Effect of relative humidity on production of extracellular pectolytic enzymes by Botrytis cinerea and Sclerotinia sclerotiorum

1969 ◽  
Vol 47 (6) ◽  
pp. 1007-1010 ◽  
Author(s):  
L. Van Den Berg ◽  
S. M. Yang

B. cinerea and S. sclerotiorum growing in a nutrient medium on the surface of carrots at 20 °C produced significantly more extracellular pectolytic enzymes when the carrots were exposed to 94–96% relative humidity than when exposed to 98–100% relative humidity. Tests in which these organisms were grown in a nutrient solution containing pectic substances showed that they produced pectolytic enzymes in significant quantities only when readily metabolizable sources of energy (e.g. ethanol, carbohydrates) were not available. These results suggest that the low relative humidity increased enzyme production by concentrating nutrients on the carrot surface to the point where they inhibited growth of the organisms and stimulated enzyme production. Tests also showed that pectolytic enzyme activity on the surface of unwashed carrots stored 9 months at 0–1 °C was substantially higher at 90–95% relative humidity than at 98–100% relative humidity. The results indicated that reduced decay at 98–100% relative humidity was largely due to lower pectolytic enzyme production.

1972 ◽  
Vol 18 (7) ◽  
pp. 1065-1072 ◽  
Author(s):  
Hassan A. Melouk ◽  
Chester E. Horner

Pectolytic enzyme activity of P. strasseri was highest in filtrates from cultures 5 and 23 days old, as determined by reducing-groups assay (RGA). Pectolytic enzyme activity, as determined by viscosity-reduction assay (VRA), was highest in cultures 7 days old. Macerating enzyme activities were highest in cultures 10 days old. Young peppermint-rhizome sections were more susceptible to maceration by P. strasseri filtrates than older sections. Colored phenolic compounds were released from macerated rhizomes and amounts released were correlated with degree of maceration.Differential inhibition of pectolytic enzyme activity (as judged by VRA and RGA assays) by a range of phenolic compounds suggests that at least two pectolytic enzymes capable of hydrolyzing α-1,4 linkages of pectic substances are produced by P. strasseri.Highest activities of pectolytic and macerating enzyme in extracts from diseased rhizomes were detected 5 days after inoculation with P. strasseri. Extracts from healthy rhizomes did not show pectolytic and macerating enzyme activity.Healthy peppermint-rhizome tissues had higher activities of polyphenoloxidase than diseased tissues; also, polyphenoloxidase activities in inoculated rhizomes decreased as time of incubation increased.


1964 ◽  
Vol 17 (3) ◽  
pp. 705 ◽  
Author(s):  
C Reinganum

The production of pectolytic enzymes in vivo and in vitro by S. Jructicola and by Rhizopus arrhizu8 Fischer in vivo is established.


1968 ◽  
Vol 46 (12) ◽  
pp. 1477-1481 ◽  
Author(s):  
L. Van Den Berg ◽  
C. P. Lentz

Tests with mycelium and conidia of five strains of Botrytis cinerea and mycelium of three strains of Sclerotinia sclerotiorum have shown that survival and growth of these organisms depended on relative humidity, temperature, and type and strain of organism. Survival of mycelium of both organisms in the absence of nutrients, for example, varied from 12 months at 95–100% relative humidity and 0 °C to less than 1 month at below 95% relative humidity and 20 °C, depending on strain. When nutrients were present growth occurred at solution equilibrium relative humidities over 93%; at equilibrium relative humidities below 93% no growth occurred and mycelium survived only up to 1 month. Growth rates of all strains of both organisms were similar between −0.8 and 35 °C with maximum rates at about 20 °C. Results also showed that mycelium and conidia of B. cinerea survive under the conditions at which vegetables are usually stored but that mycelium of S. sclerotiorum in most instances does not.


2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Pawar A. B.

