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Nicole Jousen - One of the best experts on this subject based on the ideXlab platform.
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Gossypol toxicity and detoxification in helicoverpa armigera and heliothis virescens
Insect Biochemistry and Molecular Biology, 2016Co-Authors: Corinna Krempl, Hanna M Heidelfischer, Guillermo Hugo Jimenezaleman, Michael Reichelt, Riya Christina Menezes, Wilhelm Boland, Heiko Vogel, David G Heckel, Nicole JousenAbstract:Gossypol is a polyphenolic secondary metabolite produced by cotton plants, which is toxic to many organisms. Gossypol's aldehyde groups are especially reactive, forming Schiff bases with amino acids of proteins and cross-linking them, inhibiting enzyme activities and contributing to toxicity. Very little is known about Gossypol's mode of action and its detoxification in cotton-feeding insects that can tolerate certain concentrations of this compound. Here, we tested the toxicity of Gossypol and a Gossypol derivative lacking free aldehyde groups (SB-Gossypol) toward Helicoverpa armigera and Heliothis virescens, two important pests on cotton plants. Larval feeding studies with these two species on artificial diet supplemented with Gossypol or SB-Gossypol revealed no detectable toxicity of Gossypol, when the aldehyde groups were absent. A cytochrome P450 enzyme, CYP6AE14, is upregulated in H. armigera feeding on Gossypol, and has been claimed to directly detoxify Gossypol. However, using in vitro assays with heterologously expressed CYP6AE14, no metabolites of Gossypol were detected, and further studies suggest that Gossypol is not a direct substrate of CYP6AE14. Furthermore, larvae feeding on many other plant toxins also upregulate CYP6AE14. Our data demonstrate that the aldehyde groups are critical for the toxicity of Gossypol when ingested by H. armigera and H. virescens larvae, and suggest that CYP6AE14 is not directly involved in Gossypol metabolism, but may play a role in the general stress response of H. armigera larvae toward plant toxins.
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potential detoxification of Gossypol by udp glycosyltransferases in the two heliothine moth species helicoverpa armigera and heliothis virescens
Insect Biochemistry and Molecular Biology, 2016Co-Authors: Corinna Krempl, Hanna M Heidelfischer, Michael Reichelt, Heiko Vogel, David G Heckel, Theresa Sporer, Seungjoon Ahn, Nicole JousenAbstract:The cotton bollworm Helicoverpa armigera and the tobacco budworm Heliothis virescens are closely related generalist insect herbivores and serious pest species on a number of economically important crop plants including cotton. Even though cotton is well defended by its major defensive compound Gossypol, a toxic sesquiterpene dimer, larvae of both species are capable of developing on cotton plants. In spite of severe damage larvae cause on cotton plants, little is known about Gossypol detoxification mechanisms in cotton-feeding insects. Here, we detected three monoglycosylated and up to five diglycosylated Gossypol isomers in the feces of H. armigera and H. virescens larvae fed on Gossypol-supplemented diet. Candidate UDP-glycosyltransferase (UGT) genes of H. armigera were selected by microarray studies and in silico analyses and were functionally expressed in insect cells. In enzymatic assays, we show that UGT41B3 and UGT40D1 are capable of glycosylating Gossypol mainly to the diglycosylated Gossypol isomer 5 that is characteristic for H. armigera and is absent in H. virescens feces. In conclusion, our results demonstrate that Gossypol is partially metabolized by UGTs via glycosylation, which might be a crucial step in Gossypol detoxification in generalist herbivores utilizing cotton as host plant.
Robert D Stipanovic - One of the best experts on this subject based on the ideXlab platform.
