Stefano Biricolti

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.

In flowering plants, such as Hydrangea macrophylla, the main breeding objective is to increase genetic variability in ornamental traits. This study investigates in vitro techniques, through ovule culture, to overcome the hybridization barriers and increase the efficiency of crossing in Hydrangea macrophylla in which breeding has been hampered by a fairly long breeding cycle and lack of information about its genetic resources. Two different types of media were compared, Gamborg B5 and Murashige and Skoog basal salts, to verify the germination rate of immature ovules in different intraspecific crosses. The germination rate and viability of the seedlings were influenced by the parental genotypes in the different combinations of crossing, highlighting, in some cases, the poor compatibility between some of them. The crossing combination “Parental A × Parental B”, showed the highest germinated ovules percentage (78.3%). The media used seem to less affect the ovule germination while mainly influencing the development and growth of the young seedlings and in particular the number of leaves, the branching attitude, and root length, with the Gamborg medium determining up to a 30% increase, compared to MS medium. In addition, we tested the effectiveness of using SSR markers to assess the parentage of the putative hybrids even though only three out of twelve SSR markers showed allelism. Although the number of SSR markers was low, they were allowed to profile the parentage according to Mendelian laws.