Effects of Allelochemicals on Root Growth and Pod Yield in Response to Continuous Cropping Obstacle of Peanut

Continuous cropping(CC)obstacle is a major threat in legume crops production;however,the underlying mechanisms concerning the roles allelochemicals play in CC obstacle are poorly understood.The current 2-year study was conducted to investigate the effects of different kinds and concentrations of allelochemicals,p-hydroxybenzoic acid(H),cinnamic acid(C),phthalic acid(P),and their mixtures(M)on peanut root growth and productivity in response to CC obstacle.Treatment with H,C,P,and M significantly decreased the plant height,dry weight of the leaves and stems,number of branches,and length of the lateral stem compared with control.Exogenous application of H,C,P,and M inhibited the peanut root growth as indicated by the decreased root morphological characters.The allelochemicals also induced the cell membrane oxidation even though the antioxidant enzymes activities were significantly increased in peanut roots.Meanwhile,treatment with H,C,P,and M reduced the contents of total soluble sugar and total soluble protein.Analysis of ATPase activity,nitrate reductase activity,and root system activity revealed that the inhibition effects of allelochemicals on peanut roots might be due to the decrease in activities of ATPase and NR,and the inhibition of root system.Consequently,allelochemicals significantly decreased the pod yield of peanut compared with control.Our results demonstrate that allelochemicals play a dominant role in CC obstacle-induced peanut growth inhibition and yield reduction through damaging the root antioxidant system,unbalancing the osmolytes accumulation,and decreasing the activities of root-related enzymes.

Oil Crops:A Potential Source of Biodiesel

1.Introduction Oil crops such as soybeans,sunflower,canola,rapeseed,and peanuts play a vital role in the agricultural economy,second only to food crops in terms of area and yield.Vegetable oil is known for its high energy density,containing approximately 2.25 times more calories per unit mass than carbohydrates or protein.Therefore,vegetable oil is an important source of energy and provides a variety of fatty acids necessary for human health.

A Comprehensive Evaluation on Blast-resistant Rice Germplasm Resources in Guizhou Province

Under the condition of natural infection, 60 blast-resistant rice germplasm resources were screened from the blast nursery through many years of natural identifcation, which would provide abundant parent materials for rice blast resistance breeding. The disease level of panicle blast was above grade seven in most of the core materials, including 15 of R grade, 23 of MR grade, 14 of MS grade, 7 of S grade and 1 of HS grade. The results of cross test showed in the F1 generation, 12 rice germplasm resources performed well; and the seed-setting percentages of 17 rice germplasm resources were higher than 50%, and those of 10 were below 5%.

Effect of Nitrogen Fertilizer on the Accumulation and Distribution of Dry Matter in Broomcorn Millet

[Objective] To understand the effect of nitrogen application on dry matter accumulation and allocation dynamics in broomcorn millet. [Method] The accumulation and distribution of dry matter were studied using cultivars Jin Shu 7 and Huang Mizi at different levels of nitrogen fertilizer at the jointing stage. [Result] The results showed that increasing N application led to the increase of green leaf area and the delay of leaf senescence, which was beneficial to the accumulation of dry matter.Appropriate nitrogen application(90 kg/hm2) could coordinate the translocation rate of dry matter among different plant parts, thereby enhancing the yield of broomcorn millet; among different organs, the contribution rate of stem to kernel was greater than that of leaf to kernel; there was obvious correlation between dry matter and yield. For Jin Shu 7, leaf area and dry weight of spike showed significant negative correlation with yield. [Conclusion] The formation of grain yield of broomcorn millet involved the accumulation and allocation of dry matter, the appropriate amount of nitrogen application(90 kg/hm2) could improve the rates of translocation and contribution of dry matter, thereby promoting the yield of broomcorn millet.

