Abstract:The potato has been cultivated and domesticated in South America for tens of thousands of years,but its spread between continents has only occurred in recent centuries as navigation is the only possible way.However,when and how the potato was introduced to China is still uncertain.According to the historical data of navigation and the earliest discovery of unique species between continents,it is possible that the introduction of potato to China may be in the 21st year of Yong Le of Ming Dynasty (1423) when ZHENG He returned from his sixth voyage.Results of analyzing the local chronicles showed that the potato was first planted mainly in the Peking in the first 200 years,and gradually became a royal delicacy.During the Qing Dynasty,it was widely spread in Wumeng,Wuling and Qinba mountainous regions adjacent to each other,where was the earliest concentrated potato producing area in China.

Abstract:Potatoes were scattered only in isolated mountainous areas in the late Ming and early Qing Dynasties. Its adaptation to the cold and barren land made potatoes a food for the civilians to relieve the famine in the southwestern China and its adjacent areas in the middle and late Qing Dynasty,which also provided a large number of immigrants with food security for the Qing government to implement and consolidate the national governance system of “replacement of chieftains with centrally-appointed non-hereditary officials” in the southwestern China. Its high-yield characteristics make the development of potatoes an important measure to ensure the supplies for the civilian and army during the Anti-Japanese War. Since 1950,the area,production and output value of the potato have continued to increase as the national economic development plans implemented. Its contribution to the total output value of staple crops is averagely above two times of its cultivation proportion. The potato industry will further take its unique biological advantages and highlight its important strategic position in ensuring national food security,agricultural efficiency and meeting demand-side food diversification and health needs.

Abstract:Science and technology is the support of industrial development,and solving the problems faced by industrial development has always been the purpose of scientific research on potato. Only after the overthrow of the Qing Dynasty monarchy,China began systematic scientific researches on potato. So far it has only a history of more than a hundred years. Magnificently,each stage has its outstanding goals and remarkable achievements. The variety screening and hybrid breeding started in the 1930s laid the foundation for the first variety renewal in the 1950s,with a significant increase of yield. Continuous support by the national potato science and technology projects during the "Sixth Five-Year Plan" to "Ninth Five-Year Plan" in China encouraged a systematic research on breeding,cultivation zoning,germplasm evaluation and seed potato propagation which accelerated a rapid development of the industry,so that China has become the largest potato producer in the world. The application and applied basic research since the new century has provided a strong support for improving quality and efficiency of potato industry. In particular,the studies on genetic regulation of potato traits,which is at the forefront of the disciplines,have enhanced the potential of technological innovation and competition in science and technology,and will further promote the strategic position of the potato in ensuring national food security and meeting the needs of healthy life. 

Abstract:Potato (Solanum tuberosum L.) is the world’s largest non-cereal food crop and plays an important role in the global economy and food security. Tubers are economic organs and reproductive organs of potato. They store a large amount of starch,and their development process is regulated by sugar signals. Sugar signal regulates potato tuber morphogenesis and sink-source relationship. This article summarizes the progress on plant sugar signal pathway,sugar signal regulating potato tuber morphogenesis,source-sink relation and its cross-talk with photoperiod,plant hormones and other signal pathways. On this basis,the model of sugar signal regulating potato tuber development was proposed to provide a reference for further elucidating the mechanism of sugar signal regulating potato tuber development.

Abstract:Zinc is an essential microelement for plants and human body. For a long time,zinc deficiency has been a global public health problem and one of the important factors leading to human disease and death. At present,more than 2 billion people worldwide are facing the health problems caused by zinc deficiency. The population of zinc deficiency in developing countries is particularly serious,and there are as many as 100 million zinc-deficient populations in China. 76% zinc in human body comes from plant food,and low content of zinc in crops is an important cause of zinc deficiency in human body and various symptoms of zinc deficiency or diseases. Therefore,eating natural zinc-rich plant foods is considered to be the basic way to solve the problem of zinc deficiency in human body. Potato is the fourth largest food crop in the world following rice,wheat and corn. It has high yield and rich nutrition. It is cultivated worldwide and is one of the important food sources for human beings,it also has great potential in zinc biofortification. In 2015,China began to implement a potato staple food strategy,aiming to ensure the national food security and adjust the dietary structure of the residents to promote human health. In this context,it is of great significance to study nutritional characteristics of zinc and zinc biofortification in potato to achieve zinc-rich potatoes,and then to improve human zinc nutrition and health through dietary supplements. The nutritive function of zinc in potato,the status of soil zinc in potato production areas,breeding and agronomic fortification was summarized and prospected in this article. It is proposed that zinc plays an important role in growth,yield and quality formation of potato. Agronomic fortification is currently the main technical measure for fortifying zinc nutrition in potato. Breeding fortification requires further discovery and utilization of elite germplasm resources to lay a good germplasm foundation for producing zinc-rich potatoes.

