A phenology-based vegetation index for improving ratoon rice mapping using harmonized Landsat and Sentinel-2 data

Ratoon rice,which refers to a second harvest of rice obtained from the regenerated tillers originating from the stubble of the first harvested crop,plays an important role in both food security and agroecology while requiring minimal agricultural inputs.However,accurately identifying ratoon rice crops is challenging due to the similarity of its spectral features with other rice cropping systems(e.g.,double rice).Moreover,images with a high spatiotemporal resolution are essential since ratoon rice is generally cultivated in fragmented croplands within regions that frequently exhibit cloudy and rainy weather.In this study,taking Qichun County in Hubei Province,China as an example,we developed a new phenology-based ratoon rice vegetation index(PRVI)for the purpose of ratoon rice mapping at a 30 m spatial resolution using a robust time series generated from Harmonized Landsat and Sentinel-2(HLS)images.The PRVI that incorporated the red,near-infrared,and shortwave infrared 1 bands was developed based on the analysis of spectro-phenological separability and feature selection.Based on actual field samples,the performance of the PRVI for ratoon rice mapping was carefully evaluated by comparing it to several vegetation indices,including normalized difference vegetation index(NDVI),enhanced vegetation index(EVI)and land surface water index(LSWI).The results suggested that the PRVI could sufficiently capture the specific characteristics of ratoon rice,leading to a favorable separability between ratoon rice and other land cover types.Furthermore,the PRVI showed the best performance for identifying ratoon rice in the phenological phases characterized by grain filling and harvesting to tillering of the ratoon crop(GHS-TS2),indicating that only several images are required to obtain an accurate ratoon rice map.Finally,the PRVI performed better than NDVI,EVI,LSWI and their combination at the GHS-TS2 stages,with producer's accuracy and user's accuracy of 92.22 and 89.30%,respectively.These results demonstrate that the proposed PRVI based on HLS data can effectively identify ratoon rice in fragmented croplands at crucial phenological stages,which is promising for identifying the earliest timing of ratoon rice planting and can provide a fundamental dataset for crop management activities.

Targeted mutations of BnPAP2 lead to a yellow seed coat in Brassica napus L.

The yellow seed trait is preferred by breeders for its potential to improve the seed quality and commercial value of Brassica napus.In the present study,we produced yellow seed mutants using a CRISPR/Cas9 system when the two BnPAP2 homologs were knocked out.Histochemical staining of the seed coat demonstrated that proanthocyanidin accumulation was significantly reduced in the pap2 double mutants and decreased specifically in the endothelial and palisade layer cells of the seed coat.Transcriptomic and metabolite profiling analysis suggested that disruption of the BnPAP2 genes could reduce the expression of structural and regulated genes in the phenylpropanoid and flavonoid biosynthetic pathways.The broad suppression of these genes might hinder proanthocyanidin accumulation during seed development,and thereby causing the yellow seed trait in B.napus.These results indicate that BnPAP2 might play a vital role in the regulatory network controlling proanthocyanidin accumulation.

化学实验教学改革促进师范院校培养卓越化学教师

实验教学是验证理论知识、培养实验技能、提高学生科学素养的重要途径。在课程思政引领下,广西师范大学化学与药学学院通过科学设计化学实验课程教学大纲,精心组织教学内容,开展“学”、“练”、“讲”、“写”相互协同的实验教学,实施能力导向的过程性考核评价,在实验教学中实现师范性和学术性的深度融合,促进师范院校培养高素质、专业化、创新型、卓越化学教师。

