Browsing by Author "Diaz, Gonzalo A."

Now showing 1 - 11 of 11
  • No Thumbnail Available
    Item
    Characterization and Pathogenicity of Diplodia, Lasiodiplodia, and Neofusicoccum Species Causing Botryosphaeria Canker and Dieback of Apple Trees in Central Chile
    (2022) Diaz, Gonzalo A.; Valdez, Adrian; Halleen, Francois; Ferrada, Enrique; Lolas, Mauricio; Latorre, Bernardo A.
    In recent years, the number of apple trees affected by Botryosphaeria cankers and dieback has considerably increased in central Chile. This study aimed to identify the species of Botryosphaeriaceae associated with canker and dieback symptoms, estimate disease incidence and distributions, and study their pathogenicity and virulence on apple and other fruit crops. A field survey of 34 commercial orchards of apple (7 to 30 years old) was conducted in 16 localities, obtaining 270 symptomatic branch and trunk samples in 2017 and 2018 growing seasons. The incidence of Botryosphaeria canker and dieback ranged between 5 and 40%, and a total of 255 isolates of Botryosphaeriaceae spp. were obtained from 238 cankers. Morphological identification along with phylogenetic studies of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) of the rDNA, part of the translation elongation factor 1-alpha (tef1-alpha), and part of the beta-tubulin (tub2) genes allowed us to identify Diplodia mutila (n = 49 isolates), D. seriata (n = 136 isolates), Lasiodiplodia theobromae (n = 16 isolates), and Neofusicoccum arbuti (n = 54 isolates). L. theobromae was isolated mainly from apple dieback from northern localities. All pathogens tested were pathogenic, causing canker and dieback symptoms on lignified twigs of apple, pear, walnut, and green grapevine shoots in the field. Isolates of N. arbuti were the most virulent, reproducing more severe cankers on the lignified tissues inoculated. This study reports, for the first time, D. mutila and L. theobromae associated with Botryosphaeria canker and dieback in Chile, and it is the first description of N. arbuti causing apple dieback worldwide.
  • Thumbnail Image
    Item
    Characterization of Botrytis cinerea and B. prunorum From Healthy Floral Structures and Decayed 'Hayward' Kiwifruit During Post-Harvest Storage
    (AMER PHYTOPATHOLOGICAL SOC, 2021) Riquelme, Danae; Aravena, Zdenka; Valdes Gomez, Hector; Latorre, Bernardo A.; Diaz, Gonzalo A.; Pablo Zoffoli, Juan
    Gray mold is the primary postharvest disease of 'Hayward' kiwifruit (Actinidia deliciosa) in Chile, with a prevalence of 33.1% in 2016 and 7.1% in 2017. Gray mold develops during postharvest storage, which is characterized by a soft, light to brown watery decay that is caused by Botrytis cinerea and B. prunorum. However, there is no information on the role of B. prunorum during the development and storage of kiwifruit in Chile. For this purpose, asymptomatic flowers and receptacles were collected throughout fruit development and harvest from five orchards over two seasons in the Central Valley of Chile. Additionally, diseased kiwifruits were selected after storage for 100 days at 0 degrees C and 2 days at 20 degrees C. Colonies of Botrytis sp. with high and low conidial production were consistently obtained from apparently healthy petals, sepals, receptacles, and styles and diseased kiwifruit. Morphological and phylogenetic analysis of three partial gene sequences encoding glyceraldehyde-3-phosphate dehydrogenase, heat shock protein 60, and DNA-dependent RNA polymerase subunit II were able to identify and separate B. cinerea and B. prunorum species. Consistently, B. cinerea was predominantly isolated from all floral parts and fruit in apparently healthy tissue and diseased kiwifruit. During full bloom, the highest colonization by B. cinerea and B. prunorum was obtained from petals, followed by sepals. In storage, both Botrytis species were isolated from the diseased fruit (n = 644), of which 6.8% (n = 44) were identified as B. prunorum. All Botrytis isolates grew from 0 degrees C to 30 degrees C in vitro and were pathogenic on kiwifruit leaves and fruit. Notably, B. cinerea isolates were always more virulent than B. prunorum isolates. This study confirms the presence of B. cinerea and B. prunorum colonizing apparently healthy flowers and floral parts in fruit and causing gray mold during kiwifruit storage in Chile. Therefore, B. prunorum plays a secondary role in the epidemiology of gray mold developing in kiwifruit during cold storage.
  • No Thumbnail Available
    Item
    Duration of the susceptibility of pruning wounds of different ages to infections by Phaeomoniella chlamydospora on grapevine cv. Cabernet Sauvignon in Central Chile
    (2022) Diaz, Gonzalo A.; Latorre, Bernardo A.
