Studies on seed and pollen transmission of Alfalfa Mosaic, Cucumber Mosaic and Bean Yellow Mosaic Viruses in cultivars and accesions of annual Medicago species

1995 ◽  
Vol 46 (1) ◽  
pp. 153 ◽  
Author(s):  
W Pathipanowat ◽  
RAC Jones ◽  
K Sivasithamparam
Keyword(s):  
Transmission Rate ◽  
Seed Transmission ◽  
Transmission Rates ◽  
Pollen Transmission ◽  
Immature Seeds ◽  
Annual Medicago ◽  
Carry Over ◽  
Transmission Studies ◽  
Medicago Species ◽  
Seed Coats

Seed and pollen transmission of alfalfa mosaic (AMV), cucumber mosaic (CMV) and bean yellow mosaic (BYMV) viruses was investigated in annual medic species (Medicago spp.). For seed transmission studies with AMV, graft inoculation was used to establish early infection and maximize possible transmission rates to seedlings via seed, but with CMV and BYMV aphid and/or graft inoculation was used. For pollen transmission studies, pollen taken from virus-infected plants was used to pollinate healthy plants, the seed collected and seedlings tested. The rates of AMV isolate OUI-2 transmission to seedlings through seed produced on infected plants ranged from 6 to 53% for commercial cultivars and from 7 to 65% for accessions. Accession DZA 3181.1.1 of M. sphaerocarpos had the highest overall AMV transmission rate. Only two cultivars, cvv. Borung and Hannaford of M. truncatula, and accession SA 4268 of M. orbicularis, had transmission rates of less than 10%. The rates of CMV transmission to seedlings via seed produced on infected plants of the cultivars and accessions tested were 0.3 to 13%, the greatest being found in M. polymorpha cv. Serena, but 6 out of 11 had no detectable transmission. The rates of BYMV transmission to seedlings via seed of the cultivars and accessions tested were 0.3 to 1%, but in 12 out of 15 none was detected. AMV isolate OUI-2 was transmitted to 52% of seedlings via seed produced on healthy M. polymorpha cv. Circle Valley plants pollinated from infected plants. In contrast, no transmission to seedlings by either graft-inoculation or pollination of M. polymorpha plants was detected with a second AMV isolate, OUI-1, which appeared to have lost its ablilty to be seed transmitted. No CMV or BYMV transmission to seedlings via pollination of healthy plants with pollen from infected plants was detected in M. polymorpha cvv. Circle Valley or Santiago. When empty immature pods, and dissected seed coats and embryos from immature seeds produced on AMV-infected plants of M. polymorpha were tested, AMV isolates OUI-I and OUI-2 were detected in all pods and seed coats, but only in 59% of embryos with isolate OUI-2 and in none with isolate OUI-1. CMV was detected in 12% of embryos tested from immature seeds produced on CMV-infected M. polymorpha cv. Serena plants. Transmission of all three viruses through seed, and of AMV through pollen, is cause for concern in annual medic breeding and evaluation programs. Moreover, carry-over outside the growing season in medic pastures is possible through seed with all three viruses.

Factors influencing transmission of alfalfa mosaic virus through seed of annual medics (Medicago spp.) and the genetic control of seed transmission rate

1997 ◽  
Vol 48 (7) ◽  
pp. 989 ◽  
Author(s):  
W. Pathipanawat ◽  
R. A. C. Jones ◽  
K. Sivasithamparam
Keyword(s):  
Mosaic Virus ◽  
Genetic Control ◽  
Transmission Rate ◽  
Alfalfa Mosaic Virus ◽  
Seed Transmission ◽  
Virus Concentration ◽  
Rate Condition ◽  
Reciprocal Crosses ◽  
Transmission Rates ◽  
Annual Medics

Factors likely to influence rates of transmission of alfalfa mosaic virus (AMV) through seed to seedlings of annual medics (Medicago spp.) and genetic control of the magnitude of its seed transmission rate were investigated in plants from 17 early-flowering accessions of M. polymorpha and in progenies of crosses involving M. murex cv. Zodiac × accession 5320 as parents. Plants were graft-inoculated when 6 weeks old to ensure successful and uniform infection. To exclude variation in seed transmission rates due to virus isolate or temperature, only 1 AMV isolate was used and the plants were kept under uniform temperature conditions. In M. polymorpha, significant differences were found between accessions in the levels of AMV transmitted through seed to progeny seedlings, SA 8250 giving the highest mean level of seed transmission (52%) and SA 4188 the lowest (3%). Neither virus concentration nor symptom severity influenced the rates of seed transmission obtained. However, part of the variation in seed transmission rates found in these accessions was related to their flowering times, seed transmission rates increasing as the interval between inoculation and owering increased. In seed samples collected from individual graft-inoculated plants of M. murex from (i) the F2 generation from crosses and reciprocal crosses, and (ii) the backcross progenies, the rates of transmission of AMV through seed to seedlings ranged from 0 to 77% and showed a continuous pattern of variation. Also, there was evidence of transgressive segregation for the low seed transmission rate condition. This indicates that the low seed transmission rate condition for AMV in medics is quantitatively inherited and under polygenic control. In contrast, when the pods from F2 progeny plants from the crosses and reciprocal crosses were examined, the segregation ratios obtained revealed that the smooth pod character from parent accession 5320 was controlled by a single recessive gene, for which the name sp is proposed. The presence in a plant of gene sp, or of its spiny pod-determining allele from the other parent cv. Zodiac, was not correlated with low seed transmission rates of AMV. It is concluded that selection for low rates of seed transmission and a population breeding approach can be used to produce improved M. polymorpha and M. murex cultivars with good resistance to seed-borne AMV

