Population genetic insights into the conservation of common walnut(Juglans regia)in Central Asia

The common walnut(Juglans regia)is one of the most economically important nut trees cultivated worldwide.Despite its importance,no comprehensive evaluation of walnut tree population genetics has been undertaken across the range where it originated,Central Asia.In this study,we investigated the genetic diversity and population structure of 1082 individuals from 46 populations across Central Asia.We found moderate genetic diversity of J.regia across Central Asia,with 46 populations clustered into three groups with a weak relationship between genetic and geographic distance.Our findings reveal that the western Himalaya might be the core region of common walnut genetic diversity in Central Asia and that,except for two populations in Gongliu Wild Walnut Valley,humans might have introduced walnut populations to Xinjiang,China.The observed distribution of the genetic landscape has probably been affected by historical climate fluctuation,breeding system,and prolonged anthropogenic activity.We propose the conservation of the core genetic diversity resources in the western Himalaya and pay special attention to populations from Gongliu in Xinjiang.These findings enhance our understanding of the genetic variation throughout the distribution range of J.regia in Central Asia,which will provide a key prerequisite for evidence-based conservation and management.

Antioxidant,antimicrobial,and α-glucosidase inhibitory activities of saponin extracts from walnut(Juglans regia L.) leaves

Objective:To investigate the relationship between triterpenoid saponin content and antioxidant,antimicrobial,and α-glucosidase inhibitory activities of 70%ethanolic,butanolic,aqueous,supernate and precipitate extracts of Juglans regia leaves.Methods:Triterpenoid saponins of different Juglans regia leaf extracts were measured by the vanillin method.Antioxidant activity was evaluated against DPPH and ABTS free radicals.We also assessed α-glucosidase inhibitory and antimicrobial activities of the leaf extracts.Pearson’s correlation coefficient was evaluated to determine the correlation between the saponin content and biological activities.Results:The butanolic extract was most effective against DPPH with an IC50of 6.63μg/mL,while the aqueous extract showed the highest scavenging activity against ABTS free radical with an IC50of 42.27μg/mL.Pearson’s correlation analysis indicated a strong negative correlation (r=-0.956) between DPPH radical scavenging activity (IC50) and the saponin content in the samples examined.In addition,the aqueous extract showed the best α-glucosidase inhibitory activity compared with other extracts.All the extracts had fair antibacterial activity against Bacillus subtilis,Escherichia coli,and Klebsiella pneumoniae except for the aqueous extract.Conclusions:Juglans regia extracts show potent antioxidant,antimicrobial,and α-glucosidase inhibitory activities.There is a correlation between saponin levels in Juglans regia leaf extracts and the studied activities.However,additional research is required to establish these relationships by identifying the specific saponin molecules responsible for these activities and elucidating their mechanisms of action.

核桃(Juglans regia)SRAP标记反应体系建立的研究

以核桃早实优系“绿园”和晚实优系“绿丰”及其F1杂交后代为试材,对核桃SRAP标记反应体系及SRAP标记在核桃中的多态性进行了研究。Mg2+是影响SRAP-PCR反应的重要因子,当Mg2+浓度为2.5mmol/L时,能得到较好的扩增效果。利用11对引物组合对两亲本及其杂交后代进行了SRAP-PCR扩增,以引物组合Em10-Me4多态性最高,在154个杂交后代单株中,扩增出1509条DNA条带,其中多态性条带为824条,多态性比率达54.6%。结果表明,SRAP标记可广泛应用于核桃的遗传多样性分析、种质鉴定、遗传连锁图谱的构建等方面的研究。

核桃(Juglans regia L.)维生素E代谢相关基因jrVTE3的克隆与分析

核桃(Juglans regia L.)坚果是重要的天然维生素E源。在维生素E合成代谢中,2-甲基-6-叶绿基-1,4-苯醌甲基转移酶(MPBQMTase)催化2-甲基-6-植基-1,4-苯醌(MPBQ)向2,3-二甲基-5-植基-1,4-苯醌(DMPBQ)的合成,是γ-生育酚和α-生育酚生物合成过程中的关键酶。本研究以‘香玲’核桃开花后90 d的胚组织为材料,利用RACE技术克隆了核桃MPBQMT的cDNA。序列分析表明,得到的cDNA全长1280 bp,有1020 bp的开放阅读框(ORF),编码340个氨基酸,将其命名为jrVTE3。序列同源性比较显示,jrVTE3基因与毛果杨MPBQ/MSBQ甲基转移酶基因以及蓖麻、葡萄、大豆的内膜包装蛋白基因有同源性较高;其ORF编码的多肽序列与橡胶、莴苣、毛果杨的MPBQ/MSBQ转移酶及葡萄、蓖麻的内膜包装蛋白有较高的同源性。jrVTE3编码的多肽序列中,有15个氨基酸可能为蛋白激酶磷酸化位点,多肽序列二级结构中有α–螺旋、无规则卷曲。在多肽序列中,有一个低成分复杂性区域和一个跨膜区段,还有一个第一类S-腺苷甲硫氮酸甲基转移酶(AdoMet-MTases,Class I)的保守域,这些序列结构体现了甲基转移酶结构的特点。这些结果对进一步研究核桃坚果仁中维生素E的合成的调控机制及核桃品质的遗传改良具有参考意义。

