An endogenous growth inhibitor, 3-hydroxy-β-ionone. I. Its role in light-induced growth inhibition of hypocotyls of Phaseolus vulgaris

The effects of 3-hydroxy-β-ionone on the growth of hypocotyls of dark-grown dwarl bean ( Phaseolus vulgaris L. cv. Morocco) and tall bean (cv. Kentucky Wonder) were examined. 3-Hydroxy-β-ionone inhibited growth of the hypocotyl of both cultivars at doses higher than 3 ng per plant. Seedlings of the tall cultivar responded to a slightly lesser extent to 3-hydroxy-β-ionone than those of the dwarf cultivar. Changes in the levels of 3-hydroxy-β-ionone in hypocotyls of both cultivars 24 h after the onset of light irradiation, were determined by high-performance liquid chromatography and the results compared with the results of light-induced inhibition of growth. The difference in levels of 3-hydroxy-β-ionone between the two cultivars was considerable, and the changes in its levels in the hypocotyls of each cultivar reflected the light-induced inhibition of growth of the hypocotyls of the respective cultivars. These results suggest that the endogenous growth inhibitor. 3-hydroxy-β-ionone, may play an important role in the inhibition by light of hypocotyl growth of the two cultivars and may serve to distinguish the growth habits of these cultivars.     

An endogenous growth inhibitor, 3-hydroxy-β-ionone. II. Changes in its levels associated with the light-induced growth inhibition of hypocotyls of Phaseolus vulgaris

Dark-grown, 4-day-old seedlings of dwarf bean ( Phuseolus vulgaris L. cv. Morocco) and tall bean (cv. Kentucky Wonder) were transferred to conditions of continuous light at various fluence rates, and the resulting changes in growth rates and concentration of 3-hydroxy-β-ionone, a novel endogenous growth inhibitor, were monitored. The light-induced inhibition of growth and the levels of the inhibitor concentration were dependent on the fluence rate of light applied. The growth rate of hypocotyls of both cultivars decreased rapidly and reached a plateau 18 h after the onset of light. However, the more noticeable changes were the marked inhibition of growth of the hypocotyls of the dwarf cultivar. The concentration of 3-hydroxy-β-ionone in the hypocotyls of both cultivars increased after a 20-min lag and reached plateau values after 12 h. The concentration of the inhibitor in the hypocotyls of the dwarf cultivar increased to about 4 to 8 times the level in the nonirradiated controls, while that in the hypocotyls of the tall cultivar increased only about 2- to 3-fold under the same conditions. The high concentration of 3-hydroxy-β-ionone in the dwarf cultivar under steady-state conditions in continuous light, as compared with that in the tall cultivar, may determine the growth habit of these cultivars.     

Glucose exerts a negative effect over a peroxidase from <Emphasis Type="Italic">Trichosporon asahii</Emphasis>, with carotenoid cleaving activity

Tobacco aroma compounds were generated via lutein cleavage by the combined action of a yeast and a bacterium identified as Trichosporon asahii and Paenibacillus amylolyticus, respectively. In this study, an inverse relationship between glucose concentration and the generation of three compounds, present in the tobacco aroma profile, was observed in mixed cultures. In order to identify the organism sensitive to the sugar effect, both were grown separately. The presence of glucose suppressed β-ionone production by T. asahii grown with lutein. However, the biotransformation of the ionone into its reduced derivatives (7,8-dihydro-β-ionone and 7,8-dihydro-β-ionol) by P. amylolyticus was not affected by the sugar . This pointed to the cleavage of lutein, a step within the process necessary for the synthesis of β-ionone, as the target of the glucose effect. In vitro studies with crude extracts and concentrated cell-free medium derived from T. asahii cultures showed that the carotenoid breakdown activity was located extracellularly and only detected in supernatants from yeast cells grown in the absence of the sugar. Rather than an inhibition or a mechanism affecting the enzyme secretion, the glucose effect on lutein degradation comprised another regulatory level. Further experiments showed that the enzyme responsible for lutein breakdown and susceptible to the sugar effect exhibited a high degree of identity to fungal peroxidases, studied as well, for their involvement in carotenoid cleavage.     

