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Klebsiella as an α-tocopherol source facilitating Lactobacillus plantarum fermentation in rice straw silage
Cheng Zong, Lu Tang, Tao Shao, Yu Xiao, Zhongyong Huang, Wanqi Jiang, Jiugang Zhu, Zhihao Dong, Mao Li, Qinhua Liu
2024, 23 (12): 4186-4202.   DOI: 10.1016/j.jia.2023.11.036
Abstract148)      PDF in ScienceDirect      

Silage serves as the indispensable diet of ruminants, the increasing mechanism of α-tocopherol during silage making is unclear.  Rice straw lacks chlorophyll after harvesting the grain, this can eliminate the impact of tocopherols formed by the breakdown of chlorophyll.  Here, we explored the α-tocopherol source, its influencing factor, and its relationship with dominant lactic acid bacteria in rice straw silage treated without or with different additives (sodium benzoate, Lactobacillus plantarum, cell wall degrading enzymes, the combination of L. plantarum and cell wall degrading enzymes) and vacuum times (5, 8, 11, and 14 s) after ensiling for 42 d.  We found that the pathogenic Klebsiella was traced as the source of increased α-tocopherol in rice straw silage.  The residue air in the silo, pH value, and additive variety had impacts on Klebsiella activity, which was strongly active at levels of residue air in the silo and pH that were high.  As an acidic niche creator, Lplantarum was more effective than sodium benzoate in restraining Klebsiella.  Despite having a low acidity tolerance, Klebsiella was still present in rice straw silage treated with L. plantarum.  The relationship between Klebsiella and L. plantarum was that Klebsiella could afford α-tocopherol to the multiplication of L. plantarum and residue capsular polysaccharide protected Klebsiella from escaping the extinction in rice straw silage.


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A binary gridding path-planning method for plant-protecting UAVs on irregular fields
XU Wang-ying, YU Xiao-bing, XUE Xin-yu
2023, 22 (9): 2796-2809.   DOI: 10.1016/j.jia.2023.02.029
Abstract405)      PDF in ScienceDirect      
The use of plant-protecting unmanned aerial vehicles (UAVs) for pesticide spraying is an essential operation in modern agriculture.  The balance between reducing pesticide consumption and energy consumption is a significant focus of current research in the path-planning of plant-protecting UAVs.  In this study, we proposed a binarization multi-objective model for the irregular field area, specifically an improved non-dominated sorting genetic algorithm–II based on the knee point and plane measurement (KPPM-NSGA-ii).  The binarization multi-objective model is applied to convex polygons, concave polygons and fields with complex terrain.  The experiments demonstrated that the proposed KPPM-NSGA-ii can obtain better results than the unplanned path method whether the optimization of pesticide consumption or energy consumption is preferred.  Hence, the proposed algorithm can save energy and pesticide usage and improve the efficiency in practical applications.
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Elucidation of the structure, antioxidant, and interfacial properties of flaxseed proteins tailored by microwave treatment
YU Xiao, DUAN Zi-qiang, QIN Xiao-peng, ZHU Ying-ying, HUANG Feng-hong, PENG Deng-feng, BAI Yan-hong, DENG Qian-chun
2023, 22 (5): 1574-1589.   DOI: 10.1016/j.jia.2023.04.021
Abstract306)      PDF in ScienceDirect      
The microwave treatment is commonly applied to flaxseed to release nutrients, inactivate enzymes, remove cyanogens, and intensify flavors. The current study aimed to explore the influences of microwave exposure on the antioxidant and interfacial properties of flaxseed protein isolates (FPI), focusing on the altering composition and molecular structure. The results showed that after microwave exposure (700 W, 1–5 min), more compact assembly of storage proteins and subsequent permeation by membrane fragments of oil bodies occurred for cold-pressing flaxseed flours. Moreover, the particle sizes of FPI was progressively reduced with the decrement ranged from 37.84 to 60.66% , whereas the zeta potential values initially decreased and then substantially recovered during 1–5 min of microwave exposure. The conformation unfolding, chain cross-linking, and depolymerization were sequentially induced for FPI based on the analysis of fluorescence emission spectra, secondary structure, and protein subunit profiles, thereby affecting the dispersion or aggregation properties between albumin and globulin fractions in FPI. Microwave exposure retained specific phenolic acids and superior antioxidant activities of FPI. The inferior gas–water interface absorption and the loose/porous assembly structure were observed for the foams prepared by FPI, concurrent with obviously shrinking foaming properties upon microwave exposure. Improving oil–water interface activities of FPI produced the emulsion droplets with descending sizes and dense interface coating, which were then mildly destabilized due to the lipid leakage and weakened rheological behavior with microwave exposure extended to 5 min. Our findings elucidated that microwave treatment could tailor the application functionality of protein fractions in flaxseed based on their structural remodeling.
