Comparative analysis of metabolite changes in two contrasting rice genotypes in response to low-nitrogen stress

Identification of metabolites responsible for tolerance to low nitrogen availability(low-N)will aid in the genetic improvement of rice yield under nitrogen deficiency.In this study,a backcross introgression line(G9)and its recurrent parent Shuhui 527(SH527),which show differential responses to low-N stress,were used to identify metabolites associated with lowN tolerance in rice.Differences in metabolite contents in the leaves of G9 and SH527 at three growth stages under low-N stress were assessed by gas chromatography–mass spectrometry.Many metabolites,including amino acids and derivatives,were highly enriched in G9 compared with SH527 under the control condition,suggesting that the two genotypes had basal metabolite differences.Low-N stress induced genotype-specific as well as growth stagedependent metabolite changes.Metabolites induced specifically in G9 that were involved in glycolysis and tricarboxylic acid metabolism were enriched at the tillering and grain filling stages,and metabolites involved in nitrogen and proline metabolism were enriched at the booting stage.Enrichment of pyroglutamate,glutamate,2-oxoglutarate,sorbose,glycerate-2-P,and phosphoenolpyruvic acid in G9 suggests that these metabolites could be involved in low-N stress tolerance.The results presented here provide valuable information for further elucidation of the molecular mechanisms of low-N tolerance in crops.

Identification of quantitative trait loci associated with resistance to Xanthomonas oryzae pv. oryzae pathotypes prevalent in South China

Bacterial blight(BB), which is caused by Xanthomonas oryzae pv. oryzae(Xoo), is an important rice disease responsible for significant yield losses. In the rice-growing regions of South China where BB outbreaks are common, the resistance of cultivars with BB resistance genes Xa4 and Xa21 has been lost because of rapid changes in the Xoo population structure and virulence. In this study, 421 diverse rice accessions were evaluated regarding their resistance to two Xoo strains, namely GD1358(C5) and IV, which are prevalent pathotypes in South China and overcame the resistance of Xa4 and Xa21, respectively. Using the 4.8 mio filtered SNP dataset, we conducted a genome-wide association study, which identified 13 loci associated with BB resistance, including eight new quantitative trait loci(QTL) and five QTL harboring known BB resistance genes: Xa3/Xa26, xa5, Xa35(t), Xa36(t), Xa40, Xa43(t), and xa44(t). Intriguingly, a steep peak was detected on chromosomes 5 and 11. Six QTL including three new ones, were distributed on chromosome 11, whereas a new QTL q BB5.1 and a known QTL were detected on chromosome 5. Haplotype analyses indicated that the LOC;s05 g01610(Os PRAF2) gene within the q BB5.1 region, which encodes a PRAF protein, is associated with BB resistance. Furthermore, Os PRAF2 knockout lines generated using the CRISPR-Cpf1 system were significantly more resistant to Xoo strains than the wild-type plants. Our results provide researchers and breeders with useful information regarding QTL and gene resources,which may be relevant for developing new BB-resistant rice cultivars.

Comparative microRNA profiling reveals microRNAs involved in rice resistant response to bacterial blight

Bacterial blight(BB), which is caused by Xanthomonas oryzae pv. oryzae(Xoo), is one of the most destructive bacterial diseases of rice(Oryza sativa L.). During plant defense responses, micro RNAs(mi RNAs) play important roles in regulating disease resistance. However, the functions of mi RNAs in the interaction between rice and Xoo remain relatively uncharacterized. In this study, we compared the mi RNA profiles of the BB resistant rice introgression line F329 and its susceptible recurrent parent Huang-Hua-Zhan(HHZ) at multiple time points after inoculation with Xoo. A total of 538 known and 312 novel mi RNAs were identified, among which only 17 and 26 were responsive to Xoo infection in F329 and HHZ, respectively. Compared with the expression levels in HHZ, 37 up-regulated and 53 down-regulated mi RNAs were detected in F329. The predicted target genes for the mi RNAs differentially expressed between F329 and HHZ were revealed to be associated with flavonoid synthesis, the reactive oxygen species regulatory pathway, plant hormone signal transduction, defense responses, and growth and development.Additionally, the patterns of interactions between osa-mi R390-3 p, novel_mi R_104, novel_mi R_238,osa-mi R166 k-5 p, osa-mi R529 b, and osa-mi R167 h-3 p and their target genes were further validated by quantitative real-time PCR. Furthermore, we overexpressed osa-mi R167 h-3 p in transgenic plants and proved that this mi RNA positively regulates the resistance of rice to BB. These results provide novel information regarding the mi RNA-based molecular mechanisms underlying the disease resistance of rice. The data presented herein may be useful for engineering rice BB resistance via mi RNAs.

