Effects of Chemical Control, Cultivar Resistance, and Structure of Cultivar Root System on Black Shank Incidence of Tobacco

Antonopoulos, D. F.; Melton, T. A.; Mila, A. L.

doi:10.1094/pdis-94-5-0613

Cited by 30 publications

(15 citation statements)

References 23 publications

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“…This resistance is polygenic in nature and is not race specific (Antonopoulos et al, 2010;Xiao et al, 2013). This resistance is polygenic in nature and is not race specific (Antonopoulos et al, 2010;Xiao et al, 2013).…”

Section: Development and Selection Of Lines For Resistance To Phytophmentioning

confidence: 94%

“…Flue-cured tobacco cultivar K 346 was chosen as a source of a very high level of partial resistance to P. nicotianae. This resistance is polygenic in nature and is not race specific (Antonopoulos et al, 2010;Xiao et al, 2013). Using procedures previously described by Lewis and Kernodle (2009), a single 35S:FT transgene insertion (A. thaliana FT gene under control of the CaMV 35S promoter and linked to a nptII gene conferring resistance to kanamycin) was transferred to K 346 to develop a BC 7 F 1 family segregating for FT and hereafter referred to as K 346-FT. K 346-FT plants expressing the early-flowering trait were hybridized with burley tobacco breeding line 'NC1209-23' and the standard burley tobacco cultivar TN 90LC to generate two F 1 hybrids expected to segregate for 35S:FT. NC1209-23 and TN 90LC exhibit low and low-intermediate levels of resistance to black shank, respectively.…”

Section: Development and Selection Of Lines For Resistance To Phytophmentioning

confidence: 99%

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Breeding Cycles Expedited by FT‐mediated Reduction in Generation Time

Eickholt

Lewis

2013

Crop Science

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A significant fraction of the total time required to develop new cultivars is dedicated to inbreeding, a process where alleles become fixed at the majority of loci across the plant genome to result in inbred lines exhibiting a high degree of phenotypic uniformity. After an initial cross is made between two or more lines, at least three generations of inbreeding are typically conducted in segregating populations to develop new lines that are subsequently evaluated for economically important traits (such as yield) in replicated field testing. Opportunity for selection, which increases the frequency of desirable alleles in succeeding generations, is dependent on the traits of interest and the particular breeding methodology being utilized.The time required to develop new inbred lines and to complete a breeding cycle is dependent on generation time (duration from seed to seed) and the potential to carry out multiple generations of inbreeding per year. When multiple breeding cycles are taken into consideration, this duration affects the potential rate of genetic gain per year (Fehr, 1987). A number of techniques have been described to reduce the time needed to develop inbred lines. For example, the single-seed descent (SSD) method of breeding (Brim, 1966) is used by breeders of some crops to advance multiple generations per year through utilization of greenhouse or off-season nursery facilities. Doubled-haploid procedures that can generate completely inbred lines in only a few steps have also been developed for some ABSTRACT Methods for rapid inbreeding are desirable for reducing the time required to complete a breeding cycle and to increase genetic gain per year. Constitutive expression of FLOWERING LOCUS T (FT) derived from Arabidopsis has previously been shown to reduce generation time in tobacco (Nicotiana tabacum L.) and other crop plants. Here, we used tobacco as a model system to investigate the utility of a modified single-seed descent (SSD) breeding method where transgenic expression of 35S:FT was used to reduce generation time during inbreeding. The transgene was maintained in hemizygous condition during inbreeding, and null segregants were isolated in the F 4:5 generation to create nontransgenic F 5:6 lines that were produced in nearly half the time that would have been required using conventional SSD. opportunities for selection among 35S:FT plants during inbreeding were demonstrated by selecting for quantitative levels of resistance to the soil-borne pathogen Phytophthora nicotianae. populations of selected lines exhibited significantly higher levels of resistance relative to random lines, greater frequencies of highly resistant genotypes, and lower frequencies of highly susceptible genotypes. The system outlined here could lead to more rapid commercialization of improved cultivars in crop species amenable to manipulation of flowering time via transgenic expression of FT-like genes. Strategies to enhance the frequency of favorable alleles in resulting populations can be incorporated into the method.

