A Comparison of the Disease Reactions of Stems and Detached Leaves of Soil and in vitro Grown Plants and Regenerants of Oilseed Rape to Leptosphaeria maculans and Protocols for Selection for Novel Disease Resistance

1993 ◽  
Vol 137 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Marie A. Gretenkort ◽  
D. S. Ingram
Keyword(s):  
Disease Resistance ◽  
Oilseed Rape ◽  
Leptosphaeria Maculans ◽  
Detached Leaves ◽  
Selection For

Over-expression of GbRac1 gene in transgenic tobacco enhances disease resistance to Alternaria alternata in vitro

2005 ◽  
Vol 2 (2) ◽  
pp. 73-77 ◽  
Author(s):  
Li Wei-Min ◽  
Wang Zhi-Xing ◽  
Jia Shi-Rong
Keyword(s):  
Disease Resistance ◽  
Transgenic Plants ◽  
Alternaria Alternata ◽  
Northern Blot Analysis ◽  
Challenge Test ◽  
Constitutive Expression ◽  
Degenerate Primers ◽  
Over Expression ◽  
Detached Leaves

AbstractGbRac1 gene was cloned from Gossypium barbadense with degenerate primers and 3′-RACE. Northern blot analysis indicated that GbRac1 mRNA was expressed abundantly in G. barbadense seedlings inoculated with Verticillium dehliae compared with mock-inoculated plants. A plant constitutive expression vector pRac harbouring GbRac1 gene was constructed and leaf discs of tobacco (Nicotiana tabacum L. cv. NC89) were transformed with pRac by Agrobacterium-mediated transformation. Disease challenge test of detached leaves of the transgenic plants by inoculation with Alternaria alternata showed that resistance was enhanced dramatically compared with the non-transgenic plants. Results suggest that GbRac1 gene might have potential application in the genetic engineering of plants with enhanced disease resistance.

scholarly journals Analysis of Leptosphaeria maculans Race Structure in a Worldwide Collection of Isolates

2005 ◽  
Vol 95 (9) ◽  
pp. 1061-1071 ◽  
Author(s):  
M. H. Balesdent ◽  
M. J. Barbetti ◽  
Hua Li ◽  
K. Sivasithamparam ◽  
L. Gout ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Oilseed Rape ◽  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Allele Frequencies ◽  
Gene Interactions ◽  
Avr Gene ◽  
Avr Genes ◽  
Structure Diversity

Leptosphaeria maculans, the causal agent of stem canker of oilseed rape, develops gene-for-gene interactions with its hosts. To date, eight L. maculans avirulence (Avr) genes, AvrLm1 to AvrLm8, have been genetically characterized. An additional Avr gene, AvrLm9, that interacts with the resistance gene Rlm9, was genetically characterized here following in vitro crosses of the pathogen. A worldwide collection of 63 isolates, including the International Blackleg of Crucifers Network collection, was genotyped at these nine Avr loci. In a first step, isolates were classified into pathogenicity groups (PGs) using two published differential sets. This analysis revealed geographical disparities as regards the proportion of each PG. Genotyping of isolates at all Avr loci confirmed the disparities between continents, in terms of Avr allele frequencies, particularly for AvrLm2, AvrLm3, AvrLm7, AvrLm8, and AvrLm9, or in terms of race structure, diversity, and complexity. Twenty-six distinct races were identified in the collection. A larger number of races (n = 18) was found in Australia than in Europe (n = 8). Mean number of virulence alleles per isolate was also higher in Australia (5.11 virulence alleles) than in Europe (4.33) and Canada (3.46). Due to the diversity of populations of L. maculans evidenced here at the race level, a new, open terminology is proposed for L. maculans race designation, indicating all Avr loci for which the isolate is avirulent.

scholarly journals Freezing tolerance and proline content of in vitro selected hydroxyproline resistant winter oilseed rape

2010 ◽  
Vol 46 (No. 1) ◽  
pp. 35-40 ◽  
Author(s):  
A. Janská ◽  
S. Zelenková ◽  
M. Klíma ◽  
M. Vyvadilová ◽  
T.I. Prášil
Keyword(s):  
Oilseed Rape ◽  
Freezing Tolerance ◽  
Doubled Haploid ◽  
In Vitro Selection ◽  
Proline Content ◽  
Response To Selection ◽  
Weak Correlation ◽  
Winter Oilseed Rape ◽  
Selection For

