Springer Science and Business Media LLC

Verticillium wilt diseases caused by Verticillium spp. are known in many important crops and can seriously threaten their production. We studied Verticillium albo-atrum by comparative analysis of the proteome of four hop isolates, classified by the severity of wilt symptoms as mild and lethal pathotypes, from two geographic origins. A two-dimensional electrophoresis reference map of mycelium proteins was first established, resolving up to 650 protein spots on Coomassie-stained gels in a range of pH 4–7 and MW 14 – 116 kDa. The average coefficient of variance for the 268 matched protein spots was 16% and 15%, respectively, for technical and biological variability. Principal component analysis (PCA) discriminated the geographic origin of the isolates and between the two pathotypes and showed a closer relationship among English isolates than Slovene ones. The two-dimensional electrophoresis patterns of one mild (PG1) with one lethal pathotype (PG2) from Slovenia and one mild (M) with one lethal pathotype (PV1) from England were compared. A total of 27 and 30 spots were found differentially expressed between the pathotypes, which were analysed by tandem mass spectrometry. Fifty-three proteins were identified, of which 17 matched proteins with annotated functions. The lethal pathotypes showed increased expression of peroxiredoxine and ascorbate peroxidase, a higher level of cytoskeleton components and regulators, and a higher rate of protein synthesis and energy metabolism. These results reveal differences in the expression level of the identified proteins between the two pathotypes and are discussed in relation to virulence.

Agaricus bitorquis, a species originally found in nature, produces snowwhite, tasty and well storable fruiting bodies on the common mushroom substrate. Several strains of this species were tested for susceptibility to mushroom virus, viz, the original wild isolatesA. bitorquis Nos 1, 2, 4 and 6, and the selection and breeding products ‘Somycel 2.017’, Horst B30, Horst B6, Horst K26 and Horst K32. Inoculum consisted of either mycelium or spores from virus-infected mushrooms (A. bisporus), or both. Trays withA. bisporus were always inoculated simultaneously to check the infectivity of the inoculum. UnlikeA. bisporus, the strains ofA. bitorquis tested did not show symptoms of virus disease after inoculation. Their fruiting bodies did not present mushroom virus particles, either in extracted cell-free preparations, or in ultrathin sections of the tissue. Yields ofA. bitorquis were not decreased by inoculation. The efficacy of the inoculation technique is discussed. The recent commercial availability of immune mushroom strains was a relief to Dutch mushroom growers, who found the disease difficult to eradicate by sanitary measures only.

Spontaneous epidemics of rust, early leaf spot, late leaf spot, andRhizoctonia blight simultaneously developed in a groudnut plot. Geostatistical techniques were used to describe and compare the spatial patterns of epidemics.Rhizoctonia blight exhibited a strong aggregative structure, contrasting with leaf spots and rust. The latter disease developed a general epidemic, in combination with local intensification. A strong negative interaction between rust and early leaf spot, and a close correspondence between rust intensification andRhizoctonia blight development were indicated.

Trong mùa đông năm 2018, những cây bơ 3 tuổi (Persea americana) giống "Hass" từ tỉnh Trapani (Sicilia, Ý) đã biểu hiện các triệu chứng thối thân và thối ngọn. Hai loại nấm khác nhau đã được phân lập một cách nhất quán từ các mô bị nhiễm. Đặc điểm hình thái và quá trình phân tích di truyền đa vị trí sử dụng năm vị trí gen (ITS, tef1, tub2, his3 và rpb2) đã xác định các loài nấm này là Cylindrocladiella peruviana và Pleiocarpon algeriense. Các thử nghiệm gây bệnh trên cây con 5 tháng tuổi và cây bơ 3 tuổi khỏe mạnh đã tái hiện các triệu chứng tương tự như quan sát thấy trong tự nhiên, và các tiêu chí của Koch đã được thỏa mãn đối với cả hai tác nhân gây bệnh. Hơn nữa, các mẫu nấm đã thử nghiệm cho thấy hành vi gây bệnh khác nhau giữa hai loài. Hai mẫu của Pleiocarpon algeriense tỏ ra hung hãn hơn so với các mẫu của Cylindrocladiella peruviana gây ra tổn thương lớn hơn trên cây con non. Nghiên cứu này là nghiên cứu đầu tiên báo cáo về tình trạng thối thân và thối ngọn trên cây bơ do Cylindrocladiella peruviana và Pleiocarpon algeriense gây ra.

