Control Of Plant Diseases By An Allium-based Antimicrobial Formulation

The objective of this work was to determine the antimicrobial properties of an allium-based antimicrobial formulation named VEG’LYS (https://phytoauxilium.com/) on the growth of plant pathogenic microorganisms such as fungi, oomycetes, and bacteria. Two anthracnose-related species of the fungal genus Colletotrichum, C. gloeosporioides, and C. fragariae, the oomycete Phytophthora cactorum and the bacterium Xanthomonas fragariae associated with strawberry plants and two fungi Alternaria dauci and Botrytis cinerea, associated with carrot plants were tested in vitro. In in planta experiments, A. dauci and B. cinerea were used.. VEG’LYS inhibited the growth of all plant pathogens tested. We found that both curative and preventive in planta treatments with VEG’LYS inhibited the growth of A. dauci and B. cinerea in carrot. Furthermore, after spraying VEG’LYS on carrot plants the expression of the Pathogenesis-related (PR) 10 gene correlated with the magnitude of infection both in treated and untreated plants. Additionally, it has been shown, that the field application of VEG’LYS on strawberry plants results in a reduction of bacterial and fungal pathogens of strawberry fruits stored in refrigerator. In summary, VEG’LYS is a potential resistance inducer that seems to be suitable for use in both curative and preventive treatments to reduce the diseases and rotting of fruits and vegetables caused by different plant pathogens.

The Effect of Microwave Treatment on Germination and Health of Carrot (Daucus carota L.) Seeds

The aim of the study was to evaluate the effect of microwave treatment on seed germination and health of carrot seeds using two seed lots naturally infected with the pathogens Alternaria dauci and A. radicina. Seeds of cv. Amsterdam and cv. Berlikumer varied in seed germination at the final count (50% and 29%, respectively), and seed infestation with A. radicina (38% and 5%, respectively). For treatment, seeds were placed in a Petri dish (dry treatment) or in a beaker with distilled water (wet treatment) and irradiated at power output levels 500, 650 and 750 W for 15, 30, 45, 60, 75, and 90 s. Germination and health were determined in treated and untreated (control) seed samples. Wet treatment controlled seed-borne fungi more efficiently than dry treatment. However, the exposure duration longer than 60 s frequently resulted in deterioration of seed germination. The highest seed germination in cv. Amsterdam was observed after microwave wet treatment at power output levels of 500 W for 75 s (81%), 650 W for 45 s (85%), and 750 W for 60 s (77%), whereas in the case of cv. Berlikumer this occurred when wet seeds were treated at 500 and 650 W for 60 s (46% and 43% respectively). Treating seeds soaked in water with microwaves for a period longer than 30 s, regardless of the power output, significantly decreased seed infestation with Alternaria spp. in both samples.

The heritability of tolerance to Alternaria dauci and Fusarium oxysporum in F1-hybrids of carrot

Heritability the tolerance to Alternaria dauci and Fusarium oxysporum in prospective F1-hybrids of car-rot has been discussed in the paper. As QTLs isn’t reliable enough for the determination of tolerance heritability in F1-hybrid progenies, authors used traditional methods of inoculation applying step-by-step at every stage of plant’s development. Carrot lines have been evaluated carefully at different types of infection backgrounds, tol-erant lines and lines with weak sensitivity have been selected for crossings. F1-hybrids have been obtained and evaluated at the provocative infection background. Using dispersion analysis, the authors show, that tolerance to Alternaria dauci and Fusarium oxysporum has been inherited by the paternal type.

The Effect of Acetic Acid Treatments on the Quality of Stored Carrot (Daucus carota L.) Seeds

Alternaria dauci (J.G. Kühn) J.W. Groves et Skolko and A. radicina Meier, Drechsler et E.D. Eddy are important seed-transmitted pathogens of carrot. The aim of this study was to evaluate the effects of acetic acid treatments on the quality of stored carrot seeds. Seeds of two samples were soaked for 30 min in 0.5, 1 and 2% acetic acid. Controls included untreated seeds, seeds soaked in distilled water and seeds treated with fungicide Zaprawa Nasienna T 75 WS/DS (a.i. thiram 75%). Germination, vigour and health of untreated and treated seeds were evaluated before and after 5 and 12 months of storage at 4 and 20 °C. Seeds of both samples treated with 0.5 and 1% acetic acid were characterized by higher germination capacity after storage than untreated seeds. However, treatments with 1 and 2% acetic acid negatively affected seed vigour. Generally, seeds of both samples treated with acetic acid were characterized by lower infestation with A. alternata and A. radicina after storage than untreated seeds and seeds soaked in distilled water. Moreover, acetic acid often controlled these fungi more effectively than the fungicide. Regardless of the storage duration, infestation with fungi was higher if seeds of both samples were stored at a lower temperature.

