Endophytic Fungi Regulate HbNHX1 Expression and Ion Balance in Hordeum bogdanii under Alkaline Stress.

Plants cope with abiotic stress in several ways, including by collaborating with microorganisms. Epichloë, an endophytic fungus, has been shown to improve plant tolerance to extreme external environments. Hordeum bogdanii is a known salt-tolerant plant with the potential to improve alkaline lands. NHX1 plays a key role in the transport of ions in the cell and is overexpressed in plants with increased salt tolerance. However, the expression levels of HbNHX1 in Epichloë endophytic fungal symbionts in H. bogdanii have not been elucidated. We used Hordeum bogdanii (E+) with the endophytic fungi Epichloë bromicola and H. bogdanii (E-) without the endophytic fungi and compared the differences in the ion content and HbNHX1 expression between the shoots and roots of E+ and E- plants under alkaline stress. The absorption capacity of both K+ and Na+ of H. bogdanii with endophytic fungi was higher than that without endophytic fungi. In the absence of alkaline stress, endophytic fungi significantly reduced the Cl- content in the host H. bogdanii. Alkaline stress reduced SO42- content in H. bogdanii; however, compared with E-, endophytic fungi increased the content of SO42- in E+ plants. With an increase in the alkaline concentration, the expression of HbNHX1 in the roots of H. bogdanii with endophytic fungus exhibited an upward trend, whereas the expression in the shoots exhibited a downward trend first and then an upward trend. Under 100 mmol·L-1 mixed alkaline stress, the expression of HbNHX1 in E+ was significantly higher than that in E-, indicating that endophytic fungi could increase the Na+ region in vacuoles. The external environment affects the regulation of endophytic fungi in H. bogdanii and that endophytic fungi can play a key role in soil salinization. Therefore, the findings of this study will provide technical support and a theoretical basis for better utilization of endophytic fungi from H. bogdanii in saline land improvement.

[Effects of enclosing on soil microbial community diversity and soil stoichiometric characteristics in a degraded alpine meadow]. / å›´å°å¯¹é€€åŒ–é«˜å¯’è‰ç”¸åœŸå£¤å¾®ç”Ÿç‰©ç¾¤è½å¤šæ ·æ€§åŠåœŸå£¤åŒ–å­¦è®¡é‡ç‰¹å¾çš„å½±å“.

Enclosing is an effective rehabilitation measure for degraded pastures that mimics natural recovery of vegetation. To examine the interaction between biotic and abiotic in lightly degraded and enclosing grasslands is helpful for a clear understanding of the structure and function of grassland ecosystem. In this study, soil microbial community and soil stoichiometric characteristics in lightly degraded and 10-year enclosing alpine meadows were studied by high-throughput sequencing and Biolog-Eco methods. The results showed that compared with lightly degraded grassland, the concentration of soil NH4+-N in the enclosing grassland increased significantly, while total K (TK) dramatically decreased. There was no obvious variation in soil total organic carbon (TOC), total N (TN), total P (TP), NO3--N, available P (AP), available K (AK), microbial biomass C (MBC) and microbial biomass N (MBN). The soil microbial biomass C/N was significantly enhanced. The carbon metabolic capabilities of soil microbes in different soil layers of alpine mea-dow were obviously increased with the prolonged incubation time, but there was no significant difference between lightly degraded and enclosed meadows. The OTUs of soil bacteria was significantly higher than that of fungi in alpine meadow. The microbial similarity between lightly degraded and fencing grasslands was 27.0%-32.7%. Enclosing significantly increased the fungal relative richness of Ascomycota, Zygomycetes and Chytridiomycota, while simultaneously decreased the rela-tive abundance of Basidiomycetes. Compared with lightly degraded meadow, the bacterial relative richness of Acidobacteria significantly decreased in enclosing meadow. The community composition of soil fungi and bacteria greatly varied among different soil layers. There was significant difference of fungal community composition in the upper soils between lightly degraded and enclosed grassland. The soil bacterial community diversity was greatly affected by soil TN and AK, while the fungal community diversity was significantly affected by plant aboveground biomass. Soil AK produced great influence on soil microbial carbon source utilization capacity. Generally, long-term grazing exclosure had no significant effects on soil nutrients and soil microbial community diversity of lightly degraded grassland and thus would waste the pasture resources, whereas appropriate grazing could maintain the sustainable utilization of grassland.

