COMPONENT COMPOSITION OF FLAVONOID PIGMENTS AND FLOWER COLOR IN PRUNUS MIRA AND HYBRID CULTIVARS OF ORNAMENTAL PEACH

Background. Ornamental peaches are flowering trees with petals ranging in color from white and pale pink to purplered. Because peach suffers from fungal infections, Prunus mira Koehne is often used in breeding programs as a donor of resistance. It also impacts on other traits, including flower color. The aim of this work was to study the composition of flavonoid pigments in the flowers of parent plants and new ornamental peach cultivars originated from P. mira.Objects and methods. Four new cultivars developed at the Nikita Botanical Gardens and their parental forms – P. mira and 4 cultivars with the P. persica morphotype – were included in the study. Pigments were extracted with acidified ethyl alcohol from fresh petals and identified by HPLC analysis.Results. Twelve glycosides of cyanidin and peonidin in different combinations and 8 glycosides of kaempferol and quercetin were found in the petal samples. Among colored plants, the highest amount of flavonols (114 mg g-1) and the lowest amount of anthocyanins (0.46 mg g-1) were found in P. mira petals. Anthocyanins predominate in cultivars with purple-red petals (16 mg g-1). Much more flavonols (55– 88 mg g-1) and little anthocyanins (1.2–3.4 mg g-1) were accumulated in the purple-pink flowers of hybrid cultivars. This trend persisted in the cultivars from crosses with a white-flowered parent. Conclusion. The ratio of anthocyanins and flavonols in the peach flowers depends on the plant species and determines the petals’ intermediate colors and half-tones. Using P. mira in breeding programs provides opportunities for the development of cultivars with new shades of flower color.

Transcriptomic and metabolomic profiling provide novel insights into fruit development and flesh coloration in Prunus mira Koehne, a special wild peach species

Background Flesh color is one of the most important traits for the commercial value of peach fruit. To unravel the underlying regulatory network in Prunus mira, we performed an integrated analysis of the transcriptome and metabolome of 3 fruit types with various flesh pigmentations (milk-white, yellow and blood) at 3 developmental stages (pit-hardening, cell enlargement and fruit ripening). Results Transcriptome analysis showed that an intense transcriptional adjustment is required for the transition from the pit-hardening to the cell enlargement stage. In contrast, few genes were differentially expressed (DEGs) from the cell enlargement to the fruit ripening stage and importantly, the 3 fruits displayed diverse transcriptional activities, indicating that difference in fruit flesh pigmentations mainly occurred during the ripening stage. We further investigated the DEGs between pairs of fruit types during the ripening stage and identified 563 DEGs representing the ‘core transcriptome’ associated with major differentiations between the 3 fruit types, including flesh pigmentation. Meanwhile, we analyzed the metabolome, particularly, at the ripening stage and uncovered 40 differential metabolites (‘core metabolome’) between the 3 fruit types including 5 anthocyanins, which may be the key molecules associated with flesh coloration. Finally, we constructed the regulatory network depicting the interactions between anthocyanins and important transcripts involved in fruit flesh coloration. Conclusions The major metabolites and transcripts involved in fruit flesh coloration in P. mira were unraveled in this study providing valuable information which will undoubtedly assist in breeding towards improved fruit quality in peach.

Genetic Diversity of Wild Peach (Prunus mira Koehne kov et. kpst) from Different Altitudes in the Tibetan Plateau by Pollen Morphous and RAPD Markers

To analyze the evolutionary level of Prunus mira Koehne (Prunus mira Koehne Kov et. Kpst), 15 kinds of pollen grains from five altitudes were observed using a scanning electron microscope (SEM). This study demonstrates that pollen morphous P. mira has high variation; specifically, individuals from higher altitudes are much more evolved than those from lower altitudes. This is the first time the pollen morphology of P. mira has been systematically illustrated. Furthermore, 12 random amplified polymorphic DNA (RAPD) primers generated clear and repeatable bands among all individuals based on RAPD; 107 bands ranging from 200 bp to 2000 bp were generated with an average of 8.92 bands per primer. Thus, the RAPD technique proved to be a powerful tool to reveal variation on P. mira. This study provides comprehensive information for genetic diversity of P. mira from different altitudes.