COMPORTAMENTO SINTOMATOLÓGICO TEMPORAL DA QUEIMA DAS FOLHAS DA CENOURA EM FUNÇÃO DA FLUTUAÇÃO POPULACIONAL DE ESPOROS DE Alternaria dauci NO AR

Pouco se sabe sobre a epidemiologia da queima das folhas da cenouracausada pelo fungo Alternaria dauci . Com isso, o presente projeto teve comoobjetivo avaliar a epidemiologia da doença que servirá de base para o entendimentoda ocorrência doença no Alto Vale do Itajaí/SC. Sementes do cultivar Brasília foramsemeadas e avaliou-se semanalmente a severidade da doença em função daflutuação de esporos, coletados e quantificados em laboratório a 400 (x) deaumento. Conclui-se que a flutuação de esporos ocorre praticamente constantedurante o ciclo produtivo da cultura e aumento gradativo da doença com destaquepara as semanas finais.

PROGRESSO TEMPORAL DA QUEIMA DAS FOLHAS DA CENOURA EM FUNÇÃO DA FLUTUAÇÃO POPULACIONAL DE ESPOROS DE Alternaria dauci NO AR

A cultura da cenoura no Brasil vem em uma crescente expansão de territórios cultivados e na região do Alto Vale do Itajaí em Santa Catarina tem uma grande importância socioeconômica, devido à complementação de renda de pequenos agricultores familiares. Entretanto, o fato da época de cultivo coincidir com temperaturas elevadas e alto índice de umidade, favorece o desenvolvimento da queima das folhas da cenoura causada por Alternaria dauci. A doença ocasiona queda de produtividade devido a perca de área fotossintética, resultante da coalescência das lesões e vimento dessa doença em nível de campo na região e com isso, o trabalho objetivou buscar a compreensão da doença, visando entender o progresso sintomatológico da doença na planta em relação a presença do esporo de A. dauci no ar. O trabalho foi realizado no Instituto Federal Catarinense – IFC/Campus Rio do Sul em delineamento de blocos casualizados com 3 repetições providas de cinco linhas de plantio, com semeadura do cultivar de cenoura Brasília, apresentando um total de 150 por m2, equivalente a 1.000.000 planta.ha-1. Para avaliação da queima das folhas, foram escolhidas 40plantas em cada parcela, marcadas aleatoriamente, avaliando-se semanalmente a evolução da doença em cada folha exposta através da utilização da escala diagramática da doença. A coleta dos conídios de A. dauci no ar foi realizada com a utilização de um coletor de esporos tipo “cata-vento”, com uma lâmina de microscopia untada com vaselina e substituída semanalmente. Através da visualização em microscópio óptico, com a objetiva de 10 vezes, quantificou-se o número de conídios coletados na lâmina dividida em dois pontos centrais. Ao analisar os dados obtidos foi possível observar a presença de esporos antecedendo o início da doença e se mantendo praticamente constantes até o final do ciclo da cultura, com algumas exceções, variando de 0 a 5 esporos encontrados por repetição (lamínula). Os maiores índices de severidade foram encontrados nas semanas finais progredindo de 3,68% na oitava semana de avaliação para 23% de severidade por planta na décima segunda semana. Contatou-se também um aumento na contagem de esporos a partir da sétima semana de avaliação, coincidente com o início da doença. Esse estudo servirá de modelo para a epidemiologia da doença na região e de base para a construção de um sistema de previsão.

Features of disease affected varieties and hybrids of carrots and beets created in the Primorsky vegetable experimental station in the monsoon climate of the Far East

