206 results about "Verticillium dahliae" patented technology

The invention relates to the field of microbial control, in particular to bacillusamyloliquefaciens subsp Lh-1 and application thereof. With a preservation number of CGMCC No.8548, the bacillusamyloliquefaciens subsp Lh-1 is applied in control of Verticillium dahliae, erwinia carotovora, ralstonia solanacearum, valsa leucostoma, Valsa Mali Miyabe et Yamada, Phytophthora capsici and phytophthora infestans. According to the invention, the bacillusamyloliquefaciens subsp Lh-1 and pesticide and chitosan oligosaccharide with dual effects of fertilizer and pesticide are combined into an Lh-1 microecological agent, the viable count is small, the dosage is small, the production process is simple, the cost is low, and the Lh-1 microecological agent has the dual functions of disease prevention and growth promotion. Nursery test proves that reduce the disease incidence of crop is reduced, especially for control of Verticillium dahliae, the disease incidence drops to 6%, and the control effect is significant. In addition, the Lh-1 microecological agent is a biological strain preparation, is completely free of a series of problems caused by use of chemical pesticides, thus being conducive to pollution-free production of crops, and farmers can have no need for pesticide or reduce the dosage of chemical pesticide, thus greatly saving the expenditure.

The invention discloses bacillus subtilis A16, which is preserved in China Center for Type Culture Collection (CCTCC) with CCTCC NO. 209105. The bacterial colony of the Bacillus subtilis A16 is oyster white on a beef extract peptone culture medium, has irregular shape and no luster, is not wet, has irregular edge, has diameter of 0.5-1cm, and has microfold surface, straight rod-shaped thallus and elliptic spore. The invention also discloses a preparation method and application of the bacillus subtilis A16. The bacillus subtilis A16 has broad bacteriostasis, can suppress exserohilum turcicum and helminthosporium maydis, has higher antagonism for exserohilum turcicum bacteria, helminthosporium maydis bacteria, maize curvularia leaf spot fungus, verticillium dahliae kleb, wheat scab pathogen, colletotrichum musae and banana vascular wilt bacteria, and has high prevention cure efficiency, and good safety and development application prospect.

The invention discloses a strain of bacillus subtilis and application thereof. The bacillus subtilis is Bs-03 CGMCC No. 3038 and can be used as a biological fertilizer and a biological pesticide whichcan prevent and control various diseases of plants. Experiments indicate that fermentation liquid of the bacillus subtilis Bs-03 CGMCC No. 3038 has significant effect on preventing and controlling verticillium dahliae in cotton, and cotton grows vigorously without causing phytotoxicity because of using the bacillus subtilis Bs-03 CGMCC No. 3038.

The invention discloses a gliocladium spp. strain for suppressing botrytis cinerea pers and relates to the gliocladium spp. strain. The invention provides a new strain of gliocladium spp., which can be used for suppressing the botrytis cinerea pers and have the effect of suppressing a plurality of other fungal diseases, thereby laying a material foundation for biological control of the botrytis cinerea pers and culture of new species for anti-botrytis cinerea pers by utilizing the biological technology. The gliocladium spp. strain for suppressing the botrytis cinerea pers is gliocladium roseumWY-1 which is collected in China General Microbiological Culture Collection Center with the collection No. of CGMCCNo. 1977. The gliocladium roseum WY-1 can significantly suppress pathogens of the botrytis cinerea pers, fulvia fulva, phytophthora parasitica, verticillium dahliae of tomato, fusarium wilt of tomato, valsa sordida nit, poplar fusarium wilt and blackcurrant leaf spot, and suppress the growth of mycelia of the pathogens.

The invention discloses a bacillus velezensis TK2019 microbial agent and application thereof. The bacillus velezensis TK2019 is separated from rhizosphere soil of the cotton field of the 44 regiment in the Tumxuk city of Xinjiang, and the bacillus velezensis TK2019 microbial agent is used for preparing the bacillus velezensis TK2019. When the microbial agent is applied to prevention and treatmentof cotton verticillium wilt, cotton fusarium wilt, botrytis cinerea and red date black spots, the inhibition rate of the strain TK2019 on verticillium dahliae of cotton reaches 94.37 percent, the inhibition rate of the strain TK2019 on four tested pathogenic fungi is 84.83-93.73 percent, and the stock solution and 50-time diluted solution of the bacillus velezensis TK2019 microbial agent have thehighest prevention effects which are 92.86 percent and 91.97 percent respectively. Field tests prove that the prevention effect the TK2019 microbial agent on cotton verticillium wilt is 92.69 percent,which indicates that the Bacillus velezensis TK2019 and the microbial agent thereof provided by the invention have the advantages of high efficiency, wide bactericidal spectrum and the like and havewide values for expanding the application field of microbial strains.

