Susceptible Cotton Cultivars Research Articles

Expression Profiling Analysis between Resistant and Susceptible Cotton Cultivars ( Gossypium hirsutum L.) in Response to Fusarium Wilt

Expression Profiling Analysis between Resistant and Susceptible Cotton Cultivars ( <i>Gossypium hirsutum</i> L.) in Response to Fusarium Wilt

A Cotton Gbvdr5 Gene Encoding a Leucine-Rich-Repeat Receptor-Like Protein Confers Resistance to Verticillium dahliae in Transgenic Arabidopsis and Upland Cotton

Leucine-rich-repeat receptor-like proteins (eLRR-RLPs) play significant roles in plant defense against pathogens and in plant development. Several eLRR-RLP genes such as Ve1, Gbve, and Gbve1 have been reported to confer resistance to Verticillium dahliae. Gbvdr5, a newly discovered RLP gene from V. dahliae-resistant island cotton cultivar H7124, has a short tail as Ve1. There is a cytosine deletion in Gbvdr5 homologous genes at nucleotide position 2765, which is downstream from the initiation codon in all susceptible upland cotton cultivars analyzed. This deletion was found to cause premature termination of the protein, creating a 937 aa product, but the Gbvdr5 protein had the full 1,077 aa. Transient expression analyses indicated that Gbvdr5 is localized on the plasma membrane. Quantitative polymerase chain reaction analysis revealed that the Gbvdr5 gene was activated by SA, MeJA, ABA, and ETH, and it was induced by V. dahliae isolates V991 and DF-CQ-2 in H7124, whereas was unchanged or repressed in susceptible upland cotton Simian 3. Gbvdr5-promoter-driven GUS activity was found mostly in the root tips and stem growing points of transgenic Arabidopsis. Silencing of Gbvdr5 in Verticillium-wilt-resistant cotton H7124 compromised cotton resistance to V. dahliae isolates V991 and BP2. The resistance was verified by transforming the Gbvdr5 gene into Arabidopsis and upland cotton through Agrobacterium-mediated transformation. Overexpression of the Gbvdr5 gene endowed transgenic Arabidopsis with resistance to defoliating isolate V991 and non-defoliating isolate BP2, but it had no effect on either DF-CQ-2 or JR2 of V. dahliae. The transformed cotton also had confirmed resistance to V991 and BP2. More callose deposition, more expression of the defense-related genes PR1 and PR5, and HR-mimic cell death were observed in the transgenic Arabidopsis when inoculated with V. dahliae. This demonstrated that Verticillium–plant interactions may involve some specific ways of recognizing V. dahliae and Gbvdr5 may be a suitable candidate gene for breeding Verticillium-wilt-resistant cotton lines.

A Meta-Analysis on the Effects of 2,4-D and Dicamba Drift on Soybean and Cotton

Commercial introduction of cultivars of soybean and cotton genetically modified with resistance to the synthetic auxin herbicides dicamba and 2,4-D will allow these compounds to be used with greater flexibility but may expose susceptible soybean and cotton cultivars to nontarget herbicide drift. From past experience, it is well known that soybean and cotton are both highly sensitive to low-dose exposures of dicamba and 2,4-D. In this study, a meta-analysis approach was used to synthesize data from over seven decades of simulated drift experiments in which investigators treated soybean and cotton with low doses of dicamba and 2,4-D and measured the resulting yields. These data were used to produce global dose–response curves for each crop and herbicide, with crop yield plotted against herbicide dose. The meta-analysis showed that soybean is more susceptible to dicamba in the flowering stage and relatively tolerant to 2,4-D at all growth stages. Conversely, cotton is tolerant to dicamba but extremely sensitive to 2,4-D, especially in the vegetative and preflowering squaring stages. Both crops are highly variable in their responses to synthetic auxin herbicide exposure, with soil moisture and air temperature at the time of exposure identified as key factors. Visual injury symptoms, especially during vegetative stages, are not predictive of final yield loss. Global dose–response curves generated by this meta-analysis can inform guidelines for herbicide applications and provide producers and agricultural professionals with a benchmark of the mean and range of crop yield loss that can be expected from drift or other nontarget exposures to 2,4-D or dicamba.

