Isolation of endophytic fungi from Cotoneaster multiflorus and screening of drought-tolerant fungi and evaluation of their growth-promoting effects.

In the context of climate change and human factors, the drought problem is a particularly serious one, and environmental pollution caused by the abuse of chemical fertilizers and pesticides is increasingly serious. Endophytic fungi can be used as a protection option, which is ecologically friendly, to alleviate abiotic stresses on plants, promote plant growth, and promote the sustainable development of agriculture and forestry. Therefore, it is of great significance to screen and isolate endophytic fungi that are beneficial to crops from plants in special habitats. In this study, endophytic fungi were isolated from Cotoneaster multiflorus, and drought-tolerant endophytic fungi were screened by simulating drought stress with different concentrations of PEG-6000, and the growth-promoting effects of these drought-tolerant strains were evaluated. A total of 113 strains of endophytic fungi were isolated and purified from different tissues of C. multiflorus. After simulated drought stress, 25 endophytic fungi showed strong drought tolerance. After ITS sequence identification, they belonged to 7 genera and 12 species, including Aspergillus, Fusarium, Colletotrichum, Penicillium, Diaporthe, Geotrichum, and Metarhizium. According to the identification and drought stress results, 12 strains of endophytic fungi with better drought tolerance were selected to study their abilities of dissolving inorganic phosphorus and potassium feldspar powder and producing indole-3-acetic acid (IAA). It was found that the amount of dissolved phosphorus in 7 strains of endophytic fungi was significantly higher than that of CK, and the content of soluble phosphorus was 101.98-414.51 µg. ml-1; 6 endophytic fungi had significantly higher potassium solubilization than CK, and the content of water-soluble potassium ranged from 19.17 to 30.94 mg·l-1; 6 strains have the ability to produce IAA, and the yield of IAA ranged between 0.04 and 0.42 mg. ml-1. This study for the first time identified the existence of endophytic fungi with drought tolerance and growth-promoting function in C. multiflorus, which could provide new direction for plant drought tolerance and growth promotion fungi strain resources. It also provides a theoretical basis for the subsequent application of endophytic fungi of C. multiflorus in agricultural and forestry production to improve plant tolerance.

Structural variability and differentiation of niches in the rhizosphere and endosphere bacterial microbiome of moso bamboo (Phyllostachys edulis).

The plant microbiota play a key role in plant productivity, nutrient uptake, resistance to stress and flowering. The flowering of moso bamboo has been a focus of study. The mechanism of flowering is related to nutrient uptake, temperature, hormone balance and regulation of key genes. However, the connection between microbiota of moso bamboo and its flowering is unknown. In this study, samples of rhizosphere soil, rhizomes, roots and leaves of flowering and nonflowering plants were collected, and 16S rRNA amplicon Illumina sequencing was utilized to separate the bacterial communities associated with different flowering stages of moso bamboo. We identified 5442 OTUs, and the number of rhizosphere soil OTUs was much higher than those of other samples. Principal component analysis (PCA) and hierarchical clustering (Bray Curtis dis) analysis revealed that the bacterial microorganisms related to rhizosphere soil and endophytic tissues of moso bamboo differed significantly from those in bulk soil and rhizobacterial and endosphere microbiomes. In addition, the PCA analyses of root and rhizosphere soil revealed different structures of microbial communities between bamboo that is flowering and not flowering. Through the analysis of core microorganisms, it was found that Flavobacterium, Bacillus and Stenotrophomonas played an important role in the absorption of N elements, which may affect the flowering time of moso bamboo. Our results delineate the complex host-microbe interactions of this plant. We also discuss the potential influence of bacterial microbiome in flowering, which can provide a basis for the development and utilization of moso bamboo.

Analysis of endophytic bacterial community diversity and metabolic correlation in Cinnamomum camphora.

The structure and diversity of microbial communities in the leaves of Cinnamomum camphora at different growth stages were studied by high-throughput sequencing. Moreover, the relationships between microbial communities and borneol content were analyzed in this paper. The results indicated that the community structure of endophytic bacteria in C. camphora exhibited temporal variations, with the microbial diversity presented as follows: T1 (low content period) > T3 (peak period) > T2 (small peak period). The population of endophytic bacteria and the ratio of primary metabolism in the leaves of C. camphora were T2 > T1 > T3, while the metabolic intensity of endophytic bacterial terpenoids and polyketides was T3 > T2 > T1, which had the same trend as borneol content in C. camphora. The metabolic ratio of terpenoids and polyketides in T3 was 7.44% higher than that in T1, while that in T2 was 4.10% higher than that in T1. The abundance and diversity of Clostridium_sensu_stricto_1, Ochrobactrum, Escherichia-Shigella, Pseudomonas, and Massilia significantly promoted the content of terpenoids in C. camphora. Together, those results provide the first evidence that borneol content and potential metabolic intensity in leaves of C. camphora greatly depend on microbial communities composition and diversity.