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total and percent atropisomers of Gossypol and Gossypol 6 methyl ether in seeds from pima cottons and accessions of gossypium barbadense l
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Robert D Stipanovic, Lorraine S Puckhaber, Jinggao Liu, Alois A BellAbstract:Gossypol occurs naturally in the seed, foliage, and roots of the cotton plant ( Gossypium ) as atropisomers due to restricted rotation around the binaphthyl bond. The atropisomers differ in their biological activities. (-)-(R)-Gossypol is more toxic and exhibits significantly greater anticancer activity than the (+)-(S)-atropisomer. Most commercial Upland ( Gossypium hirsutum ) cottonseeds have an (R)- to (S)-Gossypol ratio of approximately 2:3, but some Pima ( Gossypium barbadense ) seeds have an excess of (R)-Gossypol. There is no known source of cottonseed with an (R)- to (S)-Gossypol ratio of greater than approximately 70:30. Cottonseed with a high percentage of (R)-Gossypol would be of value to the pharmaceutical industry. It was theorized that G. barbadense cotton might be a source of this desirable high (R)-Gossypol seed trait. There are 671 different accessions of G. barbadense in the U.S. Cotton Germplasm Collection, few of which had been characterized with respect to their (R)- to (S)-Gossypol ratio. This work completed that analysis and found considerable variation in the atropisomer ratio. Approximately half of the accessions have an excess of (R)-Gossypol, and 52 accessions have essentially a 1:1 ratio. The highest percentage of (R)-Gossypol was found in accessions GB26 (68.2%) and GB283 (67.3%). Surprisingly, five accessions had 5% or less of (R)-Gossypol: GB516 (5.0%), GB761 (4.5%), GB577 (4.3%), GB719 (3.7%), and GB476 (2.3%). These accessions may be useful in a breeding program to reduce (R)-Gossypol in Pima seed, which is a concern to the dairy industry because of the toxicity and male antifertility activity of this atropisomer. Also, GB710 was devoid of Gossypol.
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effect of racemic and and Gossypol on the survival and development of helicoverpa zea larvae
Journal of Chemical Ecology, 2006Co-Authors: Robert D Stipanovic, Michael K Dowd, Lorraine S Puckhaber, Juan D Lopez, Sara E DukeAbstract:Gossypol is a sesquiterpene that occurs naturally in seed and other parts of the cotton plant. Because of restricted rotation around the binaphthyl bond, it occurs naturally as enantiomeric mixtures with (+)-Gossypol to (-)-Gossypol ratios that vary between 97:3 and 31:69. Commercial cotton varieties (Gossypium hirsutum) normally exhibit an approximate 3:2 ratio. (+)-Gossypol is significantly less toxic than (-)-Gossypol to nonruminant animals; thus, cottonseed containing high levels of (+)-Gossypol might be safely fed to nonruminants. Gossypol, however, is an important component in the cotton plant's defense against insect herbivores, but it is not known how cotton plants that exhibit high levels of (+)-Gossypol in the foliage might be affected by insect herbivory. To address this question, 1-d-old Helicoverpa zea larvae were fed diets with 0.16, 0.20, and 0.24% racemic, (+)-, and (-)-Gossypol. Larval pupal weights, days-to-pupation, and survival were adversely affected by all Gossypol diets compared with the control diet. Statistical differences were determined by comparing the compounds among themselves at the three levels and between the three compounds at the same level. When the compounds were compared among themselves, no large differences were observed in pupal weights or in days-to-pupation among any of the diets. Among the three compounds, at the 0.16% level, the diet containing racemic Gossypol was the most effective at reducing survival. At the 0.20 and 0.24% levels of racemic (+)- and (-)-Gossypol, survival was not statistically different. The overall results indicate that (+)-Gossypol is as inhibitory to H. zea larvae as racemic or (-)-Gossypol, and thus, cotton plants containing predominantly the (+)-enantiomer in foliage may maintain significant defense against insect herbivory.
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The peroxidative coupling of hemiGossypol to (+)- and (−)-Gossypol in cottonseed extracts
Phytochemistry, 2006Co-Authors: C.r. Benedict, Jinggao Liu, Robert D StipanovicAbstract:Abstract Peroxidase(s) present in embryo extracts of Gossypium hirsutum cv. Texas Marker 1 catalyzed a bimolecular coupling of [4-3H]-hemiGossypol to [4,4′-3H2]-Gossypol. The reaction was dependent on the addition of H2O2 and was inhibited 71–94% by 1 and 10 mM sodium azide. The phenolic coupling produced 53% (+)-Gossypol and 47% (−)-Gossypol in close agreement to the 49% (+)-Gossypol and 51% (−)-Gossypol found in the intact seed. The nearly racemic mixture of (+)-and (−)-Gossypol produced in these embryo extracts can be accounted for by non-enzymatic random coupling of the free radicals of hemiGossypol produced by the peroxidase. In contrast, peroxidase reaction mixtures containing crude embryo extracts of G. hirsutum var. marie-galante produced 73% (+)-Gossypol and 27% (−)-Gossypol. These data from the marie-galante extracts and the fact that these intact seed contain 95% (+)-Gossypol suggest a regio-stereoselective bimolecular coupling of hemiGossypol to Gossypol. The development of the peroxidative coupling of hemiGossypol to Gossypol in maturing seed of G. hirsutum cv. Texas Marker 1 was correlated to the formation of Gossypol and suggests that peroxidative coupling of hemiGossypol contributes to Gossypol biosynthesis.
