The systematics of Phytophthora sojae and P. megasperma

1989 ◽  
Vol 67 (5) ◽  
pp. 1442-1447 ◽  
Author(s):  
M. A. Faris ◽  
F. E. Sabo ◽  
D. J. S. Barr ◽  
C. S. Lin
Keyword(s):  
Temperature Response ◽  
Phytophthora Sojae ◽  
Phytophthora Megasperma ◽  
Highly Pathogenic ◽  
Formae Speciales ◽  
Type Isolate ◽  
Cardinal Temperatures

Isolates of Phytophthora from alfalfa and soybean and the type isolate of Phytophthora megasperma Drechsler from hollyhock were compared morphologically, for temperature response, and pathogenically. Highly pathogenic, host-specific isolates from soybean and alfalfa, with relatively small oogonia, were identified as P. sojae Kaufmann and Gerdemann and divided into two formae speciales: f.sp. glycines and f.sp. medicaginis, respectively. Less pathogenic isolates from alfalfa with large oogonia were identified as P. megasperma and were compared favorably with Drechsler's original isolate and description. Isolates of P. sojae differed in their cardinal temperatures from those of P. megasperma. We consider P. sojae to be distinct from P. megasperma and propose that this taxon be reintroduced to the literature.

Intraspecifïc variation in gel electrophoresis patterns of soluble mycelial proteins of Phytophthora megasperma isolated from alfalfa

1986 ◽  
Vol 64 (2) ◽  
pp. 262-265 ◽  
Author(s):  
M. A. Faris ◽  
F. E. Sabo ◽  
Y. Cloutier
Keyword(s):  
Intraspecific Variation ◽  
Gel Electrophoresis ◽  
Protein Patterns ◽  
Phytophthora Megasperma ◽  
Highly Pathogenic ◽  
Electrophoretic Patterns ◽  
Group 2 ◽  
Cardinal Temperatures ◽  
Electrophoresis Technique ◽  
Group 1

The electrophoretic patterns of the buffer-soluble proteins of 26 isolates of Phytophthora megasperma f. sp. medicaginis from diseased alfalfa plants and soil were studied. On the basis of the protein patterns, the isolates were divided into two groups which correlated with cardinal temperatures for growth, pathogenicity, and oogonia size. Group 1 (seven isolates) has minimum growth at 5 °C, optimum at 25–30 °C, and maximum at 35 °C, and is a highly pathogenic pathotype with small oogonia. Group 2 (19 isolates) has minimum growth at less than 5 °C, optimum at 20 °C, and maximum at 30 °C, and is a less pathogenic pathotype with large oogonia. The electrophoresis technique was useful in identifying differences among the Phytophthora isolates.

Elicitor-binding proteins and signal transduction in the activation of a phytoalexin defense response

1995 ◽  
Vol 73 (S1) ◽  
pp. 506-510 ◽  
Author(s):  
Jürgen Ebel ◽  
Markus Feger ◽  
Ulrich Kissel ◽  
Axel Mithöfer ◽  
Tom Waldmüller ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Glycine Max ◽  
Defense Response ◽  
Binding Sites ◽  
Binding Proteins ◽  
Cultured Cells ◽  
Phytophthora Sojae ◽  
Phytophthora Megasperma ◽  
Early Stages ◽  
Signalling Process

Inducible plant defenses against potential pathogens are thought to be activated by signal compounds released during early stages of the infection process. In the incompatible interaction between soybean (Glycine max L.) and the oomycete Phytophthora megasperma f.sp. glycinea (= Phytophthora sojae) a rapid, localized phytoalexin response is activated at the level of transcription. The phytoalexin response is also stimulated in various soybean tissues, including cultured cells, following treatment with an elicitor derived from the cell walls of the fungus. The best characterized elicitors of P. megasperma for soybean are the branched (1→3)- and (1→6)-linked β-glucans, structural polysaccharides of the hyphal walls. The glucans are naturally released during the early stages of germination of the fungal cysts in a host-independent manner. Cyclic β-glucans of Bradyrhizobium japonicum USDA 110, a symbiont of soybean, arc not active in inducing phytoalexin production in soybean. When tested in combination, B. japonicum β-glucans inhibited stimulation of phytoalexin accumulation by the fungal glucans. Surface-localized glucan-binding proteins exist in soybean cells that display high affinity and specificity for the fungal β-glucans, including an elicitor-active hepta-β-glucoside fragment derived from the polysaccharide, suggesting that elicitor action involves a transmembrane signalling process. The main component of the soybean β-glucan binding sites appears to be a 70-kDa protein. Hepta-β-glucoside binding sites exist in several other legumes, such as bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), and lupine (Lupinus albus L.). The signalling process initiated by the β-glucan elicitor, which leads to the activation of the phytoalexin defense response in soybean, involves changes in the permeability of the plasma membrane to Ca2+ and H+. Chloride channel antagonists are more efficient than calcium channel antagonists in inhibiting both the phytoalexin response and the inducible ion fluxes. The results present evidence that the observed permeability changes of the plasma membrane are primary events in the transduction of the elicitor signal(s) by the challenged soybean cells. Key words: soybean (Glycine max), Phytophthora megasperma f.sp. glycinea, β-glucan elicitor, elicitor-binding proteins, phytoalexins, Ca2+.