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Inclusion of peanut in wheat–maize rotation increases wheat yield and net return and improves soil organic carbon pool by optimizing bacterial community
ZOU Xiao-xia, HUANG Ming-ming, LIU Yan, SI Tong, ZHANG Xiao-jun, YU Xiao-na, GUO Feng, WAN Shu-bo
2023, 22 (11): 3430-3443.   DOI: 10.1016/j.jia.2023.04.018
Abstract210)      PDF in ScienceDirect      

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-Huai-Hai  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.

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Historical trends in maize morphology from the 1950s to the 2010s in China
MA Da-ling, XIE Rui-zhi, YU Xiao-fang, LI Shao-kun, GAO Ju-lin
2022, 21 (8): 2159-2167.   DOI: 10.1016/S2095-3119(21)63697-3
Abstract225)      PDF in ScienceDirect      
The morphology of the plant and ear is a preliminary selection characteristic in breeding new varieties of maize.  As new maize cultivars were developed from the 1950s through the 2010s in China, most had changes in both plant and ear morphological characteristics that contributed substantially to maize yield gains.  Over the seven decades, plant and ear height fluctuated with a small increase from the 1950s to 2000s, and then a decrease in the 2010s, while the ear ratio and internodes length below the ear decreased significantly.  Leaf angles became significantly more upright, especially for the leaves above the ear, and the leaf area per plant improved markedly.  Leaf orientation increased from the 1950s to the 2000s then decreased in the 2010s.  Tassel size and the anthesis–silking interval were both reduced substantially.  Ear diameter, kernel number, and kernel weight increased from the 1950 to the 2000s, then decreased in the 2010s under the same cultivation conditions.  We found that modern maize hybrids have a lower plant height, ear height and ear ratio which increased lodging resistance, a more erect leaf which increased high-density planting tolerance, and smaller ears and kernels which facilitated rapid dehydration during late grain filling.  These morphological selection criteria, which are suitable for mechanized operations, are proposed as the focus for future maize breeding.
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Interactions between phosphorus availability and microbes in a wheat–maize double cropping system: a reduced fertilization scheme
YU Xiao-jing, CHEN Qi, SHI Wen-cong, GAO Zheng, SUN Xiao, DONG Jing-jing, LI Juan, WANG Heng-tao, GAO Jian-guo, LIU Zhi-guang, ZHANG Min
2022, 21 (3): 840-854.   DOI: 10.1016/S2095-3119(20)63599-7
Abstract197)      PDF in ScienceDirect      
Mechanisms controlling phosphorus (P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood.  In the present study, we conducted a pot experiment for four consecutive wheat–maize seasons (2016–2018) using calcareous soils with high (30.36 mg kg–1) and low (9.78 mg kg–1) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize (Pwm) along with a reduced P fertilizer application only to wheat (Pw).  The microbial community structure along with soil P availability parameters and crop yield were determined.  The results showed that the Pw treatment reduces the annual P input by 33.3% without affecting the total yield for at least two consecutive years as compared with the Pwm treatment in the high Olsen-P soil.  Soil water-soluble P concentrations in the Pw treatment were similar to those in the Pwm treatment at the 12-leaf collar stage when maize requires the most P.  Furthermore, the soil P content significantly affected soil microbial communities, especially fungal communities.  Meanwhile, the relative abundances of Proteobacteria and alkaline phosphatase (ALP) activity of Pw were significantly higher (by 11.4 and 13.3%) than those of Pwm in soil with high Olsen-P.  The microfloral contribution to yield was greater than that of soil P content in soil with high Olsen-P.  Relative abundances of Bacillus and Rhizobium were enriched in the Pw treatment compared with the Pwm treatment.  Bacillus showed a significant positive correlation with acid phosphatase (ACP) activity, and Rhizobium displayed significant positive correlations with ACP and ALP in soil with high Olsen-P, which may enhance P availability.  Our findings suggested that the application of P fertilization only to wheat is practical in high P soils to ensure optimal production in the wheat and maize double cropping system and that the soil P availability and microbial community may collaborate to maintain optimal yield in a wheat–maize double cropping system.