Abstract:Acrylamide exists in starch-rich foods processed with high-temperature and is carcinogenic. There are many ways to produce acrylamide,and the Maillard reaction is the most important way to produce acrylamide. The multiple ways to produce acrylamide bring great troubles to the control of acrylamide in the product as well. Potato tubers are rich in substrates of Maillard reaction including asparagine and reducing sugars,which are the easiest food to form acrylamide. Reducing the content of acrylamide has always the major problem faced by the industry of processing potato. In order to guide the safe production of processing potato scientifically,especially snack foods,the acrylamide formation pathways,control paths and methods of acrylamide in processing potato were sorted out systematically,and the effects of different control conditions on the acrylamide formation were evaluated based on the statistical methods of literature. The results showed that controlling the substrate concentration,blanching,using CaCl2,NaCl,Cys,and controlling the cooking conditions can effectively control the acrylamide content of potato products.

Abstract:In recent years,the potato virus-free technology is becoming more and more matured in China. The output of virus-free seed potato is increasing year by year,but the production cost is also rising sharply,which seriously limits the promotion and application of virus-free seed potato. In this article,the agronomic processes of virus-free seed potato including the basic agronomic process of shoot tip detoxification,test tube culture,expanding propagation,medium culture,field propagation were summarized. Analyzed the mechanization production technology needed in each production process including the machine vision system,the technology of grasping and cutting tissue culture seedlings needed in the process of tissue culture,condition control system of growth in greenhouse,intelligent environment monitoring system needed in medium culture process,virus-free seed potato seeding technology needed in the virus-free seed potato seeding process was analyzed. The situation of equipment for virus-free seed potato production mechanization including the mechanical equipment needed in the process of expanding propagation,medium culture,virus-free seed potato seeding at home and abroad was summarized. Advices on strengthening the research of integrating agricultural machinery with agronomic technology,accelerating the study of mechanism of basic common technology,striving for the support of policies and funds,and accelerating the development of seed potato industry and mechanization in China are proposed to promote the automation and intelligence of the virus-free seed potato production technology and equipment,so as to increase the application of high-quality micro-potatoes and promote the development of potato industry in China.

Abstract:Potato,as an industry that enriches the people in the central and western regions of China,plays an important role in increasing income of farmers and boosting the prosperity of the industry in the context of shifting "agriculture,rural areas and farmers" work to comprehensively facilitate the rural revitalization strategy in China. With the development of potato industry in China,the impact of its yield fluctuations on the coordinated development of the upstream and downstream of the industrial chain is increasing as well. To clarify the factors affecting the fluctuation of potato yield and to explore its mechanism is of great practical significance for maintaining the stable and healthy development of potato industry in China. The VAR model was used to analyze the factors affecting the fluctuation of potato yield in China from 1982 to 2018. The mechanism influencing potato production in China was revealed. The corresponding measures and advices for rationally guiding the stable development of potato production in China were proposed. The results showed that rainfall and other natural factors had mostly negative impact on the fluctuation of yield. The social and economic development characterized by urbanization and the level of per capita disposable income of farmers,and the scientific and technological progress and policy factors characterized by mechanical farming and irrigation area had mainly positive influences. Natural conditions,scientific and technological progress and market factors had a greater impact on fluctuations of potato yield,and technological progress and policies had a long-term impact on potato yield. It is recommended to respect the fluctuation rules of potato production and make appropriate policies of guiding production. Promoting the transformation of potato production to per unit yield through improving the efficiency level of potato production. The ability to resist the impact of natural factors,to monitor the natural weather and to warn the main production areas in advance should be strengthened. The steady and healthy development of the potato industry should be promoted by adopting measures in four respects including improving consumption capacity and expanding consumption channels for a variety of potato products.

