Lorenzo Bini

Feijoa sellowiana (O. Berg) is a broadly widespread fruit tree species at a very early stage of domestication. Although appreciated for its flavored berries rich in nutrients and nutraceuticals, and as an ornamental plant, feijoa is still considered an underutilized species and little information is available about its genetic background, cultivar traceability and divergence. This study aimed to investigate, for the first time, the genetic diversity of feijoa through the application of AFLPs. Specifically, twenty cultivars from different countries and six wild types (WTs) from their area of origin (Misiones, Argentina) were analyzed. The AFLPs proved to be informative, revealing the values of the percentage of polymorphic loci (PPB), Nei’s genetic diversity (h), and the Shannon index (I) at 69.36%, 0.27, and 0.43, respectively, consistent with the average of long-lived perennial and outcrossing species. However, despite the limited number of WTs examined, the genetic variability (h) was higher (approximately 37%) within the six samples compared to cultivars. The population structure analysis identified three clusters, with WTs forming a separated cluster (III) as expected. Cultivars were divided into two clusters (I and II), with cluster I exhibiting a closer genetic proximity to WTs compared to cluster II. This finding was further confirmed using the UPGMA dendrogram based on Provesti distances. This work raised awareness of the genetic variability among the feijoa’s widespread cultivars and demonstrated that the limited genetic breeding programs over the last decades resulted in low diversity among them. Moreover, these results confirm the hypothesis that all varieties are derived from a single narrow ancestral population. The potential of this species is considerable and needs to be further investigated to exploit its peculiarities.

Araucaria araucana is an important seed and timber-yielding tree that grows naturally in the tropical and subtropical regions of the Andes in Argentina and Chile, and has also been introduced as an ornamental species in Europe. Genetic diversity has been observed in A. araucana native populations, but there have been no prior studies on the genetic diversity estimates of this species introduced in Europe. On the other hand, assessment of the genetic variation in Araucaria populations occurring in Europe might be an important tool in the selection of appropriate germplasms for ornamental nursery production and breeding strategies. In this study, morphological and genetic diversity was analysed using a previously defined descriptor list and SSR molecular markers in four putative populations of A. araucana, individuated in the Pistoia Nursery District (Tuscany, Italy). In total, 26 morphological descriptors and 28 SSR primer pairs were used for a diversity assessment of specimens. Results provide evidence for genetic and morphological correspondence among the four putative Araucaria populations. PCA and cluster analyses based on morphological traits clearly revealed three distinct clusters of specimens. SSR primers yielded 68% polymorphic loci among the considered populations, and 18 of them displayed informativeness for population genetics, according to a Polymorphic Information Content value larger than 0.25. This marker set revealed significant genetic differentiation, and UPGMA analysis enabled separation of these populations on the basis of their genetic distances into three main groups, which largely overlapped with clusters in the dendrogram obtained from the morphological data. In particular, in both cluster diagrams, all accessions belonging to a specific population were well separated from all the others due to matrix distances and differences in the canopy density that are more similar to conifers such as spruce, pine, or fir. ANOVA analysis and the FST value indicated a large between-population genetic variation. The Mantel test suggested that genetic differentiation between the four studied populations was positively correlated with morphological distance (r = 0.141, p < 0.05). Thus, both morphological and genetic markers showed applicability across populations of different seed origins and proved suitable for the identification and characterization of A. araucana accessions.