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Toxicity of (+)- and (-)-Gossypol to the plant pathogen, Rhizoctonia solani.
Journal of agricultural and food chemistry, 2002Co-Authors: Lorraine S Puckhaber, Michael K Dowd, Robert D Stipanovic, Charles R. HowellAbstract:The dimeric sesquiterpene Gossypol occurs naturally in cottonseed and other parts of the cotton plant. Gossypol exists as enantiomers because of the restricted rotation around the central binaphthyl bond. The (-)-enantiomer is toxic to nonruminant animals while the (+)-enantiomer exhibits little, if any, toxicity to these animals. Developing cotton plants with low levels of the (-)-Gossypol could expand the use of cottonseed as a feed source. Gossypol also may play a role in protecting the plant from pathogens. The relative toxicity of (+)- and (-)-Gossypol to plant pathogens has not been reported. We measured the concentration of (+)- and (-)-Gossypol in roots from cotton seedlings that were treated with the biocontrol agent Trichoderma virens that induces biosynthesis of Gossypol and related terpenoids in cotton roots. (-)-Gossypol was the minor enantiomer in control and treated roots, but levels were slightly higher in roots from T. virens-treated seed. We also determined the toxicity of the Gossypol enantiomers and the racemate to the seedling disease pathogen Rhizoctonia solani. The (+)- and (-)-enantiomers of Gossypol and the racemate are equally effective in inhibiting growth of this pathogen. The lethal doses of the Gossypols required to kill the pathogen appeared to be similar, but their toxicities are significantly less than those of related cotton and kenaf sesquiterpenes. The results indicate that altering the enantiomeric ratio in cotton roots will not adversely affect the resistance of seedlings to the seedling pathogen R. solani.
Michael K Dowd - One of the best experts on this subject based on the ideXlab platform.
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HPLC preparation of the chiral forms of 6-methoxy-Gossypol and 6,6'-dimethoxy-Gossypol.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2008Co-Authors: Michael K Dowd, Scott M. PelitireAbstract:A concentrated mixture of Gossypol, 6-methoxy-Gossypol, and 6,6'-dimethoxy-Gossypol was extracted from the root bark of St. Vincent Sea Island cotton with acetone. This extract was derivatized with R-(-)-2-amino-1-propanol to form diastereomeric Gossypol Schiff's bases. Analytical-scale reverse-phase chromatography of these Schiff's bases produced six peaks, indicating separation of the enantiomeric forms of the three Gossypol compounds. The elution order of the peaks was found to vary with the polarity of the mobile phase. The chromatography was scaled to a preparative level and was used to isolate each compound. After hydrolysis of the separated Schiff's bases, the original compounds were recovered by precipitation from solutions of diethyl ether, acetic acid, and water. Fifty injections yielded approximately 500 mg of each methoxy-Gossypol enantiomer and 300 mg of each dimethoxy-Gossypol enantiomer. Each compound was characterized for carbon and hydrogen content, optical rotation, UV-vis light absorption, and melting point. Standard curves were developed and were used to measure the concentration of each Gossypol form in the root bark and dehulled seed of St. Vincent Sea Island cotton. In seed tissue, 48% of the Gossypol compounds were methylated, and the (-)-optical form was found to be in a slight excess to the (+)-optical form (53-54%) for all three compounds. In root bark, 71% of the Gossypol compounds were methylated, and the (+)-optical form was in excess to the (-)-optical form for all three compounds. However, in this tissue the extent of enantiomeric excess decreased with the degree of methylation, with 77% of the Gossypol existing in the (+)-optical form and 59% of the 6,6'-dimethoxy-Gossypol existing in the (+)-optical form.
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Gossypol inhibits calcineurin phosphatase activity at multiple sites.