Abstract:Control effects of six different treatments on common scab of minituber cultured in vermiculite were evaluated through field experiment,and high-through sequencing technology of 16S ribosomal genes was employed to studied changes in community structure of bacteria. The results showed that the treatment of dazomet+Penicillium 34107 had the best control effect (93.43%),which was significantly greater than the Zhongshengmycin control (65.10%),and had the highest amount of commercial minitubers and economic profit of 3.483×106tuber/hm2and ￥3.570×105/hm2,repsectively. The relative abundance of Proteobacteria,Actinobacteria and Bacteroidetes were the highest in all treatments,but varied in a greater range among different treatments. Except for the treatment of Penicllium 34170，the diversity indexes of bacteria of all the others decreased,however,that of dazomet+Penicillium 34107 was higher than Zhongshengmycin and significantly higher than dazomet (P<0.05). Statistic analysis demonstrated that a total of 185 genera had significantt changes in abundance (P<0.05),of which 92 (49.7%)were common in all treatments. The treatments of dazomet and Penicillium 34107 had the largest number of significantly changed genera (112),while dazomet+Pencillium 34107 had the smallest number of only 30 genera that were signficnatly increased. The abundance of the benificial bacterium (Pseudomonas) was significantly increased in the treatments of both Pencicillium 34107 and dazomet+Penicillium 34107,indicating that Penicillium 34107 applied individiually,or especially with dazomet can promote progation of benifical bacteria in vermiculite. Correlation analysis showed that Streptomyces was significantly positively correlated with 55 genera (P<0.05,r>0.6),including Mesorhizobium,Solirubrobacter,and Asticcacaulis,et al,while negatively correlated with 8 genera (P<0.05,r＜-0.6),including Dyadobacter,Pedobacter,Paenarthrobacter,et al. The above results illumstrated that soil disinfection combined with Penicillium 34107 had the best control effect on common scab of minituber,and meantime,improved the bacterial diversity and promoted benificial bacteria. In addtion, Streptomyces was closely correlated with multiple kinds of soil bacteria. These results provide a good method and theoretical basis for the control of common scab of minituber.

Abstract:At present,the method of cutting potato tissue culture seedling is still using scissors to cut. This method has low efficiency of production and is easy to cause virus infection,which makes it difficult to control the quality of transplanting seedling. To solve the problems mentioned above,using laser to cut potato tissue culture seedlings without contact was proposed. The growth of potato tissue culture seedlings after laser cutting and mechanical shearing was compared. The experimental group used CO2laser to cut potato tissue culture seedlings under the conditions of vertical irradiation,defocus of 12 mm and light output power of 10 W,while the control group used mechanical shearing. Results showed that potato tissue culture seedlings cut with laser did not affect its biological activity. After 21 days of culture,the survival rate,plant height,number of internodes,internode length,stem diameter,root length and fresh weight of root removal of laser cutting were better than those of mechanical shearing for both single-incision and double-incision stems. It is indicated that the non-contact cutting of potato tissue culture seedlings by laser cutting instead of traditional mechanical shearing greatly simplifies the transplantation of tissue culture seedlings,effectively avoids cross-infection of the tissue culture seedlings,and promotes the stem survival of transplanted tissue culture seedlings.

Abstract:Clinically,flaviviruses can cause central nervous system (CNS) diseases and easily cause sequelae of the nervous system. Flaviviruses can enter the brain through blood-borne pathways,Trojan horse pathways,and axon transport,ultimately leading to CNS infection. When the virus enters the CNS through BBB,glial cells and nerve cells activated by the virus will release a large number of inflammatory mediators and up-regulate the expression of adhesion molecules,recruiting leukocytes to the CNS. Leukocyte infiltration can carry more viruses into the CNS and destroy the integrity of the BBB. It is generally believed that the inflammatory factors produced by glial cells and nerve cells are the main cause of increased BBB permeability. This review will focus on the research progresses of the BBB damage and the CNS invasion to better understand of pathogenesis and effectively prevent the spreading of flaviviruses.

