Volatile Secondary Compounds Research Articles

Effect of Co-Inoculation of Candida zemplinina, Saccharomyces cerevisiae and Lactobacillus plantarum for the Industrial Production of Negroamaro Wine in Apulia (Southern Italy).

The employment of multi-species starter cultures has growing importance in modern winemaking for improving the complexity and wine attributes. The assessment of compatibility for selected species/strains at the industrial-scale is crucial to assure the quality and the safety associated with fermentations. An aspect particularly relevant when the species belong to non-Saccharomyces, Saccharomyces spp. and malolactic bacteria, three categories with different biological characteristics and oenological significance. To the best of our knowledge, the present report is the first study regarding the utilization of a combined starter culture composed of three strains of non-Saccharomyces, Saccharomyces cerevisiae and Lactobacillus plantarum for production of wine at the industrial scale. More in-depth, this work investigated the oenological potential of the autochthonous characterized strains from the Apulian region (Southern Italy), Candida zemplinina (syn. Starmerella bacillaris) 35NC1, S. cerevisiae (NP103), and L. plantarum (LP44), in co-inoculation following a complete scale-up scheme. Microbial dynamics, fermentative profiles and production of volatile secondary compounds were assessed in lab-scale micro-vinification tests and then the performances of the mixed starter formulation were further evaluated by pilot-scale wine production. The above results were finally validated by performing an industrial-scale vinification on 100HL of Negroamaro cultivar grape must. The multi-starter formulation was able to rule the different stages of the fermentation processes effectively, and the different microbial combinations enhanced the organoleptic wine features to different extents. The findings indicated that the simultaneous inoculation of the three species affect the quality and quantity of several volatile compounds, confirming that the complexity of the wine can reflect the complexity of the starter cultures. Moreover, the results underlined that the same mixed culture could differently influence wine quality when tested at the lab-, pilot- and industrial-scale. Finally, we highlighted the significance of employment non-Saccharomyces and L. plantarum, together with S. cerevisiae, autochthonous strains in the design of custom-made starter culture formulation for typical regional wine production with pronounced unique quality.

Reconciling functions and evolution of isoprene emission in higher plants.

Compilation and analysis of existing inventories reveal that isoprene is emitted by c. 20% of the perennial vegetation of tropical and temperate regions of the world. Isoprene emitters are found across different plant families without any clear phylogenetic thread. However, by critically appraising information in inventories, several ecological patterns of isoprene emission can be highlighted, including absence of emission from C4 and annual plants, and widespread emission from perennial and deciduous plants of temperate environments. Based on this analysis, and on available information on biochemistry, ecology and functional roles of isoprene, it is suggested that isoprene may not have evolved to help plants face heavy or prolonged stresses, but rather assists C3 plants to run efficient photosynthesis and to overcome transient and mild stresses, especially during periods of active plant growth in warm seasons. When the stress status persists, or when evergreen leaves cope with multiple and repeated stresses, isoprene biosynthesis is replaced by the synthesis of less volatile secondary compounds, in part produced by the same biochemical pathway, thus indicating causal determinism in the evolution of isoprene-emitting plants in response to the environment.

Interacting effects of aromatic plants and female age on nest-dwelling ectoparasites and blood-sucking flies in avian nests

Some avian species incorporate aromatic plants to their nests. The "nest protection hypothesis", which posits that volatile secondary compounds contained in these plants may have antiparasite properties, has not received full support. All previous tests of this hypothesis have only considered effects on nest-dwelling ectoparasites, but not on blood-sucking flies. The "drug hypothesis" posits that aromatic plants may stimulate nestling immune system, development, or condition. We tested these hypotheses experimentally in wild blue tits, Cyanistes caeruleus, a species that adds aromatic plants to their nests. We supplemented aromatic plants to half of a sample of nests, while adding grass to the other half of nests. We quantified abundance of two groups of blood-sucking flies (blackflies and biting midges) at two different stages of the reproductive period, and abundance of three nest-dwelling ectoparasites (fleas, mites, and blowflies). Experimental supplementation of aromatic plants reduced abundance of fleas only in nests of yearling females and not in nests of older females. Blackflies and biting midges were both more numerous in nests of yearling females than in nests of older females. Mass of aromatic plants added by females was negatively related with abundance of fleas in control nests but not in experimental nests supplied with aromatic plants. Mass of plants added by females was also positively related with abundance of blackflies during the nestling stage. Finally, aromatic plants did not affect nestling growth or immune responses. We conclude that several factors such as female experience and their ability to add plants to the nest interact to explain effects of aromatic plants on different parasites.