基于硼酸盐亲和辅助电化学调控ATRP的癌胚抗原超灵敏电化学适体传感研究

癌胚抗原(CEA)是一种酸性糖蛋白,其作为一种广谱肿瘤标志物在恶性肿瘤的鉴别诊断与监测等方面具有重要价值。在此,借助于硼酸盐亲和辅助电化学调控原子转移自由基聚合(BA-eATRP)的双重信号放大作用,我们报道了一种电化学适体传感器,用于CEA的超灵敏、高选择性检测。基于BA-eATRP的电化学CEA适体传感的基本原理为:待核酸适体捕获CEA抗原后,借助于苯硼酸(PBA)基团与单糖残基上的顺式二醇基团间的选择性亲和相互作用将ATRP引发剂位点靶向性地共价偶联到CEA抗原上;随后,以二茂铁甲基丙烯酸甲酯(FcMMA)作为单体,借助于eATRP将二茂铁(Fc)探针引入电极表面。由于CEA上含有数百个顺式二醇基团,基于硼酸盐亲和的交联反应可使得在每个CEA抗原上标记数百个ATRP引发剂分子。此外,通过eATRP反应,可以在电极表面接枝长的二茂铁基聚合物链,使得每个标记有ATRP引发剂的位点均能连接上成百上千个Fc探针。因此,BA-eATRP可使得每个CEA抗原上标记上大量的Fc探针。在最佳条件下,基于BA-eATRP的电化学适体传感器能够实现浓度低为0.34Pg·mL^(-1)的CEA的高选择性检测,其线性范围为1.0-1000pg·mL^(-1)。而且,该适体传感器可用于人血清中CEA的定量分析。基于BA-eATRP的电化学适体传感器具有成本低廉、操作简便等优良特性,在CEA的超灵敏、高选择性检测方面具有广阔的应用前景。

Establishment of new convenient two-line system for hybrid production by targeting mutation of OPR3 in allopolyploid Brassica napus

The two-line pollination control system,which usually depends on the utilization of thermosensitive or photoperiod genic male-sterile lines,has been widely used in various crops.However,this system is susceptible to instability issues caused by uncontrollable weather fluctuations.A stable and handy two-line pollination control system is highly desirable in many crop species for heterosis exploitation.Oxophytodienoic acid reductase 3(OPR3)was proven to be involved in jasmonate biosynthesis.In the present study,CRISPR/Cas9(Clustered Regularly Interspaced Short Palindromic Repeat)was utilized to mutate two OPR3 homologs in Brassica napus.After two OPR3 homologs were simultaneously mutated,mutants exhibited complete male sterility,and fertility could be easily restored by exogenous MeJA treatment.Hybrids produced from crosses between the opr3 sterile lines and normal varieties exhibited heterosis.This new two-line system based on OPR3 mutation provides higher stability and convenience than traditional systems.By using exogenous MeJA treatment to restore fertility,the system enables more precise control of male fertility transition,which has great potential to significantly contribute to the maneuverable production of hybrid seeds in rapeseed as well as other Brassica species crops.

Rapeseed research and production in China

Rapeseed(Brassica napus L.) is the largest oilseed crop in China and accounts for about 20% of world production.For the last 10 years,the production,planting area,and yield of rapeseed have been stable,with improvement of seed quality and especially seed oil content.China is among the leading countries in rapeseed genomic research internationally,having jointly with other countries accomplished the whole genome sequencing of rapeseed and its two parental species,Brassica oleracea and Brassica rapa.Progress on functional genomics including the identification of QTL governing important agronomic traits such as yield,seed oil content,fertility regulation,disease and insect resistance,abiotic stress,nutrition use efficiency,and pod shattering resistance has been achieved.As a consequence,molecular markers have been developed and used in breeding programs.During 2005–2014,215 rapeseed varieties were registered nationally,including 210 winter-and 5 spring-type varieties.Mechanization across the whole process of rapeseed production was investigated and operating instructions for all relevant techniques were published.Modern techniques for rapeseed field management such as high-density planting,controlled-release fertilizer,and biocontrol of disease and pests combined with precision tools such as drones have been developed and are being adopted in China.With the application of advanced breeding and production technologies,in the near future,the oil yield and quality of rapeseed varieties will be greatly increased,and more varieties with desirable traits,especially early maturation,high yield,high resistance to biotic and abiotic stress,and suitability for mechanized harvesting will be developed.Application of modern technologies on the mechanized management of rapeseed will greatly increase grower profit.