scholarly journals Large-Scale Seedling Grow-Out Experiments Do Not Support Seed Transmission of Sweet Potato Leaf Curl Virus in Sweet Potato

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 139
Author(s):  
Sharon A. Andreason ◽  
Omotola G. Olaniyi ◽  
Andrea C. Gilliard ◽  
Phillip A. Wadl ◽  
Livy H. Williams ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Large Scale ◽  
Seed Transmission ◽  
Potato Production ◽  
Potato Leaf ◽  
Vector Transmission ◽  
Leaf Curl Virus ◽  
Seed Coats ◽  
Potato Seedlings ◽  
Leaf Curl

Sweet potato leaf curl virus (SPLCV) threatens global sweet potato production. SPLCV is transmitted by Bemisia tabaci or via infected vegetative planting materials; however, SPLCV was suggested to be seed transmissible, which is a characteristic that is disputed for geminiviruses. The objective of this study was to revisit the validity of seed transmission of SPLCV in sweet potato. Using large-scale grow-out of sweet potato seedlings from SPLCV-contaminated seeds over 4 consecutive years, approximately 23,034 sweet potato seedlings of 118 genotype entries were evaluated. All seedlings germinating in a greenhouse under insect-proof conditions or in a growth chamber were free of SPLCV; however, a few seedlings grown in an open bench greenhouse lacking insect exclusion tested positive for SPLCV. Inspection of these seedlings revealed that B. tabaci had infiltrated the greenhouse. Therefore, transmission experiments were conducted using B. tabaci MEAM1, demonstrating successful vector transmission of SPLCV to sweet potato. Additionally, tests on contaminated seed coats and germinating cotyledons demonstrated that SPLCV contaminated a high percentage of seed coats collected from infected maternal plants, but SPLCV was never detected in emerging cotyledons. Based on the results of grow-out experiments, seed coat and cotyledon tests, and vector transmission experiments, we conclude that SPLCV is not seed transmitted in sweet potato.

scholarly journals A Graft-Based Chemotherapy Method for Screening Effective Molecules and Rescuing Huanglongbing-Affected Citrus Plants

2012 ◽  
Vol 102 (6) ◽  
pp. 567-574 ◽  
Author(s):  
Muqing Zhang ◽  
Charles A. Powell ◽  
Ying Guo ◽  
Melissa S. Doud ◽  
Yongping Duan
Keyword(s):  
Survival Rate ◽  
Transmission Rate ◽  
High Titer ◽  
Critical Factor ◽  
Transmission Efficiency ◽  
Pathogen Transmission ◽  
Citrus Industry ◽  
Chemical Treatments ◽  
Bacterial Titer ◽  
Transmission Studies

Huanglongbing (HLB) is the most devastating disease of citrus. The global citrus industry is in urgent need of effective chemical treatments for HLB control because of its rapid spreading worldwide. Due to the fastidious nature of the pathogens, and the poor permissibility of citrus leaf surfaces, effective screening of chemicals for the HLB control can be challenging. In this study, we developed a graft-based chemotherapy method to rapidly screen potential HLB-controlling chemical compounds. In addition, we improved transmission efficiency by using the best HLB-affected scion–rootstock combination, and demonstrated the HLB bacterial titer was the critical factor in transmission. The HLB-affected lemon scions had a high titer of HLB bacterium, survival rate (83.3%), and pathogen transmission rate (59.9%). Trifoliate, a widely used commercial rootstock, had the highest survival rate (>70.0%) compared with grapefruit (52.6%) and sour orange (50.4%). Using this method, we confirmed a mixture of penicillin and streptomycin was the most effective compounds in eliminating the HLB bacterium from the HLB-affected scions, and in successfully rescuing severely HLB-affected citrus germplasms. These findings are useful not only for chemical treatments but also for graft-based transmission studies in HLB and other Liberibacter diseases.