Inclusion of peanut in wheat–maize rotation increases wheat yield and net return and improves soil organic carbon pool by optimizing bacterial community

Improving soil quality while achieving higher productivity is the major challenge in the agricultural industry. Wheat(Triticum aestivum L.)–maize(Zea mays L.)(W–M) rotation is the dominant planting pattern in the Huang-HuaiHai Plain and is important for food security in China. However, the soil quality is deteriorating due to the W–M rotation’s long-term, intensive, and continuous cultivation. Introducing legumes into the W–M rotation system may be an effective way to improve soil quality. In this study, we aimed to verify this hypothesis by exploring efficient planting systems(wheat–peanut(Arachis hypogaea L.)(W–P) rotation and wheat rotated with maize and peanut intercropping(W–M/P)) to achieve higher agricultural production in the Huang-Huai-Hai Plain. Using traditional W–M rotation as the control, we evaluated crop productivity, net returns, soil microorganisms(SMs), and soil organic carbon(SOC) fractions for three consecutive years. The results indicated that wheat yields were significantly increased under W–P and W–M/P(382.5–579.0 and 179.8–513.1 kg ha-1, respectively) compared with W–M. W–P and W–M/P provided significantly higher net returns(58.2 and 70.4%, respectively) than W–M. W–M/P and W–M retained the SOC stock more efficiently than W–P, increasing by 25.46–31.03 and 14.47–27.64%, respectively, in the 0–20 cm soil layer. Compared with W–M, W–M/P improved labile carbon fractions;the sensitivity index of potentially mineralizable carbon, microbial biomass carbon(MBC), and dissolved organic carbon was 31.5, 96.5–157.2, and 17.8% in 20–40, 10–40, and 10–20 cm soil layers, respectively. The bacterial community composition and bacteria function were altered as per the soil depth and planting pattern. W–M/P and W–M exhibited similar bacterial community composition and function in 0–20 and 20–40 cm soil layers. Compared with W–P, a higher abundance of functional genes, namely, contains mobile elements and stress-tolerant, and a lower abundance of genes, namely,potentially pathogenic, were observed in the 10–20 cm soil layer of W–M and the 0–20 cm soil layer of W–M/P. SOC and MBC were the main factors affecting soil bacterial communities, positively correlated with Sphingomonadales and Gemmatimonadales and negatively correlated with Blastocatellales. Organic input was the main factor affecting SOC and SMs, which exhibited feedback effects on crop productivity. In summary, W–M/P improved productivity, net returns, and SOC pool compared with traditional W–M rotation systems, and it is recommended that plant–soil–microbial interactions be considered while designing high-yield cropping systems.

Development of an Agrobacterium-mediated CRISPR/Cas9 system in pea(Pisum sativum L.)

Pea(Pisum sativum L.)is an annual cool-season legume crop.Owing to its role in sustainable agriculture as both a rotation and a cash crop,its global market is expanding and increased production is urgently needed.For both technical and regulatory reasons,neither conventional nor transgenic breeding techniques can keep pace with the demand for increased production.In answer to this challenge,CRISPR/Cas9 genome editing technology has been gaining traction in plant biology and crop breeding in recent years.However,there are currently no reports of the successful application of the CRISPR/Cas9 genome editing technology in pea.We developed a transient transformation system of hairy roots,mediated by Agrobacterium rhizogenes strain K599,to validate the efficiency of a CRISPR/Cas9 system.Further optimization resulted in an efficient vector,PsU6.3-tRNA-PsPDS3-en35S-PsCas9.We used this optimized CRISPR/Cas9 system to edit the pea phytoene desaturase(PsPDS)gene,causing albinism,by Agrobacterium-mediated genetic transformation.This is the first report of successful generation of gene-edited pea plants by this route.

Analysis of Genetic Diversity in Natural Populations of Psathyrostachys huashanica Keng Using Microsatellite (SSR) Markers

Psathyrostachys huashanica Keng is endemic to China and only distributed in Huashan Mountain in Shaanxi Province, China. In this study, 15 P. huashanica populations consisting of 450 individuals sampled across their main distribution were investigated by using the simple sequence repeats （SSRs） markers. A total of 184 alleles were detected on 24 SSR loci, and the number of alleles on each locus ranged from 2 to15, with an average of 7.667. The total gene diversity （HT= 0.683） and the coefficient of population differentiation （GST = 0.125） showed that P. huashanica had a relatively high level of genetic variation, and the genetic variation was mainly distributed within the populations. The gene flow among the populations of P. huashanica （Nm = 1.750） was much less than that of the common anemophytes （Nm = 5.24）. Correlation analysis demonstrated that the number of alleles as well as genetic diversity of the five populations of Huangpu valley decreased along with the increase of altitudes, but the correlation was not significant. Implications of these results for future P. huashanica collection, evaluation and conservation were discussed.

