Jirovecia species primarily infect oligochaetes and are typically characterized by large rod-shaped spores with a tail-like posterior prolongation. Presently, seven Jirovecia spp. are reported worldwide with only one described in China. Here, a new species, Jirovecia branchilis n. sp. was discovered in glands of oligochaetes Branchiura sowerybi Beddard, 1892 in China. Jirovecia branchilis n. sp. elicited the formation of numerous opaque xenomas of 0.12 to 0.20 mm (n = 30) in diameter. Electron microscopic observations demonstrated that the earliest developmental stages observed were uninucleate meronts residing directly with the host cytoplasm. Mature spores were rod-shaped with blunt ends and possessed a collar-like anchoring disk, a manubrium-type polar filament, a bipartite polarplast, and a three-layered spore wall. A tail-like prolongation was distinctly observed in the posterior of spores and measured 13.2–28.6 μm long (n = 30). Jirovecia branchilis n. sp. showed 98.54% sequence similarity with Janacekia tainunus isolated from the fat body of chironomidae larvae Kiefferulus tainanus based on obtained partial SSU rDNA gene sequence, but was significantly different in morphology, host, and infection sites. SSU rDNA-based phylogenetic analysis indicated Jirovecia branchilis n. sp. clustered with Janacekia tainanus within the Jirovecia-Bacillidium-Janacekia clade. In conclusion, a new species within Jirovecia, Jirovecia branchilis n. sp. is erected herein based mainly on its morphological, ecological, and to a lesser degree on its molecular characteristics. The whole relationship between Jirovecia spp., Janacekia spp., and Bacillidium spp. is in need of revision and could potentially be elucidated by using additional makers and sequencing a broader diversity of the already described species. 相似文献
Arbuscular mycorrhizal (AM) fungi can form symbiosis with 90% of the vascular plants and play important roles in ecosystem. To realize the AM fungal colonization at different succession stages in saline-alkali land and screen AM fungi species with great functions, roots and soil samples were collected from the three succession stages of Songnen saline-alkali grassland. The soil properties and AM fungal colonization were measured, and the fungus distributed extensively in three stages was annotated by sequencing for AML1/AML2 target, subsequently, maize was selected as the host to verify its colonization. The results showed that the soil properties improved with the succession of saline-alkali grassland. The plants’ communities of the three stages could be colonized by AM fungi, and the colonization rate of Leymus chinensis (the third stage) ranged from 66.67% to 100%, Puccinellia tenuiflora (the second stage) ranged from 50% to 80%, while the Suaeda glauca (the first stage) was only 35%–60%. Glomeraceae sp1 was identified as the dominant AM fungi species which occurred frequently in the succession of saline-alkali land with the isolation frequency, relative abundance, and importance value of 100%, 18.1%, and 59.1%, respectively. The colonization rate of Glomeraceae sp1 in maize ranged from 80% to 87% and similar mycorrhizal characteristics were detected in the roots of P. tenuiflora, S. glauca, and L. chinensis, indicating that Glomeraceae sp1 colonized the samples in the field. The correlation matrix indicated that colonization rate, colonization intensity, and vesicle abundance were closely related to soil conditions most, and they were related significantly to all the soil properties except cellulase activity. Besides, redundancy analysis (RDA) showed that soil properties drove the changes of AM fungal colonization and sporulation. These results will provide theoretical support for realizing the relationship between AM fungal colonization and soil conditions, and also for the exploration of AM fungi species with great functions.
