Biotic stresses do damage to the growth and development of plants, and yield losses for some crops. Confronted with microbial infections, plants have evolved multiple defense mechanisms, which play important roles in the never-ending molecular arms race of plant–pathogen interactions. The complicated defense systems include pathogen-associated molecular patterns (PAMP) triggered immunity (PTI), effector triggered immunity (ETI), and the exosome-mediated cross-kingdom RNA interference (CKRI) system. Furthermore, plants have evolved a classical regulation system mediated by miRNAs to regulate these defense genes. Most of the genes/small RNAs or their regulators that involve in the defense pathways can have very rapid evolutionary rates in the longitudinal and horizontal co-evolution with pathogens. According to these internal defense mechanisms, some strategies such as molecular switch for the disease resistance genes, host-induced gene silencing (HIGS), and the new generation of RNA-based fungicides, have been developed to control multiple plant diseases. These broadly applicable new strategies by transgene or spraying ds/sRNA may lead to reduced application of pesticides and improved crop yield.

Protoplast-based engineering has become an important tool for basic plant molecular biology research and developing genome-edited crops. Uncaria rhynchophylla is a traditional Chinese medicinal plant with a variety of pharmaceutically important indole alkaloids. In this study, an optimized protocol for U. rhynchophylla protoplast isolation, purification, and transient gene expression was developed. The best protoplast separation protocol was found to be 0.8 M D-mannitol, 1.25% Cellulase R-10, and 0.6% Macerozyme R-10 enzymolysis for 5 h at 26 °C in the dark with constant oscillation at 40 rpm/min. The protoplast yield was as high as 1.5 × 10⁷ protoplasts/g fresh weight, and the survival rate of protoplasts was greater than 90%. Furthermore, polyethylene glycol (PEG)-mediated transient transformation of U. rhynchophylla protoplasts was investigated by optimizing different crucial factors affecting transfection efficiency, including plasmid DNA amount, PEG concentration, and transfection duration. The U. rhynchophylla protoplast transfection rate was highest (71%) when protoplasts were transfected overnight at 24 °C with the 40 µg of plasmid DNA for 40 min in a solution containing 40% PEG. This highly efficient protoplast-based transient expression system was used for subcellular localization of transcription factor UrWRKY37. Finally, a dual-luciferase assay was used to detect a transcription factor promoter interaction by co-expressing UrWRKY37 with a UrTDC-promoter reporter plasmid. Taken together, our optimized protocols provide a foundation for future molecular studies of gene function and expression in U. rhynchophylla.

A serious leaf disease caused by Colletotrichum dematium was found during the cultivation of Sarcandra glabra in Jingxi, Rong’an, and Donglan Counties in Guangxi Province, which inflicted huge losses to plant productivity. Biological control gradually became an effective control method for plant pathogens. Many studies showed that the application of actinomycetes in biological control has been effective. Therefore, it may be of great significance to study the application of actinomycetes on controlling the diseases caused by S. glabra. Strains of antifungal actinomycetes capable of inhibiting C. dematium were identified, isolated and screened from healthy plants tissues and the rhizospheres in soils containing S. glabra. In this study, 15 actinomycetes strains were isolated and among these, strains JT-2F, DT-3F, and JJ-3F, appeared to show antagonistic effects against anthracnose of S. glabra. The strains JT-2F and DT-3F were isolated from soil, while JJ-3F was isolated from plant stems. The antagonism rate of strain JT-2F was 86.75%, which was the highest value among the three strains. Additionally, the JT-2F strain also had the strongest antagonistic activity when the antagonistic activities were tested against seven plant pathogens. Strain JT-2F is able to produce proteases and cellulase to degrade the protein and cellulose components of cell walls of C. dematium, respectively. This results in mycelia damage which leads to inhibition of the growth of C. dematium. Strain JT-2F was identified as Streptomyces tsukiyonensis based on morphological traits and 16S rDNA sequence analysis.

The genus Uncaria is an important source of traditional Chinese medicines with multiple therapeutic effects. The identification of the correct species and accurate determination of the contents of bioactive constituents are important for quality control of Uncaria medicinal materials. Here, an integrated evaluation system based on DNA barcoding for species identification and quantitative analysis by LC-MS/MS has been established. DNA barcoding based on the ITS2 barcode region showed sufficient discriminatory power to precisely identify 24 samples from seven Uncaria species. The length of the 24 ITS2 sequences of Uncaria samples is 227 bp, and 17 variation sites were detected. Additionally, the results of qualitative and quantitative chemical analyses by LC-MS/MS indicated that the chemical compositions of all Uncaria samples were similar; while their contents of targeted alkaloids in samples from different species and origin areas were different. The contents of rhynchophylline (RC) and isorhynchophylline (IRC) were 2.9–1612 mg/kg and 2.60–1299 mg/kg in all tested samples, respectively. This study concludes that DNA barcoding should be used as the first screening step for Uncaria medicinal materials. Then, integration of DNA barcoding with chemical analyses should be applied in quality control of Uncaria medicinal materials in the medicinal industry.

Loranthus (Taxillus chinensis) is a facultative, hemiparasite and stem parasitic plant that attacks other plants for living. Transcriptome sequencing and bioinformatics analysis were applied in this study to identify the gene expression profiles of fresh seeds (CK), baby (FB), and adult haustoria tissues (FD). We assembled 160,571 loranthus genes, of which 64,926, 35,417, and 47,249 were aligned to NR, GO, and KEGG pathway databases, respectively. We identified 14,295, 15,921, and 16,402 genes in CK, FB, and FD, respectively. We next identified 5,480 differentially expressed genes (DEGs) in the process, of which 258, 174, 81, and 94 were encoding ribosomal proteins (RP), transcription factors (TF), ubiquitin, and disease resistance proteins, respectively. Some DEGs were identified to be upregulated along with the haustoria development (e.g., 68 RP and 26 ubiquitin genes). Notably, 36 RP DEGs peak at FB; 10 ER, 5 WRKY, 6 bHLH, and 4 MYB TF genes upregulated only in FD. Further, we identified 4 out of 32 microRNA genes dysregulated in the loranthus haustoria development. This is the first haustoria transcriptome of loranthus, and our findings will improve our understanding of the molecular mechanism of haustoria.

The hemiparasitic Taxillus chinensis (DC.) Danser is a root-parasitizing medicinal plant with photosynthetic ability, which is lost in other parasitic plants. However, the cultivation and medical application of the species are limited by the recalcitrant seeds of the species, and even though the molecular mechanisms underlying this recalcitrance have been investigated using transcriptomic and proteomic methods, genome resources for T. chinensis have yet to be reported. Accordingly, the aim of the present study was to use nanopore, short-read, and high-throughput chromosome conformation capture sequencing to construct a chromosome-level assembly of the T. chinensis genome. The final genome assembly was 521.90 Mb in length, and 496.43 Mb (95.12%) could be grouped into nine chromosomes with contig and scaffold N50 values of 3.80 and 56.90 Mb, respectively. In addition, a total of 33,894 protein-coding genes were predicted, and gene family clustering identified 11 photosystem-related gene families, thereby indicating photosynthetic ability, which is a characteristic of hemiparasitic plants. This chromosome-level genome assembly of T. chinensis provides a valuable genomic resource for elucidating the genetic basis underlying the recalcitrant characteristics of T. chinensis seeds and the evolution of photosynthesis loss in parasitic plants.