scholarly journals Eutypa, Eutypella, and Cryptovalsa Species (Diatrypaceae) Associated with Prunus Species in South Africa

Plant Disease ◽  
2018 ◽  
Vol 102 (7) ◽  
pp. 1402-1409 ◽  
Author(s):  
Providence Moyo ◽  
Ulrike Damm ◽  
Lizel Mostert ◽  
Francois Halleen
Keyword(s):  
South Africa ◽  
Phylogenetic Analyses ◽  
Fruit Trees ◽  
Fungal Species ◽  
Stone Fruit ◽  
Prunus Species ◽  
Internal Transcribed Spacer Region ◽  
Eutypa Lata ◽  
Eutypa Dieback ◽  
Prunus Spp

Stone fruit trees (Prunus spp.) are economically important fruit trees cultivated in South Africa. These trees are often grown in close proximity to vineyards and are to a large extent affected by the same trunk disease pathogens as grapevines. The aim of the present study was to determine whether stone fruit trees are inhabited by Diatrypaceae species known from grapevines and whether these trees could act as alternative hosts for these fungal species. Isolations were carried out from symptomatic wood of Prunus species (almond, apricot, cherry, nectarine, peach, and plum) in stone fruit growing areas in South Africa. Identification of isolates was based on phylogenetic analyses of the internal transcribed spacer region and β-tubulin gene. Forty-six Diatrypaceae isolates were obtained from a total of 380 wood samples, from which five species were identified. All five species have also been associated with dieback of grapevine. The highest number of isolates was found on apricot followed by plum. No Diatrypaceae species were isolated from peach and nectarine. Eutypa lata was the dominant species isolated (26 isolates), followed by Cryptovalsa ampelina (7), Eutypa cremea (5), Eutypella citricola (5), and Eutypella microtheca (3). First reports from Prunus spp. are E. cremea, E. citricola, and E. microtheca. Pathogenicity tests conducted on apricot and plum revealed that all these species are pathogenic to these hosts, causing red-brown necrotic lesions like those typical of Eutypa dieback on apricot.

Occurrence of Canker and Wood Rot Pathogens on Stone Fruit Propagation Material and Nursery Trees in the Western Cape of South Africa

Plant Disease ◽  
2021 ◽  
Author(s):  
Rhona van der Merwe ◽  
Francois Halleen ◽  
Meagan Van Dyk ◽  
Vernon Guy Jacobs ◽  
Lizel Mostert
Keyword(s):  
South Africa ◽  
Management Practices ◽  
Phylogenetic Analyses ◽  
Fruit Trees ◽  
Fungal Species ◽  
Stone Fruit ◽  
Western Cape ◽  
Latent Infections ◽  
Nursery Trees ◽  
Propagation Material

Dieback and canker of young stone fruit trees can cause suboptimal growth and even death under severe conditions. One source of inoculum of canker pathogens could be through nursery trees harboring latent infections that would not be visible to inspections done according to the deciduous fruit scheme. The objectives of this study were to identify the canker and wood rot fungal pathogens present in nursery stone fruit trees as well as propagation material and to evaluate their pathogenicity. Isolations were made from scion and rootstock propagation material and from certified nursery stone fruit trees. The plant material sampled did not have any external symptoms. The certified nursery trees when cross-sectioned displayed brown discoloration from the pruning wound, bud union and often from the crown. Fungal species isolated were identified by sequencing of the relevant barcoding genes and phylogenetic analyses thereof. Canker and wood rot associated fungi were identified. Buds used for budding had low levels of infection, with 1.2% of dormant buds infected and 0.4% of green buds infected. The dormant rootstock shoots had canker pathogen incidence of 6.2% before it was planted in the nursery fields and increased as the ungrafted, rooted rootstock plants had 11.1% infection with canker and wood rot pathogens. Out of 1080 nursery trees, the canker and wood rot associated fungi infected 21.8% of trees. The canker causing pathogens that were isolated the most were Cadophora luteo-olivacea and Diplodia seriata. A low incidence of wood rot fungi was found with only 1.5% of nursery trees infected. In total 26 new reports of fungal species on stone fruit in South Africa were made. Of these, 22 have not been found on stone fruit world-wide. The pathogenicity trials’ results confirmed the pathogenic status of these newly reported species. All of the isolates tested formed lesions significantly longer than the control, 4 months after wound inoculation of 2-year-old shoots of two plum orchards. Lasiodiplodia theobromae was the most virulent species on both plum cultivars. The results of this research showed that nursery stone fruit trees and propagation material can harbor latent infections. Different management practices need to be evaluated to prevent these infections to ensure healthier stone fruit nursery trees.

