Characterization of Rheum palmatum mitochondrial genome and comparative analysis among Caryophyllales species

Objective:This work aimed to report the first complete mitochondrial genome(mitogenome)of Rheum palmatum,summarize the features of Caryophyllales mitogenomes,and to reveal the potential of utilizing the mitogenomes of R.palmatum and other Caryophyllales species for inferring phylogenetic relationships and species identification.Methods:Both Illumina short reads and PacBio HiFi reads were utilized to obtain a complete mitogenome of R.palmatum.A variety of bioinformatics tools were employed to characterize the R.palmatum mitogenome,compare the reported mitogenomes in Caryophyllales and conduct phylogenetic analysis.Results:The mitogenome of R.palmatum was assembled into a single master circle of 302,993 bp,encoding 35 known protein-coding genes,18 transfer RNA genes,and three ribosome RNA genes.A total of 249 long repeats and 49 simple sequence repeats were identified in this mitogenome.The sizes of mitogenomes in Caryophyllales varied from 253 kb to 11.3 Mb.Among them,23 mitogenomes were circular molecules,one was linear,and one consisted of relaxed circles,linear molecules,and supercoiled DNA.Out of the total mitogenomes,11 were single-chromosome structure,whereas the remaining 14 were multi-chromosomal organizations.The phylogenetic analysis is consistent with both the Engler system(1964)and the Angiosperm Phylogeny Group III system.Conclusions:We obtained the first mitogenome of R.palmatum,which consists of a master circle.Mitogenomes in Caryophyllales have variable genome sizes and structures even within the same species.Circular molecules are still the dominant pattern in Caryophyllales.Single-chromosome mitogenomes account for nearly a half of all the mitogenomes in Caryophyllales,in contrast to previous studies.It is feasible to utilize mitochondrial genomes for inferring phylogenetic relationships and conducting species identification.

A look into the past, present and future potential distributions of Talinopsis frutescens, a North American endemic lineage closely related to Cactaceae

Talinopsis frutescens(Anacampserotaceae,a family that is close related to Cactaceae)is a succulent species endemic to North America.The aim of this study was to explore,using Ecological Niche Modeling(ENM),changes in potential distribution ranges considering different climate scenarios:past conditions during the Last Inter Glacial(LIG)and the Last Glacial Maximum(LGM),the present and projections for 2070(RCP 2.6 to 8.5).A pattern of contraction is observed during the LIG,which agrees with other studies focused in species from arid environments.This pattern was followed by a migration towards the south during the LGM and a possible recent expansion to the north as is observed in the present scenario.All future projections show the same contraction and fragmentation patterns,resulting in three discontinuous areas:the northern part of the Chihuahuan Desert,the southern-central part of the Mexican Plateau,and the smallest one in the Tehuacán-Cuicatlán Valley.Our projections for future scenarios agree with other studies and support that global climate change tends to alter the current distribution of arid environment species.

Transcriptome and Metabolic Profiling Provides Insigh into Betalain Biosynthesis and Evolution in Mirabilis jalapa

Betalains are tyrosine-derived pigments that occur solely in one plant order, the Caryophyllales, where they largely replace the anthocyanins in a mutually exclusive manner. In this study, we conducted multi-species transcriptome and metabolic profiling in Mirabilisjalapa and additional betalain-producing species to identify candidate genes possibly involved in betalain biosynthesis. Among the candidates identified, betalainrelated ytochrome P450 and glucosyltransferase-type genes, which catalyze tyrosine hydroxylation or （hydroxy）cinnamoyl-glucose formation, respectively, were further functionally characterized. We detected the expression of genes in the flavonoid/anthocyanin biosynthetic pathways as well as their metabolite intermediates in betalain-accumulating M. jalapa flowers, and found that the anthocyanin-related gene ANTHOCYANIDIN SYNTHASE （MjANS） is highly expressed in the betalain-accumulating petals. However, it appears that MjANS contains a significant deletion in a region spanning the corresponding enzyme active site. These findings provide novel insights into betalain biosynthesis and a possible explanation for how anthocyanins have been lost in this plant species. Our study also implies a complex, non-uniform history for the loss of anthocyanin production across betalain producers, previously assumed to be strictly due to diminished expression of anthocyanin-related genes.