    Grapevine trunk diseases (GTDs) are one of the most important phytosanitary problems that affect grapevines (Vitis vinifera) worldwide. In Chile, Phaeomoniella chlamydospora is the major fungal trunk pathogen associated with GTDs. In the vineyards, the natural infections by P. chlamydospora are associated with air-borne conidia dispersed onto fresh pruning wounds from pycnidia. These pruning wounds are considered an important entrance for fungal trunk pathogens such as P. chlamydospora in the host in the field. However, the duration of the susceptibility of grapevine annual pruning wounds to P. chlamydospora is still unknown in Chile. Therefore, this study aimed to evaluate the period of susceptibility of pruning wounds of different ages to artificial infection of P. chlamydospora on grapevine cv. Cabernet Sauvignon, Central Chile. Artificial inoculations of a conidial suspension (10(5) conidia/mL) of P. chlamydospora were used to determine the susceptibility of pruning wounds of different ages, from 1, 15, 30, and 45 days after pruning. The experiments were conducted on lignified cuttings in a greenhouse, and on vine spurs in two vineyards (Buin and Nancagua, Central Chile) during two consecutive seasons. The results indicated that the pruning wounds of grapevine cv. Cabernet Sauvignon were very susceptible to infections by P. chlamydospora, with a percentage of pruning wounds infected from 97 to 71% for cuttings, and 96% to 60% for spurs, during the first 15 days after pruning. However, the susceptibility of pruning wounds of different ages in cuttings and spurs of grapevine, generally decreased as the time from pruning to inoculation increased. Moreover, the pruning wounds the pruning wounds remained susceptible to artificial inoculation by P. chlamydospora for up 45 days after pruning with percent of wounds infected from 8.0 to 12.2, and 8.3 to 18.8% on cuttings and spurs of grapevine, respectively. Finally, this study constitutes study constitutes the first research focalized on the susceptibility of pruning wounds of various ages of grapevine cv. Cabernet Sauvignon to artificial inoculations by P. chlamydospora in Central Chile.
  • No Thumbnail Available
    Item
    Effect water activity on in vitro mycelial growth of Neofusicoccum spp. infecting blueberry
    (2012) Latorre, Bernardo A.; Diaz, Gonzalo A.; Reed, Maria P.
    B.A. Latorre, G.A. Diaz, and M.P. Reed. 2012. Effect of water activity on mycelial growth of Neofusicoccum spp. infecting blueberry. Cien. Inv. Agr. 39(1): 221-228. Stern canker in blueberries Vaccinium corymbosum L.) is a disease which is widely distributed around the world and of growing importance in Chile, associated with Neofusicoccum species. The purpose of the present work was to study the effects of water activity (a(w)) and temperature on mycelial growth in vitro of N. arbuti, N. australe and N. parvum, obtained from blueberries with symptoms of stem canker. According to the results obtained, 25 degrees C was the optimum temperature for mycelial growth of)V. arbuti, N. australe and N. parvum. These species presented minimal growth at 35 degrees C and none at 0 and 5 degrees C. The effect of a(w) on mycelial growth was significant (P <= 0.001) and varied with the species of Neofusicoccum and the temperature. At 25 degrees C, the optimum temperature, the three species of Neofusicoccum presented minimum growth with a(w) of 0.900 and 0.920, while optimum mycelial growth was found with a(w) equal to 0.990. Independent of the Neofusicoccum species, the effect of temperature (T) and a(w) on mycelial growth was best explained by y = -721.62 + 0.24T + 788.92(w), (R-adj(2) = 0.77, P <= 0.001), suggesting that T and a(w) jointly explained 77% of the total variation on mycelial growth of Neofusicoccum spp. The results obtained provide important information for a better understanding of the biology of these plant pathogenic fungi, and suggest that temperature and a could be important parameters for understanding factors that affect the inoculum production, colonization and infection by Neofusicoccum spp. in blueberry plantations.