A complete reference genome assembly for foxtail millet and Setaria-db, a comprehensive database for Setaria

Dear Editor,,Foxtail millet(Setaria italica)and its wild ancestor green foxtail(S.viridis),are two C4 genetic model plants known for their desirable traits,such as small size,short life cycle,ease of transformation,and a compact genome size(~420 Mb)(He et al.,2023).Foxtail millet stands out as the only cultivated species within the Setaria genus.As a foundational crop for ancient east Asian agriculture civilization,it possesses remarkable drought and soil-nutrient deficiency tolerance.

恶劣天气如何影响劳动生产率?——基于快递业劳动者的适应行为研究

本文研究恶劣天气对劳动生产率的影响,探讨劳动力对天气的短期适应。研究表明,高温和降雨的恶劣天气对快递员的劳动生产率有显著负向影响。天气对劳动者的影响具有异质性,日派件量较大、年轻、入职时间短的快递员受天气影响更为显著。此外,本文发现劳动者对天气存在一定的短期适应。快递员对高温的敏感程度在8月相较于7月有所降低,并且快递员在一定程度上会根据前后几日的降雨情况调整工作量,从而降低了恶劣天气对劳动生产率的负向影响。本文认为,让劳动者能够在恶劣天气条件下合理灵活安排劳动时间,以减少恶劣天气对劳动者身心的损害,是政策制定的重要方向。

中国乡—城移民创业行为的决定机制——基于社会关系网的分析视角

本文运用2009年中国农村—城市移民调查（RUMIC）数据,研究社会关系网对我国乡—城移民创业选择行为的影响。笔者构建了一个创业选择模型,分析移民在创业和工资性工作两类就业状态之间的选择行为。理论研究发现社会关系网对移民创业选择具有提供创业资本和提高企业家能力两个作用机制。实证研究及进一步的机制检验也验证了理论模型提出的研究假说。本文的研究有助于理解中国社会关系网对于在城市移民中形成＂大众创业＂局面的显著作用及其机理。

公共卫生健康教育与流动人口传染病就医行为研究

本文研究了全国社区(村)公共卫生健康教育对流动人口常见传染病症就医行为的影响,并对其成本--效果进行分析。研究发现,基层公共卫生健康教育显著促进了流动人口就医行为,但对不同人群的效果相异。健康教育方式的有效性排序是:面对面>互联网>报刊等传统媒体。成本--效果分析表明,公共卫生健康教育最具效率的依次是中部、东部和西部地区。本文认为,国家在公共卫生健康教育投入资源的区域配置和培训方式等方面具有较大改善空间。

班级内社会网络与学习成绩——一个随机排座的实验研究

本文对小学生随机排座后的学习成绩进行跟踪研究,考察了班级处于高中心性地位的学生对与其座位距离不同的同伴学习成绩的影响。研究发现:与高中心性学生每减少1个座位距离,平均成绩可提高0.43—0.78个标准差。在中心性距离衡量的6个维度上,高中心性学生对其他学生的影响呈异质性,这可能通过信息传播和模仿机制发挥作用。因此,注重高中心性学生座位距离的辐射效应,探索多样化座位编排,不失为一种提高学生成绩乃至人力资本积累的低成本方案。

