Hampden J. Zeringue

Effects of C6C10 alkenals and alkanals on eliciting a defence response in the developing cotton boll

Abstract In separate experiments, microbial-free compressed air carried individual C 6 , C 7 , C 8 , C 9 , C 10 -alkenals and alkanals into enclosed systems containing artificially wounded and non-wounded Acala SJ-2 developing cotton boils. Two days after treatment, discs were excised from the treated cotton bolls surfaces and were extracted to determine the induction of the sesquiterpenoid naphthol phytoalexins, 2,7-dihydroxycadelene and 2-hydroxy-7-methoxy cadalene, their oxidation products lacinilene C and lacinilene C 7-methyl ether, and the coumarin phytoalexin scopoletin. Highest concentrations of the described phytoalexins were elicited by C 6 C 10 alkenals in artificially wounded cotton bolls. C 6 C 10 alkenals may function as volatile elicitors of a defence response in the cotton plant.

Relationships between cotton leaf-derived volatiles and growth ofAspergillus flavus

Microbial-free compressed air was passed continuously for 2- and 7-day test periods through enclosed systems containing wounded or nonwounded leaves of glanded or glandless cotton; the resultant emitted volatiles were bubbled through liquid cultures ofA. flavus. After two days incubation, volatiles from wounded glanded and wounded glandless cotton leaves retarded the growth ofA. flavus. After seven days incubation, fungal growth was stimulated in cultures which received volatiles from wounded or nonwounded glanded cotton leaves, but not from either type of glandless cotton leaves. Volatile profiles of the leaves were obtained by GC/MS examinations of the leaves at 2- and 7-day time periods. Purified compounds of selected identified volatiles were assayed withA. flavus to determine which volatiles might be responsible for the bioactivity described.

Inhibition of aflatoxin production in Aspergillus flavus infected cotton bolls after treatment with neem (Azadirachta indica) leaf extracts.

In separate treatments, a spore suspension ofA. flavus (control), an aqueous leaf extract of the subtropical neem tree plus a spore suspension ofA. flavus, or an aqueous neem leaf extract followed by anA. flavus spore suspension were injected 48 hr later onto the surfaces of locks of developing cotton bolls (30-day post anthesis). Thirteen days after the treatments, the seeds from the locules were harvested and both fungal growth and aflatoxin production were determined. Fungal growth was unaffected by the treatments but the seeds from locules receiving both neem leaf extracts andA. flavus simultaneously exhibited 16% inhibition of aflatoxin production, while the seeds in locules receivingA. flavus spores 48 hr after neem extract was added exhibited >98% inhibition in aflatoxin production. Neem leaf extracts contain an aflatoxin inhibiting factor, however, the neem leaf extract may need to translocate from the fibrous locule surface to the seed, prior to the fungal inoculation, for maximal effect.

The accumulation of five fluorescent compounds in the cotton leaf induced by cell-free extracts of Aspergillus flavus

Abstract (−)-Cryptocaryalactone (6-[2-acetoxy-4-phenyl-3-butenyl]-5,6-dihydro-2-pyranone) and (−)-deacetylcryptocaryalactone (6-[2-hydroxy-4-phenyl-3-butenyl]-5,6-dihydro-2-pyranone) isolated from Cryptocarya moschata seeds are natural germination inhibitors. Applied at 0.004 M, the second compound completely arrested germination of velvetleaf ( Abutilon theophrasti ) and decreased the germination rate of soybeans, but did not appear to affect corn. The first compound was not as effective; 0.004 M reduced velvetleaf germination 50%.

Identification of the bright-greenish-yellow-fluorescence (BGY-F) compound on cotton lint associated with aflatoxin contamination in cottonseed

In order to characterize the structure of the bright-greenish-yellow-fluorescence (BGY-F) compound on cotton lint associated with aflatoxin contamination in cotton seed, various in vitro and in vivo natural BGY-F reaction products were prepared. Under similar high pressure liquid chromatography separation with variable wavelength and programmable fluorescence detection (HPLC-UV/FL), combined with atmospheric pressure ionization and mass spectral determinations it was found that the BGY-F reaction products prepared from three preparations: (a) kojic acid (KA) + peroxidase (soybean peroxide or horseradish type VI and type II) + H2O2, or (b) detached fresh cotton locules + KA + H2O2, or (c) attached field cotton locules that were treated with a spore suspension of aflatoxigenic Aspergillus flavus, all resulted in identical chromatographic characteristics, and all exhibited a molecular weight of 282. Further characterization of the BGY-F reaction product with 1H- and 13C-NMR spectroscopic analysis revealed that it was a dehydrogenator dimer of 2 KA, linked through the C-6 positions.

Effects of clarified neem oil on growth and aflatoxin B1 formation in submerged and plate cultures of aflatoxigenicAspergillus spp.

