Figure - available from: Frontiers in Plant Science
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Phylogenetic tree of Ericales species based on mitochondrial genomes. Vitis vinifera (NC012119) was used as the outgroup.
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Rhododendron × pulchrum, an important horticultural species, is widely distributed in Europe, Asia, and North America. To analyze the phylogenetic and organelle genome information of R. × pulchrum and its related species, the organelle genome of R. × pulchrum was sequenced and assembled. The complete mitochondrial genome showed lineage DNA molecule...
Citations
... Fortunately, the recent and rapid progress in high-throughput sequencing technologies and assembly methods has led to more plant mitogenome projects and the production of high-quality assemblies [49]. In higher plants, mitogenomes often exhibit complex structures, which can include circular, linear, and even a variety of smaller circular forms of different sizes [21,[50][51][52]. In the present research, we successfully assembled the I. rotunda mitogenome based on PacBio HiFi sequencing data. ...
Ilex rotunda Thunb. stands as a representative tree species in subtropical evergreen broad–leaved forests, widely distributed across southeast Asia. This species holds significant value in forestry due to its ecological resilience and adaptability. Although researchers have conducted in–depth research on the plastid genome (plastome) of I. rotunda, the mitochondrial genome (mitogenome) of this species has remained undocumented. In the present study, we successfully sequenced and assembled the I. rotunda mitogenome. The mitogenome has a circular structure and is 567,552 bp in total length, with a GC content of 45.47%. The composition of the mitogenome encompasses 40 protein–coding genes, along with 3 rRNA genes and 19 tRNA genes. Notably, the mitogenome exhibits a universal distribution of repetitive sequences, but the total length of repeats contributes to a relatively small proportion (4%) of the whole mitogenome, suggesting that repeats do not serve as the primary cause of the amplification of the Ilex mitogenomes. Collinear analysis indicates that the I. rotunda mitogenome is very conservative within Aquifoliales species. Additionally, our research identified 51 fragments of plastid genomic DNA, which have migrated from the plastome into the mitogenome, with five genes from the plastome remaining intact. Eventually, the phylogenetic analyses based on the plastomes and mitogenomes of 36 angiosperms determine the Aquifoliales to be the basal group in the campanulids. This study establishes the bedrock for prospective investigations in molecular breeding research.
... However, in R. pulchrum, it was reported as non-quadripartite cycle due to lack of inverted repeat regions. Chloroplast genome size ranged between 190,698 (R. datiandingense) to 230,777 bp (R. kawakamii), while it was 146,941 bp in R. pulchrum (Shen et al. 2022). A quadripartite structure of chloroplast consists of 93 to 150 genes including protein coding genes, ribosomal genes and tRNA genes ( Table 3). ...
High species diversity, hybridization potential, broad geographical dispersal range and ornamental characteristics (i.e., attractive size, shape, structure, flowers, and evergreen) have fetched a good international market for Rhododendron. However, most species are restricted to specific geographic areas due to their habitat specificity in acidic soil and cold climates, resulting many species being classified under threat categories of the IUCN. In this review, advances in research on Rhododendron for improvement to floral display quality and stress resistance have been described. The low genetic barrier among species has created opportunities for extensive hybridization and ploidy alteration for introducing quality and adaptive traits during the development of new varieties. Recent technological advances have supported investigations into the mechanism of flower development, as well as cold tolerance and pathogen resistance mechanisms in the Rhododendron. However, most of the species have limited adaptability to drought, line-tolerance, pathogen resistance, and high-temperature conditions and this resistance ability present in few species largely remains unexplored. Additionally, the available genetic diversity and genomic information on species, and possibilities for their application in molecular breeding have been summarized. Overall, genomic resource data are scarce in the majority of the members of this genus. Finally, various research gaps such as genetic mapping of quality traits, understanding the molecular mechanism of quality-related traits and genomic assortment in Rhododendron members have been discussed in the future perspective section.
... The complete cp genome of R. farrerae was sequenced and analyzed. Our results indicate that the R. farrerae cp genome lacks the IRs, which was consistent with R. pulchrum verified using third-generation combined with second-generation sequencing methods (Shen et al. 2019(Shen et al. , 2022. Recently study reported the cp genomes of the four Rhododendron species (R. concinnum, R. henanense subsp. ...
Rhododendron farrerae Tate ex Sweet 1831 is a species of ornamental plant found in southern China. In the present study, the complete chloroplast genome of R. farrerae was sequenced. The genome was 149,453 bp in length and lacked the typical quadripartite structure. The plastid genome contained 112 genes, including 74 protein-coding genes, 34 tRNA genes, and 4 rRNA genes. The overall GC content of the genome was 35.65%. Phylogenetic analysis of 25 chloroplast genomes revealed that R. farrerae was closely related to Rhododendron huadingense. This study could provide fundamental information for the distribution, utilization, and phylogenomics of Rhododendron.