scholarly journals A Reassessment of the Species Concept in Eutypa lata, the Causal Agent of Eutypa Dieback of Grapevine

2006 ◽  
Vol 96 (4) ◽  
pp. 369-377 ◽  
Author(s):  
P. E. Rolshausen ◽  
N. E. Mahoney ◽  
R. J. Molyneux ◽  
W. D. Gubler
Keyword(s):  
Species Concept ◽  
Phylogenetic Analyses ◽  
Distinct Species ◽  
Causal Agent ◽  
Internal Transcribed Spacer Region ◽  
Eutypa Lata ◽  
The Third ◽  
Eutypa Dieback ◽  
Morphological Differences ◽  
Branch Dieback

Eutypa dieback is a vascular disease of several cultivated crops and trees worldwide. The attribution of the name to the agent responsible for branch dieback is ambiguous. Pathogenicity of Eutypa sp. first was reported on apricot and the causal agent was named E. armeniacae. However, no morphological differences were reported with the previously described E. lata, and some authors considered both species synonymous. Others regarded them as distinct species on the basis of pathogenesis and molecular analysis. We further investigated the relatedness of both species by phylogenetic analyses of the internal transcribed spacer region and β-tubulin gene. These analyses included several other taxa placed in the same family (Diatrypaceae), and yielded three groups. The isolates referred to as E. lata in previous work clustered with Diatrype stigma in one group. Isolates of E. armeniacae and E. lata clustered in a second group, supporting the synonymy of these species. The third group included other Eutypa spp. supporting the polyphyletic origin of this genus. Measurements of conidia length and secondary metabolite production of isolates supported the phylogenetic analyses. Secondary metabolites appeared to be a synapomorphic character shared by several taxa including E. lata, E. armeniacae, E. laevata, and E. petrakii var. petrakii.

scholarly journals First Report of Apricot vein clearing-associated virus (AVCaV) infecting Prunus domestica revealed by High-Throughput Sequencing in Morocco

Plant Disease ◽  
2020 ◽  
Author(s):  
Rachid Tahzima ◽  
Radouane Qessaoui ◽  
Yoika Foucart ◽  
Sebastian Massart ◽  
Kris De Jonghe
Keyword(s):  
Fruit Trees ◽  
Plant Viruses ◽  
Amino Acid Sequences ◽  
Stone Fruit ◽  
Replicase Gene ◽  
Prunus Domestica ◽  
Prunus Species ◽  
First Report ◽  
Vein Clearing ◽  
The Impact

