Allochthonous Trichoderma Isolates Boost Atractylodes lancea Herb Quality at the Cost of Rhizome Growth.

Atractylodes lancea is a perennial herb whose rhizome (AR) is a valuable traditional Chinese medicine with immense market demand. The cultivation of Atractylodes lancea faces outbreaks of root rot and deterioration in herb quality due to complex causes. Here, we investigated the effects of Trichoderma spp., well-known biocontrol agents and plant-growth-promoters, on ARs. We isolated Trichoderma strains from healthy ARs collected in different habitats and selected three T. harzianum strains (Th2, Th3 and Th4) with the strongest antagonizing effects on root rot pathogens (Fusarium spp.). We inoculated geo-authentic A. lancea plantlets with Th2, Th3 and Th4 and measured the biomass and quality of 70-day-old ARs. Th2 and Th3 promoted root rot resistance of A. lancea. Th2, Th3 and Th4 all boosted AR quality: the concentration of the four major medicinal compounds in ARs (atractylon, atractylodin, hinesol and ß-eudesmol) each increased 1.6- to 18.2-fold. Meanwhile, however, the yield of ARs decreased by 0.58- to 0.27-fold. Overall, Th3 dramatically increased the quality of ARs at a relatively low cost, namely lower yield, showing great potential for practical application. Our results showed selectivity between A. lancea and allochthonous Trichoderma isolates, indicating the importance of selecting specific microbial patches for herb cultivation.

First Report of Erysiphe astragali Causing Powdery Mildew on Astragalus mongholicus in China.

Astragalus mongholicus Bge. [A. membranaceus Bge. var. mongholicus (Bge.) Hsiao] is a highly valuable perennial medicinal plant mainly distributed in China, whose dry roots are known as Huangqi in traditional Chinese medicine for reinforcing vital energy, strengthening superficial resistance, and promoting tissue regeneration (Lin et al. 2000). A. mongholicus roots of high quality are produced in Northwest and North China. Since July 2021, powdery mildew outbreaks happened annually on the leaves of A. mongholicus in a plantation (123° 56' 40'' E, 47° 22' 20'' N) in Qiqihar city, Heilongjiang Province, China. Disease incidence reached 100% by October (Fig. 1A-C), causing severe impairment of growth. Powdery mildew spots of circular or irregular shapes emerged on upper surface of leaf, resulting in plentiful lesion specks. Dense white hyphae appeared chaotically intertwined. Hyphae were hyaline and highly flexuous, 5.3 - 10.7 µm in diameter (n = 20). Chasmothecia were globose or slightly ovoid-shaped and turned dark brown when matured. Chasmothecia (diameter: 135.2 - 222.9 µm, n = 20) existed abundantly on the diseased leaves in the fields. Conidiophores were 89.0 - 129.9 µm in length (n = 20) and composed of one cylindrical, straight foot cell, followed by two cells and one to three conidia. Conidia were slim ellipsoid-shaped, occasionally ovoid-shaped, measuring 14.6 - 24.7 µm by 6.4 to10.4 µm, length/width ratio was 1.8 - 3.0 (n = 30). Hyphal appressoria were nipple-shaped and appeared in singular, occasionally in pairs. Unbranched germ tube emerged reaching out of the germinating conidia while forming an acute angle with the long axis. Comprehensively, the pathogen exhibited micro-morphology of the genus Erysiphe. For molecular identification, pathogen was carefully scraped off diseased leaves for DNA extraction. We used the DNA samples of three biological replicates for the sequencing of the ITS rDNA fragment (primers by (White et al. 1990). All the samples resulted in an identical ITS sequence (deposited in GenBank as OQ390098.1). It displayed 99.83% identity with OP806835.1 of an E. astragali voucher collected in Iran (Fig. 1D-M, O). Hence, our pathogen was identified as an E. astragali stain. Additionally, we amplified the Mcm7 sequence (using primers by (Ellingham et al. 2019), deposited as OQ397582.1). We propagated 40-day-old A. mongholicus plants via germinating seeds in pot soil and performed pathogenicity tests. Firstly, we incubated detached healthy leaves of propagated plants with severely symptomatic leaves collected from the fields in petri dishes under saturated moisture content and room temperature. Powdery mildew symptoms emerged on each healthy leaf (n = 5) after two weeks. Further, we infected healthy plants (n = 5) by gently pressing and rubbing symptomatic leaves on each healthy leaf, and kept them in a greenhouse (24 ℃, 80% humidity, 16/8-hour light/dark cycle). After a month, symptoms emerged on a number of leaves of each infected plant. We performed micromorphology observation (Fig. 1N-P) and ITS sequencing to confirm that the results fulfilled Koch's postulates. Powdery mildew caused by E. astragali on A. strictus in Tibet (Wang and Jiang 2023) and on A. scaberrimus in Inner Mongolia (Sun et al. 2023) have been reported. Here we report powdery mildew caused by E. astragali on Astragalus mongholicus for the first time. These Astragalus spp. are all acknowledged to have medicinal values in China but their usages are quite different.

Genetic diversity and population divergence of Leonurus japonicus and its distribution dynamic changes from the last interglacial to the present in China.

BACKGROUND: Leonurus japonicus, a significant medicinal plant known for its therapeutic effects on gynecological and cardiovascular diseases, has genetic diversity that forms the basis for germplasm preservation and utilization in medicine. Despite its economic value, limited research has focused on its genetic diversity and divergence. RESULTS: The avg. nucleotide diversity of 59 accessions from China were 0.00029 and hotspot regions in petN-psbM and rpl32-trnL(UAG) spacers, which can be used for genotype discrimination. These accessions divided into four clades with significant divergence. The four subclades, which split at approximately 7.36 Ma, were likely influenced by the Hengduan Mountains uplift and global temperature drop. The initial divergence gave rise to Clade D, with a crown age estimated at 4.27 Ma, followed by Clade C, with a crown age estimated at 3.39 Ma. The four clades were not showed a clear spatial distribution. Suitable climatic conditions for the species were identified, including warmest quarter precipitation 433.20 mm ~ 1,524.07 mm, driest month precipitation > 12.06 mm, and coldest month min temp > -4.34 °C. The high suitability distribution showed contraction in LIG to LGM, followed by expansion from LGM to present. The Hengduan Mountains acted as a glacial refuge for the species during climate changes. CONCLUSIONS: Our findings reflected a clear phylogenetic relationships and divergence within species L. japonicus and the identified hotspot regions could facilitate the genotype discrimination. The divergence time estimation and suitable area simulation revealed evolution dynamics of this species and may propose conservation suggestions and exploitation approaches in the future.

[Application of tissue culture technology of medicinal plants in sustainable development of Chinese medicinal resources].

Chinese medicinal resources are the cornerstone of the sustainable development of traditional Chinese medicine industry. However, due to the fecundity of species, over-exploitation, and limitations of artificial cultivation, some medicinal plants are depleted and even endangered. Tissue culture, a breakthrough technology in the breeding of traditional Chinese medicinal materials, is not limited by time and space, and can allow the production on an annual basis, which plays an important role in the protection of Chinese medicinal resources. The present study reviewed the applications of tissue culture of medicinal plants in the field of Chinese medicinal resources, including rapid propagation of medicinal plant seedlings, breeding of novel high-yield and high-quality cultivars, construction of a genetic transformation system, and production of secondary metabolites. Meanwhile, the current challenges and suggestions for the future development of this field were also proposed.