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Characterization and fine mapping of a semi-rolled leaf mutant srl3 in rice
YU Xiao-qi, XIE Wei, LIU He, LIU Wei, ZENG Da-li, QIAN Qian, REN De-yong
2022, 21 (11): 3103-3113.   DOI: 10.1016/j.jia.2022.07.059
Abstract240)      PDF in ScienceDirect      

Moderate leaf rolling can maintain leaf erectness, improve light transmittance in the population, and improve light energy utilization, thereby increasing rice yield.  This study used ethyl methanesulfonate (EMS) to treat Yunjing 17 (YJ17) and obtained a semi-rolled leaf mutant that was named semi-rolled leaf 3 (srl3).  We found that the rolled-leaf phenotype was due to the aberrant development of bulliform cells and the loss of sclerenchymatous cells.  In addition, the shoot and root length of srl3 seedlings differed from the wild type.  The srl3 mutant had significantly lower plant height and seed-setting rate but notably greater tiller number, panicle length, and primary branch number per panicle than the wild type.   Genetic analysis showed that a single recessive nuclear gene defined the srl3 mutant, and it was precisely located in a 144-kb region between two insertion-deletion (InDel) markers, M8 and M19, on chromosome 2.  In this region, no leaf-rolling-related genes have been reported previously.  Thus, the study indicated that SRL3 is a novel leaf-rolling-related gene, and the results laid the foundation for the cloning and functional analysis of the SRL3 gene.

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Exploration of the key microbes and composition stability of microbial consortium GF-20 with efficiently decomposes corn stover at low temperatures
YU Xiao-fang, BORJIGIN Qinggeer, GAO Ju-lin, WANG Zhi-gang, HU Shu-ping, BORJIGIN Naoganchaolu, WANG Zhen, SUN Ji-ying, HAN Sheng-cai
2019, 18 (8): 1893-1904.   DOI: 10.1016/S2095-3119(19)62609-2
Abstract169)      PDF in ScienceDirect      
The microbial consortium GF-20 (GF-20) can efficiently decompose corn stover at low temperatures.  The present study explored the key microbes of GF-20 and evaluated different culture conditions on its composition stability to promote the utilization of corn stover decomposing microbes in low temperature regions.  GF-20 was subcultured to the 15th generation under different temperatures, pHs, carbon, and nitrogen sources.  Then, the dynamics of fermenting pH, cellulose enzyme activities, carbohydrate concentration, and oxidation reduction potential were determined to estimate the degradation efficiency of corn stover with GF-20.  Furthermore, the structural stability and functional microbes of GF-20 were identified on the basis of PCR-denaturing gradient gel electrophoresis (DGGE) profiling and principal component analysis.  The results showed that the offspring of GF-20 subcultured under different temperatures (4–30°C) and pH (6.0–9.0) conditions maintained stable growth, decomposition function, and composition structure.  Furthermore, consortia GF-20 had a stable composition structure, which induced GF-20 to secrete cellulose and promote substrate decomposition as corn stover and ammonium were used as sources of carbon and nitrogen, respectively.  According to the PCR-DGGE profiles, the key strains of GF-20 were determined to be Bacillus licheniformis, Cellvibrio mixtus subsp. mixtus, Bacillus tequilensis, Clostridium populeti, and Clostridium xylanolyticum.