Seed Borne Late Blight of Potato

2002 ◽  
Vol 3 (1) ◽  
pp. 14 ◽  
Author(s):  
Mary L. Powelson ◽  
Robin Ludy ◽  
Heather Heather ◽  
Debra A. Inglis ◽  
Babette Gundersen ◽  
...  
Keyword(s):  
Late Blight ◽  
Seed Piece ◽  
Transmission Rate ◽  
Seed Transmission ◽  
Management Program ◽  
Healthy Plant ◽  
Potato Seed ◽  
Stand Establishment ◽  
Seed Tubers ◽  
Healthy Seed

Planting of potato seed pieces infected with Phytophthora infestans can lead to the introduction of late blight within a planting. When infected seed pieces are planted, there are three resulting scenarios: (i) a healthy plant emerges, (ii) no plant emerges because of the rapid decay of the seed piece, or (iii) a symptomatic plant emerges. A major factor favoring stand establishment and seed transmission is the severity of seed piece infection. When infection is severe, stand is compromised and transmission rate is low. When infection is mild, the plant emerges before the seed piece decays and, in some instances, the pathogen makes its way from the seed piece to the plant where a stem lesion is formed. Diseased seed tubers are the principle source of late blight inoculum for infection of healthy seed pieces. Treatment of infected or blighted seed tubers with a seed dressing with activity against P. infestans is not a viable tactic because the products are ineffective against established infections. Conversely, treatment of healthy seed pieces provides a high level of protection against late blight spores that are spread during the seed handling and planting operations. Optimum effectiveness is achieved when products are applied immediately following cutting, as none are effective against established infections. Seed treatment reduces the risk of seed transmission of late blight and enhances stand establishment and plant vigor. This tactic should be an important component of an integrated late blight management program. Accepted for publication 16 January 2002. Published 29 January 2002.

scholarly journals Differential expression of TLP, ERF1, and R2R3MYB in annual Medicago species under salinity conditions

2015 ◽  
Vol 14 (3) ◽  
pp. 10152-10164 ◽  
Author(s):  
F. Gharaghani ◽  
F. Rafiei ◽  
N. Mirakhorli ◽  
E. Ebrahimie
Keyword(s):  
Differential Expression ◽  
Annual Medicago ◽  
Medicago Species

An improved method for artificial hybridization in annual Medicago species

1994 ◽  
Vol 45 (7) ◽  
pp. 1329 ◽  
Author(s):  
W Pathipanawat ◽  
RAC Jones ◽  
K Sivasithamparam
Keyword(s):  
Success Rate ◽  
Fold Increase ◽  
Modified Technique ◽  
Established Method ◽  
Artificial Hybridization ◽  
Annual Medicago ◽  
Improved Technique ◽  
Medicago Species ◽  
First Time ◽  
Selection Of

An improved technique for successful artificial hybridization in annual medic (Medicago spp.) is described. Using a previously reported method, only four out of seven species were successfully crossed, with the percentage of success ranging from 3 to 22%. Initial modifications to this technique gave a 7-8 fold increase in the successful crossing rate in M. murex and M. polymorpha medic, from 9 to 64% with M. murex and from 10 to 82% with M. polymorpha. Further modifications to the technique resulted in a success rate of 100% in both species. The numbers of seeds per pod obtained from crosses in both species were also increased by using the modified techniques compared to the established method. Selection of larger, more mature flowers, differences in flower cutting position, as well as post pollination position were the main modifications which accounted for the greatly improved success rate. The modified technique was subsequently applied successfully to obtain for the first time inter-specific crosses involving M. polymorphax M. murex, M. polymorphax M. sphaerocarpos, M.murexx M. sphaerocarpos, M. solerolii x M. littoralis/M.truncatula hybrid, M. solerolii x M, tornata, and M. littoralis/M.truncatula hybrid x M. sphaerocarpos.

Subterranean clover mottle virus infection of subterranean clover: widespread occurrence in pastures and effects on productivity

1992 ◽  
Vol 43 (7) ◽  
pp. 1597 ◽  
Author(s):  
JM Wroth ◽  
RAC Jones
Keyword(s):  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Dry Weight ◽  
Widespread Occurrence ◽  
Transmission Rates ◽  
Type Isolate ◽  
Growing Seasons ◽  
South West

