Kuide Yin

Crop photosynthetic capacity in response to climate change likely constrains crop productivity and adaptability to changing environments, which requests the investigation on the dynamics of photosynthetic parameters over growth season among varieties, especially in cold-temperate regions. Three Japonica rice cultivars i.e., Shoubaimao (SH), Hejiang 19 (HJ); Longjing 31, (LJ). were planted under the control, e[CO₂] (700 μmol mol^-1), warming (2°C above the air temperature) and the co-elevation of [CO₂] and temperature in open-top chambers (OTC). The objective of this study is to examine the rice photosynthetic parameters, water use efficiency (WUE) and yield formation in responses to the co-elevation of [CO₂] and temperature which is the main predicted features of future climate. e[CO₂] significantly increased A_n of SH, HJ and LJ by 37%, 39% and 23% in comparison to 34%, 34% and 27% under elevated [CO₂] plus warming, respectively. However, A_n had a weak response to warming for three cultivars. [CO₂] and temperature co-elevation significantly decreased the stomatal conductance, resulting in a significant increase of the WUE. e[CO₂] significantly increased V_{c, max}, J_max and J_max/V_{c, max}. e[CO₂] significantly increased grain yield and grain number of all cultivars. The positive effect of co-elevation of [CO₂] and temperature on grain yield was less than e[CO₂]. Warming is likely to partially offset the increased photosynthetic rate caused by e[CO₂]. The [CO₂] and temperature co-elevation may be favorable to rice crop with increasing the photosynthetic ability of rice crop and improving water use efficiency. The present study provided evidence that the rice genotypic difference in photosynthetic potential under [CO₂] and temperature co-elevation. Therefore, it is crucial to explore a broader range of phenotypes and cultivars to be applied to climate change response research, advancing the knowledge that climate change impacts rice crop under the cold-temperate climate region.

Biochar is a valuable soil amendment substance. However, no systematic study has investigated the effects of biochar on the microenvironment of saline-sodic soils and maize yield in cold areas of Heilongjiang Province. We investigated variations in soil physicochemical properties, soil bacterial and fungal community structure, maize root formation, plant dry matter accumulation, grain filling rate, and maize yield in saline soils treated with biochar (0, 20, 40, and 80 t/ha). Biochar improved saline soil properties and structure, slightly decreasing bulk density and pH and increasing the water-stable aggregate stabilization rate. Furthermore, the relative abundances of Sphingomonas, Lysobacter, Nitrospira, and Gemmatimonas and the fungal genus Guehomyces were increased, promoting the conversion of soil organic carbon and available nitrogen and phosphorus. Moreover, biochar reduced the relative abundance of some fungal pathogenic genera, including Fusarium, Gibberella, Cladosporium, Alternaria, and Epicoccum. However, shifts in soil bacterial and fungal community structure were indirectly driven by biochar-induced changes in soil physicochemical properties, with organic carbon as the most critical. Biochar promoted maize growth, development, and yield (root length, surface area, volume, dry matter accumulation, grain filling rate, and final weight). Biochar application at 40 t/ha had the greatest effect on soil microenvironment improvement, with the highest maize yield.

Drought stress is a major limiting factor for soybean production. In this study, protein elicitor AMEP412 was applied on soybean seedlings to promote drought tolerance, and its correlation with alterations in the reactive oxygen species (ROS) in leaves was studied. The plants of soybean cv. Suinong 26 were sprayed with AMEP412 at the V1 stage and then treated with drought stress and rehydration. The alterations in phenotypes, physiological indices, ROS levels and antioxidant system as well as lipid peroxidation were monitored. The results showed that spraying AMEP412 significantly promoted the drought tolerance of soybean seedlings. Soybean seedlings pre-treated with AMEP412 performed better in phenotypes and physiological indexes, like leaf relative water content (RWC), leaf relative conductivity (RC) and osmolytes (free proline, soluble sugar and protein). In addition, the in situ and quantification detection of ROS revealed that AMEP412 pretreatment led to higher accumulation of ROS at the early stage and faster scavenging of ROS at the late stage. Moreover, AMEP412 pretreatment increased the activity of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), and the levels of ascorbate (AsA) and glutathione (GSH), but decreased the level of malondialdehyde (MDA) as compared with only drought treatment. Overall, the results indicated that AMEP412 was effective in alleviating the adverse effects of drought stress, which was partially attributable to the ROS accumulation and scavenging triggered by AMEP412.

The mitochondrial calcium uniporter (MCU), as an important component of the Ca²⁺ channel uniporter complex, plays a regulatory role in intracellular Ca²⁺ signal transduction. However, only a few studies to date have investigated plant MCU genes. In this study, we identified the MCU family genes in wild soybean and investigated their expression under cold and carbonate alkaline stresses. Eleven Glycine soja MCU genes (GsMCUs) were identified and clustered into two subgroups (subgroups I and II), and subgroup II could be further divided into two branches (MCU5 and MCU6). A total of 21 pairs of GsMCUs were characterized as duplicated genes, and displayed a similar exon-intron architecture. All GsMCU proteins contained one conserved MCU domain, within which two transmembrane domains were found. An analysis of the conserved motifs further supported that the GsMCUs showed high conservation in protein sequence and structure. Moreover, we found that all GsMCUs were expressed ubiquitously in different tissues and organs, and GsMCUs from the same subgroup displayed varied tissue expression profiles. In addition, based on RNA-seq and qRT-PCR assays, six and nine GsMCUs were differentially expressed under cold and carbonate alkaline stress, respectively. Promoter analysis also uncovered the existence of two canonical cold-related cis-acting elements, LTR and DRE/CRT, as well as stress-related phytohormone-responsive elements. Our results provide valuable information about the MCU family in soybean responses to cold and carbonate alkaline stress, which will be helpful in further characterizing their biological roles in response to abiotic stress.

In previous study, we identified a novel protein elicitor AMEP412 from Bacillus subtilis BU412, which could trigger plant defense response and induce systemic acquired resistance against diseases. In this paper, the production of the new elicitor was optimised. First, optimal carbon source and nitrogen source were determined as glucose and yeast extract by single factor test. Then, effects of seven different factors on AMEP412 production was studied by Plackett-Burman design. Significant factors (yeast extract, culture temperature and culture time) were selected for further optimisation using central composite design by response surface methodology. The optimum conditions for AMEP412 production were yeast extract 21.72 g/L, culture temperature 30.84 °C and culture time 31.84 h. Under these conditions, the yield of AMEP412 was enhanced from 0.32 to 2.39 mg/mL (7.47-fold), which was quite close to the predicted one. This result significantly raised the yield of AMEP412, which laid solid foundation for its application as a biocontrol agent.

Clarifying the bacterial community composition and function in alkali soils is pivotal to the soil capability of sustaining venerable ecosystems. Using MiSeq sequencing, PICRUSt, and Biolog ( https://www.biolog.com ), we investigated the bacterial community composition and metabolic function of microbes in three soils differing in the severity of alkalinity. A high level of alkalinity deceased the diversity of microbial community and altered microbial community composition with the increase in relative abundances of 21 genera. The linear discriminate analysis and effect size analysis found most of 54 biomarkers belonged to Actinobacteria and Proteobacteria. Redundancy analysis indicated that the succession of bacterial community and metabolic characteristics of microbes were highly affected by the nutrient availability and soil moisture. The utilization rates of carbohydrates, amino acids, carboxylic acids, polymers, phenolic compound, and aminesides by microbes were positively correlated with soil nutrient concentrations but negatively correlated with the exchangeable sodium percentage and pH. Severe alkalinity inhibited the microbial community diversity and function on carbohydrate metabolisms.