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Mentha longifolia L. is an aromatic medicinal plant species in the Lamiaceae family. This study aimed to assess the diversity of 20 M. longifolia accessions collected from the Zagros Mountain range in Iran and Iraq using morphological and biochemical traits, as well as start codon targeted (SCoT) molecular markers. The evaluation of 24 quantitative and qualitative phenotypic traits revealed considerable variation, particularly for leaf size, stem features and inflorescence morphology. Substantial variation was also found for essential oil content (1.54–5.49%), total phenol content (TPC) (128.59–333.28 mg GAE/g DW), and antioxidant activity (IC50 0.44–0.58 μg/mL). Pearson correlation analysis revealed associations between essential oil percentage and leaf width, leaf number, stem length, and flower number. Principal component analysis (PCA) identified key components of variation including essential oil content, leaf morphology, TPC, and floral traits. SCoT marker analysis generated 86 fragments, with 71.52% polymorphism and an average polymorphism information content (PIC) of 0.34. The lack of geographical clustering among the M. longifolia accessions may be attributed, to some extent, to gene flow or genetic material exchange among populations. The principal coordinate analysis (PCoA) biplot based on the first two PCs further confirmed higher genetic variability among Iranian accessions than the Iraqi counterparts. Notably, the Boukan accession represented a higher genetic distance from other accessions, suggesting that it is genetically unique. The present research revealed significant phenotypic, biochemical, and molecular diversity among M. longifolia accessions from Iran and Iraq. The observed diversity provides opportunities for selecting favorable genotypes. The selected individuals can be used as parents in breeding programs, where controlled crosses and selection combine advantageous alleles to develop new cultivars with improved traits. Accordingly, accessions like Khabat and Harir with high essential oil content and antioxidant potential can contribute novel alleles in breeding programs. [ABSTRACT FROM AUTHOR]

Weed control tries to suppress competitors for a crop and often relies on differential intoxication, making use of differences in uptake, development, or metabolism. We explored the possibility of using natural signals to shift competition in favour of the crop. Using the competitive horsemint (Mentha longifolia) as a paradigm, we showed that essential oils from certain mint species suppress the seedling development of different target species in a specific and efficient manner. The specificity concerned both the donor and the receptor. We demonstrated further that the effect of horsemint oil was specific for actin filaments, and not for microtubules. Since the elimination of actin will impair auxin transport, which is essential for root regeneration in vegetatively propagating weeds, we tested the efficacy of horsemint essential oil in combination with a slow-release carrier against field bindweed (Convolvulus arvensis), a pertinent weed in organic cereal production. We observed that the development of this weed can be specifically blocked, especially if the carrier is worked into the soil. We propose that allelopathic interactions, often relying on manipulative chemical signalling, harbour significant potential for organic weed control. [ABSTRACT FROM AUTHOR]

Horsemint essential oil has many biological properties, such as antimicrobial, insecticidal, antifungal and antibacterial, which makes it used for medicinal, pharmaceutical and food purposes. Amino acid L-tyrosine has an active role in the physiology and production of essential oils. Therefore, the aim of this investigation was to evaluate the composition of horsemint essential oil in response to L-tyrosine applications. Horsemint plants treated with different doses of L-tyrosine (0, 150, 300, 450 and 600 mg/L) as a foliar spray. The essential oil was isolated from the aerial parts by hydrodistillation and analyzed by GC and GC/MS. Plants treated with L-tyrosine at 450 mg/L resulted in the maximum amounts of dry aerial parts (65.8 g/plant), essential oil percentage (4.1%) and essential oil yield (1.7 g/plant) at first harvest. Carvone was the major component, while oxygenated monoterpenes were the major chemical class. The highest value of carvone (68.6%) was obtained with essential oil isolated from plants exposed to L-tyrosine at 150 mg/L during first harvest. Essential oil extracted from pants treated with 600 mg/L L-tyrosine gave the maximum amount of oxygenated monoterpenes (83.2%) at first harvest. This study ascertained that the subordination of horsemint plants to L-tyrosine doses led to variations in the content of its essential oil production and components, and this, in turn, affected its biological activity. [ABSTRACT FROM AUTHOR]

Weed control tries to suppress competitors for a crop and often relies on differential intoxication, making use of differences in uptake, development, or metabolism. We explored the possibility of using natural signals to shift competition in favour of the crop. Using the competitive horsemint (Mentha longifolia) as a paradigm, we showed that essential oils from certain mint species suppress the seedling development of different target species in a specific and efficient manner. The specificity concerned both the donor and the receptor. We demonstrated further that the effect of horsemint oil was specific for actin filaments, and not for microtubules. Since the elimination of actin will impair auxin transport, which is essential for root regeneration in vegetatively propagating weeds, we tested the efficacy of horsemint essential oil in combination with a slow-release carrier against field bindweed (Convolvulus arvensis), a pertinent weed in organic cereal production. We observed that the development of this weed can be specifically blocked, especially if the carrier is worked into the soil. We propose that allelopathic interactions, often relying on manipulative chemical signalling, harbour significant potential for organic weed control.