An increase of 11–31% of dry mycelial mass was observed along with a slight decrease (5–10%) in aflatoxin Bi production in 5-day-old aflatoxigenicAspergillus spp. submerged cultures containing either 0.5 ml or 1.0 ml clarified neem oil (CNO) in 0.1 % Triton solution. Fungal growth and aflatoxin B1 production were also determined in potato-dextrose-agar petri plate cultures inoculated with aflatoxigenicAspergillus spp. containing an atmosphere of volatiles emitted from 0.25 ml, 0.5 ml, and 1.0 ml CNO added to the plates. After 5 days’ incubation, fungal radial growth was reduced by 7–29% and aflatoxin B1 production by 0–67%. GC/MS analysis of the head space volatiles of the CNO indicated that the reduction of fungal growth and aflatoxin B1 was probably due to low molecular weight hydrocarbons, aldehydes, alcohols, and sulfur compounds emitted at 30°C in the dry culture. These results suggest that volatiles emitted from CNO at 30° C in plate cultures were more fungistatic and consequently inhibited aflatoxin production more than neem oil added in liquid cultures.

Production of carpel wall phytoalexins in the developing cotton boll

Abstract Developing cotton bolls of Deltapine 61, grown under controlled conditions in environmental chambers, were artificially wounded on the carpel surface and treated with an elicitor, composed of cell-free mycelial extracts of Aspergillus flavus , at weekly intervals for eight weeks postanthesis. Two days after treatment, the bolls were harvested from cotton plants and discs containing the treated surfaces were excised and extracted to determine induction of the sesquiterpenoid naphthol phytoalexins, 2,7-dihydroxycadalene and 2-hydroxy-7-methoxy cadalene, their oxidation products lacinilene C and lacinilene C 7-methyl ether, and the coumarin phytoalexin-scopoletin. Maximum concentrations of the cadalenes and lacinilenes were present in bolls treated at seven weeks postanthesis; scopoletin concentrations were highest in bolls treated three weeks postanthesis. To determine the effects of the induced phytoalexins on the growth of A. flavus , a second set of wounded elicitor-treated discs were collected at weekly intervals for eight weeks postanthesis, inoculated with A. flavus and incubated on liquid plant nutrient. Fungal growth displayed a range from 80% of control for treated discs from bolls harvested one week postanthesis to 10% of control for discs from bolls harvested seven to eight weeks postanthesis. The induced phytoalexins on elicitor-treated carpel walls appear to be responsible for the reduction of fungal growth observed.

Stress effects on cotton leaf phytoalexins elicited by cell-free-mycelia extracts of Aspergillus flavus

Abstract The concentrations of five induced phytoalexins, lacinilene C, lacinilene C 7-methyl ether, scopoletin, 2-hydroxy-7-methoxycadalene, and 2,7-dihydroxycadalene, were determined in cotton leaves treated with cell-free mycelial extracts of Aspergillus flavus under a light regime of 14 hr light/10 hr dark and temperature cycles of25/20°, 30/25°, 35/30° and 40/35°. Maximum concentrations were present in plants maintained at a post-inoculation temperature regime of 30/25°. In a separate experiment, the concentrations of the same elicited phytoalexins were measured in cotton leaves treated with the fungal elicitor and maintained at different levels of plant moisture stress. Leaf moisture stress values less than -11.7 bars resulted in decreased production of the five cotton leaf phytoalexins determined two days after the fungal elicitor was applied.

Surface activity of sucrose palmitates

Abstract and SummaryInterfacial tension data are presented for cotton-seed oil-water and paraffin oil-water systems containing purified sucrose palmitates of different degrees of acylation. Both the monopalmitates and diplamitates effectively reduced interfacial tension. To be effective, the monoesters had to be dissolved in water, the diesters in oil. Although nearly inactive alone, sucrose tripalmitate was active in mixtures with the mono-and dipalmitates. Efficiencies of the sucrose palmitates were also excellent. In general, mixtures of sucrose palmitates were as effective as the most active component. When dissolved in water, the efficiency of sucrose palmitate mixtures was proportional to the monoester content, but when dissolved in oil mono-, di-, and triesters contributed to the efficiency.

Purification of surcrose esters by selective adsorption

Long chain fatty acid esters of sucrose from the solvent-free, soap-catalyzed interesterification of molten sucrose and glycerides were acidulated to destroy the soaps, washed to remove unreacted sucrose, and freed of unreacted glycerides and free fatty acids by a procedure adaptable to large scale use. Separation of the glycerides and free fatty acids from the sucrose esters was accomplished by passing the product through selected adsorbents, up to a 1:2 ratio of product to adsorbent, and eluting with selected solvents. Effectiveness of the separations was monitored by thin layer chromatography. Neutral bleaching clay would be the adsorbent of choice for a large scale purification scheme employing benzene as the eluent for the removal of glycerides and free fatty acids followed with ethanol for removal of the sucrose esters.