role of GhWOX4 transcription factors (TF), which mediates drought tolerance, plays a decisive role in plant growth and development, and is likely involved in different regulatory pathways in cotton.

Regulatory Network of Cotton Genes in Response to Salt, Drought and Wilt Diseases (Verticillium and Fusarium): Progress and Perspective

In environmental conditions, crop plants are extremely affected by multiple abiotic stresses including salinity, drought, heat, and cold, as well as several biotic stresses such as pests and pathogens. However, salinity, drought, and wilt diseases (e.g., Fusarium and Verticillium) are considered the most destructive environmental stresses to cotton plants. These cause severe growth interruption and yield loss of cotton. Since cotton crops are central contributors to total worldwide fiber production, and also important for oilseed crops, it is essential to improve stress tolerant cultivars to secure future sustainable crop production under adverse environments. Plants have evolved complex mechanisms to respond and acclimate to adverse stress conditions at both physiological and molecular levels. Recent progresses in molecular genetics have delivered new insights into the regulatory network system of plant genes, which generally includes defense of cell membranes and proteins, signaling cascades and transcriptional control, and ion uptake and transport and their relevant biochemical pathways and signal factors. In this review, we mainly summarize recent progress concerning several resistance-related genes of cotton plants in response to abiotic (salt and drought) and biotic (Fusarium and Verticillium wilt) stresses and classify them according to their molecular functions to better understand the genetic network. Moreover, this review proposes that studies of stress related genes will advance the security of cotton yield and production under a changing climate and that these genes should be incorporated in the development of cotton tolerant to salt, drought, and fungal wilt diseases (Verticillium and Fusarium).

Calcium-Dependent Protein Kinase GhCDPK28 Was Dentified and Involved in Verticillium Wilt Resistance in Cotton

Verticillium dahliae is a soil-borne fungus that causes vascular wilt through the roots of plants. Verticillium wilt caused by V. dahliae is one of the main diseases in cotton producing areas of the world, resulting in huge economic losses. Breeding resistant varieties is the most economical and effective method to control Verticillium wilt. Calcium-dependent protein kinases (CDPKs) play a pivotal role in plant innate immunity, including regulation of oxidative burst, gene expression as well as hormone signal transduction. However, the function of cotton CDPKs in response to V. dahliae stress remains unexplored. In this study, 96, 44 and 57 CDPKs were identified from Gossypium hirsutum, Gossypium raimondii and Gossypium arboretum, respectively. Phylogenetic analysis showed that these CDPKs could be divided into four branches. All GhCDPKs of the same clade are generally similar in gene structure and conserved domain arrangement. Cis-acting elements related to hormones, stress response, cell cycle and development were predicted in the promoter region. The expression of GhCDPKs could be regulated by various stresses. Gh_D11G188500.1 and Gh_A11G186100.1 was up-regulated under Vd0738 and Vd991 stress. Further phosphoproteomics analysis showed that Gh_A11G186100.1 (named as GhCDPK28-6) was phosphorylated under the stress of V. dahliae. Knockdown of GhCDPK28-6 expression, the content of reactive oxygen species was increased, a series of defense responses were enhanced, and the sensitivity of cotton to V. dahliae was reduced. Moreover, overexpression of GhCDPK28-6 in Arabidopsis thaliana weakened the resistance of plants to this pathogen. Subcellular localization revealed that GhCDPK28-6 was localized in the cell membrane. We also found that GhPBL9 and GhRPL12C may interact with GhCDPK28-6. These results indicate that GhCDPK28-6 is a potential molecular target for improving resistance to Verticillium wilt in cotton. This lays a foundation for breeding disease-resistant varieties.

A cotton WAKL protein interacted with a DnaJ protein and was involved in defense against Verticillium dahliae

Accumulating evidence indicates that plant cell wall-associated receptor-like kinases (WAKs) involve in defense against pathogen attack, but their related signaling processes and regulatory mechanism remain largely unknown. We identified a WAK-like kinase (GhWAKL) from upland cotton (Gossypium hirsutum) and characterized its functional mechanism. Expression of GhWAKL in cotton plants was induced by Verticillium dahliae infection and responded to the application of salicylic acid (SA). Knockdown of GhWAKL expression results in the reduction of SA content and suppresses the SA-mediated defense response, enhancing cotton plants susceptibility to V. dahliae. And, ecotopic overexpression of GhWAKL in Arabidopsis thaliana conferred plant resistance to the pathogen. Further analysis demonstrated that GhWAKL interacted with a cotton DnaJ protein (GhDNAJ1) on the cell membrane. Silencing GhDNAJ1 also enhanced cotton susceptibility to V. dahliae. Moreover, the mutation of GhWAKL at site Ser628 with the phosphorylation decreased the interaction with GhDNAJ1 and compromised the plant resistance to V. dahliae. We propose that GhWAKL is a potential molecular target for improving resistance to Verticillium wilt in cotton.

