Degree Of Fungal Infection Research Articles

Detection of fungal infection in apple using hyperspectral transformation of RGB images with kernel regression

Fungal infections cause the considerable losses in apple production and quality. Given its ability to perceive external and internal characteristics, hyperspectral imaging (HSI) performs well in detecting fungal infections in apples. However, high cost, time-consuming operation, and complicated processing limit the widespread application of HSI. This study proposes a novel detection method, that uses the hyperspectral transformation (HT) of RGB images, for detecting fungal infection in apples. Wiener estimation, pseudo-inverse and kernel regression (KR) were adopted to perform HT to transform the responses of RGB images into pseudo reflectance spectra (PRS). And the effects of RGB responses, band ranges and spectral resolution were further discussed. KR obtained the optimal HT and the resultant PRS in the range of 400–1000 nm and with a resolution of approximately 2.5 nm were close to the original reflectance spectra of HSI with a mean root mean square error of 0.050, the mean relative error of 12.17 %, and peak signal-to-noise ratio of 72.66. The obtained PRS were then combined with machine learning to classify the category and degree of fungal infection in apple fruit. The best category recognition was obtained by random forest and PRS. The accuracy of the calibration set (ACCC), validation set (ACCV) and prediction set (ACCP) were 93.31 %, 80.95 % and 83.33 %, respectively. The best determinations of degree of infection by Botrytis cinerea and Rhizopus stolonifer were obtained using k-nearest neighbor, convolutional neural network and PRS, resulting in an ACCP of 90 % for each model. The proposed method achieved a convenient, low-cost, and accurate detection of fungal infection types and degree in apple fruit and is expected to be useful for analysing the quality of other agricultural products.

Occurrence of mycotoxins in pulses.

Pulses, dry grains of the Fabaceae family used for food and feed, are particularly important agricultural products with increasing commercial and nutritional relevance. Similar to other plant commodities, pulses can be affected by fungi in the field and during postharvest. Some of these fungi produce mycotoxins, which can seriously threaten human and animal health by causing acute poisoning and chronic effects. In this review, information referring to the analysis and occurrence of these compounds in pulses is summarized. An overview of the aims pursued, and of the methodologies employed for mycotoxin analysis in the different reports is presented, followed by a comprehensive review of relevant articles on mycotoxins in pulses, categorized according to the geographical region, among other considerations. Moreover, special attention was given to the effect of climatic conditions on microorganism infestation and mycotoxin accumulation. Furthermore, the limited literature available was considered to look for possible correlations between the degree of fungal infection and the mycotoxin incidence in pulses. In addition, the potential effect of certain phenolic compounds on reducing fungi infestation and mycotoxin accumulation was reviewed with examples on beans. Emphasis was also given to a specific group of mycotoxins, the phomopsins, that mainly impact lupin. Finally, the negative consequences of mycotoxin accumulation on the physiology and development of contaminated seeds and seedlings are presented, focusing on the few reports available on pulses. Given the agricultural and nutritional potential that pulses offer for human well-being, their promotion should be accompanied by attention to food safety issues, and mycotoxins might be among the most serious threats. Practical Application: According to the manuscript template available in the website, this section is for "JFS original research manuscripts ONLY; optional". Since we are publishing in CRFSFS this requirement will not be done.

Frequent Arousal from Hibernation Linked to Severity of Infection and Mortality in Bats with White-Nose Syndrome

White-nose syndrome (WNS), an emerging infectious disease that has killed over 5.5 million hibernating bats, is named for the causative agent, a white fungus (Geomyces destructans (Gd)) that invades the skin of torpid bats. During hibernation, arousals to warm (euthermic) body temperatures are normal but deplete fat stores. Temperature-sensitive dataloggers were attached to the backs of 504 free-ranging little brown bats (Myotis lucifugus) in hibernacula located throughout the northeastern USA. Dataloggers were retrieved at the end of the hibernation season and complete profiles of skin temperature data were available from 83 bats, which were categorized as: (1) unaffected, (2) WNS-affected but alive at time of datalogger removal, or (3) WNS-affected but found dead at time of datalogger removal. Histological confirmation of WNS severity (as indexed by degree of fungal infection) as well as confirmation of presence/absence of DNA from Gd by PCR was determined for 26 animals. We demonstrated that WNS-affected bats aroused to euthermic body temperatures more frequently than unaffected bats, likely contributing to subsequent mortality. Within the subset of WNS-affected bats that were found dead at the time of datalogger removal, the number of arousal bouts since datalogger attachment significantly predicted date of death. Additionally, the severity of cutaneous Gd infection correlated with the number of arousal episodes from torpor during hibernation. Thus, increased frequency of arousal from torpor likely contributes to WNS-associated mortality, but the question of how Gd infection induces increased arousals remains unanswered.

