F. A. (PHIL) Aravanopoulos’s research while affiliated with Aristotle University of Thessaloniki and other places

This paper investigates leaf morphology variation of the strawberry tree (Arbutus unedo) within and between two natural contrasting populations of significant latitudinal difference (Kassandreia, Chalkidiki and Ancient Olympia, Peloponnese). This study employed 11 leaf size and shape parameters, recorded by image processing and analyzing software. The results showed that in the measurements of central tendency (parameter means) the northern population of Kassandreia presented the highest values, while in contrast the highest values in the measurements of spread were found in the southern population of Ancient Olympia. Moreover, statistically significant differences between populations were detected in leaf size, but not in leaf shape parameters. Results are discussed in the context of their value in studying quantitative population differentiation and laying the basis of more advanced studies.

Wild cherry (Prunus avium (L.) L.), is a medium sized, fast growing and rather short-lived deciduous tree, with wide natural distribution range, which includes western Eurasia and the northern part of Africa [1]. The species is a pioneer one that grows in a wide range of habitats; however, the species is extremely scattered throughout its distribution as it is highly light demanding and a weak competitor. The species natural populations are characterised by their small size and occur in small groups or are composed of single trees growing at the edges and in the gaps of forest stands. Wild cherry is an important forest tree species from an ecological (it is vital as a food source for many bird and insect species) and economic point of view (wood of wild cherry is as valuable as it is of high-quality and easy to work, therefore is often used for veneer and furniture production, cabinetry, etc.). These guidelines briefly describe the wild cherry, its reproduction, niche requirements and threats. They provide guidance on establishing a genetic monitoring plot and on recording all field level verifiers.

Silver fir (Abies alba Mill.) and King Boris fir (Abies borisii-regis Mattf.) are wind-pollinated, monoecious, generally outcrossing conifer tree species, which belong to the Abies genus. Silver fir is one of the most important forest tree species from an economic and ecological point of view in several European countries. King Boris fir is an important natural hybrid between Abies alba and Abies cephalonica Loudon, growing mainly in Greece. Both species are facing many threats and challenges due to climate change, and therefore they are both considered for forest genetic monitoring. The guidelines briefly describe Silver fir and King Boris fir, their reproduction system, environmental requirements and threats. They provide guidance on how to establish and maintain a forest genetic monitoring plot and on recording all field level verifiers and phenotypic data at the basic, standard, and advanced monitoring levels.

The recent sequencing of many Rosaceae complete genomes, including that of sweet cherry (Prunus avium L.), along with the availability of high-throughput resources offers new challenges and opportunities for cherry breeders in the genomic era towards improvement of climate-smart traits and diseases resistance against the main pathogens, which are consistently plagued the crop. Conventional breeding approaches are laborious, time consuming and inefficient to fulfill increasing demands, especially in terms of climate change. The advances both in marker-assisted and genomics-assisted breeding, high-throughput sequencing technologies, and bioinformatics tools should enable the sweet cherry breeding at a faster pace. These genomics technologies will certainly generate a large amount of data and this new knowledge might be efficiently employed in cherry breeding towards the development of varieties with elevated adaptation to climatic challenges. The rapidly accumulating genomic resources will enable the development of molecular markers associated with many important quantitative trait loci, deciphering the genomic variations in various germplasms towards the development of climate smart sweet cherries. Furthermore, an integrated approach based on a full range of -omics sciences and their outcomes would result in the development of efficient genomics-based trait selection and identification of allelic variations involved in flowering time, dormancy and defense reactions against pathogens. Especially climate change alters dramatically the susceptibility of sweet cherry cultivars to rapidly evolved pathogens, and although the recent advances in genomics resources, there are still only a few reports of genomics applications for diseases resistance evaluation in germplasm collections. In this chapter, we discuss and summarize the advances through genomics-assisted breeding towards improvement of climate-smart traits and diseases resistance in sweet cherry.

Forest trees are long lived sessile organisms that need to withstand a wide range of climatic and biotic stressors posing risk to their survival. Conservation and management of forest genetic resources for sustainable use is essential, but not an easy task and special tools, such as forest genetic monitoring are needed to recognise the state and changes in their composition. Genetic monitoring based on indicators and their verifiers can serve as an early warning system to assess a species response to environmental change at a long-term temporal scale and has been discussed in forestry for more than 20 years. The six-year LIFE implementation project LIFEGENMON, led by the Slovenian Forestry Institute, and supported by six partners from Germany, Greece and Slovenia, is intended to design, test and implement forest genetic monitoring on the transect from Germany to Greece, finding a cost-effective method to monitor forest genetic diversity. The long-term objective is to contribute to conservation of adaptability of forests to environmental changes. In the project thus far, genetic monitoring regions across the transect have been delineated, six monitoring plots for a broadleaf species Fagus sylvatica and coniferous species complex Abies alba/A. Borisii-regis have been established, phenology observations carried out and first sampling and genetic analysis using molecular markers conducted. For each step, costs have been recorded while the information content analysis of indices and verifiers is currently under progress.