European Journal of Pharmacology, 2007Co-Authors: Nicholas J Carruthers, Michael K Dowd, Paul M. StemmerAbstract:Calcineurin, the Ca2+/calmodulin-dependant serine/threonine phosphatase is the target for the immunosuppressant drugs FK506 and cyclosporine-A. These established calcineurin inhibitors each require an immunophilin protein cofactor. Gossypol, a polyphenol produced by the cotton plant, inhibits calcineurin (IC50=15 microM), in a noncompetitive, reversible manner, and is independent of any cofactor. We found that Gossypol acts by at least two mechanisms to inhibit calcineurin phosphatase activity. A calmodulin-independent form of calcineurin was less sensitive to inhibition by Gossypol than native calcineurin (IC50=41 and 18 microM, respectively) indicating that Gossypol may interfere with calmodulin binding. A fluorescence polarization based assay demonstrated that 100 microM Gossypol reduced the affinity of calmodulin for calcineurin (from K(d)=2.4 to 250 nM). Inhibition of calcineurin phosphatase activity by Gossypol could not be overcome by adding excess calmodulin or by testing the inhibition toward a calmodulin-independent calcineurin indicating that Gossypol acts at a site different from the calmodulin-binding site. Gossypol decreased the affinity of calcineurin for immunosuppressant/immunophilin complexes only in the presence of calmodulin, indicating that Gossypol blocks the effects of calmodulin binding to calcineurin. In addition, Gossypol had a stimulatory effect on native calcineurin in the absence of calmodulin, possibly indicating a calmodulin mimetic effect. Gossypol exists in two enantiomeric forms which are reported to have different potency for cell toxicity. (+) and (-) Gossypol had equivalent potency for inhibition of native and calmodulin-independent calcineurin phosphatase activity, and for inhibition of calmodulin binding. The inhibition of calcineurin by Gossypol via multiple binding sites without stereo-specificity indicates that Gossypol is not a specific calcineurin inhibitor.
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effect of racemic and and Gossypol on the survival and development of helicoverpa zea larvae
Journal of Chemical Ecology, 2006Co-Authors: Robert D Stipanovic, Michael K Dowd, Lorraine S Puckhaber, Juan D Lopez, Sara E DukeAbstract:Gossypol is a sesquiterpene that occurs naturally in seed and other parts of the cotton plant. Because of restricted rotation around the binaphthyl bond, it occurs naturally as enantiomeric mixtures with (+)-Gossypol to (-)-Gossypol ratios that vary between 97:3 and 31:69. Commercial cotton varieties (Gossypium hirsutum) normally exhibit an approximate 3:2 ratio. (+)-Gossypol is significantly less toxic than (-)-Gossypol to nonruminant animals; thus, cottonseed containing high levels of (+)-Gossypol might be safely fed to nonruminants. Gossypol, however, is an important component in the cotton plant's defense against insect herbivores, but it is not known how cotton plants that exhibit high levels of (+)-Gossypol in the foliage might be affected by insect herbivory. To address this question, 1-d-old Helicoverpa zea larvae were fed diets with 0.16, 0.20, and 0.24% racemic, (+)-, and (-)-Gossypol. Larval pupal weights, days-to-pupation, and survival were adversely affected by all Gossypol diets compared with the control diet. Statistical differences were determined by comparing the compounds among themselves at the three levels and between the three compounds at the same level. When the compounds were compared among themselves, no large differences were observed in pupal weights or in days-to-pupation among any of the diets. Among the three compounds, at the 0.16% level, the diet containing racemic Gossypol was the most effective at reducing survival. At the 0.20 and 0.24% levels of racemic (+)- and (-)-Gossypol, survival was not statistically different. The overall results indicate that (+)-Gossypol is as inhibitory to H. zea larvae as racemic or (-)-Gossypol, and thus, cotton plants containing predominantly the (+)-enantiomer in foliage may maintain significant defense against insect herbivory.
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Isolation of 6-methoxy Gossypol and 6,6'-dimethoxy Gossypol from Gossypium barbadense Sea Island cotton.
Journal of agricultural and food chemistry, 2006Co-Authors: Michael K Dowd, Scott M. PelitireAbstract:6-methoxy Gossypol and 6,6'-dimethoxy Gossypol were isolated from the seeds and root bark of a St. Vincent Sea Island variety of cotton (AZK-267, GRIN# PI 528406). Crude mixtures of Gossypol and the methoxy compounds were obtained by extraction of the tissue with acetone and precipitation with acetic acid. After recrystallization, the preparations were treated with 3-amino-1-propanol to form Gossypol Schiff's bases, which were separated by preparative reverse phase chromatography. The separated Schiff's bases were then hydrolyzed with acid, extracted into diethyl ether, concentrated, and precipitated with acetic acid. From the above procedure, both methoxy Gossypol compounds were obtained as 1:1 molar acetic acid solvates. Each compound was prepared in sufficient amounts to determine its physical properties and begin testing for bioactivity. Light absorbance differed significantly for the di-3-amino-1-propanol derivatives of Gossypol and the methoxy Gossypol compounds at 254 nm. Relative response factors were developed, which can be used for determining or correcting analytical measurements of these methylated Gossypol forms.
