scholarly journals Floral biological investigations of apple cultivars in relation to fire blight

2004 ◽  
Vol 10 (2) ◽  
Author(s):  
Zs. Orosz-Kovács ◽  
A. Farkas ◽  
T. Bubán ◽  
P. Bukovics ◽  
E. Nagy Tóth ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Optimal Conditions ◽  
Nectar Secretion ◽  
Flower Bud ◽  
Nectar Production ◽  
Sem Micrographs ◽  
Long Period ◽  
Apple Cultivars

Floral activity was studied in two apple cultivars: an Erwinia-tolerant (Treedorn') and a sensitive one (`Sampion'). Since more types of protogyny occur in apples, the period of stigma activity is different. Papillae of the exposed stigma in flowers of 'Freedom' function longer (usually more than a week) than in the delayed homogamous `Sampion'. Despite of this, cv. 'Freedom' is tolerant to Erwinia amylovora (Burr.) Winslow et al., suggesting no relationship between the floral biological type (including the exposure and longevity of stigma) and the infection by E. amylovora. According to SEM micrographs, nectary stomata in `Freedom' are already open in the flower bud, where nectar secretion starts and continues until the senescence of the stigma. However, the long period of nectar secretion does not create optimal conditions for bacterial growth, since nectar production is scant in the flowers of 'Freedom'. The surface of the nectary, its nectar-retaining capacity, and the amount and concentration of nectar may influence the susceptibility of apple cultivars. It is manifested well by the smooth nectary surface with nectary stomata rising slightly above the epidermis in flowers of cv. 'Freedom', contrasting the wrinkled, striate nectary surface with slightly sunken stomata in the flowers of 'Sampion'.

Evaluation of old Carpathian apple cultivars as genetic resources of resistance to fire blight (Erwinia amylovora)

Trees ◽  
2012 ◽  
Vol 27 (3) ◽  
pp. 597-605 ◽  
Author(s):  
Magdolna Tóth ◽  
Gitta Ficzek ◽  
Ildikó Király ◽  
Krisztina Honty ◽  
Mária Hevesi
Keyword(s):  
Genetic Resources ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Apple Cultivars

scholarly journals Inflorescence blast and flower bud abnormalities of Spiraea × vanhouttei and their causes

2008 ◽  
Vol 43 (No. 4) ◽  
pp. 135-143 ◽  
Author(s):  
V. Kůdela
Keyword(s):  
Seed Production ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Small Scale ◽  
Flower Bud ◽  
The Czech Republic ◽  
Hybrid Species ◽  
High Incidence ◽  
The Subject ◽  
Very High

In ornamental gardening, <I>Spiraea × vanhouttei</I> is a frequently planted spirea species in the Czech Republic. In 2003, there arose a suspicion of possible occurrence of fire blight caused by <I>Erwinia amylovora</I> on spirea shrubs in Prague and its environs. This suspicion was disproved for a certainty. The absence of the fire blight pathogen in symptomatic spirea plants stimulates a further effort to tackle the problem of a cause of conspicuous fire blight-like symptoms or inflorescence blast occurring on some spirea shrubs. The subject of this paper is: (i) to describe symptoms, incidence and severity of inflorescence blast, bud and flower abnormalities occurring in <I>Spiraea × vanhouttei</I> shrubs; (ii) to find out differences in the occurrence of blasted inflorescences between <I>Spiraea</I> species and cultivars with the intention of verifying the hypothesis that the blast inflorescence and sterility of some spirea species are associated with hybrid species. Symptoms of inflorescence blast are every growing season. No seed is produced by blasted inflorescences. Besides inflorescence blast, aborted floral buds appeared sporadically on a small scale. Spirea species were split into four categories according to the incidence of blasted inflorescences. Out of 52 species evaluated, 10% showed no or scarce incidence, 52% medium incidence, 27% high incidence and 11% very high incidence. The scarce incidence of blasted inflorescences was connected with the high seed production. And vice versa, very high incidence of blighted inflorescences was closely connected with no or low seed production or with high incidence of sterility. Fifteen out of the evaluated spirea species are the result of hybridization. These hybrids occur in each of the four categories of spirea species distinguished by the incidence of blasted inflorescence. However, it is remarkable that the highest incidence of hybrid spireas occurs in the category with the highest incidence of blasted inflorescence (83.33%). In the remaining three categories of spirea species, the proportion of hybrids ranged from 18 to 21%. It might indicate some connection of spirea hybrids with sterility.

scholarly journals Blackberry and raspberry are alternative resistance sources to fire blight

2017 ◽  
Vol 97 (1) ◽  
pp. 12-16 ◽  
Author(s):  
Ozer Calis ◽  
Cetin Cekic ◽  
Serhat Kara ◽  
Demet Celik Ertekin
Keyword(s):  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Pathogen ◽  
Post Inoculation ◽  
Resistance Sources ◽  
Pathogenicity Tests ◽  
Susceptibility And Resistance ◽  
Resistant Genotypes ◽  
Moderate Susceptibility

Erwinia amylovora causes fire blight mainly on pear, apple and quince trees. This bacterial pathogen also infects other Rosaceous plants, such as blackberry and raspberry. A race structure was established between an isolate of E. amylovora and berries using 40 wild blackberry and 7 wild raspberry genotypes. In pathogenicity tests, wild blackberry and raspberry genotypes had three phenotypic reactions: enhanced susceptibility, moderate susceptibility and resistance. We noted a higher bacterial growth of over 300 × 109 cfu mL-1 in plants with enhanced susceptibility, with resistant genotypes showing a bacterial growth of around 150 × 109 cfu mL-1. These results are also associated with symptoms observed at 29 days post-inoculation. This resistance is being evaluated to control fire blight.

