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An assessment of the genetic diversity of pear (Pyrus L.) germplasm resources based on the fruit phenotypic traits
ZHANG Ying, CAO Yu-fen, HUO Hong-liang, XU Jia-yu, TIAN Lu-ming, DONG Xing-guang, QI Dan, LIU Chao
2022, 21 (8): 2275-2290.   DOI: 10.1016/S2095-3119(21)63885-6
Abstract261)      PDF in ScienceDirect      

Germplasm resources are an important basis for genetic breeding and analysis of complex traits, and research on genetic diversity is conducive to the exploration and creation of new types of germplasm.  In this study, the distribution frequency, coefficient of variation, Shannon–Wiener index, and variance and cluster analyses were used to analyze the diversity and trait differences of 39 fruit phenotypic traits from 570 pear accessions, which included 456 pear accessions from 11 species and 114 interspecific hybrid cultivars that had been stored in the National Germplasm Repository of Apple and Pear (Xingcheng, China).  The comprehensive evaluation indices were screened by correlation, principal component and regression analyses.  A total of 132 variant types were detected in 28 categorical traits of pear germplasm fruit, which indicate a rich diversity.  The diversity indices in decreasing order were: fruit shape (1.949), attitude of calyx (1.908), flesh texture type (1.700), persistency of calyx (1.681), russet location (1.658), relief of area around eye basin (1.644), flavor (1.610) and ground color (1.592).  The coefficient of variation of titratable acidity in the 11 numerical traits of pear germplasm fruit was as high as 128.43%, which could more effectively reflect the differences between pear accessions.  The phenotypic differentiation coefficient Vst (66.4%) among the five cultivated pear species, including Pyrus bretschneideri (White Pear), Ppyrifolia (Sand Pear), Pussuriensis (Ussurian Pear), Psinkiangensis (Xinjiang Pear), and Pcommunis (European Pear), was higher than the within population phenotypic differentiation coefficient Vst (33.6%).  The variation among populations was the main source of variation in pear fruit traits.  A hierarchical cluster analysis divided the 389 accessions of six cultivated pear species, including Ppashia (Himalayan Pear), into six categories.  There were certain characteristics within the populations, and the differences between populations were not completely clustered by region.  For example, Sand Pear cultivars from Japan and the Korean Peninsula clustered together with those from China.  Most of the White Pear cultivars clustered with the Sand Pear, and a few clustered with the Ussurian Pear cultivars.  The Ussurian Pear and European Pear cultivars clustered separately.  The Xinjiang Pear and Himalayan Pear did not cluster together, and neither did the cultivars.  Seventeen traits, three describing fruit weight and edible rate (fruit diameter, fruit length and fruit core size), five describing outer quality and morphological characteristics (over color, amount of russeting, dot obviousness, fruit shape, and stalk length), and nine describing inner quality (flesh color, juiciness of flesh, aroma, flavor, flesh texture, flesh texture type, soluble solid contents, titratable acidity, and eating quality) were selected from the 39 traits by principal component and stepwise regression analyses.  These 17 traits could reflect 99.3% of the total variation and can be used as a comprehensive evaluation index for pear germplasm resources.