scholarly journals The Temperature Response and Aggressiveness of Peyronellaea pinodes Isolates Originating from Wild and Domesticated Pisum sp. in Israel

2016 ◽  
Vol 106 (8) ◽  
pp. 824-832 ◽  
Author(s):  
M. Golani ◽  
S. Abbo ◽  
A. Sherman ◽  
O. Frenkel ◽  
D. Shtienberg
Keyword(s):  
Spore Germination ◽  
Ascochyta Blight ◽  
Temperature Response ◽  
Limited Information ◽  
Natural Ecosystems ◽  
Pisum Fulvum ◽  
Wide Range ◽  
Close Proximity ◽  
Cardinal Temperatures ◽  
Temperature Responses

Domesticated pea fields are grown in relatively close proximity to wild pea species in Israel. Despite the major role attributed to ascochyta blight in causing yield losses in domesticated pea, very limited information is available on the pathogens prevailing in natural ecosystems. The objectives of this study were (i) to identify the species causing ascochyta blight symptoms on leaves, stems, and petioles of domesticated pea and wild Pisum plants in Israel, and (ii) to quantify the temperature response(s) and aggressiveness of such pathogens originating from Pisum plants growing in sympatric and allopatric contexts. Eighteen fungal isolates were examined and identified; three of them were sampled from Pisum sativum, 11 from Pisum fulvum, and four from Pisum elatius. All isolates were identified as Peyronellaea pinodes. Spore germination and mycelial growth took place over a wide range of temperatures, the lower and upper cardinal temperatures being 2 to 9 and 33 to 38°C, respectively; the optimal temperatures ranged from 22 to 26°C. At an optimal temperature, disease severity was significantly higher for plants maintained under moist conditions for 24 h postinoculation than for those exposed to humidity for 5 or 10 h. Analyses of the data revealed that temperature responses, spore germination rates, and aggressiveness of isolates sampled from domesticated pea plants did not differ from those of isolates sampled from adjacent or distant wild populations. Host specificity was not observed. These observations suggest that Israel may be inhabited by a single metapopulation of P. pinodes.

Phytophthora sojae. [Distribution map].

1996 ◽  
Author(s):  
Keyword(s):  
New York ◽  
North Carolina ◽  
South Dakota ◽  
New South ◽  
District Of Columbia ◽  
Phytophthora Sojae ◽  
Distribution Map ◽  
Phytophthora Megasperma ◽  
South Wales ◽  
New Distribution

Abstract A new distribution map is provided for Phytophthora sojae[Phytophthora megasperma f.sp. glycinea] Kaufm. & Gerd. Hosts: Soyabean (Glycine max). Information is given on the geographical distribution in Argentina, Australia, New South Wales, Queensland, Victoria, Canada, British Columbia, Ontario, Chile, China, Hebei, Heilongjiang, Jilin, France, Hungary, Italy, Japan, Hokkaido, Honshu, Pakistan, Russia, Russia (European), Slovenia, Switzerland, USA, Arizona, Arkansas, California, Delaware District of Columbia, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Nebraska, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Dakota, Virginia, Washington, Wisconsin.