Generation of aroma compounds from Ditaxis heterantha by Saccharomyces cerevisiae

Ditaxis heterantha, a plant of the Euphorbiaceae family, is growing wild in the semiarid regions of Mexico. The seed endosperm contains yellow pigments (carotenoids). By high-pressure liquid chromatography the total pigment (TP) was separated into seven fractions: two of them, heterathin (F4) and ditaxin (F5), characterized as apocarotenoids, represent 80% of TP. Both molecules have double bonds, which seem to be the target for degradation and aroma formation. In this work, TP, F4, and F5 were supplied to nine cultures able to degrade lutein. From these strains, only one (identified as Saccharomyces cerevisiae) was able to produce aromas from either TP or F4. Using TP as substrate, the produced aromas were 4-oxo-isophorone (1), isophorone (2), cinnamic aldehyde (6), 3-hydroxy-β-cyclocitral (7), safranal (8), geranyl (9), 3-oxo-α-ionone (10), 3-oxo-α-ionol (11), 3-oxo-7,8-dihydro-α-ionone (12), and eugenol (13). Of these aromas, only seven were produced from F4: (1), (2), (7), (8), (10), (11), and (12). In both cases, safranal was the main degradation product (30%). The enzymatic activity responsible for this effect was found in the cytosolic fraction and detected only when S. cerevisiae was grown in the presence of TP or F4.     

Ecological significance of male attractant in the defence and mating strategies of the fruit fly, Bactrocera papayae

After being acclimatized to feeding on fruit flies, the Asian house gecko, Hemidactylus frenatus Duméril & Bibron (Gekkonidae:Squamata), consumed fewer methyl eugenol (ME) fed male fruit flies, Bactrocera papayae Drew & Hancock (Tephritidae: Diptera) than when offered ME-deprived males. After one-day exposure to only ME-fed males, the geckos avoided feeding on female flies when in the presence of ME-fed males. When mechanically disturbed, the ME-fed males spontaneously ejaculated a rectal secretion which contains phenyl propanoids that deter the predator.The ME-fed males also competed significantly better than normal (ME-deprived) males for virgin females. Male B. papayae converts ME to three other phenyl propanoids which act in concert as a sex pheromone to attract females during courtship and as an allomone to the gecko.     

Isolation and identification of potent allelopathic substances in rattail fescue

Aqueous methanol extracts of rattail fescue (Vulpia myuros) inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), Digitaria sanguinalis and Lolium multiflorum. Increasing the extract concentration increased the inhibition, suggesting that rattail fescue may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of rattail fescue was purified and two main inhibitory substances were isolated and identified by spectral data as (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol. Both substances inhibited root and shoot growth of cress at concentrations greater than 0.3 μM. The concentrations required for 50% growth inhibition on root and shoot growth of cress, lettuce, alfalfa, timothy, D. sanguinalis and L. multiflorum were 2.7–19.7 μM for (−)-3-hydroxy-β-ionone, and 2.1–34.5 μM for (+)-3-oxo-α-ionol. The concentration of (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol, respectively, in rattail fescue was 7.8 and 3.7 μg g⁻¹ fresh weight. Considering the endogenous level and the inhibitory activity, (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol may work as allelopathic substances in rattail fescue through the growth inhibition of neighboring plant species.     

Bioconversion of lutein to products with aroma

A residual mud sample from the marigold flower dehydration process was screened and 19 putative colonies were isolated for their ability to degrade lutein in a chemically defined medium supplemented with marigold flower flour as a carbon source. Among the colonies isolated, two generated volatile compounds in fermentation and one was chosen for further study for its ability to produce a strong tobacco smell. This colony contained two microorganisms, identified as Geotrichum sp. and Bacillus sp. The aroma production requires the presence of both microorganisms and lutein. Using gas chromatography coupled to mass spectrometry (GC/MS), four compounds were identified: 7,8-dihydro- β-ionol, β-ionone, 7,8-dihydro-β-ionone, and 3-hydroxy-β-ionone, in proportions of 84.2%, 9.4%, 3.5%, and 2.9%, respectively. Received: 30 November 1999 / Received revision: 18 April 2000 / Accepted: 1 May 2000     

DIETARY LUFENURON REDUCES EGG HATCH AND INFLUENCES PROTEIN EXPRESSION IN THE FRUIT FLY Bactrocera latifrons (HENDEL)

Lufenuron (LFN), a chitin synthase inhibitor, impacts the fertility of Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons. We posed the hypothesis that LFN curtails egg hatch in the solanaceous fruit fly, B. latifrons. In this study, newly emerged virgin adults were sexed and fed for 12 days with varying concentrations of LFN‐laced agar diets until sexual maturation. Eggs were collected from 12‐d‐old adults and the egg hatch was assessed. Egg hatch decreased in adults reared on LFN‐treated diets. LFN‐treated media did not influence fertility after one gender was reared on experimental and the other on control media before mating. Exposure to LFN‐treated medium after mating led to reduced egg hatch. We infer that LFN is not a permanent sterilant, and reduced egg hatch depends on continuous exposure to dietary LFN after mating. Proteomic analysis identified two differentially expressed proteins, a pheromone binding protein and a chitin binding protein, between adults maintained on LFN‐treated and control diets. Expression of two genes encoding chitin synthase 2, and chitin binding protein, was altered in adults exposed to dietary LFN. LFN treatments also led to increased expression of two odorant binding proteins one in females and one in males. We surmise these data support our hypothesis and provide insight into LFN actions.     