Genome-Wide Analysis of Histone Modifications： H3K4me2, H3K4me3, H3K9ac, and H3K27ac in Oryza sativa L. Japonica

While previous studies have shown that histone modifications could influence plant growth and devel- opment by regulating gene transcription, knowledge about the relationships between these modifications and gene expression is still limited. This study used chromatin immunoprecipitation followed by high-throughput sequencing （ChlP-Seq）, to investigate the genome-wide distribution of four histone modifications： di and trimethylation of H3K4 （H3K4me2 and H3K4me3） and acylation of H3K9 and H3K27 （H3K9ac and H3K27ac） in Oryza sativa L. japonica. By analyz- ing published DNase-Seq data, this study explored DNase-Hypersensitive （DH） sites along the rice genome. The histone marks appeared mainly in generic regions and were enriched around the transcription start sites （TSSs） of genes. This analysis demonstrated that the four histone modifications and the DH sites were all associated with active transcription. Furthermore, the four histone modifications were highly concurrent with transcript regions-a promising feature that was used to predict missing genes in the rice gene annotation. The predictions were further validated by experimentally confirming the transcription of two predicted missing genes. Moreover, a sequence motif analysis was constructed in order to identify the DH sites and many putative transcription factor binding sites.

The landscape of gene-CDS-haplotype diversity in rice:Properties,population organization,footprints of domestication and breeding,and implications for genetic improvement

Polymorphisms within gene coding regions represent the most important part of the overall genetic diversity of rice.We characterized the gene-coding sequence-haplotype(gcHap)diversity of 45963 rice genes in 3010 rice accessions.With an average of 226±390 gcHaps per gene in rice populations,rice genes could be classified into three main categories:12865 conserved genes,10254 subspecific differentiating genes,and 22844 remaining genes.We found that 39218 rice genes carry>255179 major gcHaps of potential functional importance.Most(87.5%)of the detected gcHaps were specific to subspecies or populations.The inferred proto-ancestors of local landrace populations reconstructed from conserved predominant(ancient)gcHaps correlated strongly with wild rice accessions from the same geographic regions,supporting a multiorigin(domestication)model of Oryza sativa.Past breeding efforts generally increased the gcHap diversity of modern varieties and'caused significant frequency shifts in predominant gcHaps of 14266 genes due to independent selection in the two subspecies.Low frequencies of“favorable”gcHaps at most known genes related to rice yield in modern varieties suggest huge potential for rice improvement by mining and pyramiding of favorable gcHaps.The gcHap data were demonstrated to have greater power than SNPs for the detection of causal genes that affect complex traits.The rice gcHap diversity dataset generated in this study would facilitate rice basic research and improvement in the future.

“种质资源组学”数据共享与挖掘通用模式:以SoyFGB v2.0为例

Soybean(Glycine max(L.)Merr.)is a crop that originated in China.Soybean is one of the most important sources of edible vegetable protein and oil,and it has become a model legume species in genomic research.Worldwide gene banks,such as the National Crop Genebank of China(NCGC)and the United States Department of Agriculture-Agricultural Research Service(USDA-ARS)Soybean Germplasm Collection.

What Role Does the Political Environment Play in Economic Development？ --A Case Study of Fujian Province

Uncertainty induced by the political environment affects investment risk, and thus affects investment decisions, which have a close relationship with economic development. This paper investigates the economic cost of political instability using the case study of the tense relationship across-Strait in China. We use a synthetic control method to better model the counterfactual analysis of this case study. The intense situation of the relations across-Strait has great influence on the economic development of Fujian province. Fujian province is the closest province in proximity to Taiwan and also possesses the greatest preferential policies for Taiwan Residents direct investment. The empirical results of this study reveal that during 2001-2008 Fujian province＇s average annual loss in GDP per capita was 682.54 yuan. In other words, GDP per capita in Fujian has declined about 12.1 percent annually during this period compared with GDP per capita as calculated by the synthetic control method.