The invention provides a knockout method for a verticillium dahliae gene. The knockout method is characterized by comprising the following steps that: a recombinant plasmid used for homologous recombination is constructed, wherein the recombinant plasmid consists of a carrier and a homologous recombinant DNA fragment, the homologous recombinant DNA fragment contains an exogenous resistance gene used for substituting the gene to be knocked out and flanking sequences which are positioned at two sides of the exogenous resistance gene and meet the requirements of homologous recombination, and the carrier contains an exogenous conditional lethal gene; and the recombinant plasmid is transformed into the verticillium dahliae for homologous recombination through an agrobacterium-mediated method so as to obtain transformants and screen out positive transformants. ADE4 and ChsV genes of verticillium dahliae are respectively knocked out by the knockout method, and proportions of gene knockout transformants in the total transformants are 87% and 44% respectively. Therefore, compared with the prior art, the efficiency of the knockout method for the verticillium dahliae gene is greatly improved.

The invention relates to a method and kit for quickly detecting verticillium dahliae through PCR (polymerase chain reaction). A pair of specificity detection primer dali1 / dali2 is designed according to an ITS sequence of the verticillium dahliae rDNA, and a 372bp product is amplified. 2 micro liters of DNA template is directly added into a fluorescent quantitative PCR reaction liquid to be amplified; and the reaction liquid contains the pair of specificity primers and fluorescent dye, the fluorescent intensity of the reaction system is detected in real time along the PCR, a Ct value is calculated according to analysis software, and the quantity of the verticilliuim dahliae in a sample can be calculated. The kit is simple, convenient and rapid to operate, good in specificity and high in sensitivity. The kit can be used for rapidly and quantitatively detecting the verticillium dahliae, can substitute the traditional diagnosis method of separation culture and is suitable for being widely popularized in the plant disease diagnosis detection field.

The invention discloses a pathogenic related protein VdGRP1 from verticillium dahliae kleb and a coded gene thereof. The pathogenic related protein is the protein of 1) or 2): 1) the protein consisting of the amino acid sequence shown as sequence 2 in a sequence table; and 2) the protein formed by substituting and / or deleting and / or adding one or more amino acid residues of the amino acid residuesequence shown as sequence 2 in the sequence table, related to pathogenic fungi and derived from 1). A mutant strain vdgrpl of which the pathogenicity is weakened is obtained by screening a verticillium dahliae kleb mutant library mediated by agrobacterium tumefaciens and built through T-DNA insertion technology by the inventor. Southern hybridization proves that the mutant strain is a T-DNA single-insertion mutant. A gene causing mutant phenotype is obtained through TAIL-PCR technology by the inventor. Gene complementation tests prove that the mutation of the gene VdGRP1 weakens the pathogenicity of the strain vdgrpl which means that the gene VdGRP1 is a fungi pathogenic related gene.

The invention provides a nucleic acid. The nucleic acid has the sequences shown in SEQ ID NO:1 or has specific sequences in the sequences shown in SEQ ID NO:1. The invention also provides a nucleic acid complementary with the above nucleic acid. The invention also provides a method for identifying the pathotype of a fungus strain. The fungus strain is verticillium dahliae. The method comprises the following steps of: (1) preparing a sample to be detected of complete genome DNA containing verticillium dahliae; (2) detecting whether a first molecular marker exists in the sample to be detected, wherein the first molecular marker is the above nucleic acid; and (3) judging the pathotype of verticillium dahliae according to the detection result in the step (2). The invention also provides a kit.