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Spore production in the solid-state fermentation of stevia residue by Trichoderma guizhouense and its effects on corn growth
LIU Hong-jun, DUAN Wan-dong, LIU Chao, MENG Ling-xue, LI Hong-xu, LI Rong, SHEN Qi-rong
2021, 20 (5): 1147-1156.   DOI: 10.1016/S2095-3119(20)63478-5
Abstract124)      PDF in ScienceDirect      
Trichoderma is an important and widely used plant growth-promoting fungus (PGPF).  In this study, stevia residue amended with amino acids hydrolyzed from animal carcasses was used for the production of Trichoderma guizhouense NJAU 4742 by solid-state fermentation, and then its potential to promote corn plant growth was evaluated in combination with chemical fertilizer (CF) or organic fertilizer (OF).  The highest spore number of 7×109 CFU g–1 fresh weight was obtained under the following optimal parameters: material ratio of 50% (stevia residue:rice bran=1:1), pH value of 3.0 (amended with 6.67% amino acids), initial moisture content of 60%, inoculum size of 10%, material thickness of 3 cm and an incubation time of 4 days.  The aboveground corn plant biomass obtained with T. guizhouense applied alone and with CF treatments were slightly higher than those of no fertilizer control and CF treatments, respectively.  However, T. guizhouense applied with OF significantly (P<0.05) increased aboveground biomass compared to OF and yielded the highest aboveground biomass among all the treatments.  Moreover, T. guizhouense applications primarily in?uenced the fungal bulk soil community composition, among which three OTUs (OTU_2 and OTU_9 classified as Chaetomium, and OTU_4 classified as Trichoderma) were stimulated in both bulk and rhizosphere soil.  Notably, a specific OTU_3 (Phymatotrichopsis) was only stimulated by T. guizhouense applied with OF, possibly leading to high soil productivity.  These results show that it is feasible to employ stevia residue in the eco-friendly fermentation of T. guizhouense, which is strongly suggested for enhancing OF applications.
 
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Does nitrogen application rate affect the moisture content of corn grains?
ZHANG Yuan-meng, XUE Jun, ZHAI Juan, ZHANG Guo-qiang, ZHANG Wan-xu, WANG Ke-ru, MING Bo, HOU Peng, XIE Rui-zhi, LIU Chao-wei, LI Shao-kun
2021, 20 (10): 2627-2638.   DOI: 10.1016/S2095-3119(20)63401-3
Abstract89)      PDF in ScienceDirect      
Nitrogen fertilizer application is an important measure to obtain high and stable corn yield, and the moisture content of corn grains is an important factor affecting the quality of mechanical grain harvesting.  In this study, four different nitrogen fertilizer treatments from 0 to 450 kg ha–1 pure nitrogen were set for a planting density of 12.0×104 plants ha–1 in 2017 and 2018, and 18 different nitrogen fertilizer treatments from 0 to 765 kg ha–1 pure nitrogen were set for planting densities of 7.5×104 and 12.0×104 plants ha–1 in 2019, to investigate the effect of nitrogen application rate on the moisture content of corn grains.  Under each treatment, the growth of corn, leaf area index (LAI) of green leaves, grain moisture content, and grain dehydration rate were measured.  The results showed that, as nitrogen application increased from 0 to 765 kg ha–1, the silking stage was delayed by about 1 day, the maturity stage was delayed by about 1–2 days, and the number of physiologically mature green leaves and LAI increased.  At and after physiological maturity, the extreme difference in grain moisture content between different nitrogen application rates was 1.9–4.0%.  As the amount of nitrogen application increased, the corn grain dehydration rate after physiological maturity decreased, but it did not reach statistical significance between nitrogen application rate and grain dehydration rate.  No significant correlation was observed between LAI at physiological maturity and grain dehydration rate after physiological maturity.  In short, nitrogen application affected the grain moisture content of corn at and after physiological maturity, however, the difference in grain moisture content among different nitrogen application rates was small.  These results suggest that the effect of nitrogen application on the moisture content of corn grains should not be considered in agricultural production.
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A Three-Dimensional (3D) Environment to Maintain the Integrity of Mouse Testicular Can Cause the Occurrence of Meiosis
CHU Zhi-li, LIU Chao, BAI Yao-fu, ZHU Hai-jing, HU Yue , HUA Jin-lian
2013, 12 (8): 1481-1488.   DOI: 10.1016/S2095-3119(13)60376-7
Abstract1689)      PDF in ScienceDirect      
Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic cells maintain a close association throughout spermatogenesis and this association is necessary for normal spermatogenesis. In order to keep the relative integrity of the testicular tissues, and to detect the development in vitro, culture testicular tissues in a threedimensional (3D) agarose matrix was examined. Testicular tissues isolated from 6.5 d postpartum (dpp) mouse were cultured on the top of the matrix for 26 d with a medium height up to 4/5 of the 3D agarose matrix. The results showed that in this 3D culture environment, each type of testicular cells kept the same structure, localization and function as in vivo and might be more biologically relevant to living organisms. After culture, germ cell marker VASA and meiosis markers DAZL and SCP3 showed typical positive analysed by immunofluorescence staining and RT-PCR. It demonstrated that this 3D culture system was able to maintain the number of germ cells and promote the meiosis initiation of male germ cells.