Plant pathologists have traditionally worked in the area of clarifying and understanding the disease cycles of specific diseases, factors influencing epidemiology, yield loss potential and host-pathogen interactions in order to be able to minimise the disease risk, build warning systems or recommend specific control thresholds in relation to the application of fungicides. The decision support system Crop Protection Online (CPO) is an example of a threshold-based system that determines economically viable fungicide strategies. The system is based on using appropriate doses aimed at minimising the overall pesticide input. CPO is used widely by advisors and many of the thresholds are generally accepted and disseminated through newsletters. The national figures for the use of fungicides in cereals have shown a major reduction during the last 20 years and their use today is much in line with the level that can be achieved from using CPO as indicated from validation trials. The number of end-users among farmers has been stable at around 3% during the last 10 years (800–1,000 farmers). Major hurdles in increasing the number of users are believed to be: (1) the requirements for carrying out assessments in the field, (2) farm sizes getting larger, leaving less time for decision making for individual fields, (3) lack of economic incentives to change from standard treatments, (4) the failure of decision support systems to interact with other computer-based programmes on the farm, (5) the lack of compatibility of decision support systems with farmers’ ways of making decisions on crop protection in general, (6) the need for direct interactions with advisors. A sociological investigation into the farmers’ way of making decisions in the area of crop protection has shown that arable farmers can be divided into three major groups: (a) systems-orientated farmers, (b) experienced-based farmers and (c) advisory-orientated farmers. The information required by these three groups is different and has to be looked at individually from the end-user’s perspective rather than from the scientist’s perspective. New ways of entering the decision support system where specific field inspections are omitted and where regional disease data are relied on, have been investigated and tested in field trials. The results show possibilities for further developments in that direction, which might be one way of gaining more end-users.

Fusarium oxysporum f.sp. radicis lycopersici (FORL) and Fusarium solani (F.S.) are common fungi responsible for crown root rot and vascular wilt diseases that highly impact the development of plants, causing significant yield losses. This study investigated changes in the hyperspectral reflectance of normal and Fusarium (FORL and F.S.)-infected tomato plants in a growth chamber at different disease stages (3, 10, 16, 23, 31 and 37 days after inoculation (DAI)) using a spectroradiometer as an alternative to traditional approaches for the early identification and classification of such diseases. Raw spectra, significant wavebands obtained with the RELIEF algorithm and various statistical features extracted from raw spectra were used to classify healthy and infected plants using three different classification algorithms (CAs): decision tree, cubic support vector machine and k-nearest neighbor models. At different stages of the disease, the spectral bands such as 508, 711, 540, 717, 536, 644 nm and 705, 1883, 525, 518, 444, 522 nm were the most effective in distinguishing FORL and F.S.-inoculated plants from healthy plants, respectively. While FORL caused general stress in the plants, F.S. also had a negative physiological effect. All CAs proved highly successful in distinguishing healthy and diseased plants, with maximum classification accuracy achieved as early as 3 DAI. CAs using statistical parameters as input had higher accuracies than other CAs. Healthy and diseased plant classification was significantly different between the different CAs (p < 0.05), while DAI, pathogen type and inputs of the classification did not exhibit significant differences in classification (p > 0.05) according to ANOVA.

Phytophthora sojae can cause soybean phytophthora blight, and greatly reduce soybean production. It is helpful to understand the pathogenic mechanism of P. sojae to prevent soybean phytophthora blight and ensures food security. Glycosyl hydrolases (GHs) disintegrate plant cell walls for nutrition and invasion, and they may act as an important virulence factor during P. sojae infection. To reveal the role of GHs in the main stages of P. sojae life cycle, we measured the expression level of genes, which encoded GHs, and constructed P. sojae transformants for biological function verification by the gene editing technology CRISPR-Cas9. In this study, four genes, encoded special GH proteins, with conserved glycine-rich were identified in the P. sojae genome, and their sequences were similar to those of the TOS1 family genes. One of them, the xp_009520987.1, was named PsGRGH, and was significantly upregulated during the germination of spores and in the early infection stages. The results revealed that PsGRGH was involved in the growth and mycelial morphology regulation in P. sojae, and was essential for its sporangium development and virulence. In addition, PsGRGH is localized on the cell membrane and plays an important role in tolerance toward Bacillus and abiotic stress.