  • Thumbnail Image
    Item
    Germicidal effect of UV light on epiphytic fungi isolated from blueberry
    (PONTIFICIA UNIV CATOLICA CHILE, FAC AGRONOMIA INGENIERIA FORESTAL, 2012) Latorre, Bernardo A.; Rojas, Susana; Diaz, Gonzalo A.; Chuaqui, Hernan
    B.A. Latorre, S. Rojas, G.A. Diaz, and H. Chuaqui. 2012. Germicidal effect of UV light on epiphytic fungi isolated from blueberry. Cien. Inv. Agr. 39(3): 473-480. The present study examined the inactivation effect of ultraviolet (UV) light on the conidia of Botrytis cinerea Cladosporium cladosporioides, C. herbarum and Pestalotiopsis clavispora, common pathogens of blueberry (Vaccinium corymbosum), often found as epiphytes. The fungi were grown at 20 degrees C in acidified potato dextrose agar (APDA) in the dark; conidial suspensions (10(6) conidia mL(-1)) were placed the bottom of 5 cm glass Petri plates with a maximum height of 0.5 mm. Uncovered plates were immediately exposed to either UVA (lambda = 361 nm), UVB (lambda = 302 nm) or UVC (lambda = 254 nm) at doses between 40 and 110 mJ.cm(2). The results were expressed as survival ratios Nt/N0 (the number of colonies obtained after conidia were exposed to UV irradiance/the total number of fungal colonies in the non-irradiated controls). The fungal-dependent rate constants (k), a measure of the mortality rate, were estimated from an exponential model. The species in order of greatest to least resistance to UV light were Cladosporium cladosporioides, C. herbarum, R clavispora and B. cinerea. The type of fungal species and the dose of UV irradiance had a significant (P <= 0.001) influence on Nt/N0. The interaction between the fungal species and the UV irradiance dose was significant (P <= 0.004) only when the conidia were exposed to UVB or UVC. The resistance of Cladosporium spp. to UV radiation may explain the ubiquity of Cladosporium spp. in nature and could allow for the abundant populations of Cladosporium spp. often found on the foliage, flowers and fruits of blueberries.
  • Thumbnail Image
    Item
  • No Thumbnail Available
    Item
    Infection Caused by Phaeomoniella chlamydospora Associated with Esca-like Symptoms in Grapevine in Chile
    (2014) Diaz, Gonzalo A.; Latorre, Bernardo A.
    Trunk diseases such as esca have been recognized as an economically important problem of grapevine worldwide. A study was conducted to characterize the distribution of Phaeomoniella chlamydospora in Chile. A field survey of young and mature grapevines from 67 vineyards located along a 1,315-km north-south axis demonstrated that P chlamydospora was present in 94.9% of the grapevine samples showing the black-wood streaking symptom (BWS) but not the characteristic foliar symptoms of esca. Phylogenetic analysis of the ribosomal DNA internal transcribed spacer (ITS) combined with beta-tubulin (BT) genes grouped Chilean isolates together with reference isolates from South Africa and the United States, whereas Spanish isolates were clustered separately. Chilean isolates differed by only 2 to 3 bp for BT and ITS, respectively. Conidia germinated at 5 to 35 degrees C, with an optimal temperature of 25 to 30 degrees C. Isolates were pathogenic, and Koch's postulates were fulfilled in separate sets of inoculations of axenic plantlets, cuttings, 2-year-old plants, spurs, and shoots of V. vinifera. This study showed that P. chlamydospora was associated consistently with BWS and no other apparent symptom in young and mature grapevines, including nursery plants, in Chile. Inoculum was absent from the soil, grapevine pruning debris, sap samples, and herbaceous weeds, which is in contrast to past studies. At this time, Vitis spp. are the only known hosts of P. chlarnydospora in Chile.
  • No Thumbnail Available
    Item
    Inflammatory biomarkers and pendelluft magnitude in ards patients transitioning from controlled to partial support ventilation
    (2022) Cornejo, Rodrigo A.; Arellano, Daniel H.; Ruiz-Rudolph, Pablo; Guinez, Dannette, V; Morais, Caio C. A.; Gajardo, Abraham I. J.; Lazo, Marioli T.; Brito, Roberto E.; Cerda, Maria A.; Gonzalez, Sedric J.; Rojas, Veronica A.; Diaz, Gonzalo A.; Lopez, Lorena D. M.; Medel, Juan N.; Soto, Dagoberto, I; Bruhn, Alejandro R.; Amato, Marcelo B. P.; Estuardo, Nivia R.