3-oxo-α-ionol,vomifoliol and roseoside in Vitis vinifera fruit

3-Oxo-β-ionol, vomifoliol and dehydrovomifoliol were identified for the first time in fruit from Vitis vinifera. The last named compound was mainly present free in the juice while the others existed predominantly as conjugates. In the case of vomifoliol, the conjugation was with glucose, i.e. as roseoside. Hydrolytic studies on 3-oxo-α-ionol and vomifoliol gave a range of compounds which have been recognized as fruit and plant products.     

Cuelure but not zingerone make the sex pheromone of male Bactrocera tryoni (Tephritidae: Diptera) more attractive to females

In tephritid fruit flies of the genus Bactrocera Macquart, a group of plant derived compounds (sensu amplo ‘male lures’) enhance the mating success of males that have consumed them. For flies responding to the male lure methyl eugenol, this is due to the accumulation of chemicals derived from the male lure in the male rectal gland (site of pheromone synthesis) and the subsequent release of an attractive pheromone. Cuelure, raspberry ketone and zingerone are a second, related group of male lures to which many Bactrocera species respond. Raspberry ketone and cuelure are both known to accumulate in the rectal gland of males as raspberry ketone, but it is not known if the emitted male pheromone is subsequently altered in complexity or is more attractive to females. Using Bactrocera tryoni as our test insect, and cuelure and zingerone as our test chemicals, we assess: (i) lure accumulation in the rectal gland; (ii) if the lures are released exclusively in association with the male pheromone; and (iii) if the pheromone of lure-fed males is more attractive to females than the pheromone of lure-unfed males. As previously documented, we found cuelure was stored in its hydroxyl form of raspberry ketone, while zingerone was stored largely in an unaltered state. Small but consistent amounts of raspberry ketone and β-(4-hydroxy-3-methoxyphenyl)-propionic acid were also detected in zingerone-fed flies. Males released the ingested lures or their analogues, along with endogenous pheromone chemicals, only during the dusk courtship period. More females responded to squashed rectal glands extracted from flies fed on cuelure than to glands from control flies, while more females responded to the pheromone of calling cuelure-fed males than to control males. The response to zingerone treatments in both cases was not different from the control. The results show that male B. tryoni release ingested lures as part of their pheromone blend and, at least for cuelure, this attracts more females.     

Environmental and seasonal influences on red raspberry flavour volatiles and identification of quantitative trait loci (QTL) and candidate genes

Raspberry volatiles are important for perceptions of sensory quality, mould resistance and some have nutraceutical activities. Twelve raspberry character volatiles were quantified, 11 of them in fruit from two seasons, from plants from the Glen Moy × Latham mapping population growing in both open field and under cover (polytunnels). Effects of season and environment were examined for their impact on the content of α-ionone, α-ionol, β-ionone, β-damascenone, linalool, geraniol, benzyl alcohol, (Z)-3-hexenol, acetoin, acetic and hexanoic acids, whilst raspberry ketone was measured in one season. A significant variation was observed in fruit volatiles in all progeny between seasons and method of cultivation. Quantitative trait loci were determined and mapped to six of the seven linkage groups, as were candidate genes in the volatiles pathways.     

Novel Phytotoxins Produced by the Causal Fungus of the Shoot Blight of Larches

Theaspirane has been found as a naturally occurring substance in raspberry, yellow passion fruit and tea.¹⁾ The synthesis of theaspirane has been reported by some investigators.²⁾ We now report a new synthesis of theaspirane from β-ionone through dihydro-β-ionol.

When two equivalents of aluminium chloride hexahyd-rate (A1C1₃-6H₂0) is present in sodium-ammonia reduction, β-ionone (1) can be efficiently reduced to dihydro-β-iaonol (2). The bromination of 2 using cupric bromide, followed by dehydrobromination in the presence of calcium carbonate, affords a mixture of (E)-theaspirane and (Z)-theaspirane. The process of synthesis is outlined in Scheme 1.     