Evaluation of a cotton germplasm collection against Fusarium wilt race 3 isolates from Egypt

Pathogenic variation of 30 isolates of Fusarium oxysporum f. sp. vasinfectum (FOV) race 3 was evaluated on seedlings of the highly susceptible cotton cultivar 'Giza 74' in greenhouse assays. FOV isolates were clustered based upon their virulence patterns. The clusters of FOV isolates were not related to their geographic origins. Fifty-five experimental cotton genotypes were evaluated under greenhouse conditions for resistance to Fusarium wilt, in autoclaved clay loam soil infested with a mixture of equal parts (w/w) of 30 isolates of FOV race 3 at a rate of 10 g/kg of soil. Eleven genotypes were rated as highly susceptible (survival frequency from zero to 24.7%) and 21 genotypes were rated as highly resistance (survival frequency of 79.6 to 100%). The remaining genotypes displayed variable levels of partial resistance. Since no wilt nursery has been established in Egypt, greenhouse tests will continue to be the only reliable method for screening cotton breeding materials for FOV resistance. The current absence of Fusarium wilt in commercial cotton fields in Egypt demonstrates the reliability of the adopted screening procedures in discriminating cotton genotypes for resistance to Fusarium wilt.

Jasmonic acid is associated with resistance to twospotted spider mites in diploid cotton (Gossypium arboreum).

The twospotted spider mite (Tetranychus urticae Koch) is capable of dramatically reducing the yield of cotton crops and is often difficult and expensive to control. This study investigated and compared two important plant hormones, jasmonic acid (JA) and salicylic acid (SA), as constitutive and/or induced defence response components in a mite susceptible commercial cotton cultivar, Sicot 71 (Gossypium hirsutum L.) and a resistant diploid cotton BM13H (Gossypium arboreum L.). Foliar application of JA and methyl jasmonate (MeJA) reduced the mite population and leaf damage but application of other potential elicitors, SA and methyl salicylate (MeSA) did not. The concentrations of JA and SA in leaf tissues of induced and non-induced Sicot 71 and BM13H were quantified by liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS). The JA content was constitutively higher in BM13H than Sicot 71 and also highly induced by mite infestation in BM13H but not in Sicot 71. However, SA was not significantly induced in either BM13H or Sicot 71. The expression levels of JA related genes, LOX, AOS and OPR were measured by quantitative PCR and elevated expression levels of JA related genes were detected in mite-infested BM13H. Therefore, JA and MeJA were implicated as key biochemical components in both the constitutive and induced defence responses of BM13H to spider mites.

Genetic mapping of non-target-site resistance to a sulfonylurea herbicide (Envoke®) in Upland cotton (Gossypium hirsutum L.)

Acetolactate synthase (ALS) is responsible for a rate-limiting step in the synthesis of essential branched-chain amino acids. Resistance to ALS-inhibiting herbicides, such as trifloxysulfuron sodium (Envoke®), can be due to mutations in the target gene itself. Alternatively, plants may exhibit herbicide tolerance through reduced uptake and translocation or increased metabolism of the herbicide. The diverse family of cytochrome P450 proteins has been suggested to be a source of novel herbicide metabolism in both weed and crop plants. In this study we generated a mapping population between resistant and susceptible cotton (Gossypium hirsutum L.) cultivars. We found that both cultivars possess identical and sensitive ALS sequences; however, the segregation of resistance in the F2 progeny was consistent with a single dominant gene. Here we report the closely linked genetic markers and approximate physical location on chromosome 20 of the source of Envoke herbicide susceptibility in the cotton cultivar Paymaster HS26. There are no P450 proteins in the corresponding region of the G. raimondii Ulbr. genome, suggesting that an uncharacterized molecular mechanism is responsible for Envoke herbicide tolerance in G. hirsutum. Identification of this genetic mechanism will provide new opportunities for exploiting sulfonylurea herbicides for management of both weeds and crop plants.