Genome editing opens a new era of genetic improvement in polyploid crops

Sequence-specific nucleases(SSN) that generate double-stranded DNA breaks(DSBs) in genes of interest are the key to site-specific genome editing in plants. Genome editing has developed into one method of reducing undesirable traits in crops by the induction of knockout mutations. Different SSN-mediated genome-editing systems, including LAGLIDADG homing endonucleases or meganucleases, zinc-finger nucleases, transcription activator-like effector nucleases and clustered regularly interspaced short palindromic repeats, are emerging as robust tools for introducing functional mutations in polyploid crops including citrus, wheat, cotton, soybean, rapeseed, potato, grapes, Camelina sativa,dandelion, and tobacco. The approach utilizes knowledge of biological mechanisms for targeted induction of DSBs and their error-prone repair, allowing highly specific changes at designated genome loci. In this review, we briefly describe genome-editing technologies and their application to genetic improvement of polyploid crops.

Mitochondrial localization of ORF346 causes pollen abortion in alloplasmic male sterility

The Nsa cytoplasmic male sterility(CMS) system confers stable male sterility and offers great potential for production of hybrid seeds in oilseed rape. However, genes responsible for male sterility in Nsa CMS have not been identified. By mitochondrial genome sequencing of Nsa CMS and its maintainer line,we identified in an Nsa CMS line several chimeric genes encoding hypothetical proteins harboring transmembrane domains. One novel chimeric gene orf346 showed high identity with cox1 at the 50 terminal region and was co-transcribed with nad3 and rps12 genes. Transgenic plants of orf346 fused with or without mitochondrial targeting peptide conferred complete male sterility in Arabidopsis. ORF346 was mitochondrion-localized. Expression of orf346 in Escherichia coli inhibited bacterial growth, with excessive accumulation of reactive oxygen species and decreased ATP content. These results reveal a link between the newly identified mitochondrial gene orf346 and the abortion of Nsa CMS. Inadequate energy supply and excessive accumulation of reactive oxygen species may account for pollen abortion in Nsa CMS plants.

A lignified-layer bridge controlled by a single recessive gene is associated with high pod-shatter resistance in Brassica napus L.

Pod shattering causes severe yield loss in rapeseed(Brassica napus L.)under modern agricultural practice.Identification of highly shatter-resistant germplasm is desirable for the development of rapeseed cultivars for mechanical harvesting.In the present study,an elite line OR88 with strong shatter resistance and a lignified-layer bridge(LLB)structure was identified.The LLB structure was unique to OR88 and co-segregated with high pod-shatter resistance.The LLB structure is differentiated at stage 12 of gynoecium development without any gynoecium defects.Genetic analysis showed that LLB is controlled by a single recessive gene.By BSA-Seq and map-based cloning,the resistance gene location was delimited to a0.688 Mb region on chromosome C09.Transcriptome analysis suggested Bn TCP8.C09 as the gene responsible for LLB.The expression of Bn TCP.C09 was strongly downregulated in OR88,suppressing cell proliferation in the pod valve margin.KASP markers linked to the candidate gene were developed.This pod shatter-resistant line could be used in rapeseed breeding programs by direct transfer of the gene with the assistance of the DNA markers.

Complete organelle genomes of Sinapis arvensis and their evolutionary implications