Abstract:The detection of hatching information of breeding eggs is of great significance for improving the quality of hatching,rational use of breeding egg resources,and improving efficiency of hatching. At present,application of the detection of hatching information of breeding egg is backward in China due to the high labor intensity,the low degree of automation,and the serious waste of poultry egg resources. It is urgent to strengthen the study and innovation of nondestructive detection technology of hatching information of breeding egg to ensure the quality of hatching,realize the breeding of male and female separately,protect animal welfare,improve the benefits of the enterprises,and promote the healthy development of the laying hen breeding industry. The emerging technologies and progress of detecting hatching information of breeding egg at home and abroad during the last decade were summarized mainly from three aspects including fertilization test before hatching,viability detection and sex identification during hatching of breeding eggs from domestic chicken. The problems to be solved and prospects of development are pointed out to provide a comprehensive reference for the nondestructive detection of hatching information of breeding eggs.

Abstract:To provide a scientific basis for revealing the differences in metabolites related to flavor quality and improving fruit quality,Liangping pummelo fruits under normal cultivation management and no cultivation management were used to compare and analyze their spectrum of volatile substance and main bitter substances in the fruit with gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). The results showed that the total monoterpenoids,total sesquiterpenoids,total non-terpenoids and total volatile compounds in Liangping pummelo fruit under no cultivation management were significantly reduced compared with those in the fruits under normal cultivation management. However,the composition and content percentage of the main volatile compounds remained stable. The content of naringin was significantly increased in the flavedo,albedo,segment membrane and juice sacs of fruits under no cultivation management. The contents of limonin and nomilin were also significantly higher in albedo,segment membrane and juice sacs of fruits under no cultivation management. It is indicated that no cultivation management result in a decrease of the aroma and an increase of bitterness in the fruit of Liangping pomelo. The quality of fresh food was greatly reduced,and consumer acceptance was low. The economic benefits and land output values of orchard under no cultivation management caused by continuing rural-urban migration of middle-aged labor force can be improved to some extent through the help from popular health propaganda of bitter compounds.

Abstract:The effects of different combination of organic fertilizer and bacterial manure on the fruit quality and aroma of Korla pear were investigated to provide reference and basis for improving the quality and cultivation of Korla fragrant pear. The results showed that the application of organic fertilizer and bacterial manure improved the external and internal quality of fruit,significantly increased the fruit weight per fruit,contents of soluble solid and soluble sugar,solid acid ratio,sugar acid ratio and most mineral elements. The content of organic acid was significantly reduced. Organic fertilizer and bacterial manure effectively improved the total aroma substances and content of characteristic aroma,highly increased the contents of three aroma substances including alcohol substance 9-decenol,aldehyde substance 2,6,10-trimethyl-9-undecenal and alkane substance nondecane. The results of principal component analyses showed that the effect of alginic acid flushing with organic fertilizer and bio-organic bacterial manure is the best. 

Abstract:The mature fruits from 18 gray jujube producing regions in Southern Xinjiang were used to study the differences of fruit quality indicators in each producing regions and comprehensively evaluate the fruits. Based on the results of previous studies,the eugenic zone of gray jujube in Southern Xinjiang was clarified to provide a reference for improving the quality and efficiency of the jujube industry and scientifically developing the gray jujube industry in Southern Xinjiang.The results showed that there were significant differences in the quality indicators of gray jujube among different production regions. There was a close correlation between each quality. Four common factors were extracted by factor analysis,and their cumulative contribution rate was 82.058%. The contribution rate of each factor was used to calculate the comprehensive score of gray jujube in each producing regions and rank. The 18 producing regions were divided into 3 categories by cluster analysis. The results of factor analysis were basically the same as cluster analysis. The comprehensive fruit quality of gray jujube in the southeast of Tarim Basin was better than that in the northwest. The results of cross-analysis with previous researches showed that the four producing regions including Ruoqiang,Minfeng,Luopu,and Qiemo are not only extremely suitable for the growth and development of gray jujube in terms of climate factors,but the comprehensive quality of gray jujube fruit is better as well. It is indicating that these four producing regions are the best eugenic zones of gray jujube in Southern Xinjiang. The restructuring of the gray jujube eugenic zone in Southern Xinjiang is of guiding significance for developing the jujube industry.