Alternaria alternata is a potential pathogen of Tectona grandis L.f., was isolated from diseased Tectona grandis L.f. leaves from Nashik and used for the present study. Pathogen was grown on the Czapek-Dox liquid medium substituting or adding different carbon, nitrogen to study cellulolytic and pectolytic enzyme production and total phenol production. The activity of enzyme was observed on the 8th day of incubation period. A great extent of growth variation was observed on different carbon, nitrogen. Among the carbon source) the maximum loss in percentage viscosity maximum in lactose and fructose. While minimum in glucose and dextrose as compared to other nitrogen source. From nitrogen source the cellulolytic enzyme activity was maximum in control and cobalt nitrate followed by similar activity in potassium nitrate and nickel nitrate. While minimum cellulolytic enzyme activity was seen in barium nitrate.. Variation was also observe in pectolytic enzyme activity. the cellulolytic enzyme activity was maximum in glucose while minimum in dextrose as compared to lactose, control and fructose.. From nitrogen source the cellulose activity was maximum in potasium nitrate and minimum in cobalt nitrate as compared to nickel nitrate, barium nitrate and control.


2020 ◽  
pp. 16-19
Author(s):  
Е.В. Янченко

Цель исследований – дать оценку сохраняемости и болезнеустойчивости современных сортов и гибридов моркови столовой и определить корреляционные зависимости влияния биохимических показателей качества на сохраняемость и степень поражения моркови столовой различными видами болезней в процессе хранения. Исследования проводились в 2011–2016 годах во ВНИИО – филиале ФГБНУ ФНЦО по общепринятым методикам. В биохимической лаборатории отдела земледелия и агрохимии содержание сухого вещества определяли высушиванием до абсолютно сухого веса, общего сахара – по Бертрану, аскорбиновой кислоты – по Мурри, нитраты – ионоселективным методом. При характеристике моркови столовой важнейший показатель, определяющий его качество – количество сухого вещества и сахаров. В процессе хранения были выявлены следующие болезни моркови: серая гниль (Botrytis cinerea Pers. ex Fr.), белая гниль (Sclerotinia sclerotiorum (Lib.)), белая парша (Rhizoctonia carotae Rad.), альтернариоз (Alternaria radicina M., Dr. et E.). В большей степени сортообразцы моркови столовой поражались серой гнилью. Лучшими по сохраняемости сортообразцами были Корсар (94,6%), F1Берлин (94,5%), Берликум Роял (94,1%) и F1 Звезда (94%). Сохраняемость у зарубежных сортов и гибридов моркови столовой была немного выше, чем у отечественных (на 0,4%) как за счет меньшей величины убыли массы (6,3% против 6,4%), так и потерь от болезней (1,6% против 1,9%). Сохраняемость корнеплодов моркови находится в прямой корреляционной зависимости от содержания сухого вещества (r=+0,41), каротиноидов (r=+0,39), моносахаров (r­=+0,30) и суммы сахаров (r=+0,27). Проявление серой гнили находится в обратной корреляционной связи с содержанием сухого вещества и каротиноидов (r=-0,37 и r=-0,35 соответственно), белой парши – в прямой корреляции с содержанием сухого вещества , моносахаров и дисахаров (r= +0,21; r= +0,39; r= -0,41 соответственно), белой гнили в обратной корреляционной связи с содержанием сухого вещества, моносахаров и дисахаров. The purpose of the research is to assess the persistence and disease resistance of modern varieties and hybrids of carrots and to determine the correlation between the influence of biochemical quality indicators on the persistence and degree of damage to carrots by various types of diseases during storage. The research was conducted in 2011–2016 at ARRIVG – branch of FSBSI FSVC, according to generally accepted methods. In the biochemical laboratory of the Department of Agriculture and Agrochemistry, the dry matter content was determined by drying to absolutely dry weight, total sugar – by Bertran, ascorbic acid – by Murri, nitrates – by the ion-selective method. When describing carrots, the most important indicator that determines its quality is the amount of dry matter and sugars. During storage, the following diseases of carrots were detected: gray rot (Botrytis cinerea Pers. ex Fr.), white rot (Sclerotinia sclerotiorum (Lib.), white scab (Rhizoctonia carotae Rad.), alternariasis (Alternaria radicina M., Dr. et E.). To a greater extent, varieties of table carrots were affected by gray rot. The best preserved varieties were Corsar (94.6%), F1 Berlin (94.5%), Berlicum Royal (94.1%) and F1 Zvezda (94%). The persistence of foreign varieties and hybrids of table carrots was slightly higher than that of domestic ones by 0.4%. both due to a smaller amount of weight loss (6.3% vs. 6.4%) and losses from diseases (1.6% vs. 1.9%). The persistence of carrot root crops is directly correlated with the content of dry matter (r=+0.41), carotenoids (r=+0.39), monosaccharides (r=+0.30) and the amount of sugars (r=+0.27). The manifestation of gray rot is in inverse correlation with the content of dry matter and carotenoids (r=-0.37 and r=-0.35, respectively), white scab is in direct correlation with the content of dry matter (r= +0.21; r= +0.39; r= –0.41, respectively), white rot is in inverse correlation with the content of dry matter, monosaccharides and disaccharides.