Control Effect of Different Concentrations of Herbicide Atrazine on Weed in Foxtail Millet Field

The control effect of different concentrations of herbicide atrazine （before seedling after sowing） on weed in foxtail millet field was compared, which provide theoretical basis for screening suitable herbicides concentration for foxtail millet production. As a result, after spraying 25 and 40 d, plant control effect and fresh weight control effect were best by 4 500 ml/hm^2 processing, and fresh weight control effect reached 83.16% and 86.43%. Compared with spraying water （CK）, yieldincreasing effect was the best in the treatment group with atrazine at 2 250 ml/hm^2, where yield growth rate was 54.31%, followed by the treatment group with atrazine at 3 000 ml/hm^2. Therefore, 2 250 ml/hm^2 was the optiaml concentration of herbicide atrazine for millet production.

Characterization of CsWRKY29 and CsWRKY37 transcription factors and their functional roles in cold tolerance of tea plant

The WRKY gene family is most widely known as being the key plant transcription factor family involved in various stress responses and affecting plant growth and development.In this study,a total of 86 members of the CsWRKY genes were identified from the tea plant genome.Most of these genes contain several important Cis-regulatory elements in the promoter regions associated with multiple stress-responses.These genes were further classified into three groups,I,II,and III,each with 21,58,and 7 members,respectively.We showed evidence that tandem duplications,but not the whole genome duplication,are likely to drive the amplification of CsWRKY genes in tea plants.All the 86 CsWRKY genes showed differential expression patterns either in different tissues,or under exposure to diverse abiotic stresses such as drought,cold acclimation,and MeJA treatments.Additionally,the functional roles of two genes,CsWRKY29 and CsWRKY37,were examined under cold stress;and the silencing of these genes resulted in tea plant phenotypes susceptible to cold stress.Moreover,transgenic Arabidopsis lines overexpressing CsWRKY29 and CsWRKY37 genes showed higher survival rates and lower malondialdehyde levels under freezing treatment than the wild type plants.The core findings from this work provide valuable evolutionary pattern of WRKY gene family and underpinning the underlying regulatory roles of CsWRKY29 and CsWRKY37 from tea plants that conferred cold tolerance in transgenic Arabidopsis plants.

Polymorphism of Kunitz Trypsin Inhibitor Protein in Natural Populations of Wild Soybean in Hebei

Hebei Province is one of the main distribution areas growing wild soybean( Glycine soja ) in China. In this study, 461 seed samples,collected from 18 natural populations in this province, were used to electrophoretically observe the change in forms and their frequencies of the Kunitz trypsin inhibitor protein (KTI)in individual populations and geographical areas. Allelic frequencies accounted for 85% for Tia and 15% for Tib in the total samples. Twelve populations examined were polymorphic at the KTI locus, accounting for over 50% in the populations investigated. Four populations, 22% of all the populations, were found to have natural cross-pollination with varied heterozygote rates of 3% -5.5%, and the average was 1% in the total sampies. Geographically, the mean Tib frequency in the north areas was higher than in the south, and higher in the mountainous area than in the plain areas. The populations in a lake ecological environment (Baiyangdian Lake) were almost monomorphic. No obvious relationship between the frequency and the geographical distance was observed. In addition, we first found a mutation for the absence of the KTI in wild soybean.