 
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Effects of insect-resistant transgenic cotton on ground-dwelling beetle assemblages (Coleoptera)
ZHAO Cai-yun, YU Xiao-dong, LIU Yong-bo, LI Jun-sheng
2016, 15 (2): 381-390.   DOI: 10.1016/S2095-3119(15)61141-8
Abstract2284)      PDF in ScienceDirect      
We compared the ground-dwelling beetle assemblages under four scenarios in which transgenic Bt (Cry 1Ac) cotton (33B), transgenic Bt (Cry 1Ac)+CpTI cotton (SGK321), conventional cotton (33), conventional cotton (Shiyuan 321) in North China. During the survey in two years (2009–2010), 24 ground beetle species were captured with pitfall traps in 20 plots which included five replicates for each cotton type. No significant difference was observed in the number of ground beetle species captured, activity density, evenness and Shannon-Wiener diversity among the four cotton varieties. Chlaenius posticalis was less abundant in transgenic Bt+CpTI cotton (SGK321) fields than its conventional cotton (Shiyuan 321), but more abundant in transgenic Bt cotton (33B) fields compared with its conventional cotton (33). There was no significant difference for other abundant species between in transgenic cotton and in conventional cotton fields. Based on non-metric multidimensional scaling (NMDS) analysis, ground-dwelling beetle assemblages were similar in transgenic and conventional cotton over the two years, but the ground-dwelling beetle assemblages in transgenic cotton 33B significantly differed from that in the conventional cotton (strain 33) in 2010. No strong evidence that the transgenic cotton effect on ground-dwelling beetle assemblages was found in this study.
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Screening of a microbial consortium with efficient corn stover degradation ability at low temperature
Qinggeer , GAO Ju-lin, YU Xiao-fang, ZHANG Bao-lin, WANG Zhi-gang, Borjigin Naoganchaolu, HU Shu-ping, SUN Ji-ying, XIE Min, WANG Zhen
2016, 15 (10): 2369-2379.   DOI: 10.1016/S2095-3119(15)61272-2
Abstract1442)           
    To speed up the degradation of corn stover directly returned to soil at low temperature, the corn stover-degrading microbial consortium GF-20, acclimated to biological decomposition in the frigid region, was successfully constructed under a long-term limiting substrate. To evaluate its potential in accelerating the decomposition of un-pretreated corn stover, the decomposing property, fermentation dynamic and the microbial diversity were analyzed. GF-20 degraded corn stover by 32% after 15-day fermentation at 10°C. Peak activities of filter paperlyase (FPA), β-glucosidases (CB), endoglucanases (Cx), and cellobiohydrolases (C1) were 1.15, 1.67, 1.73, and 1.42 U mL–1, appearing at the 6th, 3rd, 11th, and 9th d, respectively. The pH averaged at 6.73–8.42, and the optical density (OD) value peaked at 1.87 at the 120 h of the degradation process. Cellulase, hemicellulase and lignin in corn stover were persistently degraded by 44.85, 43.85 and 25.29% at the end of incubation. Result of denaturing gradient gel electrophoresis (DGGE) profiles demonstrated that GF-20 had a stable component structure under switching the temperature and pH. The composition of the GF-20 was also analyzed by constructing bacterial 16S rDNA clone library and fungal 18SrDNA-PCR-DGGE. Twenty-two bacterial clones and four fungal bands were detected and identified dominant bacteria represented by Cellvibrio mixtus subsp., Azospira oryzae, Arcobacter defluyii, and Clostridium populeti and the fungi were mainly identified as related to Trichosporon sp.
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Expression patterns of OCT4, NANOG, and SOX2 in goat preimplantation embryos from in vivo and in vitro
YU Xiao-li, ZHAO Xiao-e, WANG Hua-yan, MA Bao-hua
2015, 14 (7): 1398-1406.   DOI: 10.1016/S2095-3119(14)60923-0
Abstract2255)      PDF in ScienceDirect      
The transcription factors, including OCT4, NANOG, and SOX2, played crucial roles in the maintenance of self-renewal and pluripotency in embryonic stem cells (ESCs). They expressed in preimplantation mammalian development with spatio- temporal pattern and took part in regulation of development. However, their expression and roles in goat had not been reported. In the present study, the expression of OCT4, NANOG, and SOX2 in goat preimplantation embryos both in vivo and in vitro were detected by real-time RCR and immunofluorescence. For in vivo fertilized embryos, the transcripts of OCT4, NANOG, and SOX2 could be detected from oocytes to blastocyst stage, their expression in morula and blastocyst stages was much higher than other stage. OCT4 protein was detected from oocyte to blastocyst, but the fluorescence was more located-intensive with nuclei from 8-cell stage, its expression present in both inner cell mass (ICM) and trophoblast cells (TE) at blastocyse stage. NANOG protein was similar to OCT4, the signaling of fluorescence completely focused on cell nuclei, while the SOX2 firstly showed nuclei location in morula. Comparing to in vivo fertilized embryo, the mRNA of these three transcription factors could be detected at 8-cell stage in parthenogenetic embryos (in vitro). Thereafter, the expressional level rose gradually along with embryo development. The locations of OCT4 and NANOG proteins were similar to in vivo fertilized embryos, and they located in cell nuclei from morula to blastocyst stage, while SOX2 protein firstly could be detected in cell nuclei at 8-cell stage. These differences suggested that OCT4, NANOG, and SOX2 played different function in regulating development of goat preimplantation embryos. These results may provide a novel insight to goat embryo development and be useful for goat ESCs isolation.