The invention relates to a single spore isolation and purification method of verticillium dahliae. The method mainly comprises the following steps: an agar medium cylinder is taken from a water agar plate by the use of a glass capillary with diameter being 1mm and is picked onto a sterilized glass slide with a sterilization needle; a verticillium dahliae strain is activated in a PDA solid medium and the activated strain is cultured in a Czapek-Dox liquid medium; spore concentration is counted under a microscope; and the spore concentration is adjusted to 102-106 cfu to prepare a spore suspension; 1 microlitre of the spore suspension is sucked up and dripped onto the surface of the water agar cylinder on the glass slide; the glass slide is moved into a culture dish for constant temperature incubation at 25 DEG C; the glass slide is detected under the microscope, and the cylinder containing a single conidiospore which has germinated germ tubes is transferred onto a PDA plate to be cultured at 25 DEG C so as to finish single spore isolation. The method is simple to operate, can be implemented by general operation staff and is suitable for mass separation. By the method, separation success rate is high. The method is also suitable for production of other fungi of microconidia.

The invention discloses application of a cotton GhLecRK1 gene in plant greensickness resistance. The nucleotide sequence of the cotton GhLecRK1 gene is as shown in SEQ ID NO.1, and the amino acid sequence is as shown in SEQ ID NO.1. The GhLecRK1 gene has higher expression in cotton roots compared with that of other tissues, and the gene is induced and expressed by verticillium dahliae; the gene inthe cotton is silenced, verticillium dahliae is more likely to infect plants, and the greensickness resistance of the cotton is reduced, so that it is indicated that the cotton has the greensicknessresistance, the gene can be applied to creation of a new disease-resistant species, and then plant variety improvement is carried out.

The invention discloses a biocontrol bacterium and azoxystrobin composition belonging to the technical field of bactericides. The biocontrol bacterium and azoxystrobin composition contains active components including bacillus subtilis and azoxystrobin. The biocontrol bacterium and azoxystrobin composition disclosed by the invention can be used for remarkably reducing the medication cost while effectively preventing and controlling various diseases such as rice sheath blight disease, rice false smut, rice blast, ear rot, seedling-stage damping-off, tomato late blight, gray mold, wheat powdery mildew, sheath blight, cotton rhizoctoniosis, foxysporum, verticillium dahliae, soybean root rot, corn sheath blight, cucumber gray mold, blight, tobacco brown spot, bacterial wilt, various field crop and garden crop root rots and damping off, so that the medication cost can be reduced, the preventing and controlling ranges can be widened, the environment pollution can be reduced, and the phytotoxicity and pesticide resistance risks can be reduced.

The invention belongs to the technical field of plant genetic engineering, and particularly relates to a cotton calcium-dependent protein kinase GhCPK33 gene for regulating the verticillium wilt resistance of cotton, and applications thereof. According to the present invention, the calcium ion-dependent protein kinase GhCPK33 gene with the characteristic of verticillium wilt induced expression isscreened by inoculating Verticillium dahliae in Gossypium hirsutum Linn and analyzing RAN-Seq data at different time points, wherein the nucleotide sequence of the gene is represented by SEQ ID NO:1,and the protein sequence encoded by the gene is represented by SEQ ID NO:2. According to the present invention, through the VIGS system, the corresponding gene in cotton is silenced, Verticillium dahliae is inoculated, and the function of the gene in the verticillium wilt resistance of cotton is quickly identified; and the isolated gene provides the negative regulation effect in the verticillium wilt resistance of cotton, and by silencing the gene, the verticillium wilt resistance of cotton can be significantly improved.

The invention relates to the plant pathology field, and specially relates to a quantitative dip in bacterial suspension method for identifying resistance to cotton verticillium wilt using vermiculite sandy soil bottomless bowl of paper. The method in the invention includes the following steps: 1) making a nutrient bowl by mixing vermiculite and sandy soil and putting them into a paper bowl; 2) sowing and culturing cotton sprouts; 3) inoculating pathogen, which requires inoculating bacterium spore suspension of cotton verticillium wilt when one true leaf of a cotton sprout grows to be flat, wherein the inoculation concentration is in the range of from 1*10<6> to 5*10<6> spores per ml, and every cotton sprout is inoculated with bacteria liquid about from 2 to 3 ml; 4) evaluating the resistance to cotton verticillium wilt. The invention is characterized by being fast, accurate, economical, environmental beneficial and so on.