Abstract:To comparison and analysis the amino acid composition and content of core apricot seed kernels in Southern Xinjiang,and to screen out high quality apricot varieties. The amino acids in 29 almonds were determined by high performance liquid chromatography (HPLC). The essential amino acids of 29 varieties of apricot seeds ranged from 4.150 to 13.276 g/100 g,the total amino acids ranged from 11.840 to 42.868 g/100 g,and the SRC values ranged from 23.168 to 67.013. The principal component analysis indicated that serine and cysteine were the characteristic amino acids of apricot kernels in Southern Xinjiang. The contents of bitter amino acids,sweet amino acids,fresh amino acids and medicinal amino acids were highest in ‘Danxing’ and lowest in ‘Luntaitianrenxing’,while sour amino acids contain the highest amount of ‘Huanna’. There are 29 varieties of apricot seeds,with ‘Danxing’ having high aminoacid content and excellent quality. 

Abstract:During a survey of parasitic disease,a species of Argulus was isolated from the cultured largemouth bass (Micropterus salmoides) at a fish farm in Wuhan,China. Morphological and morphometric analysis were conducted to identify the species and phylogenetic analysis of Argulus were carried out based on SSU rDNA. The results showed that the parasite was in faint yellow. The total length was 1.93±0.46 (1.42-2.54) mm for female and 2.18±0.49 (1.57-2.87) mm for male. The carapace was horseshoe shaped,with branched pigments scattered throughout the lobes. The sucker consisted of chitinous strips (female:44-52,male:46-47),each of which contains varying amounts of chitinous tablets (female:5-6,male:7-8). Unreleased eggs were founded in the abdomen of female and symmetrical testis were observed in the male’s abdomen. Morphological and morphometric data was in consistent with Argulus japonicus Thiele 1900. Phylogenetic analysis based on ML phylogenetic tree of SSU rDNA showed that Argulus species was divided into three clades. A. japonicus isolates were mainly clustered into Clade I and paraphyletic grouped with Argulus foliaceus and Argulus rhipidiophorus. In conclusion,we identified the Argulus sp. isolated from the largemouth bass as A. japonicus based on the above morphological and morphometric data. Further phylogenetic analysis was also conducted to discuss the phylogenetic relationship within Argulus. To our knowledge,this is the first report of the parasitism of A. japonicus on largemouth bass.

Abstract:To study the association between the polymorphism of the scxa gene sequence and the intermuscular bone (IB) quantity traits,and to obtain SNPs that are significantly related to the number of IBs in Megalobrama amblycephala,the cDNA sequence of the scxa gene in M. amblycephala was obtained by cloning. Its open reading frame is 609 bp,encoding 202 amino acids. Phylogenetic analysis showed that the scxa gene of M. amblycephala is highly related with that of zebrafish,common carp,crucian carp,and golden thread carp. The fluorescence quantitative PCR results showed that the expression of scxa in the muscle and IB was significantly higher than that in other tissues,and the expression in the muscle was significantly higher than that in IB (P <0.05). By comparing the scxa exon sequence of the IB-extreme population,2 SNPs and 1 InDel that were significantly related to the number of IB were obtained. This result indicates that scxa gene plays a potential role in the development of IB,and its polymorphism is significantly correlated with the number of IB in M. amblycephala.