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Toxicity of (+)- and (-)-Gossypol to the plant pathogen, Rhizoctonia solani.
Journal of agricultural and food chemistry, 2002Co-Authors: Lorraine S Puckhaber, Michael K Dowd, Robert D Stipanovic, Charles R. HowellAbstract:The dimeric sesquiterpene Gossypol occurs naturally in cottonseed and other parts of the cotton plant. Gossypol exists as enantiomers because of the restricted rotation around the central binaphthyl bond. The (-)-enantiomer is toxic to nonruminant animals while the (+)-enantiomer exhibits little, if any, toxicity to these animals. Developing cotton plants with low levels of the (-)-Gossypol could expand the use of cottonseed as a feed source. Gossypol also may play a role in protecting the plant from pathogens. The relative toxicity of (+)- and (-)-Gossypol to plant pathogens has not been reported. We measured the concentration of (+)- and (-)-Gossypol in roots from cotton seedlings that were treated with the biocontrol agent Trichoderma virens that induces biosynthesis of Gossypol and related terpenoids in cotton roots. (-)-Gossypol was the minor enantiomer in control and treated roots, but levels were slightly higher in roots from T. virens-treated seed. We also determined the toxicity of the Gossypol enantiomers and the racemate to the seedling disease pathogen Rhizoctonia solani. The (+)- and (-)-enantiomers of Gossypol and the racemate are equally effective in inhibiting growth of this pathogen. The lethal doses of the Gossypols required to kill the pathogen appeared to be similar, but their toxicities are significantly less than those of related cotton and kenaf sesquiterpenes. The results indicate that altering the enantiomeric ratio in cotton roots will not adversely affect the resistance of seedlings to the seedling pathogen R. solani.
Prakash N. Srivastava - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of rabbit sperm acrosomal enzymes by Gossypol
Molecular reproduction and development, 1995Co-Authors: Y. Y. Yuan, Q. X. Shi, Prakash N. SrivastavaAbstract:The effect of Gossypol on the activities of 10 acrosomal enzymes of the rabbit sperm was evaluated. Acrosin, Azocoll proteinase, neuraminidase, and arylsulfatase were significantly inhibited or completely inactivated by 12–76 μM Gossypol. Hyaluronidase, β-glucuronidase, and acid phosphatase were inhibited only at a higher concentration of Gossypol (380 μM). Phospholipase C, alkaline phosphatase, and β-N-Acetyl glucosaminidase were not inhibited even at 380 μM Gossypol. Gossypol was found to be a noncompetitive inhibitor of arylsulfatase with a Ki of 120 μM. The inhibition was reversible and dose-dependent. As the acrosomal enzymes were more sensitive to the inhibition by Gossypol compared to sperm enzymes involved in glycolysis or energy production, these assays may serve as a more reliable indicator for monitoring the occurence of Gossypol-induced sterility. © 1995 Wiley-Liss, Inc.
Lorraine S Puckhaber - One of the best experts on this subject based on the ideXlab platform.
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total and percent atropisomers of Gossypol and Gossypol 6 methyl ether in seeds from pima cottons and accessions of gossypium barbadense l
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Robert D Stipanovic, Lorraine S Puckhaber, Jinggao Liu, Alois A BellAbstract:Gossypol occurs naturally in the seed, foliage, and roots of the cotton plant ( Gossypium ) as atropisomers due to restricted rotation around the binaphthyl bond. The atropisomers differ in their biological activities. (-)-(R)-Gossypol is more toxic and exhibits significantly greater anticancer activity than the (+)-(S)-atropisomer. Most commercial Upland ( Gossypium hirsutum ) cottonseeds have an (R)- to (S)-Gossypol ratio of approximately 2:3, but some Pima ( Gossypium barbadense ) seeds have an excess of (R)-Gossypol. There is no known source of cottonseed with an (R)- to (S)-Gossypol ratio of greater than approximately 70:30. Cottonseed with a high percentage of (R)-Gossypol would be of value to the pharmaceutical industry. It was theorized that G. barbadense cotton might be a source of this desirable high (R)-Gossypol seed trait. There are 671 different accessions of G. barbadense in the U.S. Cotton Germplasm Collection, few of which had been characterized with respect to their (R)- to (S)-Gossypol ratio. This work completed that analysis and found considerable variation in the atropisomer ratio. Approximately half of the accessions have an excess of (R)-Gossypol, and 52 accessions have essentially a 1:1 ratio. The highest percentage of (R)-Gossypol was found in accessions GB26 (68.2%) and GB283 (67.3%). Surprisingly, five accessions had 5% or less of (R)-Gossypol: GB516 (5.0%), GB761 (4.5%), GB577 (4.3%), GB719 (3.7%), and GB476 (2.3%). These accessions may be useful in a breeding program to reduce (R)-Gossypol in Pima seed, which is a concern to the dairy industry because of the toxicity and male antifertility activity of this atropisomer. Also, GB710 was devoid of Gossypol.
