Arbuscular mycorrhizal fungal diversity is affected by soil salinity and soil nutrients in typical saline-sodic grasslands dominated by <i>Leymus chinensis</i>

Restoring and reconstructing the salt-affected degraded ecosystem is receiving more and more attention in many parts of the world, especially semi-arid areas. Unfortunately, knowledge about the potential role of natural arbuscular mycorrhizal (AM) fungi was limited. This work examined the regional factors that drove the variations in AM fungal diversity in Songnen Plain, a typical saline-sodic degraded grassland. Soils were sampled in 45 random sites, 150 operational taxonomic units (OTUs) belonging to Glomeromycota were identified. Among these OTUs, 129 and 103 OTUs were classified to Glomerales and Glomus, respectively. The coefficients of variation of total diversity index were 35.61% and the total effects of soil salinity and nutrients collectively accounted for 31.2, 11.8, 47.3, and 64.2% of the variations in Sobs, Chao, Shannon, and Simpson indices, respectively. The climatic variables and geographical location had no significant effects on the variations of AM fungal diversity. Multiple linear regression models showed that soil pH, electrical conductivity (EC), available N and organic C were the most main influencing factors. This research highlighted the wide distribution of AM fungi and thus might promote the development of new techniques that apply natural AM fungi to restore saline-sodic degraded grasslands.</p

Image_1_Ionomic and Metabolomic Analyses Reveal Different Response Mechanisms to Saline–Alkali Stress Between Suaeda salsa Community and Puccinellia tenuiflora Community.tif

Soil salinization imposes severe stress to plants, inhibits plant growth, and severely limits agricultural productivity and land utilization. The response of a single plant to saline-alkali stress has been well investigated. However, the plant community that usually works as a group to defend against saline–alkali stress was neglected. To determine the functions of plant community, in our current work, Suaeda salsa (S. salsa) community and Puccinellia tenuiflora (P. tenuiflora) community, two communities that are widely distributed in Hulun Buir Grassland in Northeastern China, were selected as research objects. Ionomic and metabolomic were applied to compare the differences between S. salsa community and P. tenuiflora community from the aspects of ion transport and phenolic compound accumulation, respectively. Ionomic studies demonstrated that many macroelements, including potassium (K) and calcium (Ca), were highly accumulated in S. salsa community whereas microelement manganese (Mn) was highly accumulated in P. tenuiflora community. In S. salsa community, transportation of K to aboveground parts of plants helps to maintain high K+ and low Na+ concentrations whereas the accumulation of Ca triggers the salt overly sensitive (SOS)-Na+ system to efflux Na+. In P. tenuiflora community, enrichment of Mn in roots elevates the level of Mn-superoxide dismutase (SOD) and increases the resistance to saline–alkali stress. Metabolomic studies revealed the high levels of C6C1-compounds and C6C3C6-compounds in S. salsa community and also the high levels of C6C3-compounds in P. tenuiflora community. C6C1-compounds function as signaling molecules to defend against stress and may stimulate the accumulation of C6C3C6-compounds. C6C3-compounds contribute to the elimination of free radicals and the maintenance of cell morphology. Collectively, our findings determine the abundance of phenolic compounds and various elements in S. salsa community and P. tenuiflora community in Hulun Buir Grassland and we explored different responses of S. salsa community and P. tenuiflora community to cope with saline–alkali stress. Understanding of plant response strategies from the perspective of community teamwork may provide a feasible and novel way to transform salinization land.</p

Table_1_Ionomic and Metabolomic Analyses Reveal Different Response Mechanisms to Saline–Alkali Stress Between Suaeda salsa Community and Puccinellia tenuiflora Community.docx

Soil salinization imposes severe stress to plants, inhibits plant growth, and severely limits agricultural productivity and land utilization. The response of a single plant to saline-alkali stress has been well investigated. However, the plant community that usually works as a group to defend against saline–alkali stress was neglected. To determine the functions of plant community, in our current work, Suaeda salsa (S. salsa) community and Puccinellia tenuiflora (P. tenuiflora) community, two communities that are widely distributed in Hulun Buir Grassland in Northeastern China, were selected as research objects. Ionomic and metabolomic were applied to compare the differences between S. salsa community and P. tenuiflora community from the aspects of ion transport and phenolic compound accumulation, respectively. Ionomic studies demonstrated that many macroelements, including potassium (K) and calcium (Ca), were highly accumulated in S. salsa community whereas microelement manganese (Mn) was highly accumulated in P. tenuiflora community. In S. salsa community, transportation of K to aboveground parts of plants helps to maintain high K+ and low Na+ concentrations whereas the accumulation of Ca triggers the salt overly sensitive (SOS)-Na+ system to efflux Na+. In P. tenuiflora community, enrichment of Mn in roots elevates the level of Mn-superoxide dismutase (SOD) and increases the resistance to saline–alkali stress. Metabolomic studies revealed the high levels of C6C1-compounds and C6C3C6-compounds in S. salsa community and also the high levels of C6C3-compounds in P. tenuiflora community. C6C1-compounds function as signaling molecules to defend against stress and may stimulate the accumulation of C6C3C6-compounds. C6C3-compounds contribute to the elimination of free radicals and the maintenance of cell morphology. Collectively, our findings determine the abundance of phenolic compounds and various elements in S. salsa community and P. tenuiflora community in Hulun Buir Grassland and we explored different responses of S. salsa community and P. tenuiflora community to cope with saline–alkali stress. Understanding of plant response strategies from the perspective of community teamwork may provide a feasible and novel way to transform salinization land.</p

Additional file 1 of Metabolic differences of two constructive species in saline-alkali grassland in China

