Search

Rice blast is one of the most devastating diseases, causing a significant reduction in global rice production. Developing and utilizing resistant varieties has proven to be the most efficient and cost-effective approach to control blasts. However, due to environmental pressure and intense pathogenic selection, resistance has rapidly broken down, and more durable resistance genes are being discovered. In this paper, a novel wall-associated kinase (WAK) gene, Pb4, which confers resistance to rice blast, was identified through a genome-wide association study (GWAS) utilizing 249 rice accessions. Pb4 comprises an N-terminal signal peptide, extracellular GUB domain, EGF domain, EGF-Ca2+ domain, and intracellular Ser/Thr protein kinase domain. The extracellular domain (GUB domain, EGF domain, and EGF-Ca2+ domain) of Pb4 can interact with the extracellular domain of CEBiP. Additionally, its expression is induced by chitin and polygalacturonic acid. Furthermore, transgenic plants overexpressing Pb4 enhance resistance to rice blast. In summary, this study identified a novel rice blast-resistant gene, Pb4, and provides a theoretical basis for understanding the role of WAKs in mediating rice resistance against rice blast disease. [ABSTRACT FROM AUTHOR]

The wall-associated kinases (WAKs) can perceive and transmit extracellular signals as one kind of unique receptor-like kinases (RLKs) involved in the regulation of cell expansion, pathogen resistance and abiotic stress tolerance. To understand their potential roles and screen some key candidates in Medicago truncatula (M. truncatula), genome-wide identification and characterization of MtWAKs were conducted in this study. A total of 54 MtWAK genes were identified and classified into four groups based on their protein domains. They were distributed on all chromosomes, while most of them were clustered on chromosome 1 and 3. The synteny analysis showed that 11 orthologous pairs were identified between M. truncatula and Arabidopsis thaliana (A. thaliana) and 31 pairs between M. truncatula and Glycine max (G. max). The phylogenetic analysis showed that WAK-RLKs were classified into five clades, and they exhibited a species-specific expansion. Most MtWAK-RLKs had similar exon–intron organization and motif distribution. Multiple cis-acting elements responsive to phytohormones, stresses, growth and development were observed in the promoter regions of MtWAK-RLKs. In addition, the expression patterns of MtWAK-RLKs varied with different plant tissues, developmental stages and biotic and abiotic stresses. Interestingly, plasm membrane localized MtWAK24 significantly inhibited Phytophthora infection in tobacco. The study provides valuable information for characterizing the molecular functions of MtWAKs in regulation of plant growth, development and stress tolerance in legume plants. [ABSTRACT FROM AUTHOR]

Abstract Background Wall-associated kinase (WAK)/WAK-like (WAKL) is one of the subfamily of receptor like kinases (RLK). Although previous studies reported that WAK/WAKL played an important role in plant cell elongation, response to biotic and abiotic stresses, there are no systematic studies on RcWAK/RcWAKL in rose. Results In this study, we identified a total of 68 RcWAK/RcWAKL gene family members within rose (Rosa chinensis) genome. The RcWAKs contained the extracellular galacturonan-binding domain and calcium-binding epidermal growth factor (EGF)-like domain, as well as an intracellular kinase domains. The RcWAKLs are missing either calcium-binding EGF-like domain or the galacturonan-binding domain in their extracellular region. The phylogenetic analysis showed the RcWAK/RcWAKL gene family has been divided into five groups, and these RcWAK/RcWAKL genes were unevenly distributed on the 7 chromosomes of rose. 12 of RcWAK/RcWAKL genes were significantly up-regulated by Botrytis cinerea-inoculated rose petals, where RcWAK4 was the most strongly expressed. Virus induced gene silencing of RcWAK4 increased the rose petal sensitivity to B. cinerea. The results indicated RcWAK4 is involved in the resistance of rose petal against B. cinerea. Conclusion Our study provides useful information to further investigate the function of the RcWAK/RcWAKL gene family and breeding research for resistance to B. cinerea in rose.

Abstract 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.