Integrated Transcriptome and Small RNA Sequencing Analyses Reveals Insights into the Molecular Mechanism of Seed Germination in Mung Bean

During the life cycle of a plant,seed germination is crucial.Upon ingestion of water,the dry seeds resumed energy metabolism and cellular repair.To dissect the complex mechanisms at the very beginning of seed germination,two approaches including transcriptome and small RNA sequencing were conducted during the water imbibition process of mung bean seeds compared with dry seed.The transcriptome sequencing analysis identified 10,108 differentially expressed genes(DEGs)between dry and imbibed mung bean seeds.KEGG enrichment analyses demonstrated numerous DEGs involved in hormone signaling pathways,carbohydrate,and energy metabolism.Out of the total DEGs,129 genes were investigated to involve in abscisic acid,gibberellin,and ethylene pathways,with 56 genes involved in glycolysis and TCA cycle.Through the analysis of small RNA sequencing among different samples,there were 284 miRNAs found in the imbibed and dried seeds of mung bean containing 213 known and 71 novel miRNAs.From comparison between the two types of seeds,51 miRNAs were differentially expressed.The integrated analyses of transcriptome and miRNAome data showed that 23 DEGs are the putative target genes of 8 miRNAs including miR156,miR171b-3p,miR166e-3p,miR169-1,etc.QRT-PCR was used to validate several DEGs and miRNAs.The data suggested that the seed imbibition process is regulated by a variety of DEGs and microRNAs.Meanwhile,we hope to gain a deeper insight into how mung bean seeds germinate in order to optimize seed growth.

<i>In Situ</i>Conservation of Wild Rice Populations: A Targeted Study of Common Wild Rice <i>Oryza rufipogon</i>from China

Although great accomplishments of in situ conservation have been made during the last decade throughout the world, there is an urgent need to conduct more targeted research to explore many basic questions about crop wild relatives (CWR) in situ conservation such as how to better identify and manage the target in situ conservation populations of CWR. In this study, we performed an extensive field investigation of 201 natural populations or habitats of O. rufipogon, a seriously endangered wild progenitor of cultivated rice in China. Our updated information suggests that: 1) the majority of the natural populations have been extinct throughout China, which leads to serious fragmentation of the population system as a whole;and 2) the survived populations have become small in size and thus fragmented within the population as a result of the loss of subpopulations. To assess the relationships between the biodiversity education and conservation of wild rice, we employed participatory approaches in the field investigation. Our data indicate that the continuous rapid decline of biodiversity education seemed closely related to the extinction of wild rice germplasm. These findings imply the potential necessity and huge challenge for making in situ conservation plans in the future. By means of our understanding of ecogeography, sociology and culture, and population genetics of the species, we propose a strategy for selecting in situ conservation locations as well as priority sites for establishing in situ conservation practices in China.

Control Effects of Different Doses of MCPA-Na Against Weeds in Foxtail Millet Field

[ Objective] The paper was compare the control effects of different doses of MCPA-Na on weeds in foxtail millet field. [ Method ] Different doses of MC- PA-Na were sprayed on foxtail millet field, while artificial weeding and spraying water was designed as control. The strain control effect and fresh weight control effect were calculated. [Result]The strain control effect and fresh weight control effect of 2 250 g/hm^2 MCPA-Na at 25 and 40 d post spraying were the best, and the fresh weight control effects reached 84.19% and 87.23%, respectively. Compared to CK, the yield increase effect of 1 500 g/hm^2 was the best, and the yield increase rate was 54.31% ; followed by 1 125 g/hm^2. Generally, 1 500 g/hm^2 was the best dosage of MCPA-Na in foxtail millet production. [ Conclusion]The paper provided a theoretical basis for screening the best dose of herbicide in foxtail millet production.

Rapid Detection of Fat Content in Chenopodium quinoa Willd by Near Infrared Spectroscopy

This study was conducted to find a method for rapid determination of fat content in complete quinoa （ Chenopodium quinoa Willd） seeds. The near infrared spectra of 100 quinoa samples were collected, and a mathematic model was built using the near infrared spectra, so as to perform prediction. The results showed that within the wavelength range of 1 0 000-4 000 cm ^-1 , the quantification model of fat content built by first derivative ＋vector normalization spectral pre-processing had better calibration and prediction effects, and showed a determination coefficient of cross validation （ r cv^ 2 ） of 0.939 3 and a determination coefficient of validation （ rval^2 ） of 0.923 5. The near infrared spectral model of fat could be used for rapid detection of fat contents in quinoa.

