scholarly journals Phytophthora theobromicola sp. nov.: A New Species Causing Black Pod Disease on Cacao in Brazil

2021 ◽  
Vol 12 ◽  
Author(s):  
Jennifer Decloquement ◽  
Roberto Ramos-Sobrinho ◽  
Samuel Galvão Elias ◽  
Dahyana Santos Britto ◽  
Alina Sandra Puig ◽  
...  

Black pod disease, caused by Phytophthora species, is among the main limiting factors of cacao (Theobroma cacao L.) production. High incidence levels of black pod disease have been reported in Brazil, being induced by Phytophthora capsici, Phytophthora citrophthora, Phytophthora heveae, and Phytophthora palmivora. To assess the diversity of Phytophthora species affecting cacao in Brazil, 40 new isolates were obtained from cacao pods exhibiting symptoms of black pod disease collected in different smallholder farms in 2017. Further, ten cacao-infecting isolates morphologically identified as P. citrophthora and P. palmivora were molecularly characterized. The genomic regions beta-tubulin, elongation factor 1 alpha, heat shock protein 90, and internal transcribed spacer, and the mitochondrially encoded cytochrome c oxidase I and II genes were PCR-amplified and Sanger-sequenced from the cacao-infecting Phytophthora isolates. The morphological characterization and evaluation of the mycelial growth rates for the Phytophthora isolates were performed in vitro. Based on the molecular analysis and morphological comparisons, 19 isolates were identified as P. palmivora (clade 4). Interestingly, 31 isolates grouped together in the phylogenetic tree and were placed apart from previously known species in Phytophthora clade 2. Therefore, these isolates are considered as a new species herein referred to as Phytophthora theobromicola sp. nov., which produced papillate, semipapillate, and persistent sporangia on simple sporangiophores. The P. palmivora isolates were identified as A1 mating type by pairing each isolate with known A1 and A2 tester strains of P. capsici, but no oogonia/antheridia were observed when P. theobromicola was paired with the different tester strains. The P. theobromicola and P. citrophthora isolates showed higher mycelial growth rates, when compared to P. palmivora, on different media at 10, 15, and 20°C, but similar values were observed when grown on clarified CA media at 25 and 30°C. The pathogenicity tests carried out on pods of four cacao clones (CCN51, PS1319, Cepec2004, and CP49) showed significant variability among the isolates of both Phytophthora species, with P. theobromicola inducing higher rates of necrotic lesion expansion, when compared to P. palmivora. Here, two Phytophthora species were found associated with black pod disease in the state of Bahia, Brazil, and the previously undescribed P. theobromicola seems to be prevalent in field conditions. This is the first report of P. theobromicola on T. cacao. Also, these findings are crucial to improve the disease control strategies, and for the development of cacao materials genetically resistant to Phytophthora.

2020 ◽  
Vol 7 (3) ◽  
pp. 127
Author(s):  
Rita Harni ◽  
Khaerati Khaerati ◽  
Rita Noveriza ◽  
Sri Yuliani

<p><em>Black pod disease caused by </em>Phytophthora palmivora<em> is a significant disease on cocoa crops worldwide. Citronella and geraniol are two dominant substances of citronella oil that have fungicidal activity, which is potentially used to control black pod disease. However, those two substances are relatively unstable form volatile. To improve stability can be done using nanotechnology. The study aimed to analyze the effectiveness of citronella-oil-nanoemulsions formulas on the growth of </em>P. palmivora<em> in vitro and on cocoa pods.  Eight nano formulas were prepared at the Postharvest Center in Bogor; however, the effectiveness was conducted at the Indonesian Industrial and Beverage Crops Research Institute in Sukabumi. The nano formula was prepared following spontaneous, simultaneous, and inversion methods.  The experiments were designed in a completely randomized design, with five replications.  Eight treatments were evaluated, i.e., the inversion formulas (F1, F2, F5 &amp; F7), spontaneous (F3, F6 &amp; F8), and simultaneous (F4). Two concentration levels of the formula were tested, i.e., 0.5% for in vitro and 1.0% in cacao pods. The variables observed were the inhibition rate of formula, bioassay, concentration, and inhibition rate on cacao pods. The nanoemulsion formulas of citronella oil could inhibit 23.13%–77.78% of the growth of </em>P. palmivora<em>. Formula F5 was the best, which inhibited 77.78% growth in vitro and 31.60% in cacao pods. The nanoemulsions of citronella oil affected the growth rate, fresh weight, and dry weight of </em>P. palmivora<em>. For better effectiveness of the formula on cocoa pods, the concentration should be increased.</em></p>