SlHyPRP1 and DEA1, the multiple stress responsive eight-cysteine motif family genes of tomato (Solanum lycopersicum L.) are expressed tissue specifically, localize and interact at cytoplasm and plasma membrane in vivo

Owing to rapid global climate change, the occurrence of multiple abiotic stresses is known to influence the outburst of biotic stress factors which affects crop productivity. Therefore, it is essential to understand the molecular and cell biology of key genes associated with multiple stress responses in crop plants. SlHyPRP1 and DEA1, the members of eight-cysteine motif (8CM) family genes have been recently identified as putative regulators of multiple stress responses in tomato (Solanum lycopersicum L.). In order to gain deeper insight into cell and molecular biology of SlHyPRP1 and DEA1, we performed their expression analysis in three tomato cultivars and in vivo cell biological analysis. The semi-quantitative PCR and qRT-PCR results showed the higher expression of SlHyPRP1 and DEA1 in leaf, stem, flower and root tissues as compared to fruit and seed tissues in all three cultivars. The expression levels of SlHyPRP1 and DEA1 were found to be relatively higher in a wilt susceptible tomato cultivar (Arka Vikas) than a multiple disease resistant cultivar (Arka Abhed). In vivo cell biological analysis through Gateway cloning and Bi-FC assay revealed the predominant sub-cellular localization and strong protein-protein interaction of SlHyPRP1 and DEA1 at the cytoplasm and plasma membrane. Moreover, SlHyPRP1 showed in vivo interaction with stress responsive proteins WRKY3 and MST1. Our findings suggest that SlHyPRP1 with DEA1 are co-expressed with tissue specificity and might function together by association with WRKY3 and MST1 in plasma membrane for regulating multiple stress responses in the tomato plant.

Multigene CRISPR/Cas9 genome editing of hybrid proline rich proteins (HyPRPs) for sustainable multi-stress tolerance in crops: the review of a promising approach

The recent global climate change has directly impacted major biotic and abiotic stress factors affecting crop productivity worldwide. Therefore, the need of the hour is to develop sustainable multiple stress tolerant crops through modern biotechnological approaches to cope with climate change. Hybrid proline rich proteins (HyPRPs) are the cell-wall structural proteins, which contain an N-terminal repetitive proline-rich domain and a C-terminal conserved eight-cysteine motif domain. HyPRPs are known to regulate multiple abiotic and biotic stress responses in plants. Recently, a few HyPRPs have been characterized as negative regulators of abiotic and biotic stress responses in different plants. Disruption of such negative regulators for desirable positive phenotypic traits has been made possible through the advent of advanced genome engineering tools. In the past few years, CRISPR/Cas9 has emerged as a novel breakthrough technology for crop improvement by target specific editing of known negative regulatory host genes. Here, we have described the mechanism of action and the role of known HyPRPs in regulating different biotic and abiotic stress responses in major crop plants. We have also discussed the importance of the CRISPR/Cas9 based genome editing system in targeting known negative regulatory HyPRPs for multi-stress crop tolerance using the tomato crop model. Application of genome editing to manipulate the HyPRPs of major crop plants holds promise in developing newer stress management methods in this rapidly changing climate and would lead in the future to sustain crop productivity.

The ghr-miR164 and GhNAC100 modulate cotton plant resistance against Verticillium dahlia

MicroRNAs (miRNAs) participate in plant development and defence through post-transcriptional regulation of the target genes. However, few miRNAs were reported to regulate cotton plant disease resistance. Here, we characterized the cotton miR164-NAC100 module in the later induction stage response of the plant to Verticillium dahliae infection. The results of GUS fusing reporter and transcript identity showed that ghr-miR164 can directly cleave the mRNA of GhNAC100 in the post-transcriptional process. The ghr-miR164 positively regulated the cotton plant resistance to V. dahliae according to analyses of its over-expression and knockdown. In link with results, the knockdown of GhNAC100 increased the plant resistance to V. dahliae. Based on LUC reporter, expression analyses and yeast one-hybrid (Y1H) assays, GhNAC100 bound to the CGTA-box of GhPR3 promoter and repressed its expression, negatively regulating plant disease resistance. These results showed that the ghr-miR164 and GhNAC100 module fine-tunes plant defence through the post-transcriptional regulation, which documented that miRNAs play important roles in plant resistance to vascular disease.