In 1989 and 1990, infection with subterranean clover mottle sobemovirus (SCMV) was widespread in subterranean clover ( Trifolium subterraneum L.) pastures in the south-west of Western Australia. The virus was detected in 61% of the pastures sampled and incidences of infection ranged from 1 to 50%. The virus was more common in old pastures than in pastures resown with newer cultivars during the preceeding 5 year period. When 12 isolates of SCMV were inoculated to subterranean clover plants grown in the glasshouse, symptoms varied from mild to severe. SCMV isolates P23 and F4 decreased the herbage dry weight of cw. Daliak and Woogenellup grown in plots as spaced plants by 81-88% while the Type isolate caused losses of 92%. By contrast, losses were 37-49% with cv. Karridale, a cultivar in which systemic infection was either delayed or prevented during winter. Infection decreased seed yield by c. 90% in cvv. Karridale and Woogenellup with all three isolates; seed weight was decreased 21-55%. A small proportion of cv. Woogenellup transplants outgrew the infection in new shoots during late spring to produce abundant healthy foliage. SCMV seed transmission rates in seed collected from infected transplants of cv. Woogenellup were 0.06, 0.07 and 0.43% for the Type, P23 and F4 isolates respectively. It was concluded that SCMV was present in most pastures, but at low incidences, and that it persists in them from year to year. Extended growing seasons and hard grazing are likely to increase its incidence.

Strategies for control of Phoma black stem in annual Medicago species

1989 ◽  
Vol 29 (5) ◽  
pp. 635 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Disease Severity ◽  
Medicago Truncatula ◽  
Field Trial ◽  
Subsequent Development ◽  
Field Site ◽  
Infected Seed ◽  
Annual Medicago ◽  
And Control ◽  
Medicago Species ◽  
Selection Of

Strategies for control of Phoma black stem disease in annual Medicago species through selection of cultivars with increased resistance to Phoma medicaginis, fungicidal spray applications to swards, and fungicidal control of seedborne infection, were investigated. Fiftyseven annual Medicago cultivars and lines were screened for resistance in the field in 1 m rows over 2 consecutive seasons. There were significant differences in resistance among species and also between lines and cultivars of any particular species. Three M. rugosa cultivars were very highly resistant and most cultivars and lines showed some resistance. In a field trial, the fungicides benomyl, carbendazim, flutriafol, propiconazole, thiabendazole and triadimefon were tested for their efficacy in controlling Phoma black stem disease. All fungicides reduced disease severity in the sward and, except for thiabendazole, the percentage burrs with Phoma lesions. The role and control of seed-borne P. medicaginis in causing Phoma black stem disease in Medicago truncatula and M. polymorpha var. brevispina at a field site was also investigated. Seed-borne P. medicaginis caused subsequent development of Phoma black stem disease in swards sown with infected seed. Disease appeared earlier, developed faster and became much more severe in M. truncatula cv. Cyprus than in M. polymorpha cv. Serena. Application of benomyl seed treatments (0.1 and 0.5% w/w) resulted in only a 4-5 week delay in the onset of Phoma black stem symptoms.

scholarly journals Modeling the Novel Coronavirus (SARS-CoV-2) Outbreak in Sicily, Italy

2020 ◽  
Vol 17 (14) ◽  
pp. 4964 ◽  
Author(s):  
Andrea Maugeri ◽  
Martina Barchitta ◽  
Sebastiano Battiato ◽  
Antonella Agodi
Keyword(s):  
Transmission Rate ◽  
Control Measures ◽  
Transmission Dynamics ◽  
The Novel ◽  
Epidemic Spread ◽  
Transmission Rates ◽  
Contact Precautions ◽  
Travel Restrictions ◽  
Novel Coronavirus ◽  
Reported Data

Italy was the first country in Europe which imposed control measures of travel restrictions, quarantine and contact precautions to tackle the epidemic spread of the novel coronavirus (SARS-CoV-2) in all its regions. While such efforts are still ongoing, uncertainties regarding SARS-CoV-2 transmissibility and ascertainment of cases make it difficult to evaluate the effectiveness of restrictions. Here, we employed a Susceptible-Exposed-Infectious-Recovered-Dead (SEIRD) model to assess SARS-CoV-2 transmission dynamics, working on the number of reported patients in intensive care unit (ICU) and deaths in Sicily (Italy), from 24 February to 13 April. Overall, we obtained a good fit between estimated and reported data, with a fraction of unreported SARS-CoV-2 cases (18.4%; 95%CI = 0–34.0%) before 10 March lockdown. Interestingly, we estimated that transmission rate in the community was reduced by 32% (95%CI = 23–42%) after the first set of restrictions, and by 80% (95%CI = 70–89%) after those adopted on 23 March. Thus, our estimates delineated the characteristics of SARS-CoV2 epidemic before restrictions taking into account unreported data. Moreover, our findings suggested that transmission rates were reduced after the adoption of control measures. However, we cannot evaluate whether part of this reduction might be attributable to other unmeasured factors, and hence further research and more accurate data are needed to understand the extent to which restrictions contributed to the epidemic control.

Sign in / Sign up

Export Citation Format

Share Document