RNA editing events and expression profiles of mitochondrial protein-coding genes in the endemic and endangered medicinal plant, Corydalis saxicola.

Corydalis saxicola, an endangered medicinal plant endemic to karst habitats, is widely used in Traditional Chinese Medicine to treat hepatitis, abdominal pain, bleeding hemorrhoids and other conditions. However, to date, the mitochondrial (mt) genome of C. saxicola has not been reported, which limits our understanding of the genetic and biological mechanisms of C. saxicola. Here, the mt genome of C. saxicola was assembled by combining the Nanopore and Illumina reads. The mt genome of C. saxicola is represented by a circular chromosome which is 587,939 bp in length, with an overall GC content of 46.50%. 40 unique protein-coding genes (PCGs), 22 tRNA genes and three rRNA genes were identified. Codon usage of the PCGs was investigated and 167 simple sequence repeats were identified. Twelve homologous fragments were identified between the mt and ct genomes of C. saxicola, accounting for 1.04% of the entire mt genome. Phylogenetic examination of the mt genomes of C. saxicola and 30 other taxa provided an understanding of their evolutionary relationships. We also predicted 779 RNA editing sites in 40 C. saxicola mt PCGs and successfully validated 506 (65%) of these using PCR amplification and Sanger sequencing. In addition, we transcriptionally profiled 24 core mt PCGs in C. saxicola roots treated with different concentrations of CaCl2, as well as in other organs. These investigations will be useful for effective utilization and molecular breeding, and will also provide a reference for further studies of the genus Corydalis.

Walsuraguangxiensis (Meliaceae), a new species from Guangxi, China.

Walsuraguangxiensis (Meliaceae), a new species from Guangxi, China, is here described and illustrated. The new species is easily distinguishable from the other two Chinese members of the genus by its petals being pale yellow, filaments being connate into tubes above the middle, the berry being oval and glabrous. An identification key of Walsura for 17 species is also provided.

The complete chloroplast genome of Chloranthus nervosus Collett ex Hemsl. 1890 (Chloranthaceae).

In this study, we sequenced and assembled the complete chloroplast genome of Chloranthus nervosus Collett ex Hemsl. 1890. The total length of the complete chloroplast sequence was found to be 158,002 bp. It consisted of a large single-copy (LSC) region of 87,127 bp, a small single-copy (SSC) region of 18,541 bp, and a pair of inverted repeat (IR) regions, each with a length of 26,167 bp. The overall GC content of the complete chloroplast genome was 38.9%, with the LSC region, SSC region, and IR regions exhibiting GC contents of 37.4%, 34.1%, and 43.1%, respectively. The annotation of the chloroplast genome revealed a total of 131 genes, comprising 86 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis revealed that the seven sampled species of Chloranthus were divided into two clades. Within the clade characterized by long filamentous anther connectives, C. nervosus showed the closest relation to C. japonicus. These findings validated the previous preliminary results on the phylogenetic relationships of the seven species of Chloranthus with strong support.

Biochar and organic fertilizer drive the bacterial community to improve the productivity and quality of Sophora tonkinensis in cadmium-contaminated soil.

