Evergreen azalea cultivars are used as ornamental shrubs and pot plants not only in Japan, but also in Western countries. These cultivars were developed from wild species native to Japan, and through selection and crossing, cultivar groups such as the Ryūkyū-tsutsuji, Hirado-tsutsuji, Edo-kirishima, Satsuki and pot azalea have been developed. In this study, we focused on the genetic contribution of wild species to the development of evergreen cultivars and used microsatellite loci to examine the genetic involvement of wild species, particularly Rhododendron ripense. The utilization of seven microsatellite loci enabled cultivar identification and an estimation of bud mutation lines. The results of STRUCTURE analysis revealed that the R. ripense cluster was predominant in large-flowered cultivars such as Kishi-tsutsuji, Ryūkyū-tsutsuji, and Ōkirishima. The involvement of the R. ripense cluster was also observed in pot azalea developed in Western countries. Additionally, the genetic involvement of R. scabrum was confirmed in many cultivars of Ōkirishima and Hirado-tsutsuji. Regarding small-flowered cultivars, the Yama-tsutsuji and Kurume-tsutsuji cultivar groups were dominated by the R. kaempferi cluster, while the Satsuki cultivar group was dominated by the cluster containing R. indicum, R. eriocarpum, and others. These results enable us to reevaluate the classification of azalea cultivars by conducting a more detailed study of cultivar groups composed of the same clusters.

Although the fragrant wild cyclamen, Cyclamen purpurascens, is widely used as a parent plant for breeding of fragrant cyclamen cultivars, the color variety of fragrant cyclamen is limited. To develop cultivars with a wider range of flower colors, it is crucial to understand the flavonoid biosynthetic pathway involved in flower color in C. purpurascens as a crossbreeding parent. In this study, we isolated the gene (CpurF3H) encoding flavanone 3-hydroxylase, a key enzyme in determining flower color in cyclamen, from C. purpurascens for the first time and investigated its expression and function. The full-length cDNA sequence of CpurF3H obtained from young petals contained a 1,113-bp open reading frame (ORF) encoding 371 amino acids, showing 82.1–88.0% amino acid sequence identity with F3Hs from other plant species. The expression analysis showed that CpurF3H is strongly expressed in young petals, but rapidly decreases in petals following anthesis, suggesting that it functions during the early stages of flower development. Next, in vitro assays showed that recombinant CpurF3H proteins can convert naringenin to dihydrokaempferol. In addition, a complementation assay using the Arabidopsis thaliana f3h mutant confirmed the accumulation of anthocyanins in CpurF3H-transformed plant. Overall, these results strongly suggest that CpurF3H participates in flavonoid biosynthesis and flower coloration in C. purpurascens.

Climate change has affected fruit tree production because meteorological environments determine annual yield, quality, and suitable cultivation locations. This review focuses on the physiological and physical effects of each meteorological element on fruit trees, the impact of climate change on fruit production, and adaptation strategies. The most critical role of temperature is the temporal control of developmental stage changes via developmental rate regulation. Extremely high and low temperatures can cause necrosis of fruit tree tissue, which is a physical effect of heating or freezing. Solar radiation and soil moisture drive quantitative control to determine the size and weight of the entire plant or each part of the fruit tree via photosynthesis. Climate change affects fruit trees through high temperatures and water stress. Temperature rise has altered the development of fruit trees, resulting in earlier flowering, delayed fruit coloration, changes in fruit quality, and increased risk of peel and flesh disorders. Warmer temperatures in autumn and winter delay the release from endodormancy and hardening, as well as accelerating de-hardening, resulting in freezing injuries and flowering disorders. Sunny days with extremely high temperatures cause physical damage to tissues, resulting in sunburn. Water stress reduces the photosynthesis rate, resulting in reduced fruit growth. A lot of research has been conducted on the development of adaptive measures. Adaptation strategies for fruit tree production can be divided into three stages. In Stage 1, short-term adaptation strategies focusing on production techniques include the use of shading materials or reflective films, regulation of development using greenhouses or plant growth regulators, girdling, or shifting the nitrogen fertilization period. Stage 2 involves the use of cultivars that are better adapted to climate change and is a medium-term adaptation strategy because it requires replanting. Stage 3, species or area conversion, is a long-term adaptation strategy. It refers to cultivating fruit tree species that have not been traditionally cultivated in the area or the relocation of cultivation areas. To support this strategy, maps showing future locations suitable for several species have been developed.