Rapid Detection of Starch Content in Quinoa(Chenopodium quinoa Willd.)by Near Infrared Spectroscopy

This study was conducted to establish a method for rapid determination of crude starch content in complete quinoa （ Chenopodium quinoa Willd） seeds. The near infrared spectra of 100 quinoa samples were collected, and a mathematic model was built using the near infrared spectra within the wavelength range of 1 0 000-4 000 cm^-1 by first derivative ＋vector normalization spectral pre-processing. The results showed that the quantification model of starch content had better calibration and prediction effects, and showed a determination coefficient of cross validation （ r^2 cv ） of 0.914 7 and a determination coefficient of validation （ r^2 val ） of 0.903 1. The determination of starch content in complete quinoa seeds by near infrared spectroscopy is totally feasible.

General and specialized metabolites in peanut roots regulate arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae(AM)fungi form symbiotic associations with plant roots,providing nutritional benefits and promoting plant growth and defenses against various stresses.Metabolic changes in the roots during AM fungal colonization are key to understanding the development and maintenance of these symbioses.Here,we investigated metabolic changes in the roots of peanut(Arachis hypogaea L.)plants during the colonization and development of AM symbiosis,and compared them to uncolonized roots.The primary changes during the initial stage of AM colonization were in the contents and compositions of phenylpropanoid and flavonoid compounds.These compounds function in signaling pathways that regulate recognition,interactions,and pre-colonization between roots and AM fungi.Flavonoid compounds decreased by 25%when the symbiosis was fully established compared to the initial colonization stage.After AM symbiosis was established,general metabolism strongly shifted toward the formation of lipids,amino acids,carboxylic acids,and carbohydrates.Lipid compounds increased by 8.5%from the pre-symbiotic stage to well-established symbiosis.Lyso-phosphatidylcholines,which are signaling compounds,were only present in AM roots,and decreased in content after the symbiosis was established.In the initial stage of AM establishment,the content of salicylic acid increased two-fold,whereas jasmonic acid and abscisic acid decreased compared to uncolonized roots.The jasmonic acid content decreased in roots after the symbiosis was well established.AM symbiosis was associated with high levels of calcium,magnesium,and D-(+)-mannose,which stimulated seedling growth.Overall,specific metabolites that favor the establishment of AM symbiosis were common in the roots,primarily during early colonization,whereas general metabolism was strongly altered when AM symbiosis was well-established.In conclusion,specialized metabolites function as signaling compounds to establish AM symbiosis.These compounds are no longer produced after the symbiosis between the roots and AM becomes fully established.

利用小偃麦附加系对Agropyron elongatum生化标记进行染色体定位

Isoelectric focusing (IFF) technique was used to locate biochemical loci in Agropyron elongatum by using wheat Agropy ron elongatum addition lines. There were six loci being located initially in all. The structural genes of Est E5 and Est E8 were located in 3EL, β Amy 1 in 4EL, Per E1 in 7E, and Per E4 in 5E. The α Amy E1 was relocated in 6EL. Chromosome location of these genes provide evidence of homoeology between wheat groups 3, 4, 6 and Agropyron elongatum chromosome 3E, 4E, 6E, respectively. It also indicated that chromosome rearrangement probably took place between 1E and 7E chromosomes during the evolution of the E genome.