Identification of the Aggregation Pheromone of the Melon Thrips,Thrips palmi

The objective of this study was to identify the aggregation pheromone of the melon thrips Thrips palmi, a major pest of vegetable and ornamental plants around the world. The species causes damage both through feeding activities and as a vector of tospoviruses, and is a threat to world trade and European horticulture. Improved methods of detecting and controlling this species are needed and the identification of an aggregation pheromone will contribute to this requirement. Bioassays with a Y-tube olfactometer showed that virgin female T. palmi were attracted to the odour of live males, but not to that of live females, and that mixed-age adults of both sexes were attracted to the odour of live males, indicating the presence of a male-produced aggregation pheromone. Examination of the headspace volatiles of adult male T. palmi revealed only one compound that was not found in adult females. It was identified by comparison of its mass spectrum and chromatographic details with those of similar compounds. This compound had a structure like that of the previously identified male-produced aggregation pheromone of the western flower thrips Frankliniella occidentalis. The compound was synthesised and tested in eggplant crops infested with T. palmi in Japan. Significantly greater numbers of both males and females were attracted to traps baited with the putative aggregation pheromone compared to unbaited traps. The aggregation pheromone of T. palmi is thus identified as (R)-lavandulyl 3-methyl-3-butenoate by spectroscopic, chromatographic and behavioural analysis.     

Flower-feeding affects mating performance in male oriental fruit flies Bactrocera dorsalis

1. Males of the oriental fruit fly Bactrocera dorsalis are attracted to and feed on flowers of the golden shower blossom Cassia fistula. Flowers of this plant contain methyl eugenol, the metabolites of which apparently function in the synthesis of male sex pheromone. 2. The goal of the study reported here was to determine whether feeding on C. fistula flowers enhanced male mating success. Mating frequencies of unfed (control) and fed (treated) males were compared in trials conducted 0 (same day), 2, 7, or 21 days after treated males were exposed to the flowers. Trials were performed using flowers from three trees of C. fistula to investigate whether the effects of floral feeding were similar among different plants. 3. For all three trees, treated males accounted for a disproportionately large number of matings in trials performed 0, 2, and 7 days after floral feeding by the treated males. For two of the trees, treated males also had a mating advantage 21 days after flower‐feeding. 4. Additional tests were conducted to compare female attraction to perch sites of control and treated males. When at a lek, males exhibit rigorous wing‐fanning behaviour, presumably to increase dispersal of the sex pheromone. Floral feeding had no significant effect on the level of wing‐fanning. Significantly more female sightings were recorded for perches of treated than control males, however, suggesting that the treated males produced a pheromone more attractive to females than did control males.     

A host shift from wild blue cohosh to cultivated potato by the phytophagous ladybird beetle, Epilachna yasutomii (Coleoptera, Coccinellidae)

Life history traits of the phytophagous ladybird beetle Epilachna yasutomii were compared between a nonpest population feeding on wild blue cohosh and a pest population feeding on cultivated solanaceous crops, mainly potato. Newly emerged adults of the nonpest population entered diapause early in midsummer when blue cohosh withered, while adults of the pest population were found in tomato and eggplant fields until late autumn. The pest population had larger females, a higher population growth rate, a shorter larval developmental period, and reduced longevity of overwintered females, compared with the nonpest population. ANOVA indicated that all these life history traits were influenced by the food plant, and that the number of eggs laid per female and the longevity of overwintered females were also affected by the population type. These findings suggest that the life history pattern of E. yasutomii changed to high fecundity with a short life span from low fecundity with a long life span as a result of the host shift from wild blue cohosh to cultivated solanaceous crops. Received: May 22, 1998 / Accepted: January 13, 1999     

Survival and reproduction when food is scarce: implications for a lekking Hawaiian Drosophila

Abstract.  1. In insects, larval diet can have a major impact on development, survival, and reproductive success. However, resource availability at the adult phase of the life cycle is also likely to have strong effects in species where there is an extended period of sexual maturation following adult eclosion.
2. The effect of diet on the survival and reproductive success of the lekking Hawaiian fruit fly, Drosophila grimshawi , was explored. Two generations of emerging adults were exposed to one of two feeding regimes: 'constant' and 'varied' (corresponding to food 'each day' or 'every other day' respectively). The impact of resource availability on survival and reproductive success in each generation was then investigated.
3. The probability of survival to 5 weeks old was higher for individuals fed a constant diet than individuals fed a varied diet, but was comparable for males and females.
4. There was a significant maternal effect on offspring survival. Offspring whose mothers were reared on a constant feeding regime had higher survival than offspring whose mothers were reared on a varied diet.
5. There was no relationship between feeding regime and the quantity of pheromones deposited by males (a measure of male reproductive investment); however F₂ sons were more likely to deposit pheromones and deposited a larger quantity of pheromone than their F₁ sires. The number and sex ratio of offspring (a measure of female reproductive effort) emerging from the F₁ generation was unrelated to maternal or paternal feeding regime.
6. The implications of variation in the foraging environment for mate choice in D. grimshawi are discussed.     