Comparative expression analysis in susceptible and resistant Gossypium hirsutum responding to Verticillium dahliae infection by cDNA-AFLP

Verticillium wilt caused by the soil-borne fungus Verticillium dahliae (V. dahliae), is a devastating disease of cotton, leading to serious loss of lint yield worldwide. To study its resistance responses in both susceptible (Ejing No. 1) and resistant (NJ0703 and NJ0705) upland cotton cultivars (Gossypium hirsutum), cDNA-AFLP analysis was used to identify differentially expressed transcripts from resistant and susceptible cultivars that were infected with V. dahliae strain V991. A total of 83 transcript-derived fragments (TDFs) were obtained using 64 pairs of primer combinations. Interestingly, none of the differentially expressed fragments identified from susceptible cultivar Ejing No. 1 was found from resistant cultivars (NJ0703 and NJ0705). However, there were some similarities between NJ0703 (R) and NJ0705 (R), and 10 differentially expressed fragments were identified from both two resistant cultivars. The results indicated that the susceptible and resistant upland cottons responded differently to Verticillium infection. Moreover, the expression of transcripts was further validated through quantitative real-time PCR. Data showed that the activation of the transcripts was rapid and transient upon V. dahliae infection.

Development of a rapid, accurate glasshouse bioassay for assessing fusarium wilt disease responses in cultivated Gossypium species

A rapid glasshouse‐based bioassay method to screen large numbers of cotton plants for responses to Fusarium oxysporum f. sp. vasinfectum (Fov) was developed. Different Fov inoculum concentrations and methods of inoculation were assessed using resistant and susceptible cotton cultivars. Cotton seeds were planted directly into Fov‐inoculated soil. Studies of seed germination, seedling establishment, seedling mortality and fusarium wilt symptoms (i.e. stunting, foliar symptoms and vascular browning) were performed to optimize the bioassay parameters. Growing seedlings in Fov‐inoculated soils at 5 × 104 or 1 × 105 CFU g−1 soil, in individual seedling tubes with 12 h at 28–30°C and 12 h at 15–18°C, gave consistent results when assessing Fov disease responses 6 weeks after inoculation. When fusarium wilt resistance ranks (FWRRs) and vascular browning index (VBI) means of 18 Australian and other cotton cultivars from the Fov glasshouse bioassay were compared against their fusarium field performance ranks (F‐ranks), assessed on adult plants for cotton cultivar release, Pearson’s correlation was highly significant for both comparisons. The level of congruence between field and glasshouse data indicated that this protocol should be an effective tool for large‐scale screening for Fov‐resistance responses in diverse germplasm and breeding populations and for advancing genetic research to develop molecular markers for Fov resistance in cotton.

Influence ofVerticillium dahliaeInfested Peanut Residue on Wilt Development in Subsequent Cotton

Texas ranks first in cotton production in the United States and accounts for approximately 40% of the total production. Most of the cotton production is concentrated in the Texas High Plains where cotton and peanut are commonly grown in rotation. With peanut being a legume crop, farmers routinely leave residue on the soil surface to improve soil fertility; however,V. dahliaecan survive in the crop residue contributing inoculum to the soil. A microplot study was conducted to investigate the impact of peanut residue infested withV. dahliaeon subsequent microsclerotia density in soil and Verticillium wilt development in cotton. The effects of infested peanut residue rate on percent germination of cotton seeds and on wilt incidence were monitored in 2008 and 2009. In both years microplots were planted with a susceptible cotton cultivar, Stoneville (ST) 4554B2RF. Increasing infested peanut residue rate was positively correlated with wilt incidence in cotton and negatively correlated with germination of cotton seeds. Density of microsclerotia in the soil increased significantly with increasing rates of infested peanut residue over time. Results indicate infested peanut residue serve as a source ofV. dahliaeinoculum, and removing infested residue can reduce disease development in subsequent cotton crops.