The invention relates to phytopathology and particularly relates to cotton endophytic fungi CEF-714 and an application of cotton endophytic fungi CEF-714 to preventing and treating cotton verticillium wilt. The preservation number of the cotton endophytic fungi CEF-714 is CGMCC (China General Microbiological Culture Collection Center) No.8304. The CEF-714 can be cultured on an artificial culture medium and is easy to obtain and culture, so that the industrial production as well as the popularization and the application are facilitated. Indoor bacteriostatic tests show that the inhibition effect on the cotton verticillium wilt by metabolites of the CEF-714 is 100%; the inhibition effects on the cotton verticillium wilt by generated volatile metabolites is 77.5%. A room temperature test result shows that the prevention and treatment effect on the cotton verticillium wilt by using 25% CEF-714 culture filtering solution to immerse seeds is 60.6%; the control effect on the verticillium wilt is obvious; compared with that in bacillus subtilis which is mostly applied to the production, the prevention and treatment effect is improved by about 34.7%; the CEF-714 has no toxic side effects on the growth of crops, is safe to humans and livestock, insects and the crops and has the environment-friendly effect.

The invention discloses a biocontrol bacterium and pyraclostrobin composition belonging to the technical field of bactericides. The biocontrol bacterium and pyraclostrobin composition contains active components including bacillus subtilis and pyraclostrobin. The biocontrol bacterium and pyraclostrobin composition disclosed by the invention can be used for remarkably reducing the medication cost while effectively preventing and controlling various diseases such as rice sheath blight disease, rice false smut, rice blast, ear rot, seedling-stage damping-off, tomato late blight, gray mold, wheat powdery mildew, sheath blight, cotton rhizoctoniosis, foxysporum, verticillium dahliae, soybean root rot, corn sheath blight, cucumber gray mold, blight, tobacco brown spot, bacterial wilt, various field crop and garden crop root rots and damping off, so that the medication cost can be reduced, the preventing and controlling ranges can be widened, the environment pollution can be reduced, and the phytotoxicity and pesticide resistance risks can be reduced.

The invention discloses antagonistic actinomycete for preventing and controlling continuously cropped strawberry root rot and a preparation method of a biocontrol agent of the antagonistic actinomycete. Bacterial strain B04 belongs to streptomyces hygroscopicus (Streptomyces hygroscopicus), with the strain preservation number of CGMCC NO.9918. The biocontrol strain B04 is separated from a healthy strawberry root, and has a strong inhibiting effect on pathogenic bacteria, such as fusarium, verticillium dahliae, rhizoctonia, phytophthora and the like, causing strawberry soil-borne root diseases. The antagonistic actinomycete prepared by taking wormcast and wheat bran as the main materials of fermentation medium can completely meet the nutritional requirements produced by solid fermentation of biocontrol antinomycetes. Compared with conventional fermentation, the production cost of the preparation method is reduced by 30 to 50 percent, and the preparation method is beneficial for popularization and application of the biocontrol agent of the antagonistic actinomycete. After the biocontrol agent of the antagonistic actinomycete is applied to continuously cropped soil, the biological control rate reaches greater than 70 percent, and has great significance on preventing and controlling the soil-borne diseases of strawberry, improving the quality of agricultural products and protecting the environment.

The invention relates to a volatile substance which has antibacterial activity and is produced by a biocontrol endophytic bacillius subtilis strain Jaas ed1 and an identification method thereof. The strain at least can produce 15 volatile substances, and 10 of the 15 volatile substances are bacteriostat effective substances and comprise 2-heptanone, 2-nonanone, 2-nonanol, 2-decanone, 2-decanol, 2-phenethyl alcohol, 2-undecanone, 2-cyclododecanoe, 2-undecanol and 2-tridecanone. The collecting and purifying method includes the steps that endophytic bacillius subtilis Jaas ed1 fermentation liquor is heated and stirred on a magnetic stirrer, solid phase microextraction is conducted on volatile gas through a DVB / CAR / PDMS extraction head, and finally extracted volatile substance ingredients are determined through the GC-MS. The volatile gas can inhibit mycelial growth of pathogens of watermelon fusarium wilt and germination of cotton verticillium dahliae microsclerotia, extremely-high study and application value is achieved on development of broad-spectrum antibacterial chemicals, and wide application prospects are achieved for protecting the natural quality of crops and fruits of the crops and reducing pesticide residues.