Plum (Prunus domestica L., Rosaceae) trees, like many stone fruit trees, are known to be infected by numerous plant viruses, predominantly as consequence of their clonal mode of propagation and perennial cultivation (Jelkmann and Eastwell, 2011). Apricot vein clearing-associated virus (AVCaV) is a member of the genus Prunevirus in the family Betaflexiviridae. AVCaV was first reported in Italy infecting apricot (P. armeniaca L.) associated with foliar vein clearing symptoms (Elbeaino et al. 2014). It has also been detected in various Prunus species, like plum, Japanese plum (P. salicina L.), sour cherry (P. cerasus L.), and Japanese apricot (P. mume L.), apricot and peach (P. persica L.) sourced from Asian and European countries (Marais et al. 2015), as well as in the ornamental Myrobolan plum (P. cerasifera L.) in Australia (Kinoti et al. 2017). In 2018, during the vegetative season, a survey was carried out in two different apricot and plum orchards in the southern region of Agdez (Agadir, Morocco) where stone fruit trees are grown. Five branches with leaves were sampled from three apricot and three plum trees of unknown cultivars, all asymptomatic. Total RNA was extracted from 100 mg plant tissue (leaves and cambial scrapping) using RNeasy Plant Mini Kit (QIAGEN, Hilden, Germany) and separate samples (one per species) were used for library preparation (NEBNext Ultra RNA library kit; New England BioLabs, MA, USA), and sequencing (Illumina NextSeq v2, totRNA sequencing) at Admera Health (New Jersey, USA). All generated reads (6,756,881) from the plum sample were quality filtered and submitted to the VirusDetect pipeline (Zheng et al., 2017). The plum cDNA library, a total of 20 viral contigs (68-1928 bp) mapped to several AVCaV accessions in GenBank. A reference mapping (CLC Genomics Workbench 12, Qiagen, Denmark) was conducted against all four available AVCaV full genomes (KM507062-63, KY132099 and HG008921), revealing 100% coverage of the full sequence (8358 nt) with 97-98 % nucleotide (nt) identities (BLASTn). Analysis of the derived sequences allowed to identify the location of the four predicted ORFs i.e. (ORF1: 6066 nt/2,021 aa), (ORF2: 1383 nt/460 aa), (ORF3: 666 nt/221 aa) and (ORF4: 420 nt/139 aa), previously described for the AVCaV genome (Elbeaino et al. 2014). The amino acid sequences of the encoded proteins of AVCaV isolate from Morocco also shared 97-98% identities with the corresponding sequences of complete genome AVCaV isolates in GenBank. To confirm the detection of AVCaV in the three plum samples, specific RT-PCR primers (VC37657s: 5’-CCATAGCCACCCTTTTTCAA-3’ / VC28239a: 5’-GTCGTCAAGGGTCCAGTGAT-3’) (Elbeaino et al. 2014) were used and the expected 330 bp fragment from the replicase gene was amplified in all three samples and subsequently sequenced (MT980794-96). Sanger sequences were 100% identical to corresponding HTS derived sequence. This is the first report of AVCaV infecting plum in Africa. The incidence of AVCaV in Moroccan Prunus species is unknown. Plum trees from the surveyed orchards were also confirmed to be co-infected with little cherry virus 1 (LChV-1) using HTS. Further investigation is required to determine the impact of AVCaV on these asymptomatic plum trees and other stone fruits species.

scholarly journals Diversity of Diatrypaceae Species Associated with Dieback of Grapevines in South Africa, with the Description of Eutypa cremea sp. nov.

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 220-230 ◽  
Author(s):  
Providence Moyo ◽  
Lizel Mostert ◽  
Christoffel F.J. Spies ◽  
Ulrike Damm ◽  
Francois Halleen
Keyword(s):  
South Africa ◽  
Cross Section ◽  
Internal Transcribed Spacer ◽  
Dominant Species ◽  
Phylogenetic Analyses ◽  
Morphological Characters ◽  
Internal Transcribed Spacer Region ◽  
Canker Pathogen ◽  
Grapevine Canker ◽  
First Time

Recent studies in grape-growing areas including Australia, California, and Spain have revealed an extensive diversity of Diatrypaceae species on grapevines showing dieback symptoms and cankers. However, in South Africa, little is known regarding the diversity of these species in vineyards. The aim of this study was, therefore, to identify and characterize Diatrypaceae species associated with dieback symptoms of grapevine in South Africa. Isolates were collected from dying spurs of grapevines aged 4 to 8 years old, grapevine wood showing wedge-shaped necrosis when cut in cross section as well as from perithecia on dead grapevine wood. The collected isolates were identified based on morphological characters and phylogenetic analyses of the internal transcribed spacer region (ITS) and β-tubulin gene. Seven Diatrypaceae species were identified on grapevine, namely Cryptovalsa ampelina, C. rabenhorstii, Eutypa consobrina, E. lata, E. cremea sp. nov., Eutypella citricola, and E. microtheca. The dying spurs yielded the highest diversity of species when compared with the wedge-shaped necrosis and/or perithecia. C. ampelina was the dominant species in the dying spurs, followed by E. citricola, whereas E. lata was the dominant species isolated from the wedge-shaped necroses and perithecia. These results confirm E. lata as an important grapevine canker pathogen in South Africa, but the frequent association of C. ampelina with spur dieback suggests that this pathogen plays a more prominent role in dieback than previously assumed. In some cases, more than one species were isolated from a single symptom, which suggests that interactions may be occurring leading to decline of grapevines. C. rabenhorstii, E. consobrina, E. citricola, E. microtheca, and E. cremea are reported for the first time on grapevine in South Africa.