Vegetative compatibility groups in Verticillium dahliae isolates from olive in western Turkey

Verticillium wilt, caused by Verticillium dahliae, is the most serious disease in olive cultivation areas in western Turkey. Two hundred and eight isolates of V. dahliae from olive (Olea europea var. sativa) trees were taken for vegetative compatibility analysis using nitrate non-utilizing (nit) mutants. One isolate did not produce a nit mutant. Nit mutants of 207 isolates were tested against tester strains of internationally known vegetative compatibility groups (VCGs) 1A, 2A, 2B, 3, 4A and 4B, and also paired in many combinations among themselves. One hundred and eighty nine of the isolates (90.9%) were strongly compatible with T9, the tester strain of VCG1A, and thus were assigned to VCG1A. Eight isolates were assigned to VCG2A and four isolates to VCG4B. One isolate was heterokaryon self-incompatible (HSI) and five isolates could not be grouped to any of the VCGs tested. Pathogenicity assays were conducted on a susceptible olive cultivar (O. europea cv. Manzanilla) and a susceptible local cotton cultivar (Gossypium hirsutum cv. Cukurova 1518). Both cotton and olive inoculated with all VCG1A isolates showed defoliating symptoms in greenhouse tests. This is the first report on VCGs in V. dahliae from olive trees in Turkey which demonstrates that VCG1A of the cotton-defoliating type is the most commonly detected form from olive plants in the western part of Turkey.

Development of AFLP and derived CAPS markers for root-knot nematode resistance in cotton

Resistance to root-knot nematode (Meloidogyne incognita) is determined by a single major gene rkn1 in Gossypium hirsutum Acala NemX cotton. Bulked segregant analysis (BSA) combined with amplified fragment length polymorphism (AFLP) was used to identify molecular markers linked to rkn1. DNA pools from homozygous susceptible (S) and resistant (R) bulks of an F2:3 originating from the intraspecific cross NemX × SJ-2 were screened with 128 EcoR1/Mse1 primer combinations. Putative AFLP markers were then screened with 60 F2:7 RIL plants and four AFLP markers were found linked to rkn1. The linkage of AFLP markers to rkn1 was also confirmed in a F2 population. The closest AFLP marker was converted to a cleaved amplified polymorphic sequence (CAPS) marker (designated GHACC1) by aligning the sequences from both susceptible and resistant parents. GHACC1 linkage to rkn1 was confirmed in the F2 (1R:3S), F2:7 RIL (1R:1S) and the backcross population SJ-2 × F1 (NemX × SJ-2) (1 heterozygous: 1 homozygous). The four AFLP markers, GHACC1 plus two SSR markers (CIR316 and BNL1231) linked to rkn1 from previous work were mapped to intervals of 2.6–14.2 cM from the rkn1 locus, and the genomic region around rkn1 was spanned to about 28.2 cM in the F2:7 population. The PCR-based GHACC1 and CIR316 markers were tested on 21 nematode resistant and susceptible cotton breeding lines and cultivars. GHACC1 was suitable for nematode resistance screening within G.␣hirsutum, but not G. barbadense, whereas CIR316 was useful in both species, indicating their␣potential for utilization in marker-assisted selection.

Phytotoxicity on cotton ex-plants of an 18.5 kDa protein from culture filtrates of Verticillium dahliae

A phytotoxic protein that evokes the typical symptoms of Verticillium wilt disease in seedlings of Gossypium hirsutum L. (Upland cotton) was isolated from culture filtrates of Verticillium dahliae. The protein was purified by ammonium sulfate precipitation, Sephadex-G100 fractionation, and native PAGE. The 18.5 kDa protein, designated VD18.5, appears to be a single subunit protein with an isoelectric point between 3 and 5. VD18.5 induces symptoms of leaf dehydration, chlorosis, necrosis and stem discoloration in seedlings of the disease susceptible cotton cultivar Siokra 1–4. The LD 50 of VD18.5 on protoplasts of Siokra 1–4 was 18 μg mL −1. VD18.5 had no noticeable effect on Pima S-7, which is a disease resistant cultivar. Phytotoxic activity was partially destroyed at high temperature and was abolished by digestion with proteinase K. Mass spectrometry fingerprinting and protein sequence data from VD18.5 yielded no significant matches when submitted to the Mascot search engine and NCBI non-redundant protein databases, respectively. These results suggest that VD18.5 is a novel protein that may be involved in the development of some of the symptoms associated with Verticillium wilt disease in the cotton plant.