Sinapis arvensis,belonging to the genus Sinapis of the family Brassicaceae,has good agronomic characters that make it a valuable genetic resource for crop improvement and is a cytoplasmic source of heterologous cytoplasmic male sterility(CMS).In addition,S.arvensis has played an important role in the evolution of the six major cultivated Brassica species involved in the triangle of U.Using next-generation sequencing,we assembled and revealed the gene composition of S.arvensis cytoplasmic genome.The chloroplast genome comprises 153,590 bp,with 112 individual genes,including 4 r RNA,29 t RNA,and 79 proteincoding genes.The mitochondrial genome comprises 240,024 bp,with 54 genes,including 18 t RNA,three r RNA and 33 protein-coding genes.Genome structure and evolutionary analysis indicated that the sequences of the S.arvensis organellar genomes were more similar to those of Brassica nigra and B.carinata than to those of other Brassicaceae species.Four mitochondrial open reading frames displaying chimeric structural features and encoding hypothetical proteins with transmembrane domains may account for the infertility of Nsa CMS previously derived from somatic cell hybridization between B.napus and S.arvensis.These results will not only contribute to utilize the germplasm resource of S.arvensis,and comprehend the evolution of organelle genomes within the Brassicaceae family,but also help to identify genes conditioning the alloplasmic male sterility of Nsa CMS in B.napus.

Identification of compact germplasm resources suitable for high density cultivation in Brassica napus L.

Branch angle is an important plant architecture trait and is considerably important for the ideal plant architecture of high density cultivation of rapeseed. In this study,12 representative rapeseed lines were first measured for whole-plant branch angles using image processing technology. Top branch angle (TBA) and basal branch angle (BBA) were significantly different in each line in which TBA was greater than BBA. Then, 156 rapeseed germplasm lines were evaluated for TBA and BBA in main cultivated regions of the Yangtze River Basin (Zunyi; Wuhan; Lu'an). In these three environments, the TBA and BBA of the rapeseed germplasm sources varied, in which ranges of 33.44°-73.17°and 18.73°-59.11°, 29.66°-61.91°and 22.32°-60.16°, and 28.47°-76.32°and 22.98°-72.68°, respectively. ANOVA showed that TBA and BBA were susceptible to environmental and had broadsense heritability (H2) values of 89.09%and 87.40%, respectively. Interactions of genotype by environment were also significant. There was diversity in branch angle among rapeseed genotypes. GGE biplot analysis showed that compact accession lines (Nilla, Purler and AV-SAPPHI) were the most desirable compact genotypes in all environments. Stability analysis showed that the genotype with the most minimum branch angle was stable for compact plant architecture.

Antimicrobial and Antioxidant Activities of Extracts from Bulbs of Lycoris aurea

[Objectives]To explore the antimicrobial and antioxidant activities of flavonoid and polysaccharide extracts from bulbs of Lycoris aurea.[Methods]The disc diffusion method was used to evaluate the antimicrobial activity of flavonoid and polysaccharide extracts from the bulbs of L.aurea.The antioxidant activity was determined by scavenging of hydroxyl and 1,1-diphenyl-2-picrylhydrazine(DPPH)free radicals,and reducing ability.[Results]Flavonoids were effective on 7 microorganisms,but polysaccharides had no effect.Flavonoids had better hydroxyl free radical scavenging activity and reducing capacity than polysaccharides,but weaker than ascorbic acid.However,flavonoids had similar DPPH free radical activity to ascorbic acid.The strong antibacterial and antioxidant activities of flavonoids were mainly attributed to the high content of total phenols in the extract,which was(76.71±4.42)mg/g.[Conclusions]The study shows that flavonoids from bulbs of L.aurea could be regarded as a new potential source of natural bacterial inhibitors and antioxidants.

An efficient approach for obtaining plant organelle genomes

Plant organelle(plastid and mitochondrial)genomes contain substantial information for plant evolution and adaptation.Therefore,it’s important to reveal plant whole-genome sequences including plastid and mitochondrial genomes.To decode these sequences,it is required to efficiently separate organelle genomic DNA from nucleus genome,which is difficult and laborious.In this study,an efficient procedure was established to obtain plant organelle genomes without extraction of plastid and mitochondria.Organelle DNA was extracted from three materials including Sinapis arvensis var.‘Yeyou 18’,a cytoplasmic male sterile line(Nsa CMS)and its corresponding maintainer line‘Zhongshuang 4’.DNA was sequenced by Roche 454 FLXt and Illumina Miseq platforms.Organelle genomes were assembled using the generated reads and public organelle genome sequences.This research presented a procedure that efficiently assembled organelle genomes and subsequent fill gaps by extending the consensus contig terminals.This method enabled us to assemble plant plastid and mitochondrial genomes simultaneously.The obtained organelle genomes could accelerate understanding of mitochondrial rearrangements and laid a foundation for further study of Sinapis arvensis evolution and sterility gene of Nsa CMS.