2012 ◽  
Vol 10 (3) ◽  
pp. 254-257
Author(s):  
Erwin Aragon ◽  
Claudia Rivera ◽  
Helena Korpelainen ◽  
Aldo Rojas ◽  
Paula Elomaa ◽  
...  

A total of 60 farmers' cacao accessions (Theobroma cacao L.) from Nicaragua were investigated using microsatellite markers to reveal their genetic composition and to identify potentially resistant genotypes against the black pod disease caused by Phytophthora palmivora. These accessions were compared with 21 breeders' accessions maintained locally, two Criollo accessions from Costa Rica and two accessions from Ecuador. The analyses showed a low level of differentiation among groups of farmers' accessions (FST = 0.06) and that six Nicaraguan accessions were genetically closely related to the two Criollo accessions used as a reference. In addition, seven distinct genotypes were found to have allelic composition that may indicate linkage to resistance alleles, thus being potential parental lines in future breeding programmes.


Phytotaxa ◽  
2018 ◽  
Vol 364 (2) ◽  
pp. 181 ◽  
Author(s):  
MUNAZZA KIRAN ◽  
JUNAID KHAN ◽  
HASSAN SHER ◽  
DONALD H. PFISTER ◽  
ABDUL NASIR KHALID

A new species, Amanita griseofusca in section Vaginatae is described and illustrated here from Pakistan. Distinguishing characters of the new species include medium-sized basidiomata, greyish brown pileus surface with white to beige, membranous volval remnants present as one (large) to a few (small) warts, close lamellae which are cream colored with a pink tone, striations one third of the total pileus radius, broadly ellipsoidal to ellipsoidal basidiospores and white loose saccate volva turning beige at maturity. Molecular data inferred from partial nuc rDNA internal transcribed spacer region (ITS), partial nuc rDNA larger subunit region (LSU) and partial translation elongation factor 1-alpha (tef1) confirms the novelty of the present taxon.


Author(s):  
Sakti Widyanta Pratama ◽  
Sri Sukamto ◽  
Lis Nur Asyiah ◽  
Yeni Vida Ervina

Black pod disease caused by Phytophthora palmivorafungus is one of the important diseases on cocoa crop. Pod rot is the most important disease because it may cause loss of cocoa pod. Until now, the fungal pathogen of cocoa black pod disease is still a crucial problem and there is no fungicide that is really effective against the disease. One alternative to control the cocoa black pod disease is by using biological agents as biofungicide, including utilizing Pseudomonas fluorescenceand Bacillus subtilis bacteria. The research was done by isolation of P. palmivora from infected pods of Kaliwining Experimental Station to obtain pure cultures of fungus and by multiplication of P. fluorescence and B. subtilis. Antagonist test was performed by inoculating P. palmivora into a petri dish in a distance of 3 cm from the edge. P. fluorescenceand B. Subtilis were inoculated into petridishes in three days after the fungal treatment. Control was inoculated with isolate of P. palmivora only. Fungal growth was measured everyday by measuring radius of fungal colonies first time 24 hours after inoculation. Growth of Phytophthora palmivora in the two treatmens were used to calculate the percentage of inhibition. The results of this study indicated that P. fluorescence and B. subtiliswere able to inhibit fungal growth of P. palmivora. Both bacterial antagonists had the same effectiveness in inhibiting the growth of P. palmivora fungus based on the percentage of inhibition and effectiveness criteria. Based on the results of translucent zones indicated that B. subtiliswas more powerfull in inhibiting growth of P. Palmivora compared to P. fluorescence. Key words: Black pod disease of cocoa, biological control, Phytophthora palmivora, Pseudomonas fluorescence, Bacillus subtilis