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Section: Development and Selection Of Lines For Resistance To Phytophmentioning

confidence: 94%

Section: Development and Selection Of Lines For Resistance To Phytophmentioning

confidence: 99%

Breeding Cycles Expedited by FT‐mediated Reduction in Generation Time

Eickholt

Lewis

2013

Crop Science

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“…The most characteristic symptoms are that the pith of stem is dry, brown to black and is separated into plate‐like discs (Qu, Shao, Csinos, & Ji, ). Black shank of tobacco can be effectively managed using an integrated approach that includes cultural practices, chemical control and host resistance (Antonopoulos, Melton, & Mila, ; Csinos & Bertrand, ).…”

Section: Introductionmentioning

confidence: 99%

Mating type and sensitivity of Phytophthora nicotianae from tobacco to metalaxyl and dimethomorph in Henan province, China

Cui

Gao

Guo

et al. 2018

Journal of Phytopathology

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Phytophthora nicotianae causes black shank, one of the most important diseases of tobacco worldwide. Metalaxyl and dimethomorph are two fungicides which have been used widely for control of this disease in Henan province, China. A study was conducted to determine the level of metalaxyl and dimethomorph sensitivity in isolates of P. nicotianae from tobacco in Henan province and mating type structure of the pathogen population. A total of 32 isolates were isolated from 11 cities in Henan province. Sensitivity of all isolates to metalaxyl and dimethomorph was tested in vitro, and mating types of all isolates were determined by pairing known A1 and A2 testers. For metalaxyl, EC50 values of 32 P. nicotianae isolates ranged from 0.08 to 2.82 mg/L. Sixteen isolates were sensitive, and the rest were intermediate to metalaxyl. None were classified as resistant isolates. For dimethomorph, EC50 values of 32 P. nicotianae isolates ranged from 0.07 to 0.59 mg/L. All isolates were sensitive to dimethomorph. Thirty‐one isolates were A2 mating type, and one isolate was A0 mating type. No isolate was identified as A1 mating type. These results suggested that the P. nicotianae population in Henan province has already exhibited intermediate resistance to metalaxyl and was still sensitive to dimethomorph, and asexual reproduction was the major form of reproduction for the P. nicotianae population.

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“…A stable breeding line designated as "WZ" was developed from this effort. Several flue-cured tobacco hybrids with WZ in their pedigree have exhibited high levels of resistance to multiple races of P. nicotianae in field and laboratory experiments (Antonopoulos et al, 2010). These observed levels of resistance are somewhat unexpected based on the parentage of these cultivars.…”

mentioning

confidence: 98%

An Introgressed Nicotiana rustica Genomic Region Confers Resistance to Phytophthora nicotianae in Cultivated Tobacco

Drake

Lewis

2013

Crop Science

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Black shank, caused by the pathogen Phytophthora nicotianae, is an important disease affecting tobacco (Nicotiana tabacum L.) production in many parts of the world. Host resistance offers an efficient means of reducing economic loss due to this pathogen. Previous observations suggested that a genomic region introgressed from Nicotiana rustica L. may affect resistance to black shank. The effect of this genomic region, designated as Wz, on resistance to multiple races of P. nicotianae had not previously been investigated in a systematic way, however. We used growth chamber and field experiments to evaluate resistance of a doubled haploid (DH) mapping population segregating for the Wz region. We also genotyped the population with amplified fragment length polymorphism (AFLP) markers found to be polymorphic between the parental lines. In addition, we determined resistance and marker genotypes for individuals of a larger BC1F1 population segregating for Wz. A set of 29 AFLP markers determined to be of N. rustica origin were found to cosegregate with each other and were associated with resistance to both race 0 and race 1 of P. nicotianae in the DH population. A selected subset of these markers was also found to cosegregate with resistance in the BC1F1 population. Consistent with other introgressed alien genomic regions in N. tabacum, no recombination was observed between these selected markers. The N. rustica‐derived genetic variation and associated DNA markers will be of value for breeding for black shank resistance in tobacco.

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Effects of Chemical Control, Cultivar Resistance, and Structure of Cultivar Root System on Black Shank Incidence of Tobacco

Cited by 30 publications

References 23 publications

Breeding Cycles Expedited by FT‐mediated Reduction in Generation Time

Breeding Cycles Expedited by FT‐mediated Reduction in Generation Time

Mating type and sensitivity of Phytophthora nicotianae from tobacco to metalaxyl and dimethomorph in Henan province, China

An Introgressed Nicotiana rustica Genomic Region Confers Resistance to Phytophthora nicotianae in Cultivated Tobacco

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