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Olive leaves are a highly available by-product from table olive and olive oil production. They are nowadays strongly valuable for their major bioactive compounds and their beneficial effects. To determine the differences between two Croatian domestic (Lastovka, Oblica) and two introduced (Leccino, Frantoio) cultivars, physical and chemical analysis of olive leaves were performed: surface area, color variability, total phenolic amounts, and essential oil volatile profiles were analyzed at three harvest periods. All cultivars greatly differed in surface area, with cv. Lastovka being the smallest. Color variability resulted in an overall decrease in darkness and amounts of green and yellow that could be attributed to a decrease in photosynthetic demand and chlorophyll content. The highest amount of total phenolic content occurred in the summer months, followed by a reduction until October. Essential oils volatiles were determined by GC-MS and showed great diversity not only amongst cultivars but also between harvest periods, with overall 45 compounds identified. Principal component analysis distinguished domestic cultivar Oblica from the other observed cultivars, mainly due to its essential oil volatile fingerprint. Compounds that differentiated cv. Oblica were aldehydes ((E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, decanal), ketones ((E)-β-damascone, dihydrodehydro-β-ionone), sesquiterpenes (cyclosativene, α-copaene, α-muurolene) and saturated hydrocarbons (tetradecane, hexadecane). Essential oil volatile fingerprint attributed the highest to the biodiversity of domestic cv. Oblica through all three harvest periods.

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Pyrethrin is a specialized metabolite of Dalmatian pyrethrum (Tanacetum cinerariifolium (Trevir.) Sch. Bip.), Asteraceae, known worldwide as an effective bioinsecticide. It consists of six active compounds: Pyrethrin I and II, cinerin I and II, and jasmolin I and II. Pyrethrin accumulates mainly in the flower heads and its content depends on numerous factors, such as the flower developmental stage. This study aims to investigate the accumulation patterns of six pyrethrin compounds in the flower heads of Dalmatian pyrethrum over the eight developmental stages (FS1 to FS8), and to make a comparison in six natural populations. Ultrasound assisted extraction was used to extract the pyrethrin, while qualitative and quantitative analysis was performed by High performance liquid chromatography. The accumulation patterns of different pyrethrin compounds were generally similar and also synchronous between different populations, while the pyrethrin I/pyrethrin II ratio showed irregular patterns. In all populations studied, the highest increase of all compounds was observed from FS1 to FS2. Their concentration continuously increased, reaching the highest values at FS4 stage (2–5 rows of open disc flowers), and generally decreased gradually towards FS6 or FS7 and then stagnated until the FS8 stage. Despite the very similar accumulation pattern of pyrethrin compounds in the different populations, the significant differences in their content suggest a different genetic background. Knowledge of the dynamics of pyrethrin compounds accumulation across flower development stages is valuable for determining the optimal harvest time of pyrethrum flower heads.

Immortelle (Helichrysum italicum (Roth) G. Don; Asteraceae) is a perennial plant species native to the Mediterranean region, known for many properties with wide application mainly in perfume and cosmetic industry. A total of 18 wild H. italicum populations systematically sampled along the eastern Adriatic environmental gradient were studied using AFLP markers to determine genetic diversity and structure and to identify loci potentially responsible for adaptive divergence. Results showed higher levels of intrapopulation diversity than interpopulation diversity. Genetic differentiation among populations was significant but low, indicating extensive gene flow between populations. Bayesian analysis of population structure revealed the existence of two genetic clusters. Combining the results of FST - outlier analysis (Mcheza and BayeScan) and genome-environment association analysis (Samβada, LFMM) four AFLP loci strongly associated with the bioclimatic variables Bio03 Isothermality, Bio08 Mean temperature of the wettest quarter, Bio15 Precipitation seasonality, and Bio17 Precipitation of driest quarter were found to be the main variables driving potential adaptive genetic variation in H. italicum along the eastern Adriatic environmental gradient. Redundancy analysis revealed that the partitioning of genetic variation was mainly associated with the adaptation to temperature oscillations. The results of the research may contribute to a clearer understanding of the importance of local adaptations for the genetic differentiation of Mediterranean plants and allow the planning of appropriate conservation strategies. However, considering that the identified outlier loci may be linked to genes under selection rather than being the target of natural selection, future studies must aim at their additional analysis.

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