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In vitro Selection of DNA Aptamers and Fluorescence-Based Recognition for Rapid Detection Listeria monocytogenes
LIU Guo-qing, LIAN Ying-qi, GAO Chao, YU Xiao-feng, ZHU Ming, ZONG Kai, CHEN Xuejiao
2014, 13 (5): 1121-1129.   DOI: 10.1016/S2095-3119(14)60766-8
Abstract2078)      PDF in ScienceDirect      
Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment (SELEX) was used to select and PCR amplify DNA sequences (aptamers) capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential (log) phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monocytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.
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Identification of QTLs for Starch Content in Sweetpotato (Ipomoea batatas (L.) Lam.)
YU Xiao-xia, ZHAO Ning, LI Hui, JIE Qin, ZHAI Hong, HE Shao-zhen, LI Qiang , LIU Qing-chang
2014, 13 (2): 310-315.   DOI: 10.1016/S2095-3119(13)60357-3
Abstract1701)      PDF in ScienceDirect      
Sweetpotato (Ipomoea batatas (L.) Lam.) breeding is challenging due to its genetic complexity. In the present study, interval mapping (IM) and multiple quantitative trait locus (QTL) model (MQM) analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18, a cultivar susceptible to stem nematodes, with high yield and moderate starch, and Xu 781, which is resistant to stem nematodes, has low yield and high starch content. Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map, explaining 9.1-38.8% of the variation. Especially, one of them, DMFN_4, accounted for 38.8% of starch content variation, which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato. All of the six QTLs had a positive effect on the variation of the starch content, which indicated the inheritance derived from the parent Xu 781. Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map, explaining 14.3 and 16.1% of the variation, respectively. They had a negative effect on the variation, indicating the inheritance derived from Xu 781. Seven of eight QTLs were co-localized with a single marker. This is the first report on the development of QTLs co-localized with a single marker in sweetpotato. These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.
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Development of SRAP Markers Linked to a Gene for Stem Nematode Resistance in Sweetpotato, Ipomoea batatas (L.) Lam.
ZHAO Ning, ZHAI Hong, YU Xiao-xia, LIU Zhe-sheng, HE Shao-zhen, LI Qiang, MA Dai-fu , LIU Qing-chang
2013, 12 (3): 414-419.   DOI: 10.1016/S2095-3119(13)60241-5
Abstract1554)      PDF in ScienceDirect      
Sequence-related amplification polymorphism (SRAP) markers closely linked to stem nematode resistance gene were developed in sweetpotato, Ipomoea batatas (L.) Lam. Using bulked segregant analysis (BSA), 200 SRAP primer combinations were screened with the resistant and susceptible bulked DNA from the 196 progenies of an F1 single-cross population of resistant parent Xu 781×susceptible parent Xushu 18, 77 of them showed polymorphic bands between resistant and susceptible DNA. Primer combinations detecting polymorphism between the two bulks were used to screen both parents and 10 individuals from each of the bulks. The results showed that primer combination A9B4 produced 3 specific bands in the resistant plants but not in the susceptible plants, suggesting that the markers, named Nsp1, Nsp2 and Nsp3, respectively, linked to a gene for stem nematode resistance. Primer combination A3B6 also produced a SRAP marker named Nsp4 linking to the resistance gene. Amplified analysis of the 196 F1 individuals indicated that the genetic distance between these markers and the resistance gene was 4.7, 4.7, 6.3, and 9.6 cM, respectively.
