Isolation of the Phytoalexin Medicarpin from Leaflets of Arachis hypogaea and Related Species of the Tribe Aeschynomeneae

1985 ◽  
Vol 40 (5-6) ◽  
pp. 313-316 ◽  
Author(s):  
R. N. Strange ◽  
J. L. Ingham ◽  
D. L. Cole ◽  
M. E. Cavill ◽  
C. Edwards ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Arachis Hypogaea ◽  
Related Species ◽  
Natural Infection ◽  
Spore Suspension ◽  
Cercospora Arachidicola

Abstract A phytoalexin produced by the leaflets of seven cultivars of Arachis hypogaea (groundnut) after natural infection by Cercospora arachidicola or Phoma arachidicola has been characterised as the isoflavonoid (+)-medicarpin (3-hydroxy-9-methoxypterocarpan). Treatment of excised ground­nut leaflets with an aqueous solution of CuSO4 or with a spore suspension of the fungus Helmin-thosporium carbonum has also been found to stimulate medicarpin biosynthesis.

Applications of Mixtures of Copper Fungicides and Chlorothalonil for Management of Peanut Leaf Spot Diseases

2001 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
A. K. Culbreath ◽  
T. B. Brenneman ◽  
R. C. Kemerait
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Cercospora Arachidicola ◽  
Copper Oxychloride ◽  
Copper Hydroxide ◽  
Cercosporidium Personatum ◽  
Late Leaf Spot ◽  
Copper Fungicides

Management of early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum) of peanut (Arachis hypogaea) in the southeastern U.S. is dependent upon multiple applications of foliar fungicides. Field experiments were conducted from 1997 to 2000 to compare the efficacy of mixtures of copper hydroxide or copper oxychloride and reduced rates of chlorothalonil with that of full rates of chlorothalonil alone or chlorothalonil + propiconazole. In all tests, rates per ha of 0.70 kg of chlorothalonil + 0.70 kg of copper oxychloride or higher provided leaf spot control that was similar (P > 0.05) to that achieved with standard rates of chlorothalonil (0.84 kg/ha) + propiconazole (0.063 kg/ha). Application of chlorothalonil at 0.56 kg/ha + copper oxychloride at 0.56 kg/ha controlled leaf spot as well as (P > 0.05) chlorothalonil alone at 1.26 kg/ha in five of six tests in which that treatment was evaluated. In three of four tests in 1998 and 1999, application of chlorothalonil at 0.63 kg/ha + copper hydroxide at 0.63 kg/ha controlled leaf spot as well as chlorothalonil alone at 1.26 kg/ha. In both tests in 2000, application of chlorothalonil at 0.84 kg/ha + copper hydroxide at 0.63 kg/ha controlled leaf spot as well as chlorothalonil alone at 1.26 kg/ha. There were no consistent yield differences among the chlorothalonil, chlorothalonil + propiconazole, or chlorothalonil + copper treatments. Accepted for publication 8 November 2001. Published 16 November 2001.

Effect of In-Furrow and Early-Season Banded Applications of Fungicides on Incidence of Early Leaf Spot of Peanut

2015 ◽  
Vol 16 (4) ◽  
pp. 225-229
Author(s):  
Albert K. Culbreath ◽  
Robert C. Kemerait ◽  
Yun-Ching Tsai ◽  
Timothy B. Brenneman ◽  
Katherine L. Stevenson ◽  
...  
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
Cercospora Arachidicola ◽  
Early Season ◽  
Fungicide Application

Field experiments were conducted in Tifton, GA, in 2012-2014 to determine the effect of in-furrow applications of prothioconazole and early-season banded applications of prothioconazole or pyraclostrobin on incidence of early leaf spot (Cercospora arachidicola) of peanut (Arachis hypogaea). In each year, border rows were planted in May as a source of inoculum for plants in the treatment plots. Plots were planted in August or September after epidemics of early leaf spot were severe in the border plots. Fungicide application regimes included two rates (100 and 200 g a.i./ha) of prothioconazole applied in-furrow at planting, and 200 g a.i./ha of prothioconazole or 164 g a.i./ha of pyraclostrobin applied concentrated in a 30-cm band 21 days after planting (DAP). Incidence (percent of leaflets with one or more leaf spot) of early leaf spot was monitored until 54 to 57 days after planting in each year. In all years, disease incidence was below 10% at 28 DAP in plots treated with 200 g a.i./ha of prothioconazole in-furrow compared to over 40% in nontreated plots at the same time. In-furrow applications of 100 g a.i./ha of prothioconazole were less effective, but suppressed leaf spot incidence compared to the control. Banded applications of either fungicide at 21 DAP resulted in a decrease in leaf spot incidence, and prevented increase in leaf spot incidence for 19 days or longer. Accepted for publication 30 November 2015. Published 3 December 2015.