Phytotaxa ◽  
2020 ◽  
Vol 440 (2) ◽  
pp. 89-100
Author(s):  
NABAHAT BESSADAT ◽  
BRUNO HAMON ◽  
NELLY BATAILLE-SIMONEAU ◽  
KIHAL MABROUK ◽  
PHILIPPE SIMONEAU

During a biodiversity survey of Alternaria associated with leaf spot and blight of Solanaceae, a large collection of strains was obtained from samples collected in north-western regions of Algeria in 2013–2018 growing seasons. Amongst these strains, three isolates recovered from tomato and potato had morphological traits different from that usually observed for Alternaria species previously reported on Solanaceae. Based on analysis of a sequence dataset corresponding to portions of the glyceraldehyde-3-phosphate dehydrogenase (gpd), translation elongation factor 1-alpha (tef1) and RNA polymerase second largest subunit (rpb2) genes along with morphological observations, isolates were identified as a new species in the section Japonicae. This novel species, described here as Alternaria telliensis, is phylogenetically and morphologically distinct from A. japonica and A. nepalensis in this section. Pathogenicity tests were performed and isolates were found to be weakly pathogenic to tomato and potato (Solanaceae) while highly aggressive on radish, cabbage and turnip (Brassicaceae) plants.


Phytotaxa ◽  
2015 ◽  
Vol 226 (3) ◽  
pp. 261 ◽  
Author(s):  
Liu Gao ◽  
Zhuoya Wei ◽  
Bo Wang ◽  
Mark L. Gleason ◽  
Rong Zhang ◽  
...  

Scleroramularia is a genus that includes species of the sooty blotch and flyspeck (SBFS) fungal complex that blemishes the surface of apple, pawpaw, and other fruit. In a survey of SBFS on banana (Musa basjoo), an isolate associated with the flyspeck mycelial type of SBFS was obtained from Zhanjiang, Guangdong, China. Based on analysis of morphology and phylogeny (the nuclear ribosomal internal transcribed space region and translation elongation factor 1-alpha), it was delimited as a new species of Scleroramularia, described here as S. musae. Conidia of S. musae have more septa than other species presently known in the genus.


Phytotaxa ◽  
2019 ◽  
Vol 415 (4) ◽  
pp. 179-188
Author(s):  
XIANG-NYU CHEN ◽  
MING ZHANG ◽  
TAI-HUI LI ◽  
NIAN-KAI ZENG

Heimioporus sinensis, collected from tropical and subtropical areas of China, is introduced as a new species based on both morphological characters and molecular data. The species is characterized by the purplish red to deep magenta pileus, the reticulated stipe, the irregularly reticulate to reticulate-alveolate basidiospores 11.5–13.5 × 8–9.5 μm, and a trichodermal to intricately trichodermal pileipellis. Phylogenetic analyses based on the nuc 28S rDNA D1-D2 domains (28S) and the translation elongation factor 1-α gene (tef1-α) showed that H. sinensis is a distinct member of the genus Heimioporus in the subfamily Xerocomoideae.


Zootaxa ◽  
2009 ◽  
Vol 2014 (1) ◽  
pp. 41-50 ◽  
Author(s):  
BJARTE H. JORDAL

A new species of the Malagasy genus Dolurgocleptes Schedl, 1965 is described and illustrated. This is the second species known for the genus, which is restricted to the montane rainforests of north-eastern Madagascar. Dolurgocleptes is transferred from the tribe Dryocoetini to Polygraphini and placed near Polygraphus Erichson, based on examination of internal and external morphological characters and molecular data from Elongation Factor-1α and Cytochrome Oxidase I.


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