scholarly journals Evaluation of a Cider Apple Germplasm Collection of Local Cultivars from Spain for Resistance to Fire Blight (Erwinia amylovora) Using a Combination of Inoculation Assays on Leaves and Shoots

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1223-1227 ◽  
Author(s):  
Alejandro Martínez-Bilbao ◽  
Amaya Ortiz-Barredo ◽  
Emilio Montesinos ◽  
Jesús Murillo
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Integrated Management ◽  
Germplasm Collection ◽  
Direct Selection ◽  
Breeding Programs ◽  
Detached Leaf ◽  
Apple Cultivars ◽  
Apple Production ◽  
Inoculation Assay

Fire blight, caused by the bacterium Erwinia amylovora, is among the three most important diseases of apple. A major effective method for its integrated management is the reduction of the susceptibility of the host. Cider apple production in Spain is based on local apple cultivars with minimum crop management and phytosanitary control. After the entry of fire blight in Spain, the selection and planting of cultivars with low susceptibility to this disease has thus become of paramount importance. In consequence, and as part of a wider characterization effort, we undertook the evaluation of an apple germplasm collection of local apple cultivars from Spain for susceptibility to fire blight. Because of the quarantine status of E. amylovora in Europe, we evaluated the use of a detached leaf inoculation assay in combination with a traditional shoot inoculation assay to reduce the amount of plant material to evaluate and to minimize pathogen manipulation. Comparison of the susceptibility values for 78 apple cultivars indicated a low but significant correlation (r = 0.56; α = 0.01) between the leaf and shoot inoculation methods. Although the detached leaf assay was not reliable for the direct selection of cultivars with low susceptibility, it was useful to optimize resources and limit the potential dispersal of the pathogen by allowing the exclusion of medium and highly susceptible cultivars from further evaluation. Shoot inoculation of 103 apple cultivars allowed the identification of 48 cultivars with high levels of resistance to fire blight, which could serve as starting material both for apple production and for breeding programs.

scholarly journals Resistance of apple varieties and selections to Erwinia amylovora in the Czech Republic

2008 ◽  
Vol 44 (No. 3) ◽  
pp. 91-96 ◽  
Author(s):  
J. Korba ◽  
J. Šillerová ◽  
V. Kůdela
Keyword(s):  
Czech Republic ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Relative Resistance ◽  
Lesion Development ◽  
The Czech Republic ◽  
Apple Cultivars ◽  
Moderately Resistant ◽  
Resistant Genotypes ◽  
Experimental Plots

Sixty-four apple cultivars and selections of potential interest to apple producers and plant breeders in the Czech Republic were tested for their relative resistance to the fire blight pathogen over six years. Level of fire blight resistance was evaluated according to the extent of lesion development on the shoots tips after artificial inoculation in experimental plots under insectproof nets. Cultivars Quinte (resistant) and Yellow transparent (high susceptible) were included in the tests. Of 64 apple cultivars and selections tested, none were high resistant, 3.1% were evaluated as resistant, 10.9% moderately resistant, 57.8% moderately susceptible, 21.9% susceptible and 6.3% high susceptible. Resistant apple genotypes, showing blight necrosis of shoots of 11–12%, were only cultivars Selena and Quinte. Moderately resistant genotypes (blight necrosis 13.1–25.0%) were Kordona, Golden Smoothee, Julia, HL 323, Melodie, HL 421 and S 634/3. High susceptible genotypes (blight necrosis more then 80.1%) were comprised cultivars Vesna, Topas, Yellow transparent and Vanda. The remaining genotypes were moderately susceptible (blight necrosis 26.1–60.0%) and susceptible (blight necrosis 60.1–80.0%). During six experimental years, quantitative variability was recorded in the blight score. Differences between cultivars in susceptibility to fire blight were often statistically significant.

scholarly journals Transcriptional profile of AvrRpt2EA-mediated resistance and susceptibility response to Erwinia amylovora in apple

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Susan Schröpfer ◽  
Isabelle Vogt ◽  
Giovanni Antonio Lodovico Broggini ◽  
Andreas Dahl ◽  
Klaus Richter ◽  
...  
Keyword(s):  
Heat Shock ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Disease ◽  
Resistance Response ◽  
Heat Shock Transcription Factors ◽  
Induce Resistance ◽  
Apple Cultivars ◽  
Shock Proteins ◽  
Susceptible Response

AbstractMost of the commercial apple cultivars are highly susceptible to fire blight, which is the most devastating bacterial disease affecting pome fruits. Resistance to fire blight is described especially in wild Malus accessions such as M. × robusta 5 (Mr5), but the molecular basis of host resistance response to the pathogen Erwinia amylovora is still largely unknown. The bacterial effector protein AvrRpt2EA was found to be the key determinant of resistance response in Mr5. A wild type E. amylovora strain and the corresponding avrRpt2EA deletion mutant were used for inoculation of Mr5 to induce resistance or susceptible response, respectively. By comparison of the transcriptome of both responses, 211 differentially expressed genes (DEGs) were identified. We found that heat-shock response including heat-shock proteins (HSPs) and heat-shock transcription factors (HSFs) are activated in apple specifically in the susceptible response, independent of AvrRpt2EA. Further analysis on the expression progress of 81 DEGs by high-throughput real-time qPCR resulted in the identification of genes that were activated after inoculation with E. amylovora. Hence, a potential role of these genes in the resistance to the pathogen is postulated, including genes coding for enzymes involved in formation of flavonoids and terpenoids, ribosome-inactivating enzymes (RIPs) and a squamosa promoter binding-like (SPL) transcription factor.

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