В течение четырех лет (2016–2019 годы) на опытном поле Приморской овощной опытной станции – филиал ФГБНУ «Федеральный научный центр овощеводства» на естественном инфекционном фоне проводились исследования по изучению устойчивости перспективных сортообразцов моркови и столовой свеклы местной селекции к грибным и бактериальным заболеваниям в период вегетации в условиях муссонного климата Дальнего Востока для дальнейшего использования в селекционном процессе. Были испытаны сорта моркови Тайфун, Лидер, Гарант, Приморская 22 и гибрид F1 Форвард, а также сорта столовой свеклы Приморская 4, Приморская цилиндрическая и пять номерных образцов. Оценку пораженности листьев моркови проводили для всего комплекса болезней: Alternaria dauci(Kuhn.) Groves & Skolko, Cercospora carota (Pass.) Solh., Xanthomonas carotae Dows, листьев столовой свеклы – для Сercospora beticolaSass. Первые признаки болезней (A. dauci) обнаруживались на листовой поверхности моркови со второй декады июля – начала первой декады августа и во второй декаде августа – начале сентября их распространенность составляла 100% с максимальным средневзвешенным баллом поражения 2,6. Первые признаки пораженности образцов столовой свеклы церкоспорозом были отмечены в первой – второй декадах июля и ко второй декаде августа распространенность болезни почти на всех образцах составила 100%. При этом прослеживалась прямая зависимость распространенности и степени поражения растений болезнями от количества выпавших осадков и температуры воздуха. Наибольшую устойчивость к заболеваниям на листовой поверхности моркови показал гибрид моркови F1 Форвард и к церкоспорозу – образец столовой свеклы ПООС 22. Сорт моркови Лидер и образец столовой свеклы ПООС 22 могут быть использованы в селекционной работе для создания сортов и гибридов с повышенной устойчивостью к инфекционным болезням. For four years (2016–2019), research on the resistance of promising varieties of carrots and beets of local selection to fungal and bacterial diseases during the growing season in the monsoon climate of the Far East was conducted on the experimental field of the Primorsky vegetable experimental station - a branch of the FSBSI Federal Scientific Vegetable Center against a natural infectious background. Carrot varieties Typhoon, Leader, Garant, Primorskaya 22 and hybrid F1 Forward were tested, as well as beet varieties Primorskaya 4, Primorskaya cylindrical and 5 numbered samples. Carrot leaf infestation was evaluated for the entire complex of diseases: Alternaria dauci (Kuhn.) Groves & Skolko, Cercospora carota (Pass.) Solh., Xanthomonas carotae Dows, and beet leaves – for Cercospora beticola Sass. The first signs of diseases (A. dauci) were detected on the leaf surface of carrots from the second decade of July – the beginning of the first decade of August and in the second decade of August – early September, their prevalence was 100% with a maximum weighted average score of 2.6. The first signs of infection of table beet samples with cercosporosis were noted in the first and second decades of July and by the second decade of August, the prevalence of the disease in almost all samples was 100%. At the same time, there was a direct dependence of the prevalence and degree of plant diseases on the amount of precipitation and air temperature. The greatest resistance to diseases on the leaf surface of carrots showed a hybrid of carrots F1 Forward and cercosporosis – a sample of beet POOS 22. The Leader carrot variety and the POOS 22 beet sample can be used in breeding work to create varieties and hybrids with increased resistance to infectious diseases.

Diketopiperazines from Alternaria dauci

Alternaria dauci is the causal agent of Alternaria leaf blight (ALB), a foliar disease of carrot crops (Daucus carota) around the world. In terms of phytotoxic metabolites production, A. dauci has received limited attention. Previous studies carried out on the secondary metabolites involved in the pathogenicity of this fungus have only reported the isolation of a ubiquitous non-selective phytotoxin known as zinniol. Because of this, the aim of this research is directed towards the isolation and identification of secondary metabolites involved in the plant-pathogen interaction process. A. dauci was cultured in the Czapek-Dox medium, and the culture filtrate was extracted with ethyl acetate. The leaf-spot assay of fractions resulting from the partition process showed a phytotoxic effect in the ethyl acetate fraction. The chromatographic separation of ethyl acetate fraction allowed the isolation of seven diketopiperazines, identified as cyclo-(pro-val) (1), cyclo-(pro-leu) (2), cyclo-(pro-phe) (3), cyclo-(val-leu) (4), cyclo-(val-phe) (5), cyclo-(leu-phe) (6) and cyclo-(leu-tyr) (7). The structures of the different metabolites were established by comparing their spectroscopic (1H NMR) and spectrometric (GC-MS) data with those reported in the literature. Resumen. Alternaria dauci es el agente causal del tizón de la hoja (ALB), una enfermedad foliar que afecta los cultivos de zanahoria (Daucus carota) alrededor del mundo. En términos de producción de metabolitos fitotóxicos, A. dauci ha recibido una atención muy limitada. Estudios previos llevados a cabo sobre los metabolitos secundarios involucrados en la patogenicidad de este hongo, solo han reportado el aislamiento de una fitotoxina no selectiva y ubicua conocida como zinniol. Debido a lo anterior, el objetivo de esta investigación se dirige al aislamiento e identificación de metabolitos secundarios implicados en la interacción planta-patógeno. Para esto el fitopatógeno se cultivó en medio Czapek-Dox y el filtrado del cultivo se extrajo con acetato de etilo. La evaluación de las fracciones resultantes de la partición, en el ensayo de manchas foliares en hojas, mostró un efecto fitotóxico en la fracción de acetato de etilo. La separación cromatográfica de la fracción de acetato de etilo permitió el aislamiento de siete dicetopiperazinas identificadas como ciclo-(pro-val) (1), ciclo-(pro-leu) (2), ciclo-(pro-phe) (3), ciclo-(val-leu) (4), ciclo-(val-phe) (5), ciclo-(leu-phe) (6) y ciclo-(leu-tyr) (7). Las estructuras de los diferentes metabolitos se establecieron comparando sus datos espectroscópicos (1H RMN) y espectrométricos (CG-EM) con los reportados en la literatura.