A study was conducted to investigate the effect of different storage periods and temperatures on pollen viability in vitro and in vivo in plum genotypes ‘Valerija’, ‘Čačanska Lepotica’ and ‘Valjevka’. In vitro pollen viability was tested at day 0 (fresh dry pollen) and after 3, 6, 9 and 12 months of storage at four different temperatures (4, −20, −80 and −196 °C), and in vivo after 12 months of storage at distinct temperatures. In vitro germination and fluorescein diacetate (FDA) staining methods were used to test pollen viability, while aniline blue staining was used for observing in vivo pollen tube growth. Fresh pollen germination and viability ranged from 42.35 to 63.79% (‘Valjevka’ and ‘Čačanska Lepotica’, respectively) and 54.58 to 62.15%, (‘Valjevka’ and ‘Valerija’, respectively). With storage at 4 °C, pollen viability and germination decreased over the period, with the lowest value after 12 months of storage. Pollen germination and viability for the other storage temperatures (−20, −80 and −196 °C) were higher than 30% by the end of the 12 months. Pollination using pollen stored at 4 °C showed that pollen tube growth mostly ended in the lower part of the style. With the other storage temperatures, pollen tube growth was similar, ranging between 50 and 100% of the pistils with pollen tubes penetrated into the nucellus of the ovule in the genotype ‘Čačanska Lepotica’. The results of these findings will have implications for plum pollen breeding and conservation.

The efficacy of sweet cherry production is highly dependent on the regularity of flowering events and genetic-determined relations between female sporophyte and male gametophyte, which became even more important with higher flowering temperatures caused by climate change. Special attention is paid to the genetic diversity that provides essential sources of potential temperature-tolerance genes. Our study aimed at the genetic and reproductive characterization of Balkan cherry cultivars of autochthonous origin (‘Canetova’, ‘G-2’, ‘Dolga Šiška’ and ‘Ohridska Crna’), and six potential pollenizers. To identify S-haplotypes, the polymerase chain reaction (PCR) method was used to detect the S-ribonuclease (S-RNase) and S-haplotype-specific F-box protein (SFB) alleles, combined with fragment analysis and S-RNase sequencing. Pollination experiments were performed at three Balkan localities over two flowering seasons, and the fluorescence microscopy method was used to assess the cultivars’ male/female reproductive behaviour. A novel S-RNase allele S₄₀ was identified in ‘Ohridska Crna’ for the first time. ‘Ohridska Crna’ also demonstrated the best adaptability to higher temperatures regarding primary ovule longevity. This feature makes it desirable from the aspect of breeding new cultivars that can withstand the impacts of climate change. The findings on male-female relations and their temperature dependence open up the possibility for yield prediction and smart horticultural decisions that can be made to guide cherry production.

Ethylene is the simplest signalling molecule with a hormone-like function that plays a major role in many developmental processes, including ripening of climacteric apple fruit. The allelic polymorphisms of ACS1 and ACO1 genes, encoding for ACC synthase and ACC oxidase, which catalyse the last two steps in the ethylene biochemical pathway, were analysed in nineteen indigenous apple accessions grown in individual growers' orchards in the regions of central and southwestern Serbia. A polymorphism was detected using the polymerase chain reaction (PCR) for the ACS1 gene and the additional enzymatic digestion of the PCR product with BamH1 and RsaI for the ACO1 gene. The ACS1-1 and ACS1-2 alleles of the ACS1 gene, as well as the a and c alleles of the ACO1 gene were identified. The polymorphisms observed upon PCRs and digestion with restriction enzymes were generated in two genotypes for both genes, i.e. the ACS1 gene - ACS1-1/1 and ACS1-1/2, and the ACO1 gene - aa and ac. Out of nineteen apple accessions, sixteen were homozygous for the allele ACS1-1 and three were heterozygous (ACS1-1/2); regarding the ACO1 genotype, fourteen were homozygous for the allele a and five were heterozygous (ac allelic constitution). The molecular survey in the current study provides an increase in the number of apple accessions with potential to be used as parents in breeding programmes, aiming to obtain high quality cultivars that retain fruit texture during long storage. Therefore, the heterozygous accessions for the ACS1 gene - 'J-LuN/1', 'Kraljica' and 'Šumatovka', may have an important position in future breeding programmes.

DoiFil - Repository of Digital Object Identifiers (DOIs) Issued by Faculty of Philology, University of Belgrade