Limited Evidence for Accumulation of Latent Infections of Canker-Causing Pathogens in Shoots of Stone Fruit and Nut Crops in California

2021 ◽  
Author(s):  
Yong Luo ◽  
Franz Niederholzer ◽  
Dani Lightle ◽  
Dan Felts ◽  
John Lake ◽  
...  
Keyword(s):  
Latent Infection ◽  
Latent Infections ◽  
Botryosphaeria Dothidea ◽  
Limited Evidence ◽  
Age Classes ◽  
Pcr Assay ◽  
Current Season ◽  
Real Time Quantitative Pcr ◽  
Growing Seasons ◽  
Quantitative Pcr Assay

Prevalence of latent infections of the canker-causing fungi Botryosphaeria dothidea and species of Cytospora, Diplodia, Lasiodiplodia, Neofusicoccum, and Phomopsis in young shoots of almond, prune and walnut trees in California was studied to test the hypotheses that 1) latent infections accumulate from current-season shoots to 1-year-old shoots in the orchard and 2) there are distinct associations among pathogen taxa present as latent infections in the same shoot. Samples of newly-emerged and 1-year-old shoots were periodically collected in each almond, prune, and walnut orchard for two growing seasons. A real-time quantitative PCR assay was used to quantify latent infection with three parameters: incidence, molecular severity and latent infection index. Diplodia spp. were absent from most samples. For almond, Lasiodiplodia spp. and Cytospora spp. were detected with a maximum incidence >90%, while B. dothidea and Neofusicoccumspp. incidence was <20% in most cases. In prune orchards, the incidence levels of B. dothidea were >50% in most cases, while those of Cytospora spp. and Lasiodiplodia spp. were 30 - 60% and 30 - 100%, respectively. For walnut, many samplings showed higher incidence in 1-year-old (30 – 80%) than in newly-emerged shoots (10 – 50%). Accumulation of latent infection between the two shoot age classes was detected in only few cases. The percentages of samples showing coexistence of two, three and four pathogen taxa in the same shoot were 20 – 25%, <10% and <5%, respectively. Pairwise associations among pathogen taxa in the same shoot were significant in many cases.

scholarly journals Relationships Among Propagule Numbers of Botryosphaeria dothidea, Latent Infections, and Severity of Panicle and Shoot Blight in Pistachio Orchards

Plant Disease ◽  
2003 ◽  
Vol 87 (7) ◽  
pp. 846-853 ◽  
Author(s):  
N. Ahimera ◽  
G. F. Driever ◽  
T. J. Michailides
Keyword(s):  
Disease Severity ◽  
Latent Infection ◽  
Assessment Method ◽  
Latent Infections ◽  
Botryosphaeria Dothidea ◽  
Growing Seasons ◽  
Risk Assessment Method ◽  
Shoot Blight ◽  
Fruit Disease

Experiments were conducted between 1999 and 2001 to monitor the presence of propagules of Botryosphaeria dothidea and frequencies of latent infections on pistachio leaves and fruit clusters and to determine their relationships to panicle and shoot blight severity in commercial orchards. Numbers of B. dothidea propagules recovered from washing leaves and fruit clusters varied among the growing seasons and sampling dates. Lower numbers of B. dothidea propagules were obtained in 1999 and 2001 than in 2000. For the orchard in Glenn County, up to 75 propagules per leaf and 21 propagules per fruit cluster were recorded in 1999, compared with 365 and 248 propagules per leaf and fruit cluster, respectively, in 2000. Although more propagules were detected per leaf, the infection levels were higher on fruit clusters, suggesting that pistachio fruit is more susceptible to B. dothidea infection than leaves. Latent infections were detected as soon as leaves or fruit clusters started to expand and more infections were obtained in 2000 than 1999 or 2001. Significant (P < 0.05) relationships between propagules on leaves or frequency of infections on leaves (independent variables) and propagules on fruit clusters or frequency of infected fruit clusters (dependent variables) with r values ≥ 0.50 provide support for the role of latent infection in panicle and shoot blight later in the season. Propagules on leaves and fruit clusters were not significantly correlated to disease severity, but frequencies of latent infection on leaves and fruit clusters were positively correlated (P ≥ 0.05) with leaf and fruit disease severity under field conditions with r2 ranging between 0.25 and 0.42. Quantitative relationships between latent infections and disease severity may be incorporated in a prediction model for disease development or be used to develop a risk assessment method to guide growers in their effort to control panicle and shoot blight of pistachio.