The invention provides a nucleic acid with a sequence represented by SEQ ID NO:1 or SEQ ID NO:2, or comprising a specific sequence of a sequence represented by the SEQ ID NO:1 or a specific sequence of a sequence represented by the SEQ ID NO:2. The invention also provides a nucleic acid complementary to the above nucleic acid. The invention also provides a method for identifying a fungal strain pathogenic type. The fungal strain is verticillium dahliae. The method comprises the steps that: (1) a total genomic DNA test sample comprising verticillium dahliae is prepared; (2) whether a first molecular marker exists in the test sample is detected, wherein the first molecular marker is the nucleic acid; and (3) verticillium dahliae strain pathogenic type is determined according to the detection result of the step (2). The invention also provides a kit.

The present invention provides non-specific exciton gene VdNEP of Verticillium dahliae capable of causing disease resisting allergic reaction on cotton and other plant and its application. VdNEP protein can induce the expression of Arabidopsis thalianum disease course related gene. Low concentration VdNEP protein can induce suspended cotton cell to synthesize gossypol as phytoalexin, while high concentration VdNEP protein can induce the allergic death of suspended cotton cell. When it is injection to cotton cotyledon, the protein in low concentration may cause allergic necrosis spot and the protein in high concentration may cause cotyledon wilting. Treating mature cotton euphylla with the protein will cause the euphylla dewatering. Applying VdNEP provides new way of improving plant disease resistance and has wide application foreground.

The invention discloses a bacillus amyloliquefaciens strain HMB28353, the strain is preserved in China General Microbiological Culture Collection Center, and the preservation number is CGMCC No. 13209. The invention also discloses a microbial agent produced by using the bacillus amyloliquefaciens HMB28353. The bacillus amyloliquefaciens HMB28353 has high antibacterial effect on cucumber target leaf spot, and the average control effect is above 90.0%; also, the bacillus amyloliquefaciens HMB28353 is not easy to generate resistance in controlling cucumber target leaf spot, and the persistence of the antibacterial effect is good; in addition, the bacillus amyloliquefaciens HMB28353 does not have the problem of environmental pollution; and the HMB28353 strain also has the characteristic of wide antibacterial spectrum, and besides cucumber target leaf spot bacteria, the HMB28353 strain also has good inhibiting effects on verticillium dahliae kleb, fusarium oxysporum f. sp. vasinfectum, cotton rhizoctonia solani or botrytis cinerea pers.

The invention discloses a soybean rhizosphere azotobacter for producing activated calcium carbonate (ACC) and realizing the antagonistic effect on various pathogenic fungi and a purpose thereof. The soybean rhizosphere azotobacter is Burkholderia sp. GDSD571 and has the preservation number being CGMCC No.5039 in General Microbiology Center of China Microbial Strain Preservation Management Committee. The Burkholderia sp. GDSD571 CGMCC No.5039 provided by the invention has high nitrogen fixation activity and ACC ammonialyase activity, can realize the effective antagonistic effect on gibberella zeae, sclerotinia sclerotiorum and verticillium dahliae and has wide application prospects in nitrogen fixation microbial agent and microbial organic fertilizer production.

The invention provides verticillium dahliae protein capable of inducing resistance allergic reaction on tobaccos and other plants. The amino acid sequence of the protein is indicated in SEQ (sequencer) ID NO:2. One coding follows the gene of the protein in the invention, and the nucleotide sequence of the protein is indicated in SEQ ID NO:1. The protein in the invention can induce generation of defense signal molecules relative to disease resistance of the tobaccos. Under relatively low concentration, the protein can induce expression of genes relative to disease resistance of the plants; and secondary metabolites are increased to improve the capability of defending pathogenic bacteria of a cell wall. When the protein is injected into the tobacco plant, necrotic spots are formed, and simultaneously, the capability of resisting tobacco mosaic virus (TMV) of the whole tobacco is strengthened. The protein has the advantages of obviously enhancing resistance of the plants, being low in concentration, having a rapid effect, and providing a new path for improving disease resistance of the plants, so that the protein has a wide application prospect on agricultural production.