Genetic diversity of Chinese summer soybean germplasm revealed by SSR markers

There are abundant soybean germplasm in China. In order to assess genetic diversity of Chinese sum- mer soybean germplasm, 158 Chinese summer soybean ac- cessions from the primary core collection of G. max were used to analyze genetic variation at 67 SSR loci. A total of 460 alleles were detected, in which 414 and 419 alleles oc- curred in the 80 Huanghuai and the 78 Southern summer accessions, respectively. The average number of alleles per locus was 6.9 for all the summer accessions, and 6.2 for both Huanghuai and Southern summer accessions. Marker diver- sity (D) per locus ranged from 0.414 to 0.905 with an average of 0.735 for all the summer accessions, from 0.387 to 0.886 with an average of 0.708 for the Huanghuai summer acces- sions, and from 0.189 to 0.884 with an average of 0.687 for the Southern summer accessions. The Huanghuai and Southern summer germplasm were different in the specific alleles, allelic-frequencies and pairwise genetic similarities. UPGMA cluster analysis based on the similarity data clearly separated the Huanghuai from Southern summer soybean accessions, suggesting that they were different gene pools. The results indicate that Chinese Huanghuai and Southern summer soybean germplasm can be used to enlarge genetic basis for developing elite summer soybean cultivars by ex- changing their germplasm.

Genome-wide association study for starch content and constitution in sorghum(Sorghum bicolor(L.) Moench)

Starch is the most important component in endosperm of sorghum grain.Usually,two types of starch are present:amylose(AM)and amylopectin(AP).The levels of AM and AP contents play a significant role in the appearance,structure,and quality of sorghum grains and in marketing applications.In the present study,a panel of 634 sorghum(Sorghum bicolor(L.)Moench)accessions were evaluated for starch,AM,and AP contents of grain,which included a mini core collection of 242 accessions from the International Crops Research Institute for the Semi-Arid Tropics(ICRISAT)in India,and 252 landraces and 140 cultivars from China.The average starch content was 67.64%and the average AM and AP contents were 20.19 and 79.81%,respectively.We developed a total of 260000 high-confidence single nucleotide polymorphism(SNP)markers in the panel of 634 accessions of S.bicolor using specific locus amplified fragment sequencing(SLAF-seq).We performed genome-wide association studies(GWAS)of starch,AM,and AM/AP of grain and SNP markers based on a mixed linear model(MLM).In total,70 significant association signals were detected for starch,AM,and AM/AP ratio of grain with P<4.452×10^-7,of which 10 SNPs were identified with significant starch,51 SNPs were associated with AM,and nine SNPs were associated with the AM/AP ratio.The Gene Ontology(GO)analysis identified 12 candidate genes at five QTLs associated with starch metabolism within the 200-kb intervals,located on chromosomes 1,5,6,and 9.Of these genes,Sobic.006G036500.1 encodes peptidyl-prolyl cis-trans-isomerase CYP38 responsible for hexose monophosphate shunt(HMS)and Sobic.009G071800 encodes 6-phospho-fructokinase(PFK),which is involved in the embden-meyerhof pathway(EMP).Kompetitive allele specific PCR(KASP)markers were developed to validate the GWAS results.The C allele is correlated with a high starch content,while the T allele is linked with a low level of starch content,and provides reliable haplotypes for MAS in sorghum quality improvement.

Waxy allelic diversity in common millet(Panicum miliaceum L.) in China

A set of 132 accessions of commonmillet, Panicum miliaceum L., from12 provinces of China were assessed for endosperm starch type （waxy or non-waxy） using I2-KI staining, amylose and amylopectin contents using the dual-wavelength colorimetric method, and genotype of Waxygenes conditioning amylose content by gene sequencing. Endosperm starch content varied from 57.69% to 74.70%, while the amylose and amylopectin contents of the starch ranged from 0 to 23.29% and from 41.99% to 70.24%, respectively. Sequencing two Wx genes, including Wx-L （intron 5-exon 7 and intron 8–9） andWx-S （exon 9–intron 10） revealed several polymorphisms （S0, S？15, LC, LF, LY）. Marker M5-R11 linking to the Wx-S gene may be used to discriminate waxy common millet accessions from non-waxy ones. Among the 132 accessions, 68 with the S？15 allele had waxy endosperm starch with the amylose content range 0–2.58% and 64 accessions with the S0 allele had non-waxy endosperm starch with amylose content range 3.94%–23.29%. Five genotypes including So15/LF （45% of the accessions）, S0/LF （25%）, S0/LY （12%）, S0/LC （11%）, and S？15/LY （7%） were identified. Six new SNPs were detected at the Wx-L locus. These results will facilitate common millet breeding, especially of cultivars free of amylose.