QTL mapping for yield components of Brassica napus L. using double haploid and immortalized F_2 populations

Effective silique number per plant(ESN), seeds per silique(SS), thousand seeds weight(TSW), silique length(SL) and silique density(SD) are important seed yield potential determinant traits in rapeseed(Brassica napus L.), which are controlled by quantitative trait loci(QTL). Mapping QTL to delimited chromosomal region offers an effective method for genetic dissection of these traits. A set of 96 double haploid(DH) lines were developed by crossing 2 Brassica napus lines R1 and R2, and an immortalized F_2(IF_2) population containing 124 combinations was developed by crossing those DH lines. DH populations were planted at 2 locations for 2 years and IF_2 populations were planted in 2 locations for 1 year. Based on the established 2,217.2 cM length high density genetic map, 42 QTLs were identified, with 26 QTLs detected repeatedly in different environments or populations, including 8 for SL, 7 for TSW, 4 for ESN, 4 for SS and 3 for SD. Among these identified QTLs, 3, 4, 1, 1 and 3 QTLs were considered as major QTLs for SL, TSW, ESN, SS and SD, respectively. In addition, 2 QTLs on A9 chromosome which control multiple traits were identified. These results warrant further study of fine mapping for yield and yield components.

Genetic relationship of rapeseed yield-related traits revealed by elite lines under multiple environments

To provide a theoretical basis for further improvement of Brassica napus yield, additive dominance with additive - by - additive epistatic effects （ ADAA） genetic model and a 6 X 8 partial dial- lel cross design were used to analyze the genetic effects and correlations of five yield related traits of 14 excellent Brassica napus parental lines and their 46 and F2 populations. The results showed that silique density （SD） , siliques per plant （SPP） , seeds per silique （SPS） and thousand - seed weight （TSW） exhibited not only additive and dominant effects, but also significant epistatic effects. The dominant effects of all five yield - related traits were obviously greater than their additive effects and epistatic effects. Yield per plant （YPP） showed significant genetic correlation with SD, SPP and SPS, and the main component of the genetic correlation was the dominance correlation. SPP and SPS both showed a significant negative correlation with TSW. The SD of rapeseed was genetically correlated with all three components of yield to a certain extent, and there were different components of genetic effects positively correlated with the three yield components, indicating that SD is a potential trait to reconcile the conflict between TSW and SPP as well as SPS.

Chromosome-scale genome assembly-assisted identification of Brassica napus BnDCPA1 for improvement of plant architecture and yield heterosis

Plant architecture can act as a pivotal determinant of crop yield by maximizing photosynthate accumulation in grains,but no B.napus rapeseed ideotype has yet been defined.However,semi-dwarf and compact(SDC)rapeseed plant types with the capacity to maximize silique number per hectare and seed weight per silique are expected to optimize plant architecture for groundbreaking seed yield,avoiding lodging and promoting mechanical harvest(Liu et al.,2022).In this study,we report the mutant dc1,which exhibits DC plant architecture with significantly increased silique number in the main inflorescence compared with currently cultivated high and loose(HL)plant types like those of elite cultivars(Figure 1A and Supplemental Figure 1).

Benzisoxazole core and benzoxazolopyrrolidine via HDDA-derived benzyne with PTIO/DMPO

A novel method for HDDA-derived benzyne trapped by nitrone was developed. This research described a simple and efficient pathway for the synthesis of benzisoxazoles from arynes and PTIO(2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl), C-C and C-O bonds were formed in a single step without catalyst under mild conditions. The unexpected cleavage of C-N bond contributed to the formation of isoxazole ring, as indicated by DFT studies. Furthermore, we obtained the structure of benzoxazolopyrrolidine when the trapping agent is DMPO(5,5-dimethyl-1-pyrroline N-oxide).