Abstract:The coding sequence of the leptin receptor (lepr) gene in Chinese perch was obtained by RACE cloning method,and four different subtypes of lepr from alternative splicing of the 3′ end of mRNA were obtained. The long-form receptor lepr-L was 3 474 bp in length encoding 1 157 amino acids,and three short subtypes of leptin receptor were lepr-S1,lepr-S2 and lepr-S3,with coding sequence of 1 512bp,945 bp,and 915 bp in length,encoding 503,314 and 304 amino acids,respectively. Sequence analysis and multiple amino acid sequences alignment revealed that the lepr-L contains complete functional domains exclusively,none of the short receptor subtype contains the transmembrane region and intracellular structure,and lepr and its leptin binding domain (LBD) sequence are highly conserved. The lepr gene is highly expressed in the gill,followed by the kidney and pituitary. The lepr mRNA abundance significantly increased at 2 h after intraperitoneal injection of the homologous recombination leptins protein B not A (P<0.05). These results indicated that different leptins may lead to different expression changes of lepr mRNA,and lead to various physiological functions.

Abstract:Tetraploid loach (Misgurnus anguillicaudatus) exhibits superior growth performance but delayed reproductive development when compared with diploid individuals. To understand the potential molecular mechanism of this physiological difference between-ploidy,the full-length cDNA and 5′-flanking sequence of cyp19a1a in loach were cloned and analyzed,and the expression of cyp19a1a between-ploidy were compared using qRT-PCR method. The results showed that,the full-length cDNA of cyp19a1a was 1 905 bp,which contained a 29 bp 5′UTR,301 bp 3′UTR and 1 575 bp ORF. Some important functional domains were predicted in the cyp19a1a protein,such as I-helix region,aromatase specific conservative region and heme-binding region. Using hiTAIL-PCR method,a 2 040 bp 5′-flanking sequence was cloned,and the typical function element TATA-box,as well as some important transcription factor binding sites such as SP1,AP-1,C/EBPβ,SRY,ER,CREB,GR were predicted. At the age of 12 month,the body length and weight of tetraploids were significantly higher than those of diploids loach (P<0.05). However,the gonadal development of tetraploids was delayed obviously. In both diploids and tetraploids,the cyp19a1a expression was the highest in the gonad,while cyp19a1b was the highest in the brain. The loach cyp19a1a exhibited higher expression in tetraploids than in diploids in all tissues except for the testis. The cyp19a1b expression in the brain was significantly higher in tetraploid female than in diploid female,while an opposite result was observed in male (P<0.05). Combining all results obtained in the present study,it was suggested that the higher expression of cyp19a1a in tetraploids should be due to the special developmental stage of the gonads,and the delayed sexual maturity in tetraploids may partially contribute to its superior growth performance. In addition,as cyp19a1a and estrogen also regulate fish growth through the GH-IGF pathway,it is speculated that the differential expression of cyp19a1a between-ploidy might be related to the different growth performance and reproductive development of diploid and tetraploid loach.

Abstract:To study the role of L protein in the snakehead vesiculovirus (SHVV) proliferation,the first 900 bases of the SHVV L gene was amplified and inserted into pET-32a (+) to construct pET32a-L prokaryotic expression plasmid,and transformed into E. coli BL21 (DE3) competent cells. Different temperature,IPTG concentration and induction time were designed and the best expression conditions were selected. The purified protein was purified by NI-NTA affinity chromatography column,and was used to immunize New Zealand white rabbits to prepare polyclonal antibodies. Western blot was used to identify the specificity of the antibody.Indirect immunofluorescence was used to study the location of L protein in channel catfish ovary (CCO) cells after SHVV infection. The results showed that the purified L protein was about 42 ku. The L protein polyclonal antibody can react specifically with the L protein,and the L protein is mainly localized in cytoplasm,indicating that the L protein polyclonal antibody has been successfully prepared.