scholarly journals Fertilization, including chemotactic phenomena in the Fucaceae

1948 ◽  
Vol 135 (880) ◽  
pp. 293-301 ◽  
Keyword(s):  
Aqueous Solution ◽  
Related Species ◽  
Plant Hormone ◽  
Marked Effect ◽  
Inert Gas ◽  
Closely Related Species ◽  
Fucus Serratus ◽  
Arylacetic Acids ◽  
Species Being

Chemotaxis between gametes particularly of the Fucaceae is discussed and techniques for its detection described. Cell-free preparations of Fucus serratus and F. vesiculosus eggs have been obtained which exert a chemotactic attraction on the sperms of F. serratus , F. vesiculosus and F. spiralis , the same chemotactic mechanism among these closely related species being indicated. The chemotactic principle is easily expelled from aqueous solution by a stream of inert gas, and may be recovered in a cooled receiver; it seems therefore to be a simple compound. Various arylacetic acids have a marked effect on the Fucus sperms studied but this effect is distinct from true chemotaxis and is not related to the plant hormone or herbicide activities of the responsible acids.

scholarly journals Selection Indices for Simultaneous Selection for Pod Yield and Leafspot Resistance in Peanut (Arachis hypogaea L.)1

1987 ◽  
Vol 14 (1) ◽  
pp. 51-54 ◽  
Author(s):  
R. N. Iroume ◽  
D. A. Knauft
Keyword(s):  
Arachis Hypogaea ◽  
Breeding Value ◽  
Direct Selection ◽  
Index Selection ◽  
Cercospora Arachidicola ◽  
Pod Yield ◽  
Arachis Hypogaea L ◽  
Yield Gain ◽  
Selection For ◽  
Disease Pressure

Abstract The objective of this study was to investigate the possibility of index selection for pod yield and leafspot resistance, causal organisms Cercospora arachidicola Hori and Cercosporidium personatum (Berk. and Curt.) Deighton, in peanut (Arachis hypogaea L.). Eleven crosses were evaluated in the S1 and S2 generations under natural disease pressure for pod yield and disease reaction. Leafspot severity was measured by leaf necrotic area and defoliation. Variances for each trait and covariances between traits were estimated by progeny analysis. Economic weights assigned to the different characters were derived as the ratio of the pod yield for a genotype to the theoretical pod yield gain from leafspot resistance. Indices were constructed and their efficiency both as predictor of the breeding value and relative to individual selection for either trait was evaluated. Index selection for increased pod yield and reduced leafspot susceptibility was between 87% and 100% as efficient as direct selection for either trait. Combining several leafspot severity readings with pod yield did not improve the efficiency of the index. Fourteen to 17% of the breeding value of the population was accounted for by the traits combined in various indices. This indicated that there is potential for improvement of these indices.

Diversity of Seed Storage Proteins of Arachis hypogaea and Related Species

Crop Science ◽  
2012 ◽  
Vol 52 (4) ◽  
pp. 1676-1688 ◽  
Author(s):  
Raphael G. Calbrix ◽  
Vadim Beilinson ◽  
H. Thomas Stalker ◽  
Niels C. Nielsen
Keyword(s):  
Arachis Hypogaea ◽  
Related Species ◽  
Storage Proteins ◽  
Seed Storage ◽  
Seed Storage Proteins

The chemical basis of gregariousness in cirripedes

1962 ◽  
Vol 156 (965) ◽  
pp. 500-520 ◽  
Keyword(s):  
Aqueous Solution ◽  
Related Species ◽  
Marine Organisms ◽  
Similar Response ◽  
Aqueous Extracts ◽  
Neutral Surface ◽  
Surface Rendering ◽  
Chemical Basis ◽  
Chemical Treatments ◽  
Physical And Chemical

Surfaces on which the cypris larvae of barnacles do not settle readily were treated with aqueous extracts of whole barnacles. Cyprids then settled on the treated surfaces as readily as they do on surfaces bearing adult barnacles, thus simulating the gregarious response to their own species. It is inferred that a settling factor, present in barnacle tissues, was transferred to a neutral surface rendering it favourable for settlement. The settling factor was shown to be non-dialyzable and stable to boiling in aqueous solution. When attached to a surface, it resisted severe physical and chemical treatments. The settling factor evoked a greater response from cyprids of the species used in preparing the extract than from cyprids of other species. Extracts made from other cirripedes and from all other arthropods tested, promoted settlement, but were less effective than extracts made from the same species of cirripede. The settling factor was found to be located mainly in the integument of arthropods and was present in greater amount in newly moulted individuals. It is suggested that the settling factor to which the cyprid responds may be the arthropodins of its own species, and that arthropodins of related species evoke a similar response. No evidence was found for chemotaxis, the cyprids responding to the settling factor only after alighting on the treated surface. It is thought likely that cyprids, in common with the larvae of many other sedentary marine organisms, may not be capable of detecting or responding to such chemical releasers in the sea unless they are in contact with the surface on which the chemical is adsorbed or from which it is diffusing.

