Plant and Soil最新文献

Background and aims

Drought has a substantial adverse impact on maize growth during the jointing stage. Nitrogen (N) is an essential nutrient that fosters the growth and yield of maize. However, the underlying mechanisms behind the connection between N and drought tolerance require elucidation.

Methods

In this study, we explored the effects of drought and N application on maize during the jointing stage using soil column cultivation. The investigation includes phenotypic analyses, measurements of physiological indexes, microstructural observations, and proteomics analyses.

Results

The impacts of N on maize plants under drought stress were as follows: (1) The supply of N enhanced the root water uptake capacity by reducing the biosynthesis of lignin in the root endodermis and increasing the proportion of deep nodal roots; (2) N reduced the inhibition of photosynthate assimilation caused by drought, resulting in increased leaf area, chlorophyll content, biomass and higher levels of growth-promoting hormones; (3) N improved drought tolerance in maize plants, probably caused by N strengthening the root antioxidant system and thus maintaining reactive oxygen species (ROS) homeostasis.

Conclusions

The physiological mechanisms of N in alleviating drought in maize at the jointing stage, as explored in this study, provide a theoretical foundation and potential strategies for dryland maize cultivation or the selection and design of new drought-tolerant maize lines.

Background and aims

Despite plant-soil interactions being able to influence the functional characteristics of vegetation, it remains unclear whether and how the effects of different coastal reclamation patterns on plant-soil interactions would change vegetation allocation strategies and biodiversity.

Methods

This study evaluated the vegetation characteristics, soil quality, and plant-soil interactions in three different types of wetlands: a natural coastal wetland (NCW), a reclaimed wetland with sea embankments on a native wetland (SEW), and a reclaimed wetland formed through land reclamation from the sea (LRW).

Results

The findings indicated that different reclamation patterns significantly impacted the ecological characteristics of Spartina alterniflora and Phragmites australis communities in coastal wetlands (P < 0.05), while Suaeda salsa communities were insensitive to reclamation. Reclamation activities improved the integrated soil quality index by 5% in SEW and 27% in LRW. Notably, enhancing soil quality may boost above ground biomass allocation while reducing biodiversity. Additionally, plant-soil interactions in reclaimed wetlands showed light incoordination, with the higher coordination degree potentially promoting root allocation and biodiversity.

Conclusion

Coastal reclamation impacts plant-soil interactions, varying by reclamation patterns and community types. In the future restoration and management of reclaimed wetlands, zoned management should be implemented according to different types of plant communities, with appropriate thinning and replanting of native species based on the plants growth status to promote species diversity. Moreover, management practices such as improving soil aeration and inoculating beneficial microbial formulations are recommended to enhance coordinated plant-soil interactions.

Graphical abstract

Background and aim

Soil bacterial and fungal communities play different but mutually interrelated roles in releasing enzymes that catalyze organic matter decomposition. In Malaysian Borneo, decreasing litter inputs caused by forest degradation lead to reductions in soil organic carbon (SOC) and C/N ratio. Enzyme activities also decrease with forest degradation. However, it is unclear if/how changes in microbial community compositions affect soil enzymes, despite their importance in ecosystem processes. We investigated how reduced SOC substrate affects microbial community compositions and further influences enzyme activities during forest degradation.

Methods

We used 16S and ITS amplicon sequencing and ergosterol extraction to derive microbial absolute and relative abundances. A principal coordinate analysis was performed on absolute abundances to analyze patterns of bacterial and fungal community compositions. Structural equation modeling (SEM) was conducted to investigate how SOC affects enzyme activities via microbial community compositions.

Results

Fungal community composition shifted more distinctly than bacterial community composition along the forest degradation gradient. SEM suggested that reduced SOC influenced bacterial and fungal community compositions, while fungal community composition affected activities of acid phosphatase, β-glucosidase, and leucine aminopeptidase.

Conclusion

Changes in fungal community composition may be due to different responses of fungal phyla to changing quality of bulk soil organic matter with decreasing litter input during forest degradation. Variations in fungal community composition subsequently induced changes in enzyme activities. By contrast, bacterial community composition did not change because labile organic matter of bacterial substrates was available throughout degradation course, particularly such matter being supplied as fungal decomposition by-products.

Aims

Artificial selection of microbiota is an innovative approach to steer plant phenotype. Still, driving ecological determinants governing the success of this approach are yet to be characterized. We aimed to test the importance of the plant species and the soil type on the effects of selected microbiota.