Relationship between Yield Potential and Percentage Yield Suppression Caused by the Southern Root‐Knot Nematode in Cotton

Currently available cotton (Gossypium hirsutum L.) cultivars support significant reproduction of the southern root‐knot nematode [Meloidogyne incognita (Kofoid &amp; White) Chitwood], but they have not been evaluated for differing levels of yield suppression (tolerance) to this nematode. If nematode tolerant (low yield suppression) but susceptible (high nematode reproduction) cotton cultivars can be identified, they could be grown rather than intolerant cultivars to reduce yield loss. The objective of this study was to evaluate a collection of M. incognita–susceptible cotton cultivars for tolerance to parasitism by this nematode. The yield potential and percentage yield loss to M. incognita were measured in 12 genotypes in 2002 and 2003 by comparing yields in 1,3‐dichloropropene–fumigated and nonfumigated plots. The percentage yield suppression caused by M. incognita differed among cotton genotypes in both 2002 and 2003. Yield suppression ranged from 18.0 to 47.3% in 2002 and from 8.5 to 35.7% in 2003. Though significant levels of tolerance were measured in our study, 2 yr of data on percentage yield suppression show that tolerance is not consistently related to specific cultivars in the absence of nematode resistance: susceptible cultivars did not consistently express tolerance, but resistant germplasm did. Thus, it appears unlikely that cotton cultivar selection for tolerance to M. incognita can be utilized to minimize yield suppression. Regression analysis based on the 2 yr of field data revealed a relationship in which percentage yield suppression caused by M. incognita increased linearly as yield potential increased. Because the absolute and percentage losses to nematodes increase as yield potential increases, nematode management becomes increasingly important and beneficial in cotton.

Comparative Biochemical Changes in Resistant and Susceptible Cotton Cultivars to Leaf Curl Virus at Germination and Early Seedling Stage: α-amylase, Starch, Total Soluble Sugars in Seed, Radicle and Plumule

Comparative Biochemical Changes in Resistant and Susceptible Cotton Cultivars to Leaf Curl Virus at Germination and Early Seedling Stage: α-amylase, Starch, Total Soluble Sugars in Seed, Radicle and Plumule

Some Physiological Characteristics in Resistant and Susceptible Cotton Cultivars Infected with Cotton Leaf Curl Virus

Eight cultivars/lines of Gossypium hirsutum (CIM-443, CIM-448, CIM-1100, FH-634, S-111, S-113, Cedix, and LRA 5166) resistant to cotton leaf curl virus (CLCuV), one moderately-resistant (cv. NIAB-Krishma), and one susceptible (cv. S-12) were used. All the resistant lines remained free of all disease symptoms, whereas in moderately-resistant and susceptible cvs. leaf curling and vein thickening occurred. Cultivars with varying degree of CLCuV-resistance had different pattern of accumulation of macronutrients. Leaf N content was lowest in S-12, but increased considerably due to disease. Leaf K and Ca contents of S-12 were lower in the diseased leaves than in healthy ones. Chlorophyll a and b contents were highest in lines S-111, S-113 and S-12. A marked reduction in chlorophyll b content was observed in the diseased leaves of S-12. Leaf water potential in S-12 and NIAB-Krishma was also decreased due to disease. The most distinctive characteristic to differentiate between lines was epicuticular wax content, since all the resistant lines had considerably higher wax content on their leaf surfaces than the moderately-resistant or susceptible cultivars.

Induction of delta-cadinene synthase and sesquiterpenoid phytoalexins in cotton by Verticillium dahliae.

Phytoalexin biosynthesis occurred earlier in the resistant cotton cultivar Seabrook Sea Island 12B2 (SBSI) (Gossypium barbadense) than in the susceptible cotton cultivar Rowden (G. hirsutum) after inoculation with a defoliating isolate of the pathogen Verticillium dahliae. This was demonstrated by significantly higher levels of phytoalexins in SBSI 12 h after inoculation. Furthermore, by 48 h after inoculation of SBSI, the phytoalexins hemigossypol and desoxyhemigossypol achieved levels (23.9 and 10.5 microgram/g of fresh tissue, respectively) sufficient to completely inhibit conidial germination. Rowden required 96 h to attain comparable levels. Similarly, the activity of delta-cadinene synthase, a key enzyme required for the biosynthesis of the terpenoid phytoalexins, increased more rapidly in the resistant cotton cultivar than in the susceptible one. The changes in phytoalexin concentrations and enzyme activity are consistent with the hypothesis that phytoalexins are an essential component in protecting the plant from infection by V. dahliae.