Abstract:Citrus wilsonii Tanaka is a kind of medicinal citrus local variety in southern Shaanxi Province. It can be made into Chinese herbal medicine or soaked in water to treat gastric acid,bloating and dyspepsia. In order to provide theoretical basis for the development and utilization of Citrus wilsonii Tanaka resources,the ultrasound-assisted ethanol extraction technology and components of total phenol from Citrus wilsonii Tanaka were studied. Firstly,the five extraction parameters were investigated by single factor test and Placket-Burman design. Three factors with significant effect were selected as ethanol volume fraction,liquid-solid ratio and ultrasonic temperature. On this basis,the central composite design response surface method was used to further optimize. The optimal conditions were as follows:soaking time 15 min,ethanol volume fraction 44%,liquid-solid ratio 45.5 mL/g,ultrasonic time 20 min,ultrasonic temperature 34℃. Under the condition,the total phenol content per gram of Citrus wilsonii Tanaka lyophilized powder was 16.29±0.12 mg gallic acid equivalent. In addition,the results of HPLC showed that there were 18 kinds of phenols in the extract,including 4 kinds of flavonols,1 kind of flavanols,6 kinds of dihydroflavones,4 kinds of phenolic acids and 3 kinds of polymethoxyflavones. Naringin accounted for 91.36% of the total phenol.

Abstract:Nootkatone is a typical aroma substance of citrus fruits,and valencene is often used as a precursor substance to produce nootkatone in industry. Compared with the method of physical extraction and chemical synthesis,the biotransformation method to produce nootkatone has the advantages of high specificity,speed and efficiency,and can be added to food and cosmetics. In order to screen strains with specific biotransformation functions,soil samples were obtained from citrus orchards,and the growth curve and the yield of the nootkatone produced by the transformation of valencene were used as indicators to carry out preliminary screening and re-screening of the strains. SPME-GC-MS was used to measure and analyze the types and contents of the products produced by valencene biotransformation. The results of physiological and biochemical tests and 16S rDNA sequencing showed that the screened strains were identified as Burkholderia sp.,which was named Burkholderia sp. PZQ14. On the basis of LB medium,the transformation amount of nootkatone was used as an indicator to carry out a single factor test of medium composition,and then the effect of the combination of different mass concentrations of the culture medium components on nootkatone yield was investigated by response surface optimization test. The results showed that the optimal medium components were as follows:glucose concentration of 38 g/L,peptone concentration of 25 g/L,and FeSO4 concentration of 0.60 g/L. The content of nootkatone was 328.69±17.88 mg/L and the transformation ratio was 35.73%±1.24% when three validation tests were conducted under these conditions. The nootkatone yield increased by 251 mg/L and the transformation ratio increased by 27.30% compared with LB medium. It will provide a new way to increase the yield of nootkatone and lay a theoretical foundation for the further industrial production of nootkatone.

Abstract:Compared with the cold air freezing method, the liquid nitrogen freezing method has a faster freezing rate and is more conducive to maintaining the quality of frozen aquatic products. It has been used in the processing of aquatic products such as shrimp and pufferfish. In order to study the effect of different liquid nitrogen freezing temperature on the quality of seasoned grass carp fillets,the grass carp (Ctenopharyngodon idellus) were seasoned by vacuum dipping and frozen with liquid nitrogen at -60℃,-80℃,-100℃ and -196℃. The results showed that the liquid nitrogen freezing temperature significantly influenced the quality of seasoned fish fillets. As the freezing temperature decreased,the freezing rate of seasoned fish fillets significantly increased,and the hardness,chewiness,and salt-soluble protein content of the seasoned fish fillets increased,while the thawing loss rate and the cooking loss rate decreased. Moreover,the texture characteristics,cooking loss rate and salt-soluble protein content of fish fillets frozen by liquid nitrogen spraying at -80℃ were not significantly different from those frozen by liquid nitrogen spraying at -100℃ and liquid nitrogen dipping at -196℃,but significantly higher than those frozen at -18℃ and -60℃. Furthermore,the conditioning treatment could improve the freezing-thawing stability of fish fillets. And the quality stability of fish fillets seasoned for 6 h was the best. Grass carp fillets with high qualities could be obtained by freezing fish fillets with liquid nitrogen at -80℃ for 6 h.The study can provide technical support for the production of high-quality frozen and conditioned grass carp fillets,and the appropriate temperature for the processing of frozen conditioned aquatic products.