Methods

We previously selected rhizosphere microbiota associated to Brachypodium distachyon leaf greenness in a sandy cambisol. Three selection treatments were applied: low greenness, high greenness, and random (control). We tested the reproducibility of selected effects by inoculating the evolved microbiota on different Poaceae species (B. distachyon, maize, wheat and oat), either in the sandy cambisol used for selection, or in a clayey calcaric stagnosol.

Results

Maize and wheat were not affected. B. distachyon greenness was altered in the intended way, while oat showed significant, but opposite, phenotypic changes. These effects were reproducible in the two different soils. The rhizosphere microbiota of B. distachyon and oat were significantly impacted by selected inoculants. We identified microbial sub-communities either positively or negatively associated with greenness, revealing the presence of a soil-independent microbial sub-community that is always associated with higher greenness in B. distachyon.

Conclusions

The effect of selected inoculants was dependent on plant species, but not on the soil type. Thus, despite plant species dependency, plant phenotype changes induced by selected microbiota seemed transferable under different pedological contexts. This may have consequences for plant breeding programs that include microbiota selection, as we show that the plant species dependence is paramount for success across different soils.

Background and aims

The impact of fertilization on the temporal dynamics of soil microbial community and function along subtropical forest succession is not well understood. The study aims to explore how the seasonal changes in fungal and bacterial communities and multifunctionality respond to fertilization in two subtropical forest stages.

Methods

Here, we examined soil bacterial and fungal communities using Illumina Miseq sequencing and soil multifunctionality index in a 4-year experiment of nitrogen (N) and phosphorus (P) addition in three growth seasons in young and mature stages in a Chinese subtropical forest.

Results

Our results showed that 10-22.44% variation of total, saprotrophic, ectomycorrhizal (EM) and pathogenic fungal communities were explained by fertilization (2.5-4.5%), forest stage (2.1-2.5%), season (2.3-12.52%) and soil variables (6.8-12.8%). In addition, 8.1-9.9% variation of total, oligotrophic and copiotrophic bacterial communities were explained by fertilization (2.5-3.8%), forest stage (0.7-1.1%), season (2.2-2.7%) and soil variables (5.3-6.6%). Furthermore, the temporal dynamics of the community composition of total, saprotrophic, and EM fungi, but not pathogenic fungi and bacterial groups, were affected by N fertilization in the young forest and by P fertilization in the mature forest (except for saprotrophic fungi). Additionally, the temporal dynamics of soil multifunctionality index was affected by N fertilization in the mature forest, but not in the young forest, and not by P fertilization in either forest stage.

Conclusion

This study revealed that fertilization influenced the temporal dynamics of the soil fungal community and multifunctionality index, but not the bacterial community. However, these effects varied by forest successional stages and fertilization type, underscoring the need to consider both forest stage and fertilization when assessing the impacts of nutrient addition on soil microbes in subtropical forests.

Aims

Copper (Cu) is an essential microelement for plants but it’s toxic at elevated concentration. The natural variation, physiological and genetic basis of rice in response to Cu toxicity was revealed herein.

Methods

The genotypic variation of rice sensitivity to excess Cu was investigated by using a natural collection of 183 rice accessions, Cu deposition in the whole root tips and the cell fractions of Cu-tolerant DF82, DF93 and sensitive ZH11 was determined, the expression levels of the potential genes related to Cu transport and cell wall modeling were compared.

Results

The sensitivity of rice in response to excessive Cu showed large variation with a relative root elongation at 18 ~ 107%. A slightly higher Cu concentrations in the root tips of DF93 than that of DF82 and ZH11 however, more Cu was deposited in the root cell wall and extremely lower Cu was accumulated in the symplastic space of the DF82 and DF93. The expression of OsCOPT1 was reduced in the root tips of DF93, while the transcriptions of OsCOPT7 and OsHMA5 were more abundant. In addition, the expression of several genes encoding the enzymes and receptor kinases potentially involved in cell wall remodeling was regulated by excessive level of Cu, and certain members displayed varied expression pattern in DF93 and ZH11.

Conclusions

The differential partition of Cu in cell wall and symplastic space contributes to the natural variation of Cu tolerance in rice, which is likely attributed to the differentially expressed genes responsible for Cu transport and cell wall remodeling.

Background and aims

Microbial necromass carbon (MNC) is regarded as a considerable source of soil organic carbon (SOC). However, the impacts of fire on MNC and its contribution to SOC remain unexplored in forest ecosystems. In this study, we aim to evaluate how fire affects over the long-term soil MNC and its contribution to SOC in subtropical forests.

Methods

We established a paired fire platform along a recovery time of 1, 5, 9, and 27 years, encompassing high severity burned and unburned plots in subtropical Pinus yunnanensis forests. Soil MNC, SOC, as well as physicochemical soil properties were measured.