The wall-associated kinases (WAKs) can perceive and transmit extracellular signals as one kind of unique receptor-like kinases (RLKs) involved in the regulation of cell expansion, pathogen resistance and abiotic stress tolerance. To understand their potential roles and screen some key candidates in Medicago truncatula (M. truncatula), genome-wide identification and characterization of MtWAKs were conducted in this study. A total of 54 MtWAK genes were identified and classified into four groups based on their protein domains. They were distributed on all chromosomes, while most of them were clustered on chromosome 1 and 3. The synteny analysis showed that 11 orthologous pairs were identified between M. truncatula and Arabidopsis thaliana (A. thaliana) and 31 pairs between M. truncatula and Glycine max (G. max). The phylogenetic analysis showed that WAK-RLKs were classified into five clades, and they exhibited a species-specific expansion. Most MtWAK-RLKs had similar exon–intron organization and motif distribution. Multiple cis-acting elements responsive to phytohormones, stresses, growth and development were observed in the promoter regions of MtWAK-RLKs. In addition, the expression patterns of MtWAK-RLKs varied with different plant tissues, developmental stages and biotic and abiotic stresses. Interestingly, plasm membrane localized MtWAK24 significantly inhibited Phytophthora infection in tobacco. The study provides valuable information for characterizing the molecular functions of MtWAKs in regulation of plant growth, development and stress tolerance in legume plants.

Background: Wall-associated kinase (WAK)/WAK-like (WAKL) is one of the subfamily of receptor like kinases (RLK). Although previous studies reported that WAK/WAKL played an important role in plant cell elongation, response to biotic and abiotic stresses, there are no systematic studies on RcWAK/RcWAKL in rose. Results: In this study, we identified a total of 68 RcWAK/RcWAKL gene family members within rose (Rosa chinensis) genome. The RcWAKs contained the extracellular galacturonan-binding domain and calcium-binding epidermal growth factor (EGF)-like domain, as well as an intracellular kinase domains. The RcWAKLs are missing either calcium-binding EGF-like domain or the galacturonan-binding domain in their extracellular region. The phylogenetic analysis showed the RcWAK/RcWAKL gene family has been divided into five groups, and these RcWAK/RcWAKL genes were unevenly distributed on the 7 chromosomes of rose. 12 of RcWAK/RcWAKL genes were significantly up-regulated by Botrytis cinerea-inoculated rose petals, where RcWAK4 was the most strongly expressed. Virus induced gene silencing of RcWAK4 increased the rose petal sensitivity to B. cinerea. The results indicated RcWAK4 is involved in the resistance of rose petal against B. cinerea. Conclusion: Our study provides useful information to further investigate the function of the RcWAK/RcWAKL gene family and breeding research for resistance to B. cinerea in rose. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Disease has an effect on crop yields, causing significant losses. As the worldwide demand for agricultural products increases, there is a need to pursue the development of new methods to protect crops from disease. One mechanism of plant protection is through the activation of the plant immune system. By exogenous application, 'plant activator molecules' with elicitor properties can be used to activate the plant immune system. These defence-inducing molecules represent a powerful and often environmentally friendly tool to fight pathogens. We show that the secondary bile acid deoxycholic acid (DCA) induces defence in Arabidopsis and reduces the proliferation of two bacterial phytopathogens: Erwinia amylovora and Pseudomonas syringae pv. tomato. We describe the global defence response triggered by this new plant activator in Arabidopsis at the transcriptional level. Several induced genes were selected for further analysis by quantitative reverse transcription-polymerase chain reaction. We describe the kinetics of their induction and show that abiotic stress, such as moderate drought or nitrogen limitation, does not impede DCA induction of defence. Finally, we investigate the role in the activation of defence by this bile acid of the salicylic acid biosynthesis gene SID2, of the receptor-like kinase family genes WAK1-3 and of the NADPH oxidase-encoding RbohD gene. Altogether, we show that DCA constitutes a promising molecule for plant protection which can induce complementary lines of defence, such as callose deposition, reactive oxygen species accumulation and the jasmonic acid and salicylic acid signalling pathways. [ABSTRACT FROM AUTHOR]

The Wall-Associated Kinase, one of the receptor-like kinase (RLK) gene families in plant, plays important roles in cell expansion, pathogen resistance and heavy metal stress tolerance in Arabidopsis thaliana. Here, we isolated a cDNA encoding a novel WAK from indica rice and designated as OsiWAK1 ( Oryza sativa indica WAK-1). In this study, the RNAi construct with OsiWAK1 gene cloned in sense and antisense orientation separated by a functional intron under constitutive promoter, was introduced through biolistic gene gun method into the rice cultivar 'IR-50' to determine the effect of OsiWAK1 transcript silencing on rice plant development. Examination of the transgenic plants reveals that OsiWAK1 transcript silencing in rice results in dwarf plants because of the reduction in the size of leaves, flag-leaves, internodes and panicle. The development of root primordia during germination, root hairs and lateral rooting was also effected. Microscopic analysis revealed that the decrease in size is due to reduction in the cell size but not the number of cells. In addition, the transgenic plants also exhibited sterile phenotype due to anther indehiscence and 40 % reduction in pollen viability. These data suggest that OsiWAK1 may play an important role in rice plant growth and development. [ABSTRACT FROM AUTHOR]