一株3-苯氧基苯甲酸降解菌的筛选及其协同Bacillus licheniformis G-04降解高效氯氰菊酯的研究

【目的】从长期受拟除虫菊酯类农药污染的白菜根系土壤分离1株3-苯氧基苯甲酸(3-phenoxybenzoic acid, 3-PBA)降解菌,并探究其与Bacillus licheniformis G-04协同作用对高效氯氰菊酯(beta-cypermethrin,Beta-CP)的降解及污染土壤的生物修复,为土壤农药残留危害处理提供优良菌种。【方法】采用富集驯化、筛选纯化方法,筛选3-PBA降解菌,并通过形态和生理生化特征以及16S rRNA序列分析进行鉴定。利用Origin 8.0分析3-PBA降解菌与B. licheniformis G-04的生长降解动力学过程。同时,采用高效液相色谱法评估两菌株协同降解Beta-CP的能力及其对受Beta-CP污染土壤的修复作用。【结果】筛选得到1株3-PBA高效降解菌HA516,48 h对3-PBA (100 mg/L)的降解率达到87.73%,经鉴定为皮特不动杆菌(Acinetobacter pittii);构建了该菌株和B. licheniformis G-04的生长降解动力学方程,结果表明模型与实验数据能较好拟合;以6.7∶3.3的接种比例先接种B. licheniformis G-04,24 h后再接入A. pittii HA516协同作用,在48 h,Beta-CP (50 mg/L)的降解率达78.37%,较单菌株(B. licheniformisG-04)的降解率(40.47%)提高了37.90%,半衰期从58.39h缩短为24.51h。土壤修复实验表明,第7天协同组对Beta-CP(30mg/kg)的降解率较单菌株提高了33.26%,达到79.27%。【结论】A.pittiiHA516是1株3-PBA高效降解菌,能与B. licheniformis G-04协同增效降解Beta-CP,可作为修复3-PBA或拟除虫菊酯类农药污染的优良微生物资源。

Zipfian interpretation of textbook vocabulary lists： comments on Xiao et al.＇s Corpus-based research on English word recognition rates in primary school and word selection strategy

Now that the latest technology can process huge amounts of data that was previously unimaginable, scientists can challenge established beliefs and prac- tices in many information-related fields. Xiao et al. （2017） made such a challenge, focusing on the effec- tiveness of English textbooks popularly used in Chi- nese primary schools. They first assumed that pupils＇ word recognition rate would equal the coverage rate of their textbook vocabulary lists. Then they used four reference corpora to calculate the latter, one of which was self-developed with an automatic web crawler. Finally, they concluded that textbook vocabulary lists were limited in timeliness, that the word recognition increment of the 6th graders was relatively small, and that word selection in textbook compilation should be adjusted. We would like to comment on their study from a Zipfian perspective as applied linguists in language acquisition.

Adsorption and desorption mechanisms on graphene oxide nanosheets: Kinetics and tuning

A knowledge of the adsorption and desorption behavior of sorbates on surface adsorptive site(SAS)is the key to optimizing the chemical reactivity of catalysts.However,direct identification of the chemical reactivity of SASs is still a challenge due to the limitations of characterization techniques.Here,we present a new pathway to determine the kinetics of adsorption/desorption on SASs of graphene oxide(GO)based on total internal reflectance fluorescence microscopy.The switching on and off of the fluorescent signal of SAS lit by carbon dots(CDs)was used to trace the adsorption process and desorption process.We find that sodium pyrophosphate(PPi)could increase the adsorption equilibrium of CDs thermodynamically and promote the substrate-assisted desorption pathway kinetically.At the single turnover level,it was disclosed that the species that can promote desorption may also be an adsorption promoter.Such discovery provides significant guidance for improving the chemical reactivity of the heterogeneous catalyst.