Three novel sooty moulds species of Trichomerium from Yunnan, China

Phytotaxa ◽  
2021 ◽  
Vol 518 (4) ◽  
pp. 271-280
Author(s):  
HUI YANG ◽  
SAJEEWA S.N. MAHARACHCHIKUMBURA ◽  
CHAO DENG ◽  
JIAN-KUI LIU
Keyword(s):  
Yunnan Province ◽  
Leaf Surface ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
Fungal Species ◽  
Ziziphus Mauritiana ◽  
Internal Transcribed Spacer Region ◽  
Large Subunit Rdna ◽  
Three New Species ◽  
Sooty Moulds

Collection of three sexual morphic fungal species occurring on the leaf surface of three plant species (Dalbergia obtusifolia, Syzygium fluviatile and Ziziphus mauritiana) collected in Yunnan Province, China, have shown that they are morphologically distinct. Phylogenetic analyses of partial sequences of internal transcribed spacer region (ITS) and large subunit rDNA (LSU) placed the three species in Trichomerium (Trichomeriaceae) but are sufficiently different from all known species. Therefore, three new species, Trichomerium multisetosum, T. xishuangbannaense and T. yunnanense are described with detailed, illustrated descriptions and notes.

scholarly journals Evaluation of the Prunus interspecific progenies for resistance to Plum pox virus

2013 ◽  
Vol 49 (No. 2) ◽  
pp. 65-69 ◽  
Author(s):  
J. Salava ◽  
J. Polák ◽  
I. Oukropec
Keyword(s):  
Interspecific Hybrids ◽  
Agronomic Traits ◽  
Fruit Trees ◽  
Fruit Production ◽  
Stone Fruit ◽  
Plum Pox Virus ◽  
Prunus Amygdalus ◽  
Prunus Species ◽  
Sources Of Resistance ◽  
Resistance Transfer

Sharka disease caused by the infection with the Plum pox virus (PPV) in stone fruit trees is worldwide the most devastating for stone fruit production. Until now, good sources of resistance to PPV within the peach group have not been available. There are no commercial cultivars of peach that are resistant to PPV. Other Prunus species are known to show varying levels of resistance. Interspecific hybrids GF 677 (Prunus amygdalus × P. persica) and Cadaman (P. davidiana × P. persica) were revealed to be resistant to PPV. The resistance to a Dideron isolate of the descendants of Cresthaven × GF 677 and Cresthaven × Cadaman and their progenitors was evaluated after inoculation by chip-budding in a sealed screenhouse. Results demonstrate a certain level of resistance in both progenies of interspecific hybrids and indicate a potential for PPV resistance transfer to commercial peach cultivars but it will be necessary to perform backcrosses with peach cultivars of agricultural interest in order to return pomological and agronomic traits. For the definitive confirmation of resistance/susceptibility it will be necessary to wait until the adult stage of hybrids.

scholarly journals Identification of Pseudomonas Isolates Associated With Bacterial Canker of Stone Fruit Trees in the Western Cape, South Africa

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 882-892 ◽  
Author(s):  
Khumbuzile N. Bophela ◽  
Yolanda Petersen ◽  
Carolee. T. Bull ◽  
Teresa. A. Coutinho
Keyword(s):  
South Africa ◽  
Pseudomonas Syringae ◽  
Bacterial Species ◽  
Fruit Trees ◽  
Stone Fruit ◽  
Bacterial Disease ◽  
Bacterial Canker ◽  
Western Cape ◽  
Vegetable Crops ◽  
Phylogenetic Groups

Bacterial canker is a common bacterial disease of stone fruit trees. The causal agents responsible for the disease include several pathovars in Pseudomonas syringae sensu lato and newly described Pseudomonas species. Pseudomonad strains were isolated from symptomatic stone fruit trees, namely apricot, peach, and plum trees cultivated in spatially separated orchards in the Western Cape. A polyphasic approach was used to identify and characterize these strains. Using a multilocus sequence typing approach of four housekeeping loci, namely cts, gapA, gyrB, and rpoD, the pseudomonad strains were delineated into two phylogenetic groups within P. syringae sensu lato: P. syringae sensu stricto and Pseudomonas viridiflava. These results were further supported by LOPAT diagnostic assays and analysis of clades in the rep-PCR dendrogram. The pseudomonad strains were pathogenic on both apricot and plum seedlings, indicative of a lack of host specificity between Pseudomonas strains infecting Prunus spp. This is a first report of P. viridiflava isolated from plum trees showing symptoms of bacterial canker. P. viridiflava is considered to be an opportunistic pathogen that causes foliar diseases of vegetable crops, fruit trees, and aromatic herbs, and thus the isolation of pathogenic P. viridiflava from twigs of plum trees showing symptoms of bacterial canker suggests that this bacterial species is a potentially emerging stem canker pathogen of stone fruit trees in South Africa.