Summer variation in the concentration of steroidal sapogenins in and the degree of fungal infection on Narthecium ossifragum plants from Møre og Romsdal County, Norway.

Thirty-nine leaf samples of Narthecium ossifragum collected from eight sites in Møre og Romsdal County, Norway, during June-September 1997 and 41 leaf samples collected at five sites in the same county during June-August 1998 were analysed for the concentrations of steroidal sapogenins using GC-MS. The 1998 samples were also examined for fungal elements (conidia and hyphae) after incubation in a moist chamber for 10-14 days. The highest 1997 and 1998 leaf sapogenin concentrations (4881 and 7115 mg/kg dry matter, respectively) were 13-14 times greater than the lowest sapogenin concentrations found (344 and 531 mg/kg dry matter, respectively). The results did not reveal systematic differences in sapogenin concentrations between the two seasons, or between samples harvested early or late in the same seasons, or between sapogenin concentrations in plants harvested at different sites. Cladosporium magnusianum was the predominant fungus found in the samples. The degree of fungal infection on the samples was in generally low, but the number of C. magnusianum colonies in the moist chamber preparations and fungal elements (conidia and hyphae) in leaf washings and on leaves tended to increase with time. Factor analysis and multiple regression analysis performed on the chemical and fungal results suggest that sporulation may have occurred in the fungi in response to increase in sapogenin concentrations.

Isolation of a fungus from shell lesions of New Zealand abalone, Haliotis iris Martyn and H. australis Gmelin

Shell irregularities characterized by deposition of conchiolin on the inner shell surface of abalone, Haliotis spp., have been reported in populations along the South Island of New Zealand for over 50 years. A previously reported, but unidentified, fungus associated with these shell lesions is isolated for the first time from Haliotis iris, the black footed paua, and H. australis, the yellow footed paua, both obtained from Jacks Bay, South East Otago. Fungal hyphae measured 1.20 – 2.38 μm (=1.83 μm) in diameter. Occasionally, wider hyphae that measured 2.38 – 3.60 μm (= 2.60 μm) in diameter with an apical swelling that measured 4.80 – 7.20 × 7.20 – 15.00 μm (= 6.20 × 11.80 μm) were observed within lesions. Visible growth of aerial hyphae was observed on plates within 12 d at 16 °C on several media. Three morphologically indistinguishable isolates were obtained: two originated from H. iris shells and one from an H. australis shell. We examined 8 fungal and/or bacterial media and determined that the fungus grew best on a dilute medium (yeast extract, glucose, shell extract (+/-peptone agar) at 15 °C. Fungal growth was observed between 7 – 20 °C but not at room temperature (24 °C). Sporulation has not been induced , therefore the fungus is provisionally identified as a member of the Class Deuteromycotina. No significant relationship between animal length and incidence of shell mycosis was observed. Abalone condition was not influenced by the shell mycosis in either species. The number of circulating haemocytes was significantly elevated in infected H. australis (1.19 × 107 cells ml−1) relative to uninfected individuals (6.72 × 106 cells ml−1) but not between infected and uninfected H. iris. No significant relationships were observed between the degree of fungal infection and protein levels of whole haemolymph, serum or sex (immature, male or female; p<0.050; N=34). We are currently attempting to determine the taxonomic placement of the fungus and further characterize its growth physiology and pathogenicity.

Microscopical and Mycological Investigations on Wood of Pendunculate Oak ( Quercus robur L) Relative to the Occurrence of Oak Decline

Microscopical studies exhibited great differences between healthy and damaged pendunculate oak trees ( Quercus robur L.) relative to the state of sapwood vessels and the degree of fungal infection. In the sapwood of damaged trees deposits, discolorations and early tylosis formations were found which frequently occurred in combination with fungal infections. These results lead to the assumption that the defence reaction of the trees probably induced by fungal infection changes the structure of the tree vessels to such an extent that their water transfer function is disturbed. Some fungal genera playing an important role in the discussion of the causes of oak decline could be isolated. Fungal hyphae in the vessels and tylosis formation in the vessels cause the breakdown of the water economy in the trees. These observations, however, are not evidence for causal predisposition of tree damage by fungal infections.