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effect of racemic and and Gossypol on the survival and development of helicoverpa zea larvae
Journal of Chemical Ecology, 2006Co-Authors: Robert D Stipanovic, Michael K Dowd, Lorraine S Puckhaber, Juan D Lopez, Sara E DukeAbstract:Gossypol is a sesquiterpene that occurs naturally in seed and other parts of the cotton plant. Because of restricted rotation around the binaphthyl bond, it occurs naturally as enantiomeric mixtures with (+)-Gossypol to (-)-Gossypol ratios that vary between 97:3 and 31:69. Commercial cotton varieties (Gossypium hirsutum) normally exhibit an approximate 3:2 ratio. (+)-Gossypol is significantly less toxic than (-)-Gossypol to nonruminant animals; thus, cottonseed containing high levels of (+)-Gossypol might be safely fed to nonruminants. Gossypol, however, is an important component in the cotton plant's defense against insect herbivores, but it is not known how cotton plants that exhibit high levels of (+)-Gossypol in the foliage might be affected by insect herbivory. To address this question, 1-d-old Helicoverpa zea larvae were fed diets with 0.16, 0.20, and 0.24% racemic, (+)-, and (-)-Gossypol. Larval pupal weights, days-to-pupation, and survival were adversely affected by all Gossypol diets compared with the control diet. Statistical differences were determined by comparing the compounds among themselves at the three levels and between the three compounds at the same level. When the compounds were compared among themselves, no large differences were observed in pupal weights or in days-to-pupation among any of the diets. Among the three compounds, at the 0.16% level, the diet containing racemic Gossypol was the most effective at reducing survival. At the 0.20 and 0.24% levels of racemic (+)- and (-)-Gossypol, survival was not statistically different. The overall results indicate that (+)-Gossypol is as inhibitory to H. zea larvae as racemic or (-)-Gossypol, and thus, cotton plants containing predominantly the (+)-enantiomer in foliage may maintain significant defense against insect herbivory.
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Toxicity of (+)- and (-)-Gossypol to the plant pathogen, Rhizoctonia solani.
Journal of agricultural and food chemistry, 2002Co-Authors: Lorraine S Puckhaber, Michael K Dowd, Robert D Stipanovic, Charles R. HowellAbstract:The dimeric sesquiterpene Gossypol occurs naturally in cottonseed and other parts of the cotton plant. Gossypol exists as enantiomers because of the restricted rotation around the central binaphthyl bond. The (-)-enantiomer is toxic to nonruminant animals while the (+)-enantiomer exhibits little, if any, toxicity to these animals. Developing cotton plants with low levels of the (-)-Gossypol could expand the use of cottonseed as a feed source. Gossypol also may play a role in protecting the plant from pathogens. The relative toxicity of (+)- and (-)-Gossypol to plant pathogens has not been reported. We measured the concentration of (+)- and (-)-Gossypol in roots from cotton seedlings that were treated with the biocontrol agent Trichoderma virens that induces biosynthesis of Gossypol and related terpenoids in cotton roots. (-)-Gossypol was the minor enantiomer in control and treated roots, but levels were slightly higher in roots from T. virens-treated seed. We also determined the toxicity of the Gossypol enantiomers and the racemate to the seedling disease pathogen Rhizoctonia solani. The (+)- and (-)-enantiomers of Gossypol and the racemate are equally effective in inhibiting growth of this pathogen. The lethal doses of the Gossypols required to kill the pathogen appeared to be similar, but their toxicities are significantly less than those of related cotton and kenaf sesquiterpenes. The results indicate that altering the enantiomeric ratio in cotton roots will not adversely affect the resistance of seedlings to the seedling pathogen R. solani.
