[Diversity and Predictive Functional of Caragana jubata Bacterial Community in Rhizosphere and Non-rhizosphere Soil at Different Altitudes].

Caragana jubata, as the main dominant plant in the alpine and subalpine regions of northern China, is an important component of the local ecosystem. However, few studies have paid attention to its impact on the soil ecosystem and its response to environmental changes. Thus, in this study, we used high-throughput sequencing technology to investigate diversity and predictive function of rhizosphere and bulk soil bacteria communities of C.jubata from different altitudes. The results indicated that 43 phyla, 112 classes, 251 orders, 324 families, and 542 genera were obtained from the soil. The dominant phyla in all sample sites were Proteobacteria, Acidobacteria, and Actinobacteria. There were significant differences in bacterial diversity index and community structure between the rhizosphere and bulk soil at the same altitude, whereas the differences across altitudes were insignificant. PICRUSt analysis showed that the functional gene families were mainly related to 29 sub-functions, including amino acid metabolism, carbohydrate metabolism, and metabolism of cofactors and vitamins, and the abundance of metabolism was highest. There were significant correlations between the relative abundances of genes involved in the level Ⅱ metabolic pathway of bacteria and phylum-level taxa, such as Proteobacteria, Acidobacteria, and Chloroflexi. The predicted functional compositions of soil bacteria also showed a significantly positive correlation with the dissimilarity in bacterial community structure, indicating that there was a strong relationship between bacterial community structure and functional genes. This study preliminarily discussed the characteristics and functional prediction analysis of bacterial communities in the rhizosphere and bulk soil of C.jubata at different altitudinal gradients, which provided data support for the ecological effects of constructive plants and their responses to environmental changes in high altitude areas.

[Differences in Bacterial Community Structure in Rhizosphere Soil of Three Caragana Species and Its Driving Factors in a Common Garden Experiment].

The soil bacterial diversity and community structures in rhizosphere soil of Caragana microphylla, Caragana liouana, and Caragana roborovskyi in a common garden experiment were measured using the high-throughput sequencing technique, with the aim of investigating the factors driving the variation in the bacterial community structure. The results indicated that 42 phyla, 55 classes, 123 orders, 244 families, and 558 genera were obtained from the rhizosphere soil. The dominant phyla in all sample sites were Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Acidobacteria (relative abundance>1%). At the genus level, Phenylobacterium, Ensifer, and Chitinophaga were dominant. Two-way analysis of variance showed that species had a significant effect on the Shannon index and Simpson index of rhizosphere soil bacteria of the three Caragana species, whereas the Chao1 index, Shannon index, and Simpson index were significantly affected by the interaction of provenances and species. There was a significant difference among the three species in the composition of bacterial communities, and the cluster analysis indicated that the composition of the soil bacterial community significantly differed among provenances in C. liouana and C. roborovskyi. Based on the redundancy analysis, mean annual precipitation and altitude were the dominant factors influencing the rhizosphere soil bacterial community structure. Overall, the present results indicated that there were intraspecific and interspecific differences in the diversity and community structures of rhizosphere soil bacteria, and the bacterial community structure was mainly affected by the provenance climate. These results provide a theoretical basis for understanding the adaptation strategies and ecological restoration of the three Caragana species.

[Fungal community diversity and driving factors in rhizosphere soil of Caragana species across semi-arid regions]. / åŠå¹²æ—±åŒºé”¦é¸¡å„¿å±žæ¤ç‰©æ ¹é™ åœŸå£¤çœŸèŒç¾¤è½å¤šæ ·æ€§åŠé©±åŠ¨å› ç´ .

To investigate fungal community diversity in rhizosphere soil of Caragana species, and their relationships with ecological factors in the semi-arid regions of China, we collected soil samples from Caragana liouana and C. microphylla in different habitats. By using Illumina MiSeq high-throughput sequencing technology, we analyzed fungal diversity, community composition, and the driving factors. Results showed that 7 phyla, 20 classes, 43 orders, 66 families, and 78 genera were recorded from the rhizosphere soil. The dominant phyla in all sample sites were Ascomycota (37.7%), Basidiomycota (13.7%), and Zygomycota (4.3%). At the genus level, Penicillium, Geomyces, and Mortierella were dominant, and Rhizophagus and Glomus were also found in rhizosphere soil. The fungal Chao1 index, ACE index, and Simpson index of C. microphylla were significantly higher than those of C. liouana. There was significant difference between the two species in the composition of fungal communities. Results of redundancy analysis showed that soil organic carbon, total nitrogen, electrical conductivity, available potassium, altitude, total phosphorus and aridity index exhibited significant impacts on soil fungal diversity. Overall, those results enhanced our understanding of the relationships between rhizospheric microbial community diversity of Caragana species and ecological factors, and provided important information on the adaptive mechanisms of desert plants in semi-arid regions.

[Characteristics and influence factors in leaf and soil carbon stable isotopes of Caragana jubata.] / é¬¼ç®­é”¦é¸¡å„¿å¶ç‰‡å’ŒåœŸå£¤ç¢³ç¨³å®šåŒä½ç´ ç‰¹å¾åŠå ¶å½±å“å› ç´ .

In order to explore the relationship of plant carbon (C) cycling with its habitat in the high-altitude regions, a leguminous shrub, Caragana jubata, that mainly distributed in those areas was studied. We collected leaf and soil samples of C. jubata from 35 sites along an east-west transect across the alpine regions of China. We measured leaf carbon stable isotope (δ13C), soil δ13C, and the difference between leaf and soil δ13C (Δδ13C) of each sampling site. We further analyzed the effects of climatic factors, leaf and soil elements on leaf δ13C, soil δ13C and Δδ13C. Results showed that leaf δ13C ranged from -30.9‰ to -27.1‰, with a mean value of -28.4‰, soil δ13C ranged from -26.2‰ to -23.2‰, with a mean value of -25.3‰, and Δδ13C ranged from 2.0‰ to 7.7‰, with a mean value of 3.1‰. δ13C values of leaf was significantly lower than that of soil. Soil δ13C initially decreased and subsequently increased with increasing leaf δ13C. Leaf δ13C was negatively correlated with growing season temperature and leaf C content. Soil δ13C was negatively correlated with relative humidity and mean temperature of the warmest month, and was positively correlated with soil carbon:nitrogen (C:N). Soil δ13C firstly decreased and subsequently increased with soil C content. Δδ13C was positively correlated with leaf C content, soil C content, and soil C: N. Climatic factors directly affected leaf δ13C and Δδ13C, and indirectly affected leaf δ13C, soil δ13C and Δδ13C through their effects on leaf and soil elements. The C cycle of C. jubata was affected by climatic factors, leaf and soil elements in the alpine regions.