High chemical diversity of a plant species is accompanied by increased chemical defence in invasive populations

Mechanisms contributing to the invasive success of plants are still only partly understood. A main assumption is that an escape from specialized enemies in introduced ranges allows a reduction of chemical defences resulting in an increase in growth and reproduction and thus increased competitive ability of introduced plants. Not only variation in concentration but also variation in composition of chemical compounds between individuals may be a key advantage for plants introduced to novel areas impeding adaptation of different plant antagonists. To investigate quantitative and qualitative variation of putative defence compounds and investment of resources in growth, we conducted a common garden experiment in the native range with seeds of 13 native and 9 introduced populations of Tanacetum vulgare, an aromatic plant forming different chemotypes. After 3.5 months, plants of introduced populations had similar biomass but more stems and higher concentrations of volatile secondary compounds (mainly terpenes) than plants of native populations. Both native and invasive T. vulgare populations exhibited high chemotypic variation with nine chemotypes occurring on both continents, whereas several were found exclusively either in plants originating from the native (n = 10) or invasive (n = 2) range. Due to the known negative effects of many mono- and sesquiterpenes on various organisms, we propose that high concentrations of these secondary compounds accompanied by high chemotypic diversity may facilitate the invasion success of a plant species.

Caching as a Behavioral Mechanism to Reduce Toxin Intake

We hypothesized that caching could be a mechanism to remove volatile secondary compounds from a plant-based diet. This mechanism has been demonstrated in 1 herbivore and has been hypothesized as a widespread mechanism for reduction of intake of toxins. We examined this hypothesis in both the field and the laboratory by documenting the ability of herbivorous rodents to manipulate alpha-pinene, the major terpene in juniper (Juniperus osteosperma). First, we dismantled middens of Neotoma albigula and found that cached plant material was devoid of alpha-pinene, whereas surrounding trees contained alpha-pinene. In laboratory trials, we examined the ability of woodrat species (N. albigula, N. lepida, and N. bryanti) to reduce toxin intake by storing food before consumption. Each species responded differently when offered terpene-treated pellets. N. albigula controlled terpene intake by increasing reliance on the terpene-free cache. N. lepida controlled terpene intake by decreasing total intake but did not change cache consumption. N. bryanti did not regulate terpene intake. All 3 species abandoned more food in the foraging cage when the food contained terpene. In an additional laboratory trial with N. albigula, we determined that increased abandonment was not related to cache size.

Aromatic plants in nests of the blue tit Cyanistes caeruleus protect chicks from bacteria

Several bird species add fresh fragments of plants which are rich in volatile secondary compounds to their nests. It has been suggested, although never tested, that birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites, but have been shown to improve growth and condition of chicks at fledging. To understand the mechanisms underlying such benefits, we experimentally tested the effects of these plants on the bacteria living on blue tits. Aromatic plants significantly affected the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect on the bacteria living on adult blue tits. This study provides the first evidence that fresh plants brought to the nests by adult birds limit bacterial richness and density on their chicks.

PREY PREFERENCE BY DELPHASTUS CATALINAE (COLEOPTERA: COCCINELLIDAE) ON BEMISIA ARGENTIFOLII (HOMOPTERA: ALEYRODIDAE): EFFECTS OF PLANT SPECIES AND PREY STAGES

Abstract Plant species and insect stages were studied for their effects on feeding by predator Delphastus catalinae (Horn) (Coleoptera: Coccinellidae) on the silverleaf whitefly (Bemisia argentifolii Bellows and Perring) (Homoptera: Aleyrodidae). To study the influence of plant species, immature whitefly prey were presented simultaneously to starved predator adults on leaf cuttings of five different plant species: cotton (Gossypium hirsutum L.), tomato (Lycopersicon esculentum Miller), hibiscus (Hibiscus rosa-sinensis L.), cowpea (Vigna unguiculata [L.], Walpers ssp. unguiculata), and collard (Brassica oleracea var. acephala DC). Percentage predation over 24 h was significantly highest on cotton, followed in rank order by collards, cowpea, tomato, and hibiscus. Different predation rates may have been caused by differential response to volatile secondary compounds released by the leaf cuttings. Host stage preference was studied by presenting individual adult predators with equal numbers of prey (200 per re...

Metabolic Studies of Volatile Constituents in Tissue Cultures of Petroselinum crispum (Mill) Nyman

Summary Callus cultures of Petroselinum crispum maintained in different hormonal and nutritional conditions accumulated essentially β-elemene, myristicin and apiole, but their synthetic capacities decreased with repeated subculture. Elevated levels of sucrose and exclusion of 2,4-dichlorophenoxyacetic acid from the culture media encouraged greater synthesis of these principal volatile secondary compounds. The cell suspension cultures of P. crispum cv. «Plain-leaved» and -Paramount- were capable of reducing exogenous monoterpene aldehydes, citral and citronellal into geraniol and nerol, and citronellol respectively. These products were extracted from both cultures over a period of 10 to 12 hours. Higher biotransformation capacities were demonstrated by cultures of «Plain-leaved».