scholarly journals Apricot latent virus – Review

2012 ◽  
Vol 39 (No. 3) ◽  
pp. 144-148 ◽  
Author(s):  
L. Grimová ◽  
P. Ryšánek
Keyword(s):  
Fruit Trees ◽  
Prunus Armeniaca ◽  
Latent Virus ◽  
Stone Fruit ◽  
Prunus Species ◽  
Viral Pathogen ◽  
Spot Disease ◽  
Mediterranean Countries ◽  
Management Approaches ◽  
Contemporary Management

Apricot latent virus (ApLV) is a definitive species of the Foveavirus genus, the Betaflexiviridae family. Although the virus is not highly prevalent, it was identified in several European and Mediterranean countries thus far. Biological experiments demonstrated that, in addition to the only known natural host, Prunus armeniaca, ApLV can be experimentally graft-transmitted to several Prunus species. Therefore, the eradication of the viral pathogen largely depends on the use of virus-free propagating materials and rootstocks, which should be seriously considered when designing and implementing stone fruit certification schemes. Although ApLV is not present on the list of viruses and other pathogens that require testing in the EPPO certification schemes for the production of healthy stone fruit trees for planting, Peach asteroid spot disease (PAS) causing agent whose occurrence was often justly correlated with ApLV, is included on the list. This review summarises the current available knowledge of ApLV on the biological, morphological, physicochemical and molecular levels and includes the contemporary management approaches.

Fungal Pathogens Associated With Canker Diseases of Almond in California

Plant Disease ◽  
2020 ◽  
pp. PDIS-10-19-2128
Author(s):  
Leslie A. Holland ◽  
Florent P. Trouillas ◽  
Mohamed T. Nouri ◽  
Daniel P. Lawrence ◽  
Maria Crespo ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Phylogenetic Analyses ◽  
Elongation Factor ◽  
Central Valley ◽  
Disease Diagnosis ◽  
Mature Trees ◽  
Internal Transcribed Spacer Region ◽  
Canker Disease ◽  
Eutypa Lata ◽  
Almond Orchards

Almond canker diseases are destructive and can reduce the yield as well as the lifespan of almond orchards. These diseases may affect the trunk and branches of both young and mature trees and can result in tree death soon after orchard establishment in severe cases. Between 2015 and 2018, 70 almond orchards were visited throughout the Central Valley of California upon requests from farm advisors for canker disease diagnosis. Two major canker diseases were identified, including Botryosphaeriaceae cankers and Ceratocystis canker. In addition, five less prevalent canker diseases were identified, including Cytospora, Eutypa, Diaporthe, Collophorina, and Pallidophorina canker. Seventy-four fungal isolates were selected for multilocus phylogenetic analyses of internal transcribed spacer region ITS1-5.8S-ITS2 and part of the translation elongation factor 1-α, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase gene sequences; 27 species were identified, including 12 Botryosphaeriaceae species, Ceratocystis destructans, five Cytospora species, Collophorina hispanica, four Diaporthe species, two Diatrype species, Eutypa lata, and Pallidophorina paarla. The most frequently isolated species were Ceratocystis destructans, Neoscytalidium dimidiatum, and Cytospora californica. Pathogenicity experiments on almond cultivar Nonpareil revealed that Neofusicoccum parvum, Neofusicoccum arbuti, and Neofusicoccum mediterraneum were the most virulent. Botryosphaeriaceae cankers were predominantly found in young orchards and symptoms were most prevalent on the trunks of trees. Ceratocystis canker was most commonly found in mature orchards and associated with symptoms found on trunks or large scaffold branches. This study provides a thorough examination of the diversity and pathogenicity of fungal pathogens associated with branch and trunk cankers of almond in California.

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