Results

Burning effects on SOC and MNC were observed solely in surface layer. Initially, the fire greatly reduced both variables, however, they recovered to pre-fire levels by 9 years post-fire and showed positive responses by 27 years post-fire. Interestingly, we found that fire strengthened the relationships between MNC and microbial α-diversity, as well as litter input. Additionally, reduced litter input resulting from fire, directly or through decreased soil nutrients, explained the loss of MNC across all sites at both soil depths.

Conclusions

Our work provides robust evidence that the effects of fire on MNC and its contribution to SOC largely depend on soil depth, time since fire, and plant litter input. These insights hold significant implications for fire management and post-fire recovery efforts in this and similar forest ecosystems.

Background and aims

Plant investment in secondary metabolites can be driven by abiotic factors such as nitrogen (N) availability and variation in biotic factors such as root-associated microbes. However, few studies have tested their combined effect on allelopathy. Here, we test whether and how N addition (i.e. eutrophication) and soil microbes modify allelopathic effects of the invasive plant Solidago canadensis on germination of the native plant Crepidiastrum sonchifolium.

Methods

We first grew Solidago at three N levels with a live or sterilized soil inoculum. Then we exposed seeds of Crepidiastrum to aqueous extracts made of the Solidago plants. We analysed the biomass, soil microbiome (bacteria and fungi), and flavonoid, phenolic and saponin contents of Solidago, and the effects of the aqueous extracts on germination of Crepidiastrum.

Results

We found that Solidago produced 67% more biomass on live soil than on sterilized soil, and that N addition only resulted in more biomass on live soil. Soils that had been sterilized accumulated higher relative abundances of bacteria involved in N transformation, and tended to have higher relative abundances of pathotrophic fungi. When grown in soil that had been sterilized, the total flavonoid content of Solidago was 22% higher, and the aqueous extracts had stronger negative allelopathic effects on germination of Crepidiastrum.

Conclusion

The presence of natural soil microbial communities may enhance invasiveness of Solidago by promoting its growth and thereby competitive ability, but may simultaneously decrease the negative allelopathic impact on native neighbors.

Background and Aims

Plant roots respond to soil nutrient availability, but also to the identity of neighbor plants, and root exudates play a role therein. However, how root exudates influence root behavior is not well understood.

Methods

A sequence of eight experiments was designed to investigate whether and how root growth and distribution of maize (Zea mays L.) was affected when growing with neighboring wheat (Triticum aestivum L.). We focused on the role of 6-methoxy-benzoxazolin-2-one (MBOA), an important allelochemical in root exudates.

Results

We found that maize roots distributed away from neighboring wheat roots but not from other roots. Root length of maize was reduced by 37%, 40%, and 64% when maize was grown with live wheat plants, with residuals of wheat root exudates, or when directly treated with wheat root exudates, respectively. MBOA concentration in root exudates of wheat/maize intercropping was 315% higher than in maize monoculture. The expression of IAA-related genes in maize roots was down-regulated by the MBOA treatment. MBOA addition decreased maize root length, but wheat root length was not affected under the same concentration.

Conclusions

Our findings demonstrate that root exudate MBOA is an important specific mediator in maize-wheat interspecific interactions, providing new insights into the design and management of sustainable intercropping systems.

Background and aims

Leaf silicon (Si) accumulation may mitigate diverse biotic and abiotic stresses, including nutrient deficiencies. In tropical montane forests, we therefore predicted that leaf litter Si will be negatively correlated with soil fertility, and that leaf litter Si and soil water soluble Si will decrease in colder and wetter environments due to reduced uptake of Si through transpiration and Si leaching from soil.

Methods

We examined leaf litter Si and soil water extractable Si from topsoil and subsoil along soil fertility and climate gradients in two tropical montane forest area, Fortuna (multiple parent materials) and Baru (uniform volcanic deposits) in western Panama. To consider the effects of species turnover on leaf litter Si along the gradients, we measured leaf Si in 136 tree species in this region.

Results

Leaf litter Si was uncorrelated with soil fertility across Fortuna and Baru. As predicted, leaf litter Si and water extractable Si from subsoil increased with temperature and decreased with precipitation only in Baru. High leaf Si accumulation occurred in some families such as Burseraceae, Magnoliaceae and Ulmaceae. Leaf litter Si was correlated with community-weighted mean leaf Si and water extractable Si from subsoil, suggesting synergistic effects of species turnover and subsoil Si availability on leaf litter Si.

Conclusion

Our study suggests that leaf litter Si concentration is not linked with soil fertility. However, variation in leaf litter Si could be driven by climate factors and possibly mediated by species turnover and subsoil Si availability in tropical montane forests.