scholarly journals Real-Time Quantitative PCR Assay for Monitoring of Nervous Necrosis Virus Infection in Grouper Aquaculture

2011 ◽  
Vol 49 (3) ◽  
pp. 1090-1096 ◽  
Author(s):  
H.-C. Kuo ◽  
T.-Y. Wang ◽  
P.-P. Chen ◽  
Y.-M. Chen ◽  
H.-C. Chuang ◽  
...  
Keyword(s):  
Virus Infection ◽  
Real Time ◽  
Quantitative Pcr ◽  
Nervous Necrosis Virus ◽  
Necrosis Virus ◽  
Pcr Assay ◽  
Real Time Quantitative Pcr ◽  
Quantitative Pcr Assay

scholarly journals Determination of RhD Zygosity: Comparison of a Double Amplification Refractory Mutation System Approach and a Multiplex Real-Time Quantitative PCR Approach

2001 ◽  
Vol 47 (4) ◽  
pp. 667-672 ◽  
Author(s):  
Rossa W K Chiu ◽  
Michael F Murphy ◽  
Carrie Fidler ◽  
Benny C Y Zee ◽  
James S Wainscoat ◽  
...  
Keyword(s):  
Real Time ◽  
Quantitative Pcr ◽  
Gene Dosage ◽  
Amplification Refractory Mutation System ◽  
Pcr Assay ◽  
Real Time Quantitative Pcr ◽  
Mutation System ◽  
Allele Specific ◽  
Quantitative Pcr Assay

Abstract Background: Rh isoimmunization and hemolytic disease of the newborn still occur despite the availability of Rh immunoglobulin. For the prenatal investigation of sensitized RhD-negative pregnant women, determination of the zygosity of the RhD-positive father has important implications. The currently available molecular methods for RhD zygosity assessment, in general, are technically demanding and labor-intensive. Therefore, at present, rhesus genotype assessment is most commonly inferred from results of serological tests. The recent elucidation of the genetic structure of the prevalent RHD deletion in Caucasians, as well as the development of real-time PCR, allowed us to explore two new approaches for the molecular determination of RhD zygosity. Methods: Two methods for RhD zygosity determination were developed. The first was based on the double Amplification Refractory Mutation System (double ARMS). The second was based on multiplex real-time quantitative PCR. For the double ARMS assay, allele-specific primers were designed to directly amplify the most prevalent RHD deletion found in RhD-negative individuals in the Caucasian population. The multiplex real-time quantitative PCR assay, on the other hand, involved coamplification and quantification of RHD-specific sequences in relation to a reference gene, albumin, in a single PCR reaction. A ratio, ΔCt, based on the threshold cycle, was then determined and reflects the RHD gene dosage. Results: The allele-specific primers of the double ARMS assay reliably amplified the RHD-deleted allele and therefore accurately distinguished homozygous from heterozygous RhD-positive samples. The results were in complete concordance with serological testing. For the multiplex real-time quantitative PCR assay, the ΔCt values clearly segregated into two distinct populations according to the RHD gene dosage, with mean values of 1.70 (SD, 0.17) and 2.62 (SD, 0.29) for the homozygous and heterozygous samples, respectively (P &lt;0.001, t-test). The results were in complete concordance with the results of serological testing as well as with the double ARMS assay. Conclusion: Double ARMS and real-time quantitative PCR are alternative robust assays for the determination of RhD zygosity.

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