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Levels of Germinable Seed in Topsoil and Yak Dung on an Alpine Meadow on the North-East Qinghai-Tibetan Plateau
YU Xiao-jun, XU Chang-lin, WANG Fang, SHANG Zhan-huan , LONG Rui-jun
2013, 12 (12): 2243-2249.   DOI: 10.1016/S2095-3119(13)60652-8
Abstract1566)      PDF in ScienceDirect      
In order to clarify the interactive mechanism between grazing yak and alpine meadow on the Qinghai-Tibetan Plateau, our study assessed seed density (by species) in the topsoil of alpine meadow with different grazing intensities in the Tianzhu area, north-eastern margins of the Qinghai-Tibetan Plateau and their rates of occurrence in yak dung. Seed density in the topsoil of the lightly grazed, moderately grazed, heavily grazed and extremely grazed alpine meadows in November, 2010 were 1 551, 1 692, 2 660 and 1 830 grains m-2, while in the same meadows in April, 2011 densities were 1 530, 2 404, 2 530 and 2 692 grains m-2, respectively. In the cold season pasture, mean seed density in yak dung from November to April in the lightly grazed, moderately grazed, heavily grazed and extremely grazed sites were 121, 127, 187, and 120 grains kg-1 of dry yak dung. The proportion of total seed numbers in yak dung to soil seed bank in lightly grazed, moderately grazed, heavily grazed and extremely grazed alpine meadow was 1.40, 2.62, 0.69, and 0.90%. 12 species out of the 47 were not found in topsoil but were found in yak dung, 10 species out of 45 were not found in yak dung but were found in the topsoil. Endozoochorous dispersal by yaks is therefore very important for soil seed bank and plant biodiversity and population dynamics in alpine meadows.
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AFLP Fingerprinting and Genetic Diversity of Main Sweetpotato Varieties in China
LIU De-gao, ZHAO Ning, ZHAI Hong, YU Xiao-xia, JIE Qin, WANG Lian-jun, HE Shao-zhen, LIU Qing-chang
2012, 12 (9): 1424-1433.   DOI: 10.1016/S1671-2927(00)8674
Abstract1710)      PDF in ScienceDirect      
AFLP fingerprinting of the 98 main sweetpotato varieties planted in China has been constructed. Using 17 AFLP primer combinations which were selected from 1 208 primer combinations and generated the most amounts of polymorphic bands, AFLP analysis of the 98 main sweetpotato varieties gave a total of 410 clear polymorphic bands with an average of 24.12 polymorphic bands per primer combination. Each one of the 98 sweetpotato varieties could be clearly distinguished by EcoR I-cta/Mse I-ggc primer combination which generated the most polymorphic bands. AFLP-based genetic distance ranged from 0.0546 to 0.5709 with an average of 0.3799. The dendrogram based on AFLP markers indicated that sweetpotato varieties coming from the same regions or having same parents were clustered in the same groups. Analysis of molecular variance (AMOVA) revealed greater variations within regions (94.08%) than among regions (5.92%). Thus, the genetic variations mainly existed within regions, while the variations among regions were very low in the tested sweetpotato varieties. Significant genetic variations existed between “Northern” and “Southern” sweetpotato varieties when Yangtze River was used as the dividing line.
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Evaluation of the Resistance of Different Tea Cultivars to TeaAphids by EPG Technique
LIANG Li-yun, LIU Li-fang, YU Xiao-ping , HAN Bao-yu
2012, 12 (12): 2028-2034.   DOI: 10.1016/S1671-2927(00)8740
Abstract1198)      PDF in ScienceDirect      
In order to investigate the resistance of tea plant to tea aphid, the feeding behavior of tea aphids on six different tea cultivars was monitored by (EPG) technique. The result showed that the duration of E1, E2 as well as (E1+E2) which was feeding waveforms of Toxoptera aurantii (Boyer) in tea phloem was significantly different by variance analysis (P<0.05) and so did the duration of the probing of T. aurantii in all the tea tissues. And the six tea cultivars were classified into three groups with cluster analysis, based on the six major parameters which were durations of np, C, E1, E2, F, and G waveforms, then the six major parameters of these three groups were detected by variance analysis, and the rank of six different tea cultivars’ resistance to T. aurantii from strong to weak was Zhongcha 108, Sucha 1, Anjibaicha, Longjing 43, Xicha 5, and Sucha 120. As this result was in accord with the investigation into the tea field, we concluded that EPG technique was one of the most important means to examine tea plant resistance to T. aurantii and the durations of waveform E1, E2 and (E1+E2) were important parameters for evaluating resistance of tea plants to tea aphids.
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