Abstract:An independently driven and steered four-wheel platform for detecting phenotype of field crop was designed to stably and effectively obtain phenotype information of field crop with high flexibility. It mainly consists of the walking system,the control system and the acquisition system of phenotype information. Creo software is used to design the structure of the platform and perform finite element simulation analysis under different working conditions of the main frame. A control system is developed with Siemens 1200 series PLC as the main controller to realize the platform’s in-situ steering,lateral movement and Ackerman steering mode control. The four-wheel coordinated control method based on fuzzy PID was used to realize the synchronous movement of four-wheel. This platform can load RGB cameras,thermal infrared cameras,hyperspectral cameras and other sensors for phenotypic information collection according to the requirements of detection,and form a mobile darkroom during the collection process,effectively reduce the impact of the external environment on the effect of collecting phenotypic information. The results of field test showed that a single uninterrupted operation was up to 6 hours under full power. The results of four-wheel coordinated motion test showed that the maximum deviation rate of the wheel speed was 1%,and the average deviation rate of the platform driving straight on cement ground and in the field was 2.14 % and 2.57%,with good mobile stability. When RGB and thermal infrared cameras were loaded for the acquisition of crop phenotypic information,120 breeding plots in field were detected per hour. The RGB images of cotton under the non-dark room environment and the dark room environment in different time periods were collected separately and the leaf area was extracted. The results showed that the RGB images collected by the platform were more stable and reliable. The results of collecting and analyzing RGB images,thermal infrared and hyperspectral images under the dark room environment showed that the images collected by the platform had good quality and effective information.

Abstract:In order to solve the problem of the lack of accurate and controllable seed metering device for mechanical film mulching and hole sowing of rapeseed in actual production,a combined device of positive and negative pressure for rapeseed was designed,which adopted negative pressure seed sucking,positive pressure seed unloading,duck mouth hole forming and secondary seed feeding,so as to meet the requirements of 1-3 seeds for mechanical film mulching and hole sowing of rapeseed. By establishing the mechanical model of seed sucking,seed carrying and unloading process and combining with FLUENT simulation analysis,the structure and parameters of the combined positive and negative pressure seeding device for rapeseed were determined.The negative pressure,the height of seed layer,rotation speed of seed metering wheel spindle and positive pressure were selected to carry out the single factor test of seed metering performance with the right rate of seeds per hill and rate of no seed hill as the test index,and the optimization and verification of working parameters were carried out according to the quadratic orthogonal rotation center combination test of response surface method. The results showed that:the primary and secondary factors affecting the right rate of seeds per hill were negative pressure,rotation speed of seed metering wheel spindle and positive pressure.The optimal working parameters of seed metering performance was rotation speed of seed metering wheel spindle at 7.5 r/min,negative pressure at -2 000 Paand positive pressure at 850 Pa.The results of bench verification test showed that the right rate of seeds per hill (1-3) was 88.15%,and the rate of no seed hill was 4.43%,which met the requirements of rapeseed production requirements of mechanical film laying and hole sowing. This study provides a reference for the improvement of rapeseed seed metering device structure.

Abstract:A texture analyzer was used to conduct the compression and shearing tests on the lateral X axis,lateral Y axis and longitudinal Z axis of Allium chinense seed to explore the effects of force directions and loading speed on the seed mechanical properties of Allium chinense. The results showed that the compression limit loading range of Allium chinense seed in X,Y and Z directions was 89.20-139.20,120.70-294.70 and 101.40-184.60 N,respectively. The compression shear test of Allium chinense seed was conducted at the loading speed of 20,40,60,80,and 100 mm/min. The average elastic modulus of Allium chinense seed under different loading speeds was 1.65,1.07,1.89,2.01,1.85 MPa,and the average elastic modulus of Allium chinese seed in X,Y and Z directions was 2.65,1.30 and 1.13 MPa,respectively. The mean cutting force of Allium chinense seed at different loading speeds was 20.05,12.74,11.23,14.02,16.72 N,respectively. The mean cutting force of Allium chinense seed in X,Y and Z directions was 11.06,18.07,15.73 N,respectively. The minimum cutting force of Allium chinense seed was 6.12 N.It is indicated that the force direction and loading speed have significant effects on the ultimate load,elastic modulus and cutting force. The anti-extrusion and anti-shear ability of Allium chinense seed in y direction was good. It will provide reference for studying the sowing,harvesting,transportation of Allium chinense and designing the machine and tool for Allium chinense.