Variations in soil population of Fusarium oxysporum f. sp. vasinfectum as influenced by fertiliser application and growth of different crops

During the 1995–96 growing season, the effects of fertiliser application and growth of different crops on the population of Fzrsarium oxysporum f. sp, vasinfictum (Fov) in field soils were examined. In soil samples collected 35 days after fertiliser application, densities of Fov were significantly lower in soils receiving 180 units of anhydrous ammonia than in those receiving 40 or 180 units of urea. When compared with samples collected at sowing, densities of Fov were significantly reduced in soil samples from plots planted to either the less susceptible cotton cultivar DP90 or soybean. The proportions of Fov in the total F: oxysporum population increased significantly in soils planted to the most susceptible cotton cultivar Siokra 1–4, but decreased significantly in soils planted to the less susceptible cultivar DP90.

Effects of plant residue, soil characteristics, cotton cultivars and other crops on fusarium wilt of cotton in Australia

The incidence and severity of fusarium wilt of cotton in glasshouse trials increased when levels of plant residue in the soil were increased by the incorporation of whole cotton plants (6-week-old seedlings dried out for a further 6 weeks) into the soil. In non-residue-supplemented potting mix, disease incidence was &lt;50%, but ranged from 74 to &gt;90% in residue-supplemented potting mix. The disease was significantly affected by soil microflora and soil type, but not affected by soil pH in the range 4.0–8.5. Although the same amount of inoculum was added to both autoclaved and untreated soils, the disease was less severe in autoclaved soils than in untreated soils regardless of soil type. Among the 4 clay soils investigated, the disease was less severe in a grey sandy clay and a brown heavy clay than in a dark grey heavy clay. Compared with the soils collected at the end of the 1995–96 growing season, the disease became more severe in the soil of plots planted to the most susceptible cotton cultivar Siokra 1-4, but less severe in the soil of plots planted to the less susceptible cotton cultivar DP90 at the end of the 1996–97 growing season. However, no significant differences were observed in the soil of plots planted to cotton cultivar Siokra L22, sorghum, maize or soybean.

Characterisation of a population of Fusarium oxysporum f.sp. vasinfectum causing wilt of cotton in Australia

Following the discovery of fusarium wilt in Australian cotton crops in 1993, isolates of Fusarium oxysporum f. sp. vasinfectum were collected from 6 cotton farms on the Darling Downs of Queensland. Using a range of procedures the Australian isolates could not be differentiated from each other, but they did differ from foreign isolates of the pathogen in a number of characteristics. Pathogenically, the isolates behaved similarly to race 6 of the pathogen when inoculated onto differential lines. Using aesculin hydrolysis tests, however, it was difficult to match local isolates with any of the known races. Additionally, none of the foreign isolates examined produced detectable volatile compounds when grown on a starch substrate, while all Australian isolates produced a distinctive odour during these tests. The local strain was not vegetatively compatible with any of the foreign isolates and belonged in a single, unique vegetative compatibility group. It is speculated that the Australian strain arose locally, perhaps from a minor population becoming prominent in response to wide-scale planting of highly susceptible cotton cultivars. These findings have significant implications for control of the disease and spread of the pathogen in Australia.

Inhibition of susceptible water soaking and/or hypersensitive reaction in cotton by exopolysaccharide of avirulentXanthomonas campestris pv.malvacearum

The exopolysaccharide (EPS) of avirulentXanthomonas campestris pv.Malvacearum race-32 did not contain the watersoaking (WS)— inducing factor but contained necrotic reaction (NR)-inducing factor and induced NR on resistant cotton (cv. 101-102B) on which the viable cells of the same avirulent race-32 produced hypersensitive reaction (HR). NR and HR were differentiated on the basis of the induction period required, visible reaction on infiltrated areas, bacterial constituents or metabolite responsible, involvement of host constituent during these reactions and its chemical inhibition. Pre and/or challenge inoculation of EPS of avirulent race-32 (3 mg per infiltration or lesion) in susceptible or resistant cotton cultivars, on pre-and/or post-infiltrated (0–8 h) exponential-phase culture of virulent race-32 inhibited the WS and/or HR of the virulent race in susceptible or resistant cotton.