Additional file 1: Table S1. Significantly different primary metabolites between S. salsa and P. tenuiflora. Table S2. Significantly different phenolic compounds between S. salsa and P. tenuiflora

Table_2_Ionomic and Metabolomic Analyses Reveal Different Response Mechanisms to Saline–Alkali Stress Between Suaeda salsa Community and Puccinellia tenuiflora Community.docx

Soil salinization imposes severe stress to plants, inhibits plant growth, and severely limits agricultural productivity and land utilization. The response of a single plant to saline-alkali stress has been well investigated. However, the plant community that usually works as a group to defend against saline–alkali stress was neglected. To determine the functions of plant community, in our current work, Suaeda salsa (S. salsa) community and Puccinellia tenuiflora (P. tenuiflora) community, two communities that are widely distributed in Hulun Buir Grassland in Northeastern China, were selected as research objects. Ionomic and metabolomic were applied to compare the differences between S. salsa community and P. tenuiflora community from the aspects of ion transport and phenolic compound accumulation, respectively. Ionomic studies demonstrated that many macroelements, including potassium (K) and calcium (Ca), were highly accumulated in S. salsa community whereas microelement manganese (Mn) was highly accumulated in P. tenuiflora community. In S. salsa community, transportation of K to aboveground parts of plants helps to maintain high K+ and low Na+ concentrations whereas the accumulation of Ca triggers the salt overly sensitive (SOS)-Na+ system to efflux Na+. In P. tenuiflora community, enrichment of Mn in roots elevates the level of Mn-superoxide dismutase (SOD) and increases the resistance to saline–alkali stress. Metabolomic studies revealed the high levels of C6C1-compounds and C6C3C6-compounds in S. salsa community and also the high levels of C6C3-compounds in P. tenuiflora community. C6C1-compounds function as signaling molecules to defend against stress and may stimulate the accumulation of C6C3C6-compounds. C6C3-compounds contribute to the elimination of free radicals and the maintenance of cell morphology. Collectively, our findings determine the abundance of phenolic compounds and various elements in S. salsa community and P. tenuiflora community in Hulun Buir Grassland and we explored different responses of S. salsa community and P. tenuiflora community to cope with saline–alkali stress. Understanding of plant response strategies from the perspective of community teamwork may provide a feasible and novel way to transform salinization land.</p

Comparative metabolomics of two saline-alkali tolerant plants <i>Suaeda glauca</i> and <i>Puccinellia tenuiflora</i> based on GC-MS platform

Suaeda glauca and Puccinellia tenuiflora are two important saline-alkali tolerant plants that can improve the soil properties. For exploring the different tolerance mechanisms between them, GC-MS-based metabolomics was used to comprehensively evaluate the primary metabolites differences, a total of 51 different metabolites were present in different quantities. The identified compounds were mainly 11 sugars, 7 amino acids, 5 alcohols and 18 organic acids; they play an important role in responding to the saline-alkali stress and distinguish between S. glauca and P. tenuiflora. All identified metabolites classes showed similar trend to largely accumulate in P. tenuiflora roots and S. glauca shoots, this reveals that the two plants used different physiological strategies to cope with saline-alkali stress.</p

Correlation of CD8⁺ CTLs with prognosis in the entire cohort (n = 332).

<p>Using the established CD8⁺ CTLs infiltrate status for Kaplan Meier survival analysis, results demonstrated that positive CD8⁺ CTLs infiltrate status were statistically significant associated with longer DFS (Log-rank test: P = 0.003; Fig. 2A) and longer OS (Log-rank test: P = 0.011; Fig. 2B).</p

The specific responses to mechanical wound in leaves and roots of <i>Catharanthus roseus</i> seedlings by metabolomics

<p>The mechanical wound is one of the unavoidable threats to survival of plants. More researchers focus on the effect of mechanical wound to the over-ground tissues. And the effects of wound to roots were frequently ignored, although it is an important organ for plant growth. In our studies, the metabolomics study was performed to reveal the mechanical wound effects in <i>Catharanthus roseus</i> on roots and leaves by combining gas chromatography-mass spectrometer (GC-MS), liquid chromatograph-mass spectrometer (LC-MS) and statistical analyses. The metabolic response of TIAs and PCs in plants to wound was most active at 0.5 h after treatment via Q value analysis. At this time point, then significantly responsive primary metabolites and specific secondary compounds (TIAs and PCs) were screened by PLS-DA score plot. In this case, the treatments of CK, LT (wound to leaves) and RT (wound to roots) were clearly distinguished. The targeted compounds include 8 sugars, 4 TIAs and 12 PCs and they displayed specific responses to CK, LT and RT treatments. Under RT group, plants invest more resources on the local responses using TIAs and the color reactions to regulate wound close using PCs. Whereas, LT group might lay emphasis on systemic responses via TIAs induced by SA (salicylic acid) and gallic acid. Our studies provide some basic data for further investigations of the defensive mechanism on roots treated by mechanical wound.</p

Bivariate Cox analysis of CD8⁺ CTLs infiltrate status with Ki-67 expression for disease-free survival (DFS) (A) and overall survival (OS) (B) (n = 320).

<p>CTLs cytotoxic T lymphocytes; HR hazard ratio; 95%-CI 95%-confidence interval.</p

Univariate analysis and multivariate Cox analysis of CD8⁺ CTLs infiltrate status for overall survival (OS) in the entire cohort (n = 332).

<p>CTLs cytotoxic T lymphocytes; ER estrogen receptor; PR progesterone receptor; HER-2 human epidermal growth factor receptor 2; HR hazard ratio; 95%-CI 95%-confidence interval.</p>a<p>The total number of available cases for Ki-67 expression in univariate analysis is 320.</p