Cosegregation of Avr4 and Avr6 in Phytophthora sojae

1996 ◽  
Vol 74 (5) ◽  
pp. 800-802 ◽  
Author(s):  
Mark Gijzen ◽  
Helga Förster ◽  
Michael D. Coffey ◽  
Brett Tyler
Keyword(s):  
Glycine Max ◽  
Genetic Mapping ◽  
Resistance Genes ◽  
Gene Interaction ◽  
Phytophthora Sojae ◽  
Phytophthora Megasperma ◽  
Incomplete Dominance ◽  
Soybean Plants ◽  
Race 2 ◽  
Gene For Gene

The F2 progeny resulting from a cross of Phytophthora sojae race 2 (avirulent on Rps4 and Rps6) and race 7 (virulent on Rps4 and Rps6) were tested for their ability to cause disease on soybean plants carrying the Rps4 or the Rps6 resistance genes. Of 55 F2 progeny analyzed, 41 individuals were avirulent on both of these genes and 14 were virulent on Rps4 and Rps6, indicating that avirulence on Rps4 and Rps6 is dominant and linked. These results support the suggestion that the soybean–Phytophthora relationship is a gene for gene interaction and that the presumptive Avr4 and Avr6 genes are either tightly linked or identical. Keywords: avirulence, genetic mapping, Glycine max, incomplete dominance, Phytophthora megasperma f.sp. glycinea.

scholarly journals A temperature response function for modeling leaf growth and development of the African violet (Saintpaulia ionantha Wendl.)

2004 ◽  
Vol 34 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Nereu Augusto Streck
Keyword(s):  
Response Function ◽  
Growth And Development ◽  
Leaf Growth ◽  
Temperature Response ◽  
Simulation Models ◽  
African Violet ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Cardinal Temperatures

Response functions used in crop simulation models are usually different for different physiological processes and cultivars, resulting in many unknown coefficients in the response functions. This is the case of African violet (Saintpaulia ionantha Wendl.), where a generalized temperature response for leaf growth and development has not been developed yet. The objective of this study was to develop a generalized nonlinear temperature response function for leaf appearance rate and leaf elongation rate in African violet. The nonlinear function has three coefficients, which are the cardinal temperatures (minimum, optimum, and maximum temperatures). These coefficients were defined as 10, 24, and 33ºC, based on the cardinal temperatures of other tropical species. Data of temperature response of leaf appearance rate and leaf elongation rate in African violet, cultivar Utah, at different light levels, which are from published research, were used as independent data for evaluating the performance of the nonlinear temperature response function. The results showed that a generalized nonlinear response function can be used to describe the temperature response of leaf growth and development in African violet. These results imply that a reduction in the number of input data required in African violet simulation models is possible.

scholarly journals Phenomics data processing: Extracting temperature dose-response curves from repeated measurements

2021 ◽  
Author(s):  
Lukas Roth ◽  
Hans-Peter Piepho ◽  
Andreas Hund
Keyword(s):  
Temporal Resolution ◽  
Stem Elongation ◽  
Temperature Response ◽  
Repeated Measurements ◽  
High Temporal Resolution ◽  
Asymptotic Model ◽  
Parametric Modelling ◽  
Response Curves ◽  
Starting Point ◽  
Cardinal Temperatures

Temperature is a main driver of plant growth and development. New phenotyping tools enable quantifying the temperature response of hundreds of genotypes. Yet, particularly for field-derived data, the process of temperature response modelling bears potential flaws and pitfalls with regard to the interpretation of derived parameters. In this study, climate data from three growing seasons with differing temperature distributions served as starting point for a wheat stem elongation growth simulation, based on a four-parametric Wang-Engel temperature response function. To extract dose-responses from the simulated data, a novel approach to use temperature courses with high temporal resolution was developed. Linear and asymptotic parametric modelling approaches to predict the cardinal temperatures were investigated. An asymptotic model extracted the base and optimum temperature of growth and the maximum growth rate with high precision, whereas simpler, linear models failed to do so. However, when including seasonally changing cardinal temperatures, the prediction accuracy of the asymptotic model was strongly reduced. We conclude that using an asymptotic model based on temperature courses with high temporal resolution is suitable to extract meaningful parameters from field-based data. Consequently, applying the presented modelling approach to high-throughput phenotyping data of breeding nurseries may help selecting for climate suitability.

Isolation of highly pathogenic pathogens and identification of formae speciales of Rehmannia glutinosa L.

2013 ◽  
Vol 21 (11) ◽  
pp. 1426-1433 ◽  
Author(s):  
Zhen-Fang LI ◽  
Yan-Qiu YANG ◽  
Lin-Kun WU ◽  
Yang SHU ◽  
Yong-Po ZHAO ◽  
...  
Keyword(s):  
Rehmannia Glutinosa ◽  
Highly Pathogenic ◽  
Formae Speciales
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