2016 ◽  
Vol 146 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Hong-Jie Liang ◽  
Xiao-Ming Lu ◽  
Zu-Qing Zhu ◽  
Fu-Xing Zhu

1982 ◽  
Vol 60 (3) ◽  
pp. 219-223 ◽  
Author(s):  
Kerry T. Hubick ◽  
David R. Drakeford ◽  
David M. Reid

Two watering systems used for growing minimally stressed plants are described. An aeroponics system, which relies on a mist of nutrient solution applied to roots without a root support medium, affords control over water availability and easy access to roots. A continuous circulation system, which constantly circulates nutrient medium, also provides control over water availability as well as control over pO2 and stress duration in flooded plants. A comparison is made of the growth characteristics of plants grown in the two systems with those grown by traditional watering methods. The significance of watering prehistory to stress physiology experiments is discussed.


Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1241-1241 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild or sand rocket, are widely cultivated in Italy. Rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. In winter 2003, a severe disease was observed on D. tenuifolia grown in unheated glasshouses on commercial farms near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. The disease was extremely severe in the presence of high relative humidity and mild temperature (15°C). Necrotic tissues became covered with white mycelium that produced dark sclerotia. Diseased stem tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 1.23 to 3.00 × 1.40 to 5.38 mm (average 2.10 × 2.85 mm). Sclerotia produced on PDA measured 1.00 to 4.28 × 1.00 to 6.01 mm (average 2.38 × 3.23 mm). Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants of D. tenuifolia grown in 18-cm-diameter pots in a glasshouse. Inoculum, 2 g per pot of wheat kernels infested with mycelium and sclerotia of each isolate, was placed on the soil surface around the base of each plant. Three replicates of five pots each were used per isolate. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 10 and 26°C (average 15°C) with an average relative humidity of 80% and were watered as needed. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and eventually wilted. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of infection of D. tenuifolia by S. sclerotiorum in Italy as well as worldwide. The disease currently has been observed in the Liguria Region but not yet in other areas where sand rocket is cultivated. The economic importance of this disease for the crop can be considered medium at the moment, but is expected to increase in the future. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 75, 1949.


2014 ◽  
Vol 32 (1) ◽  
pp. 31-39
Author(s):  
Joanna Marcinkowska

Seeds of 11 Austrian winter pea genotypes, harvested at Radzików (CEP) in 1993 and 1994, were evaluated for fungi occurrence on Coon's agar medium in Petri plates. Number of species isolated depended on the genotype and year of collection. <i>Alternaria alternata, Stemphylium botryosum</i> were found on all the tested samples and <i>Phoma pinodella</i> and <i>Fusarium poae</i> were also common while <i>Botrytis cinerea, Sclerotinia sclerotiorum</i> and <i>Mycosphaerella pinodes</i> appeared to be common only in 1993. Three species occurred only once. The mycoflora was richer in 1993. The common seed inhabitants usually transmitted higher percentage of fungi than species occuring more seldom.


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