Comparison of methyl eugenol metabolites, mitochondrial COI, and rDNA sequences of Bactrocera philippinensis (Diptera: Tephritidae) with those of three other major pest species within the dorsalis complex

Males of the oriental fruit fly, Bactrocera dorsalis (Hendel) and some of its sibling species have strong affinity for methyl eugenol (ME). Methyl eugenol ingested by male flies is biotransformed in the crop to two ME metabolites that eventually accumulate in the rectal gland, which is known to serve as a reservoir for B. dorsalis sex pheromones. When fed with ME, males of laboratory and wild B. philippinensis Drew and Hancock selectively accumulated two metabolites, 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol, in the rectal gland, as was seen for B. dorsalis sensu stricto, B. invadens Drew, Tsuruta and White, and B. papayae Drew and Hancock. Phylogenetic analysis of COI and rDNA sequence data of these four taxa also revealed a close relationship among B. philippinensis, B. dorsalis s.s., B. invadens, and B. papayae (all four are members of the dorsalis species complex). This result corroborates pheromone analysis. The usefulness of pheromonal analysis as a chemotaxonomy tool to complement molecular and other analysis in differentiation of closely related sibling species within the Bactrocera dorsalis complex, for which use of morphological characters had been inadequate, is highlighted.     

Phytotoxic substances with allelopathic activity may be central to the strong invasive potential of Brachiaria brizantha

The grass Brachiaria brizantha, native to eastern Africa, becomes naturalized and dominant quickly in the non-native areas. It was hypothesized that phytotoxic chemical interaction between this plant and native plants may play an important role in the invasion of B. brizantha. However, no potent phytotoxic substance has been reported in this species. Therefore, we investigated possible allelopathic activity and searched for phytotoxic substances with allelopathic activity in B. brizantha. An aqueous methanol extract of B. brizantha inhibited the growth of roots and shoots of garden cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum) seedlings. The extract was purified by several chromatographic runs and three allelopathically active substances were isolated and identified by spectral analysis as (6R,9R)-3-oxo-α-ionol, (6R,9S)-3-oxo-α-ionol and 4-ketopinoresinol. (6R,9R)-3-Oxo-α-ionol and (6R,9S)-3-oxo-α-ionol inhibited root and shoot growth of garden cress at concentrations greater than 30 and 10 μM, respectively. The activity of (6R,9S)-3-oxo-α-ionol was 5.3- to 6.2-fold that of (6R,9R)-3-oxo-α-ionol. The stereochemistry of the hydroxyl group at position C-9 may be important for the inhibitory activities of those compounds. 4-Ketopinoresinol inhibited root and shoot growth of garden cress at concentrations greater than 30 μM. The growth inhibitory activity of (6R,9S)-3-oxo-α-ionol was the greatest and followed by 4-ketopinoresinol and (6R,9R)-3-oxo-α-ionol. These results suggest that those phytotoxic substances may contribute to the allelopathic effect caused by B. brizantha and may be involved in the invasion of B. brizantha.     

Influences of food sources on reproduction and aggregation pheromone production of Riptortus pedestris (Hemiptera: Alydidae) in its adult stage

The dietary importance of sweet persimmon fruit (SPF) was determined in adult bean bug, Riptortus pedestris, by investigating the effect of feeding SPF and soybean seeds and peanut on longevity, weight change, fecundity and ability for pheromone production in the bean bug. Adult female R. pedestris fed on SPF had significantly shorter lifespans than those fed on soybean, while in males there was no significant difference. Males and females fed on SPF were significantly lighter than those fed on soybean seeds. Females fed on SPF did not lay eggs at all, but those fed on soybean laid 155.8 eggs, and those fed on soybean seed complemented with peanut seed laid 120.8 eggs in 50 days. The amount of pheromone components (E)‐2‐hexenyl (E)‐2‐hexenoate and (E)‐2‐hexenyl (Z)‐2‐hexenoate produced by male R. pedestris fed on SPF was significantly less than that produced by males fed on soybean. Other pheromone components, tetradecyl isobutyrate and octadecyl isobutyrate, were not produced by adult males fed on SPF. This difference was apparent at one week after emergence and was more at three weeks after emergence. In the present study, we demonstrated that SPF had adverse effect on female survivorship, reproduction of female adults and production of the aggregation pheromone by adult males, compared to soybean food. These results suggested that SPF is unsuitable for adult R. pedestris. Management of nearby vegetation of fruit orchards may play an important role in reducing damage by adult R. pedestris.