Martina Grdiša

Efficiency of morphological trait descriptors in discrimination of Ocimum basilicum L. accessions

Abstract Most commercial basil cultivars belong to the species Ocimum basilicum L. Moreover, within O. basilicum species, there are five main botanical varieties (var. basilicum L., var. difforme Benth., var. minimum L., var. purpurascens Benth. and var. thyrsiflorum /L./ Benth.) that are mainly found on the market. High levels of both morphological and chemical variability exist within the species due to the intraspecific hybridization and long-term uses throughout the world. The aim of this work was to study the resolving power of morphological traits for reliable identification of basil accessions. Phenotypic dissimilarities between pairs of accessions were calculated, and the unweighted pair-group method dendrogram was constructed. Six clearly defined clusters have been detected, giving a good representation of traditional taxonomic relationships. To compare the efficiency of the morphological traits in accession identification, confusion probability and discriminating power of each trait were calculated. Our results show that with a careful analysis and stringent selection of traits, morphological markers provide an inexpensive and reliable method for routine screening of a large number of accessions, in order to monitor and manage germplasm collections.

Genetic Diversity and Structure of Dalmatian Pyrethrum (Tanacetum cinerariifolium Trevir. /Sch./ Bip., Asteraceae) within the Balkan Refugium

Dalmatian pyrethrum (Tanacetum cinerariifolium Trevir. /Sch./ Bip.) is an outcrossing, perennial insecticidal plant, restricted to the eastern Adriatic coast (Mediterranean). Amplified fragment-length polymorphisms (AFLP) were used to investigate the genetic diversity and structure within and among 20 natural plant populations. The highest level of gene diversity, the number of private alleles and the frequency down-weighted marker values (DW) were found in northern Adriatic populations and gradually decreased towards the southern boundary of the species range. Genetic impoverishment of these southern populations is most likely the result of human-related activities. An analysis of molecular variance (AMOVA) indicated that most of the genetic diversity was attributed to differences among individuals within populations (85.78%), which are expected due to the outcrossing nature of the species. A Bayesian analysis of the population structure identified two dominant genetic clusters. A spatial analysis of the genetic diversity indicated that 5.6% of the genetic differentiation resulted from isolation by distance (IBD), while 12.3% of the genetic differentiation among populations followed the pattern of isolation by environmental distance (IBED). Knowledge of the genetic diversity patterns of the natural populations and the mechanism behind these patterns is required for the exploitation and possible conservation management of this endemic and economically important species.

Effects of Ocimum spp. essential oil on Monilinia laxa in vitro

One of the most important postharvest diseases of peach and nectarine is brown rot caused by the fungus Monilinia laxa. Increasing concern related to the toxic effect of the pesticide residues on fruits has enhanced the interest for the control of postharvest pathogenic fungi using biologically active constituents of plants such as essential oils. Species from genus Ocimum are known to possess essential oils with antifungal and fungicidal properties. The present paper reports the results of essential oil composition of four basil taxa and preliminary screening of their antifungal activity against M. laxa. The greatest effectiveness was achieved by the essential oils from Ocimum basilicum var. purpurascens and Ocimum tenuiflorum, whose activity was high throughout the testing period of twenty-three days.

Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae)

Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic diversity and structure also provide the baseline data for conservation of S. officinalis genetic resources valuable for future breeding programmes.

Chemical diversity of the natural populations of Dalmatian pyrethrum (Tanacetum cinerariifolium /Trevir. /Sch. Bip.) in Croatia

Dalmatian pyrethrum (Tanacetum cinerariifolium (Trevir.) Sch.Bip.) is a plant species endemic to the east Adriatic coast. The bioactive substance of Dalmatian pyrethrum is a natural insecticide, pyrethrin, a mixture of six active components (pyrethrins I and II, cinerins I and II, and jasmolins I and II). The insecticidal potential of pyrethrin was recognized decades ago, and dried and ground flowers have traditionally been used in Croatian agriculture and households.

Conservation of Medicinal and Aromatic Plants in Croatia

The use of medicinal and aromatic plants (MAP) in Croatia has a very long tradition. Commercial gathering was economically important source of income in many Croatian regions. However, gathering in the wildness has a negative impact on biodiversity, collected plant material is not uniform and its price is significantly lower. Current production of medicinal and aromatic crops in Croatia is very limited. The MAP cultivation on family farms is usually marginal activity. MAP producers and processors generally agree that marketing opportunities do exist in case of a number of species. Natural MAP populations in Croatia show great biodiversity in morphological, biochemical and genetic level. The assessment of biodiversity is a starting point for efficient conservation of plant genetic resources and its use in plant breeding programmes. The main aim of the management of plant genetic resources is conservation, characterization, evaluation and documentation of the existing genetic biodiversity. For the purpose of conservation of these valuable genetic resources, The Collection of Medicinal and Aromatic Plants has been established at the Faculty of Agriculture, University of Zagreb, Croatia. Characterization and evaluation of accessions in plant genebanks is traditionally based on morphological traits. Currently, the analysis of target species including Dalmatian sage (Salvia officinalis L.), Dalmatian pyrethrum (Tanacetum cinerariifolium/Trevir./Sch. Bip.) and basils (Ocimum spp.) has been carried out on morphological, biochemical and genetic level.

Microsatellite markers in common bean (Phaseolus vulgaris L.)

Common bean is one of the most cultivated and consumed grain legumes worldwide, showing a high level of genetic diversity. Here is presented a detailed review of development and mapping of simple sequence repeats (SSRs, microsatellite markers) in the common bean. In the last 25 years, common bean has been the subject of numerous genetic studies, in which the identification and use of SSRs were conducted, and lead to the development of genetic maps. First genetic maps of common bean have been developed in the 1990s and were based on different molecular markers, and included domestication genes and important agronomic traits. Later, SSRs allowed the genetic mapping of more narrow crosses that are often of interest in plant breeding. Most genetic maps have been correlated with the core map established in the recombinant inbred population BAT93 x Jalo EEP558, and includes different markers, RFLP (restriction fragment length polymorphism), RAPD (random amplified polymorphic DNA), AFLP (amplified fragment length polymorphism), and SSRs in particular. More than 2, 000 SSR markers are available for the common bean and they are an important tool to evaluate the genetic diversity of common bean landraces. SSRs are also useful to evaluate intra-specific diversity within the genus Phaseolus.

Genetic Diversity of Croatian Common Bean Landraces

In Croatia, the majority of the common bean production is based on local landraces, grown by small-scale farmers in low input production systems. Landraces are adapted to the specific growing conditions and agro-environments and show a great morphological diversity. These local landraces are in danger of genetic erosion caused by complex socio-economic changes in rural communities. The low profitability of farms and their small size, the advanced age of farmers and the replacement of traditional landraces with modern bean cultivars and/or other more profitable crops have been identified as the major factors affecting genetic erosion. Three hundred accessions belonging to most widely used landraces were evaluated by phaseolin genotyping and microsatellite marker analysis. A total of 183 different multi-locus genotypes in the panel of 300 accessions were revealed using 26 microsatellite markers. Out of 183 accessions, 27.32% were of Mesoamerican origin, 68.31% of Andean, while 4.37% of accessions represented putative hybrids between gene pools. Accessions of Andean origin were further classified into phaseolin type II (“H” or “C”) and III (“T”), the latter being more frequent. A model-based cluster analysis based on microsatellite markers revealed the presence of three clusters in congruence with the results of phaseolin type analysis.