[Characteristics of soil microbes and enzyme activities in different degraded alpine meadows]. / é€€åŒ–é«˜å¯’è‰ç”¸åœŸå£¤å¾®ç”Ÿç‰©åŠé ¶æ´»æ€§ç‰¹å¾.

Soil microbial biomass C and N, microbial diversities and enzyme activity in 0-10 cm and 10-20 cm soil layers of different degraded grasslands (non-degradation, ND; light degradation, LD; moderate degradation, MD; sever degradation, SD; and black soil beach, ED) were measured by Biolog and other methods. The results showed that: 1) There were significant diffe-rences between 0-10 cm and 10-20 cm soil layers in soil microbial biomass, diversities and inver-tase activities in all grasslands. 2) The ratio of soil microbial biomass C to N decreased significantly with the grassland degradation. In the 0-10 cm soil layer, microbial biomass C and N in ND and LD were significantly higher than that in MD, SD and ED. Among the latter three kinds of grasslands, there was no difference for microbial biomass C, but microbial biomass N was lower in MD than in the other grasslands. The average color change rate (AWCD) and McIntosh Index (U) also decreased with grassland degradation, but only the reduction from ND to MD was significant. There were no differences among all grasslands for Shannon index (H) and Simpson Index (D). The urease activity was highest in MD and SD, and the activity of phosphatase and invertase was lowest in ED. In the 10-20 cm soil layer, microbial biomass C in ND and LD were significantly higher than that in the other grasslands. Microbial biomass N in LD and ED were significantly higher than that in the other grasslands. Carbon metabolism index in MD was significantly lower than that in LD and SD. AWCD and U index in ND and LD were significantly higher than that in ED. H index and D index showed no difference among different grasslands. The urease activity in ND and MD was significantly higher than that in the other grasslands. The phosphatase activity was highest in MD, and the invertase activity was lowest in MD. 3) The belowground biomass was significantly positively correlated with microbial biomass, carbon metabolic index and phosphatase activity, and the urease activity was negatively correlated with microbial biomass N, H index and D index.

Molecular Phylogeny of Grassland Caterpillars (Lepidoptera: Lymantriinae: Gynaephora) Endemic to the Qinghai-Tibetan Plateau.

Gynaephora (Lepidoptera Erebidae: Lymantriinae) is a small genus, consisting of 15 nominated species, of which eight species are endemic to the Qinghai-Tibetan Plateau (QTP). In this study, we employed both mitochondrial and nuclear loci to infer a molecular phylogeny for the eight QTP Gynaephora spp. We used the phylogeny to estimate divergence dates in a molecular dating analysis and to delimit species. This information allowed us to investigate associations between the diversification history of the eight QTP species and geological and climatic events. Phylogenetic analyses indicated that the eight QTP species formed a monophyletic group with strong supports in both Bayesian and maximum likelihood analyses. The low K2P genetic distances between the eight QTP species suggested that diversification occurred relatively quickly and recently. Out of the eight species, five species were highly supported as monophyletic, which were also recovered by species delimitation analyses. Samples of the remaining three species (G. aureata, G. rouergensis, and G. minora) mixed together, suggesting that further studies using extensive population sampling and comprehensive morphological approaches are necessary to clarify their species status. Divergence time estimation results demonstrated that the diversification and speciation of Gynaephora on the QTP began during the late Miocene/early Pliocene and was potentially affected by the QTP uplift and associated climate changes during this time.