Excessive Cd accumulation in soil reduces the production of numerous plants, such as Sophora tonkinensis Gagnep., which is an important and widely cultivated medicinal plant whose roots and rhizomes are used in traditional Chinese medicine. Applying a mixture of biochar and organic fertilizers improved the overall health of the Cd-contaminated soil and increased the yield and quality of Sophora. However, the underlying mechanism between this mixed fertilization and the improvement of the yield and quality of Sophora remains uncovered. This study investigated the effect of biochar and organic fertilizer application (BO, biochar to organic fertilizer ratio of 1:2) on the growth of Sophora cultivated in Cd-contaminated soil. BO significantly reduced the total Cd content (TCd) in the Sophora rhizosphere soil and increased the soil water content, overall soil nutrient levels, and enzyme activities in the soil. Additionally, the α diversity of the soil bacterial community had been significantly improved after BO treatment. Soil pH, total Cd content, total carbon content, and dissolved organic carbon were the main reasons for the fluctuation of the bacterial dominant species. Further investigation demonstrated that the abundance of variable microorganisms, including Acidobacteria, Proteobacteria, Bacteroidetes, Firmicutes, Chloroflexi, Gemmatimonadetes, Patescibacteria, Armatimonadetes, Subgroups_ 6, Bacillus and Bacillus_ Acidiceler, was also significantly changed in Cd-contaminated soil. All these alterations could contribute to the reduction of the Cd content and, thus, the increase of the biomass and the content of the main secondary metabolites (matrine and oxymatrine) in Sophora. Our research demonstrated that the co-application of biochar and organic fertilizer has the potential to enhance soil health and increase the productivity and quality of plants by regulating the microorganisms in Cd-contaminated soil.

The chloroplast genome of Archontophoenix alexandrae (Arecaceae): an important landscape tree for the subtropics.

Archontophoenix alexandrae, known as king palm, is an important landscape tree for the subtropics and potential sources of dietary fiber. In this study, the complete chloroplast genome of A. alexandrae was determined through Illumina sequencing method. The chloroplast genome was 159,196 bp in length and contained a small single-copy region (17,763 bp), a large single-copy region (87,055 bp) and a pair of IR regions (27,189 bp). 135 genes were determined in the A. alexandrae chloroplast genome, including 86 CDS, 39 tRNA genes, and 8 rRNA genes. Archontophoenix alexandrae showed the closest relationship with Veitchia arecina in the phylogenetic analysis.

[Characteristics of standing vegetation and soil seed bank in desert riparian forest in lower reaches of Tarim River under effects of river-flooding].

An investigation was made on the standing vegetation and soil seed bank in desert riparian forest in lower reaches of Tarim River under effects of river-flooding. The results showed that the standing vegetation in non-flooded and flooded sites was composed of 14 species in 13 genera of 8 families, and 26 species in 21 genera of 10 families, respectively, and some shallow-rooted and hygrophilous species were recorded in flooded sites. The indices per unit area plant species number, vegetative coverage, plant density, and species diversity of the vegetation were all higher in flooded than in non-flooded sites. The species number of the soil seed bank in flooded sites was 19, with 5 species more than that in non-flooded sites, and the seed bank density in flooded sites was 2.94 times higher than that in non-flooded sites. The proportion of annual herbaceous species seeds in flooded sites increased by 23.07% while that of shrub species seeds decreased by 20.99%, compared with those in non-flooded sites, and the proportion of perennial herbaceous species seeds had less difference between these two sites. River-flooding increased the diversity of soil seed bank. In flooded and non-flooded sites, the co-occurrence species in seed bank and in standing vegetation were 18 and 9, with the similarity coefficients of species composition between soil seed bank and standing vegetation being 0.842 and 0.667, respectively.

[Contribution of soil seed bank to the regeneration of damaged vegetation on floodplain].

A field germination experiment of soil seed bank was carried out on two typical floodplains in the lower reaches of Tarim River, and a comparison was made between the soil seed banks and corresponding seedling banks on the two floodplains, aimed to assess the contribution of soil seed bank to the regeneration of damaged vegetation. The results showed that there were 12 plant species in the soil seed banks, and the life forms were mainly perennial herbs and shrubs. The soil seed banks had a density of 282.5 seeds m(-2) and 173.2 seeds x m(-2), and the seeds in top soil (0-2 cm) accounted for 76.9% and 71.0% of the total, respectively. The soil seed banks had significant effects on the seedlings species composition and density, and 84.7% and 99.4% of the seedlings on the two floodplains were emerged from corresponding soil seed banks. The similarity coefficient between soil seed bank and seedling bank of the two floodplains was 0.72 and 0.63, respectively, and there existed significant positive correlation between seedling density and soil seed bank density, illustrating that soil seed bank made important contribution to the natural regeneration of vegetation.