    The transition from controlled to partial support ventilation is a challenge in acute respiratory distress syndrome (ARDS) patients due to the risks of patient-self-inflicted lung injury. The magnitude of tidal volume (V-T) and intrapulmonary dyssynchrony (pendelluft) are suggested mechanisms of lung injury. We conducted a prospective, observational, physiological study in a tertiary academic intensive care unit. ARDS patients transitioning from controlled to partial support ventilation were included. On these, we evaluated the association between changes in inflammatory biomarkers and esophageal pressure swing (Delta P-es), transpulmonary driving pressure (Delta P-L), V-T, and pendelluft. Pendelluft was defined as the percentage of the tidal volume that moves from the non-dependent to the dependent lung region during inspiration, and its frequency at different thresholds (- 15, - 20 and - 25%) was also registered. Blood concentrations of inflammatory biomarkers (IL-6, IL-8, TNF-alpha, ANGPT2, RAGE, IL-18, Caspase-1) were measured before (T-0) and after 4-h (T-4) of partial support ventilation. Pendelluft, Delta P-es, Delta P-L and V-T were recorded. Nine out of twenty-four patients (37.5%) showed a pendelluft mean >= 10%. The mean values of Delta P-es, Delta P-L, and V-T were - 8.4 [- 6.7; - 10.2] cmH(2)O, 15.2 [12.3-16.5] cmH(2)O and 8.1 [7.3-8.9] m/kg PBW, respectively. Significant associations were observed between the frequency of high-magnitude pendelluft and IL-8, IL-18, and Caspase-1 changes (T-0/T-4 ratio). These results suggest that the frequency of high magnitude pendelluft may be a potential determinant of inflammatory response related to inspiratory efforts in ARDS patients transitioning to partial support ventilation. Future studies are needed to confirm these results.
  • Thumbnail Image
    Item
    Low Occurrence of Patulin-Producing Strains of Penicillium in Grapes and Patulin Degradation during Winemaking in Chile
    (AMER SOC ENOLOGY VITICULTURE, 2011) Diaz, Gonzalo A.; Yanez, Lina; Latorre, Bernardo A.
    Penicillium expansum has emerged as the cause of storage decay of table grapes (Vitis vinifera) and has been frequently isolated from apparently healthy clusters of grapes in Chile. The objectives of this study were to identify patulin-producing strains of Penicillium associated with winegrapes and wineries in Chile and to determine the potential presence of patulin in wines made with grapes infected with P. expansum. In this study, P. brevicompactum, P. expansum, and P. glabrum were identified on apparently healthy grape clusters and in the air of vineyards and wineries. Of 132 Penicillium isolates, 4 P. brevicompactum and 11 P. expansum strains were patulin-producing, determined by HPLC-UV/DAD. Patulin was also detected in Cabernet Sauvignon musts produced with grapes contaminated with a patulin-producing strain of P. expansum. However, patulin concentrations decreased during fermentation by 67.3 to 83.3%. Overall, the frequency of P. expansum isolation from grapes was relatively low; thus, considering the rapid degradation of patulin produced during fermentation, the risk of patulin contamination of bottled wine appears to be low.
  • Thumbnail Image
    Item
    Occurrence of Neofusicoccum parvum Causing Canker and Branch Dieback of European Hazelnut in Maule Region, Chile
    (2024) Lolas, Mauricio; Latorre, Bernardo; Ferrada, Enrique; Grinbergs, Daina; Chilian, Javier; Ortega-Farias, Samuel; Campillay-Llanos, William; Diaz, Gonzalo A.
  • Thumbnail Image
    Item
    Ochratoxigenic Aspergillus species on grapes from Chilean vineyards and Aspergillus threshold levels on grapes
    (ELSEVIER, 2009) Diaz, Gonzalo A.; Torres, Rene; Vega, Mario; Latorre, Bernardo A.
    This study reports the incidence of ochratoxigenic strains of Aspergillus on Chilean grapes (Vitis vinifera) and wineries, and production of OTA levels in wines with grapes having different levels of contamination with OTA-producing Aspergillus carbonarius was studied. A. carbonarius, A. niger, A. niveus, A. paradoxus, A. versicolor, A. wentii, and A. westerdijkiae were identified on apparently healthy clusters of red and white grape cultivars. However, A. carbonarius and A. niger were the most frequently identified species, mow abundant on red than white grape cultivars. Aspergillus spp. populations increased between veraison and harvest, but the isolation frequencies were relatively low over the entire growing season. At the winery, A. carbonarius, A. niger and A. westerdijkiae were occasionally found in the air, exclusively during winemaking. OTA-producing strains were only found among isolates of A. carbonarius, A. niger, A. wenti, and A. westerdijkiae. producing 2 to 17 mu g/L of OTA in liquid medium; however, A. westerdijkiae produced the highest OTA concentration in vitro. Red wines elaborated with 0.5% of grapes infected with an OTA-producing strain of A. carbonarius (Aspuc-SB36) exceeded the 2 mu g/L of OTA tolerance established for wines by the European Community. Therefore, a threshold below 0.5% infected berries is proposed for red wines. ELISA tests proved to be useful for detecting OTA in broth culture as in wine samples. (C) 2009 Elsevier B.V. All rights reserved.