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GDNF Up-Regulates c-Myc Transcription via the PI3K/Akt Pathway to Promote Dairy Goat Male Germline Stem Cells (mGSC) Proliferation
SUN Jun-wei, ZHU Hai-jing, LIU Chao, LI Ming-zhao , HUA Jin-lian
2013, 12 (6): 1054-1065.   DOI: 10.1016/S2095-3119(13)60263-4
Abstract1395)      PDF in ScienceDirect      
Studies have demonstrated that regulation of GDNF on male germline stem cells (mGSCs) mainly through Ras/Erk1/2, Src family kinase and PI3K/Akt signaling pathways, but the signaling pathways GDNF-mediated are different when the species and cell lines varied. Whether GDNF regulates self-renewal of mGSCs isolated from livestock has not been reported. Here, we purified mGSCs from dairy goat testis using mixed enzymes and fibronectin. Immunofluoresce staining revealed the cultured dairy mGSCs expressed Vasa, Nanos2, Ngn3, Tert, Dazl, Lin28, Oct4, CD49f, Stra8 and GFRa1, reflecting that these cells were mGSCs phenotype. Then we cultured these dairy goat mGSCs in different concentrations of GDNF (0, 5, 10, or 20 ng mL-1) to optimize the best concentration of GDNF to sustain the dairy goat mGSCs self-renewal, after that the inhibitor of PI3K (LY294002, 10 μmol L-1) was added to the medium which contains the optimal concentration of GDNF we obtained by experiments. The mGSCs cultured in different media were compared through the population doubling time (PDT), capacity of cell proliferation evaluated by PCNA and BrdU immunofluorescence staining, RT-PCR, QRT-PCR, Western blotting and flow cytometry. Results showed that 10 ng mL-1 was the optimal concentration of GDNF to maintain goat mGSCs self-renewal and GDNF up-regulates c-Myc transcription via the PI3K/Akt pathway to promote goat mGSCs proliferation. This study provides us an efficient model to study the mechanism in mGSCs proliferation and differentiation in goat, and has important implications in unveiling signaling pathways in livestock GSCs.
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Transplantation of Goat Bone Marrow Mesenchymal Stem Cells (gMSCs) Help Restore Spermatogenesis in Endogenous Germ Cells-Depleted Mouse Models
WANG Fang, LIU Chao, ZHANG Shan-shan, LIU Wei-shuai , HUA Jin-lian
2013, 12 (3): 483-494.   DOI: 10.1016/S2095-3119(13)60249-X
Abstract1668)      PDF in ScienceDirect      
Mesenchymal stem cells (MSCs) derived from bone marrow are a well-characterized population of adult stem cells that can be maintained and propagated in culture for a long time with the capacity to form a variety of cell types. This study investigated the characteristics of dairy goat bone marrow MSCs (gMSCs) and their differentiation potential toward germ cells in vitro, and to test their potential in vivo, these cells were transplanted into seminiferous tubes of endogenous germ cells-depleted mouse models. The results showed that characteristic gMSC lines were established and a small population of gMSCs transdifferentiated into male germ cell-like cells which expressed Stra8 after induction with retinoic acid (RA), as analysed by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence. Further, we transplanted the gMSCs into endogenous germ cells-depleted mouse models. A variety of analysis demonstrated that gMSCs might differentiate into male germ cells and helped spermatogenesis in endogenous germ cells depleted mouse models at 30 d after transplantation. The gMSCs could be used as a potential source of cells for reproductive studies and a neoadjuvant therapy for the spermatogenesis anomaly. Moreover, these cells may offer a new strategy for male infertility and an alternative approach for production of transgenic animals.
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