In the present paper we studied the genetic diversity and genetic structure of five Norway spruce (Picea abies (L.) Karsten) natural populations situated in Serbia, belonging to the southern lineage of the species at the southern margin of the species distribution range. Four populations occur as disjunct populations on the outskirts of the Dinaric Alps mountain chain, whereas one is located at the edge of Balkan Mountain range and, therefore, can be considered as ecologically marginal due to drier climatic conditions occurring in this region. Due to the negative effect of biotic and abiotic stress factors, the sustainability of these populations is endangered, making conservation of their genetic resources one of the key measures of Norway spruce persistence in Serbia under climatic changes. The insight on genetic diversity and genetic structure of the studied spruce populations can provide the information required for the initiation of programs aimed at the conservation and utilization of spruce genetic resources at the rear edge of species environmental limits. Norway spruce genetic variation and population genetic structure were estimated using eight EST-SSR markers. The results showed that mean expected heterozygosity was 0.616 and allelic richness 10.22. Genetic differentiation among populations was low (Fst=0.007). No recent bottleneck effect or isolation by distance were detected. Bayesian clustering, obtained with STRUCTURE, grouped the populations into two genetic clusters, whereas UPGMA analysis distinguished three main groups approximately in line with the geographic area of occurrence. Based on the study results and the EUFORGEN Pan-European strategy for genetic conservation of forest trees, the establishment of additional dynamic gene conservation units must be considered in Serbia in order to protect the adaptive and neutral genetic diversity of the species.

To further understand the impact of grafting on fruit characteristics and to comprehend the mechanisms involved in graft-induced changes we studied homo- and hetero- grafted Cucurbita pepo cultivars (cv.) that vary in fruit size and shape. C. pepo cv. ‘Munchkin’ and cv. ‘Big Moose’ as well as cv. ‘Round green’ and cv. ‘Princess’ were homo-grafted and reciprocally hetero-grafted. The results show significant changes in fruit size when ‘Big Moose’ was grafted onto ‘Munchkin’ rootstocks in comparison to homo-grafted controls. Statistically significant changes were also observed in fruit shape when cv. ‘Princess’ was grafted on cv. ‘Round green’.This is the first report of such phenotypic changes after intra-species/inter-cultivar grafting in Cucurbitaceae. Additionally, we found significant changes in i) secondary metabolite profile, ii) global DNA methylation pattern and iii) miRNA expression patterns in grafted scions and iv) DNA methylation on graft-induced phenotypic changes in grafted plants. Our results contribute to further understanding graft-induced effects on fruit morphology in intra-species grafting. Furthermore, our results pave the way for understanding the role of phenolic metabolites and epigenetic molecular mechanisms on the phenotypic changes recorded.

The consequences of silviculture and management on the genetic variation and structure of long-impacted populations of forest tree are reviewed assessed and discussed, using Mediterranean forests as a working paradigm. The review focuses on silviculture and management systems, regeneration schemes, the consequences of coppicing and coppice conversion to high forest, the effects of fragmentation and exploitation, and the genetic impact of forestry plantations. It emerges that averaging genetic diversity parameters, such as those typically reported in the assessment of forest population genetics, do not generally present significant differences between populations under certain silvicultural systems/forest management methods and “control” populations. Observed differences are usually rather subtler and regard the structure of the genetic variation and the lasting adaptive potential of natural forest tree populations. Therefore, forest management and silvicultural practices have a longer-term impact on the genetic diversity and structure and resilience of long-impacted populations of forest tree; their assessment should be based on parameters that are sensitive to population perturbations and bottlenecks. The nature and extent of genetic effects and impact of silviculture and forest management practices, call for a concerted effort regarding their thorough study using genetic, genomic, as well as monitoring approaches, in order to provide insight and potential solutions for future silviculture and management regimes.

An increasing demand for cherry production (Prunus avium L.) in Greece led to the development of new high quality sweet cherry cultivars. Self-incompatibility in cherry is one of the most challenging issues for the species' cultivation and top breeding priority. Τhe present study focuses on the development of new hybrids with improved traits such as productivity, fruit size, organoleptic characteristics and self compatibility. For this purpose, thirty different cultivars were crossed and produced hybrids that were evaluated according to 34 morpho-physiological characteristics. The results were analyzed using the XLSTAT (version 2014.1) software and a dendrogram was constructed using the Agglomerative Hierarchical Clustering (AHC) method. Optimal hybrid clustering was achieved when characteristics of great economic importance such as fruit shape and size, growth habit and days to blooming were included in the analysis. Based on the results, new sweet cherry hybrids with the special character of self-compatibility were developed. Our findings provide crucial new information for sweet cherry future breeding programs and cultivation.