An Overview of the Molecular Genetics of Plant Resistance to the Verticillium Wilt Pathogen Verticillium dahliae

Verticillium dahliae is a soil-borne hemibiotrophic fungus that can lead to plant vascular disease and significant economic loss worldwide. Its hosts include over 400 dicotyledon plant species, such as annual herbs, perennials, and woody plants. The average yield loss of cotton crop caused by Verticillium wilt is approximately 10–35%. As the control of this disease is an urgent task for many countries, further understanding of the interaction between plants and V. dahliae is essential. Fungi can promote or inhibit plant growth, which is important; however, the most important relationship between plants and fungi is the host–pathogen relationship. Plants can become resistant to V. dahliae through diverse mechanisms such as cell wall modifications, extracellular enzymes, pattern recognition receptors, transcription factors, and salicylic acid (SA)/jasmonic acid (JA)/ethylene (ET)-related signal transduction pathways. Over the last decade, several studies on the physiological and molecular mechanisms of plant resistance to V. dahliae have been undertaken. In this review, many resistance-related genes are summarised to provide a theoretical basis for better understanding of the molecular genetic mechanisms of plant resistance to V. dahliae. Moreover, it is intended to serve as a resource for research focused on the development of genetic resistance mechanisms to combat Verticillium wilt.

Dynamic infection of Verticillium dahliae in upland cotton

Verticillium wilt, an infection caused by the soilborne fungus Verticillium dahliae, is one of the most serious diseases in cotton. No effective control method against V. dahliae has been established, and the infection mechanism of V. dahliae in upland cotton remains unknown. GFP-tagged V. dahliae isolates with different pathogenic abilities were used to analyse the colonisation and infection of V. dahliae in the roots and leaves of different upland cotton cultivars, the relationships among infection processes, the immune responses and the resistance ability of different cultivars against V. dahliae. Here, we report a new infection model for V. dahliae in upland cotton plants. V. dahliae can colonise and infect any organ of upland cotton plants and then spread to the entire plant from the infected organ through the surface and interior of the organ. Vascular tissue was found to not be the sole transmission route of V. dahliae in cotton plants. In addition, the rate of infection of a V. dahliae isolate with strong pathogenicity was notably faster than that of an isolate with weak pathogenicity. The resistance of upland cotton to Verticillium wilt was related to the degree of the immune response induced in plants infected with V. dahliae. These results provide a theoretical basis for studying the mechanism underlying the interaction between V. dahliae and upland cotton. These results provide a theoretical basis for studying the mechanism underlying the interaction between V. dahliae and upland cotton.

Genome-Wide Analysis and Expression Profiling of Rice Hybrid Proline-Rich Proteins in Response to Biotic and Abiotic Stresses, and Hormone Treatment

Hybrid proline-rich proteins (HyPRPs) belong to the family of 8-cysteine motif (8CM) containing proteins that play important roles in plant development processes, and tolerance to biotic and abiotic stresses. To gain insight into the rice HyPRPs, we performed a systematic genome-wide analysis and identified 45 OsHyPRP genes encoding 46 OsHyPRP proteins. The phylogenetic relationships of OsHyPRP proteins with monocots (maize, sorghum, and Brachypodium) and a dicot (Arabidopsis) showed clustering of the majority of OsHyPRPs along with those from other monocots, which suggests lineage-specific evolution of monocots HyPRPs. Based on our previous RNA-Seq study, we selected differentially expressed OsHyPRPs genes and used quantitative real-time-PCR (qRT-PCR) to measure their transcriptional responses to biotic (Magnaporthe oryzae) and abiotic (heat, cold, and salt) stresses and hormone treatment (Abscisic acid; ABA, Methyl-Jasmonate; MeJA, and Salicylic acid; SA) in rice blast susceptible Pusa Basmati-1 (PB1) and blast-resistant near-isogenic line PB1+Pi9. The induction of OsHyPRP16 expression in response to the majority of stresses and hormonal treatments was highly correlated with the number of cis-regulatory elements present in its promoter region. In silico docking analysis of OsHyPRP16 showed its interaction with sterols of fungal/protozoan origin. The characterization of the OsHyPRP gene family enables us to recognize the plausible role of OsHyPRP16 in stress tolerance.