宁夏农林科学院

To investigate the effects of different ventilation ratios on γ-polyglutamic acid(PGA)production by microbial fermentation,using Bacillus licheniformis BYBC1.21056 as the starting strain,the effects of different ventilation ratios(1.0:0.7,1.0:1.0,1.0:1.3,1.0:1.6,1.0:1.9)on intracellular metabolism and gene expression of strain BYBC1.21056 were analyzed by combining metabolomics and transcriptomics.The results showed that the high ventilation ratio(1.0:1.9)most favored γ-PGA synthesis,achieving a yield of 105.54 g/L,demonstrating that ventilation was a key factor influencing fermentation.Metabolomic analysis results showed that a total of 916,1 164,and 1 081 significantly different metabolites were identified between the experimental group and the control group,respectively,after fermentation 24,48 and 72 h.Among them,the unique significantly different metabolites were 293,563 and 412,respectively.Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis results indicated that,compared with the control group,the significantly upregulated metabolic pathways for significantly different metabolites were tryptophan metabolism,nucleotide metabolism,glycerophospholipid metabolism,purine metabolism,nicotinic acid and nicotinamide metabolism,etc.in the experimental group after fermentation 24,48,and 72 h.Transcriptome analysis results revealed that there were 882 upregulated genes and 1 025 downregulated genes at 24 h,373 upregulated genes and 506 downregulated genes at 48 h,and 461 upregulated genes and 394 downregulated genes at 72 h.The results showed that increasing the ventilation ratio altered gene expression in B.licheniformis,thereby regulating its metabolism and affecting γ-PGA synthesis.

Drought is the primary constraint limiting maize yield improvement.Phenotypic plasticity describes how a given genotype responds to environmental variation;therefore,evaluating drought plasticity in maize inbred lines is essential.Using drought-resistance-related data for 201 inbred lines evaluated across five environments and two water regimes during 2019-2020,we assessed drought resistance using three approaches,including factor analysis,and classified the lines into four levels:highly resistant(HR),resistant(R),moderately resistant(MR),and weakly resistant(WR).Lines such as KA105,KB020,and Zong 31 showed strong drought resistance.Plasticity was then quantified using the Finlay-Wilkinson(FW)regression,and two drought plasticity patterns were defined:G×E positive plasticity(a genotype shows a significantly better positive response than its overall mean performance in specific environments)and no G×E positive plasticity(a genotype performs stably across environments and does not show a significantly better positive response relative to its overall mean in any environment).KA105 and M1801 were classified as the G×E positive plasticity type,whereas 09B-6-2 was classified as the no G×E positive plasticity type.Overall,KA105 combined strong drought resistance with G×E positive plasticity,indicating that it is a promising germplasm source for drought-resistance breeding with potential for broad application.

This experiment aimed to investigate the effects of guanidinoacetic acid on the growth performance,serum biochemical indices,and slaughter performance of weaned Tan × Hu F1 crossbred lambs.A total of 60 healthy weaned male Tan × Hu F1 crossbred lambs with an initial body weight of(29.35±3.39)kg were randomly divided into four groups with 15 replicates per group and one lamb per replicate.The control group was fed a basal diet,while experimental groups 1,2,and 3 were fed the basal diet supplemented with 1.0,2.0,and 3.0 g/d guanidinoacetic acid per lamb,respectively.The pre-test period was seven days,and the formal test period was 60 days.The results showed that compared with the control group,there were no significant differences in final weight,average daily feed intake,average daily gain,and nutrient apparent digestibility of the experimental groups(P＞0.05).The concentrations of total protein(TP),albumin(ALB),and globulin(GLB)in the serum of experimental groups were increased,and serum urea nitrogen(BUN)content was decreased.Total antioxidant capacity(T-AOC)and catalase(CAT)activity in serum were significantly increased in experimental groups 1 and 2(P＜0.05).The total fat thickness(GR value)in experimental group 3 was increased,and the shear force of the longissimus dorsi muscle was significantly decreased in experimental groups 2 and 3(P＜0.05).The study shows that dietary supplementation with guanidinoacetic acid can promote protein metabolism,enhance antioxidant capacity,and improve the meat quality of Tan × Hu F1 crossbred lambs.The recommended supplemental level is 2.0～3.0 g/d guanidinoacetic acid per lamb.

Aims As a dominant and keystone species in temperate coniferous forests of China,Pinus tabuliformis exhibits strong environmental adaptability.Investigating the stoichiometric characteristics of leaves,twigs and roots in both current-year(newly developed)and perennial(≥ 1 year old,mature)organs,as well as their relationships,is essential for understanding intraspecific variation and plant resource allocation strategies. Methods This study was conducted in natural P.tabuliformis forests across nine regions in China.A total of 81 individual trees were sampled to measure the carbon(C),nitrogen(N)and phosphorus(P)content in their six organs(current-year leaves,perennial leaves,current-year twigs,perennial twigs,absorptive roots and transport roots). Important findings(1)Current-year organs exhibited higher N and P contents but lower C∶N,C∶P,and N∶P ratios compared to perennial organs.Stoichiometric traits showed considerable intraspecific variation across organs of different ages,with organ age identified as the primary factor influencing these differences.(2)Standardized major axis analysis revealed that perennial leaves had higher P content per unit mass than current-year leaves,whereas current-year twigs and absorptive roots showed higher C,N and P contents than their perennial counterparts(perennial twigs and transport roots).(3)Additionally,absorptive roots had significantly higher C,N and P contents per unit mass than both current-year leaves and twigs.(4)Redundancy analysis indicated that the main environmental drivers of stoichiometric traits in current-year and perennial leaves were mean annual temperature and soil P content,respectively.The most significant environmental factors affecting the stoichiometric traits of current-year and perennial twigs were annual precipitation and soil P content,respectively;while the main environmental factors influencing absorptive and transport roots were soil moisture and soil N content,respectively.This study reveals the resource allocation strategies and environmental adaptability of leaves,twigs,and roots across different age classes in P.tabuliformis.The findings demonstrate that the studies on the stoichiometry of evergreen species should fully consider age-related differences among organs,which is essential for elucidating their nutrient allocation strategies and environmental adaption mechanisms.