The invention discloses a bacillus amyloliquefaciens HMB28388 strain. The strain is collected in CGMCC, and the collection number is CGMCC No.13210. The invention also discloses a microbial inoculant produced by means of the strain and an application of the strain in preventing and treating plant diseases such as cucumber target spot. The HMB28388 strain disclosed by the invention is high in efficacy on the cucumber target spot, and the average control effect is 90.0% above. Secondly, drug resistance is unlikely to generate by using the strain to prevent and treat the cucumber target spot, and no environmental pollution problems are available; the strain is simple to prepare and use and low in cost; in addition, the HMB28388 strain is wide in antibacterial spectrum. Besides the cucumber target spot, the HMB28388 strain also has very good inhibiting action on verticillium wilt of cotton, cotton-wilt fusarium, rhizoctonia solani of cotton or botrytis cinerea.

The invention discloses verticillium dahliae Kleb. pathogenic associated protein VdSENP1, an encoding gene thereof, and application. The protein VdSENP1 is protein possessing one of the following amino acid residue sequences: 1) an amino acid residue sequence shown as a sequence table SEQ ID No. 2; and 2) protein which is associated with fungus pathopoiesis and is derived from 1) by substituting and / or deleting and / or adding one or more of amino acid residues on the basis of the amino acid residue shown in the sequence table SEQ ID No. 2. The protein and the encoding gene thereof have extremely important meaning on culturing verticillium-wilt-resistant cotton and improving cotton output and quality.

The invention discloses a new Kosteletzkya virginica (L.) Presl. sesquiterpene compound, and a preparation method and a use thereof, and belongs to the chemical field of natural products. The above new cadinane type sesquiterpene compound is obtained by extracting and separating from a raw material the rhizome of a halophyte Kosteletzkya virginica (L.) Presl. through chemical processes of the natural products. The structural formula of the compound is shown in the specification, is named as virginicin, has a strong killing effect on Verticillium dahliae, and can be used for controlling cotton verticillium wilt.

The invention relates to the plant pathology field. A gene VdGFP playing an important role in pathogenicity is cloned from verticillium dahliae V07DF2 strains, and a nucleotide sequence of the gene and an amino acid sequence of an encoded protein are provided. Specifically, the invention discloses the verticillium dahliae pathogenicity-related gene VdGFP. The gene has the nucleotide sequence shown in SEQIDNO:1 or SEQIDNO:2, and the gene-encoded protein has the sequence shown in SEQIDNO:3. The verticillium dahliae pathogenicity-related gene VdGFP can be used for reducing the pathogenicity of verticillium dahliae.

The invention belongs to the technical field of plant genetic engineering, and relates to a transcription factor GhWRKY1-like gene for regulating verticillium dahliae and drought resistance of cottonand application. RAN-Seq data at different time points after upland cotton is inoculated with verticillium dahliae bacteria are analyzed, a transcription factor gene GhWRKY1-like expressed by verticillium dahliae is obtained through screening, and the nucleotide sequence of the transcription factor gene GhWRKY1-like is shown as SEQ ID NO: 1; and the protein sequence is shown as SEQ ID NO: 2. A VIGS system is utilized, verticillium dahliae is inoculated after GhWRKY1-like is silenced in cotton, and it is rapidly proved that the gene has a forward regulation effect on verticillium dahliae resistance of the cotton. GhWRKY1-like overexpressed cotton and arabidopsis thaliana materials are utilized to further verify the forward regulation function of the gene in verticillium dahliae resistance and drought resistance, that is, overexpression of the gene can significantly improve the resistance of plants to verticillium dahliae and drought.

The invention provides a prevention and treatment effect on verticillium dahliae by using antagonistic fungi, namely bacillus axarquiensis. An antagonistic strain TUBP1 which has high antifungal activity on verticillium dahliae is obtained by separating via preliminary screening and secondary screening through an agar plate diffusion method. The strain is determined to be bacillus axarquiensis through morphologic observation, physiological and biochemical experiments and gene sequence analysis of 16S rDNA (ribosome Deoxyribose Nucleic Acid) and gyrB; the antifungal activity of fermentation liquid on verticillium dahliae is determined by using a growth rate method and an oxford cup method respectively; the growth inhibition rate on mycelium of verticillium dahliae is 78.62+ / -3.48% and the diameter of an inhibition zone is 21+ / -3.86mm; in a room-temperature pot experiment, the bio-control effect of the TUBP1 is 42.56%; in a plot experiment, the bio-control effect of the TUBP1 is 40.16%. An in vitro live test shows that the antagonistic fungi, namely bacillus axarquiensis can be used for preparing a medicine for preventing and treating verticillium dahliae.