Twelve doubled haploid (DH) winter oilseed rape plants with altered levels of proline and/or freezing tolerance were obtained by in vitro selection for resistance to trans-4-hydroxy-l-proline (Hyp) in five segregating microspore populations. No significant response to selection either in proline content or in freezing tolerance, compared with the non-selected control populations, was observed. When data from all examined materials were combined, a weak correlation between proline content and freezing tolerance was observed.

scholarly journals New Avirulence Genes in the Phytopathogenic Fungus Leptosphaeria maculans

2002 ◽  
Vol 92 (10) ◽  
pp. 1122-1133 ◽  
Author(s):  
M. H. Balesdent ◽  
A. Attard ◽  
M. L. Kühn ◽  
T. Rouxel
Keyword(s):  
Gene Cluster ◽  
Oilseed Rape ◽  
Single Gene ◽  
Leptosphaeria Maculans ◽  
Phytopathogenic Fungus ◽  
Gene Control ◽  
Avirulence Genes ◽  
Avr Gene ◽  
Avr Genes

Leptosphaeria maculans, the causal agent of stem canker of oilseed rape (Brassica napus), develops gene-for-gene interactions with oilseed rape, and four L. maculans avirulence (AVR) genes (AvrLm1, AvrLm2, AvrLm4, and alm1) were previously genetically characterized. Based on the analysis of progeny of numerous in vitro crosses between L. maculans isolates showing either already characterized or new differential interactions, this work aims to provide an overview of the AVR genes that may specify incompatibility toward B. napus and the related species B. juncea and B. rapa. Two novel differential interactions were thus identified between L. maculans and B. napus genotypes, one of them corresponding to a complete resistance to European races of L. maculans. In both cases, a single gene control of avirulence was established (genes AvrLm3 and AvrLm7). Similarly, a single gene control of avirulence toward a B. rapa genotype, also resistant to European L. maculans isolates, was demonstrated (gene AvrLm8). Finally, a digenic control of avirulence toward B. juncea was established (genes AvrLm5 and AvrLm6). Linkage analyses demonstrated that at least four unlinked L. maculans genomic regions, including at least one AVR gene cluster (AvrLm1-AvrLm2-AvrLm6), are involved in host specificity. The AvrLm3-AvrLm4-AvrLm7 region may correspond either to a second AVR gene cluster or to a multiallelic AVR gene.

scholarly journals In Vitro Mutagenesis followed by Polymorphism Detection Using Start Codon Targeted Markers to Engineer Brown Spot Resistance in Kalanchoe

2019 ◽  
Vol 144 (3) ◽  
pp. 193-200
Author(s):  
Rui Li ◽  
Lu Fan ◽  
Jingdong Lin ◽  
Mingyang Li ◽  
Daofeng Liu ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Brown Spot ◽  
Start Codon ◽  
Chemical Mutagenesis ◽  
In Vitro Mutagenesis ◽  
Aesthetic Value ◽  
Disease Resistant ◽  
Detached Leaves ◽  
Mutant Lines

Kalanchoe (Kalanchoe blossfeldiana) is a common potted flower that is popular throughout the world. Brown spot (caused by Stemphylium lycopersici) is one of the common foliage diseases in kalanchoe. This disease tends to infect leaves of kalanchoe plants in hot and humid environments, reducing their aesthetic value. The current investigation aimed to generate mutations resistant to brown spot in ‘Mary’ kalanchoe through chemical mutagenesis followed by molecular marker identification. Putative mutants were developed by treating embryogenic calluses with ethyl methanesulfonate (EMS) at median lethal doses (LD50)–either a 0.8% concentration for 2 hours or a 1.0% concentration for 0.5 hours. Brown spot crude toxin solution was used as the selection agent to identify disease-resistant calluses during tissue culture. The optimal crude concentration (60%) was determined by soaking calluses with different concentrations of crude pathogen: 0%, 20%, 40%, 60%, and 80% (v/v). A total of 32 anti-brown spot lines were regenerated and tested for disease resistance with detached leaves. Three regenerated EMS mutant lines showed no obvious brown spot lesions on their leaves after the disease resistance assay and were subjected to polymorphism identification by start codon targeted (SCoT) molecular markers. Three (SCoT40, SCoT71, and SCoT72) of 45 selected primers were chosen to identify the mutants. This work may lay the foundation for further development of new disease-resistant cultivars of kalanchoe.

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