Effects of Reduced Tillage, Resistant Cultivars, and Reduced Fungicide Inputs on Progress of Early Leaf Spot of Peanut (Arachis hypogaea)

Plant Disease ◽  
2004 ◽  
Vol 88 (8) ◽  
pp. 858-864 ◽  
Author(s):  
W. S. Monfort ◽  
A. K. Culbreath ◽  
K. L. Stevenson ◽  
T. B. Brenneman ◽  
D. W. Gorbet ◽  
...  
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Conventional Tillage ◽  
Reduced Tillage ◽  
Cercospora Arachidicola ◽  
Standard Interval ◽  
Resistant Cultivars ◽  
Tillage Practices ◽  
Moderately Resistant

Field experiments were conducted in 2000 and 2001 on Georgia Green, Florida MDR-98, and C-99R peanut (Arachis hypogaea) cultivars in Tifton, GA, to determine the effects of tillage practices on early leaf spot (Cercospora arachidicola) epidemics under standard fungicide regimes and fungicide regimes with fewer applications. Leaf spot epidemics were suppressed in reduced tillage (strip-till) plots compared with conventional tillage plots and were suppressed in MDR-98 and C-99R cultivars compared with the standard runner-type cultivar, Georgia Green. Within tillage and cultivar combinations, leaf spot intensity typically was lower in plots treated with fungicides at standard intervals (seven total applications) than in those treated at extended intervals (four total applications). However, in most cases, leaf spot control in extended interval treatments in the strip-till system was comparable to that in the standard interval treatments in conventional tillage. Based on these results, the number of fungicide applications could be reduced without compromising control of leaf spot when reduced tillage is used, especially if combined with moderately resistant cultivars. Suppression of leaf spot epidemics in the strip-till plots did not coincide with higher yields in either year. In 2001, yields were lower in strip-till plots than in conventional tillage plots. Yields were typically higher in the cultivar C-99R than in Georgia Green, regardless of the tillage treatment.

Geographical Distribution of Genetic Diversity in Arachis hypogaea

2001 ◽  
Vol 28 (2) ◽  
pp. 80-84 ◽  
Author(s):  
C. C. Holbrook ◽  
T. G. Isleib
Keyword(s):  
Disease Resistance ◽  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Germplasm Collection ◽  
Cercospora Arachidicola ◽  
Root Knot Nematode ◽  
Sources Of Resistance ◽  
Arachis Hypogaea L ◽  
Race 1 ◽  
The U.S

Abstract The U.S. maintains a large (> 8000 accessions) and genetically diverse collection of peanut (Arachis hypogaea L.) germplasm. It is costly to screen all accessions within this collection for traits that could be useful in cultivar development. The objective of this research was to identify countries of origin that are rich sources of resistance to important peanut diseases. This would allow peanut breeders to focus their efforts on smaller subsets of the germplasm collection. Accessions in the peanut core collection were evaluated for resistance to late (Cercosporidium personatum Berk. & M. A. Curtis) and early (Cercospora arachidicola Hori) leaf spot, tomato spotted wilt Tospovirus (TSWV), the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1], and Cylindrocladium black rot (CBR)[Cylindrocladium crotalarie (Loos) Bell & Sobers]. These data then were examined to determine if genes for resistance clustered geographically. Several geographical areas that appear to be rich sources for disease-resistant genes were identified. China had a relatively large number of accessions with resistance to the peanut root-knot nematode. Peru appeared to be a rich source of material with resistance to CBR. Resistance to late leaf spot was more frequent than expected in accessions from Bolivia and Ecuador. Bolivia was also a valuable source of resistance to early leaf spot. Early leaf spot resistance also was more prevalent than expected in accessions from India, Nigeria, and Sudan. India, Israel, and Sudan were valuable origins for material with resistance to TSWV. Accessions with multiple disease resistance were most common in India, Mozambique, and Senegal. This information should enable plant breeders to utilize more efficiently the genes for disease resistance that are available in the U.S. germplasm collection.

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