Mentha longifolia (L.) L. is the most widespread wild-growing mint species found, and its chemical composition is extremely diverse. We studied the essential oil (EO) yield, composition, and chemotaxonomy of five, northern Hungarian accessions of the species in a cultivation experiment covering two vegetation years at two parallel sites. The long-term goal is to establish the cultivation of this stress-tolerant species in Hungary as a source of flavoring and preservative agents for commercial use. Essential oil yield (1–2 mL/100 g) was observed to be dependent on both the accession and the year. Accession HV1 is assumed to be a new, presumably rare chemotype containing carvacrol (19.28–20.56%), 1,8-cineole (14.87–17.45%), thymol (13.36–13.90%), carvacryl acetate (8.81–10.40%), and para-cymene (7.24–8.01%). Only minor fluctuations occurred in concentrations of these constituents due to habitats and years. A radical change in essential oil composition was observed in accession HV2, as one batch was based on thymol (19.79%) and 1,8-cineole (14.93%), while the others were rich in dihydrocarvone isomers (up to 69%). Although this needs further investigation, it does explain the coexistence of limonene-oxo and γ-terpinene pathways in horsemint. According to the literature, the pathway leading to thymol isomers and/or esters may be rare in the entire Mentha genus. We also demonstrated that known chemotypes of horsemint may differ in variability of their EO composition. Our results also led to the conclusion that any declaration on chemotype needs detailed examination and is not realistic on the basis of a single sample. Assumptions were made about the potential areas of utilization: beside fragrance and flavoring uses of essential oils free from pulegone and menthofurane, thymol-based ones may be used as antioxidative and anti-spoilage agents.

Effect of sodium alginate coating enriched with horsemint essential oil ( HEO) on the quality of bighead carp ( Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate ( SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen ( TVB-N), peroxide value ( PV), thiobarbituric acid ( TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly ( P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA. [ABSTRACT FROM AUTHOR]

Abstract: The need for biodiesel feedstocks growing on non-arable lands is widely recognized. We present results of the synthesis and characterization of new biodiesels we produced from oils of highbush cranberry, dotted horsemint, and American hazelnut growing in Northern Wisconsin. These biodiesels, particularly those derived from highbush cranberry, exhibited remarkably good low-temperature properties, a condition that is crucial for wider usage of any biodiesel in cold climates. We also present the results on determination of the oxidative stability of the above biodiesels and discuss the growing conditions and habitats of the related plants. [Copyright &y& Elsevier]

Several phytophagous insects exhibit distinct preference for their host plants. In widely distributed generalist insects, host preference can be influenced by geographic variation in host plant distribution and abundance as well as by prior experience. We have studied host preference of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), a pest of cotton in Texas and other neighboring states, by measuring olfactory orientation to horsemint (Monarda punctata L.) and cotton (Gossypium hirsutum L.). Horsemint is one of the primary, native, wild hosts of cotton fleahopper during late-spring and early summer in Texas, and it is commonly believed to be the main source of this pest in cotton. Although the abundance of horsemint, and therefore the fleahopper exposure to it, varies geographically, cotton fleahopper's preference for this native host-plant is maintained across two ecoregions in Texas, TX High Plains (Lubbock area) and Brazos Valley (College Station area). Similarly, preference for horsemint was retained regardless of prior experience with cotton throughout all the life stages of the insect. This fixed preference of cotton fleahopper to horsemint could be because of their ancestral insect-plant interaction, better fitness of cotton fleahopper on horsemint, and relatively low abundance of horsemint compared with cotton. Information gained from this study could be used to implement cultural control practices such as trap cropping, to develop attractants to monitor this pest, or both. [ABSTRACT FROM AUTHOR]

The role of four spring weeds as hosts for the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), and the spring emergence periods of fleahopper nymphs from cotton, Gossypium hirsutum (L.), stalks and silverleaf nightshade, Solanum elaeagnifolium (Cav.), stems were studied for five years. Vacuum samples from horsemint, Monarda punctata (L.), contained the largest number of fleahoppers in all but one year of the study. Sampling two species of primrose, Oenothera laciniata Hill and O. grandis (Britt.) Smyth, yielded more fleahoppers than two species of gaura, Gaura sinuata (Ser.) and Gaura villosa, (Torr.). Redstem stork's-bill, Erodium cicutarium (L.) L'Hér., samples contained the least number of fleahoppers. The interval between the last fleahoppers found in spring weed hosts and the first fleahoppers found in cotton was short enough to allow infestation of a new cotton crop in three of five years studied. Eggs survived the winter and nymphs emerged from cotton stalks and nightshade stems beginning in March and continued to emerge until the first week of July. [ABSTRACT FROM AUTHOR]

Mentha longifolia (L.) L. is the most widespread wild-growing mint species found, and its chemical composition is extremely diverse. We studied the essential oil (EO) yield, composition, and chemotaxonomy of five, northern Hungarian accessions of the species in a cultivation experiment covering two vegetation years at two parallel sites. The long-term goal is to establish the cultivation of this stress-tolerant species in Hungary as a source of flavoring and preservative agents for commercial use. Essential oil yield (1–2 mL/100 g) was observed to be dependent on both the accession and the year. Accession HV1 is assumed to be a new, presumably rare chemotype containing carvacrol (19.28–20.56%), 1,8-cineole (14.87–17.45%), thymol (13.36–13.90%), carvacryl acetate (8.81–10.40%), and para-cymene (7.24–8.01%). Only minor fluctuations occurred in concentrations of these constituents due to habitats and years. A radical change in essential oil composition was observed in accession HV2, as one batch was based on thymol (19.79%) and 1,8-cineole (14.93%), while the others were rich in dihydrocarvone isomers (up to 69%). Although this needs further investigation, it does explain the coexistence of limonene-oxo and γ-terpinene pathways in horsemint. According to the literature, the pathway leading to thymol isomers and/or esters may be rare in the entire Mentha genus. We also demonstrated that known chemotypes of horsemint may differ in variability of their EO composition. Our results also led to the conclusion that any declaration on chemotype needs detailed examination and is not realistic on the basis of a single sample. Assumptions were made about the potential areas of utilization: beside fragrance and flavoring uses of essential oils free from pulegone and menthofurane, thymol-based ones may be used as antioxidative and anti-spoilage agents. [ABSTRACT FROM AUTHOR]