核桃(Juglans regia L．)光合影响因子的研究

以普通核桃'清香'为试材,利用CI-301PS便携式光合作用测定仪,在田间条件下,测定了核桃净光合速率的日变化及季节变化,进行了核桃净光合速率与光合影响因子的相关性研究,为核桃栽培管理提供一定的科学依据。结果表明:核桃净光合速率日变化与叶温极显著正相关,与光合有效辐射、蒸腾速率、气孔导度显著正相关,与胞间CO_2浓度极显著负相关。核桃净光合速率季节变化与蒸腾速率呈极显著正相关,与叶绿素含量呈显著正相关,与胞间CO_2的浓度呈显著负相关。

核桃(Juglans regia L.)青皮提取物抗氧化及抑菌活性的研究

核桃青皮是核桃(Juglans regia L.)加工的副产物,因含有多种活性成分,可能是一种潜在的天然抗氧化剂和抑菌剂来源。本研究旨在研究核桃青皮提取物的抗氧化能力和抑菌活性,为开发新的饲用抗生素替代品提供参考。以蒸馏水及25%、50%、75%和100%的甲醇、乙醇,丙酮为溶剂分别提取8和12h获得核桃青皮提取物。通过测定提取物中的总酚和总黄酮含量,根据还原能力和2,2-二苯基-1-苦肼基(DPPH)自由基清除率评价其抗氧化能力;以大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌为受试菌,分别测定抑菌圈直径、最小抑菌浓度(MIC)及抑菌率评价其抑菌活性。结果表明,有机溶剂浓度显著影响提取物中的总酚和黄酮含量(P<0.01);除丙酮外,提取时间对提取物中总酚和黄酮含量均有显著的影响(P<0.05);在所有提取溶剂中,以25%乙醇提取8h获得的总酚和黄酮最高,分别达到25.35和12.63mg·g-1。有机溶剂浓度对提取物的还原能力具有显著的影响(P<0.01),而提取时间仅对丙酮提取物的还原能力具有显著影响(P<0.05),其中25%乙醇提取物的还原能力在各处理中最高,为0.366。有机溶剂浓度对提取物的DPPH自由基清除率具有显著的影响(P<0.01),而提取时间仅对甲醇提取物的自由基清除率有显著影响(P<0.01),其中75%丙酮提取物可清除88.81%的自由基,在各处理中最高。有机溶剂浓度对大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌的抑菌圈直径和最小抑菌浓度(MIC)均有显著的影响(P<0.01);从提取时间来看,除甲醇提取物对大肠杆菌以及丙酮提取物对枯草芽孢杆菌的抑菌圈直径无显著影响外(P>0.05),其他均有显著的差异(P<0.01);此外,提取时间显著影响对大肠杆菌的MIC(P<0.05),乙醇和丙酮提取物的金黄色葡萄球菌MIC以及丙酮提取物的枯草芽孢杆菌MIC有显著差异(P<0.05),其他提取物的MIC均不受提取时间的影响(P>0.05)。抑菌率测试结果表明核桃青皮25%乙醇提取物对枯草芽孢杆菌的抑菌活性强于对大肠杆菌和金黄色葡萄球菌的抑制。由此可见,所有核桃青皮提取物均具有一定的抗氧化及抑菌活性,尤其以25%乙醇8h提取物的作用最好。

基于SSR标记的中亚生态区核桃(Juglans regia L.)遗传多样性与种群结构分析

【目的】从分子水平探究中国新疆与吉尔吉斯斯坦和塔吉克斯坦2个中亚国家共6个区域核桃种质资源间的遗传多样性及亲缘关系。【方法】采用SSR分子标记方法对采自6个区域的137份核桃种质资源进行遗传多样性和居群遗传结构分析。【结果】利用14对引物共检测到130个等位变异位点,变异范围为6~13,平均每对SSR引物可检测到9.2857个等位位点;14个SSR位点的占比范围为0.6257~0.8651,平均值0.7634;平均Shannon’s多样性指数(I)为0.4598;种群总基因多样性(Ht)平均值为3.2481;种群内基因多样性(Hs)平均值为2.1089;种群间的遗传分化指数(Gst)范围为0.0578~0.4068,平均值为0.2595;基因流(Nm)平均值为3.0174;各个等位基因频率整体分布不均匀。UPGMA聚类结果显示,137份供试材料在遗传相似性系数为0.75时分成3个类群。其中,第一类群共42份,包括中国新疆阿克苏地区16份,中国新疆和田地区21份,吉尔吉斯斯坦5份;第二类群共44份,包括中国新疆伊犁地区12份、吉尔吉斯斯坦32份;第三类群共51份,包括中国新疆喀什地区19份、塔吉克斯坦13份和中国新疆伊犁地区19份。聚类结果在一定程度上表明了居群间亲缘关系的距离,总体分布与地理分布有关,不同区域之间存在一定的基因交换。聚类结果与居群间遗传距离和遗传一致度结果一致。【结论】SSR分子标记结果表明,中亚生态区不同地理分布的核桃种质资源遗传多样性存在差异,为揭示中亚生态区核桃种群结构及传播途径提供了依据。

A Complete Technique in Improving Quality and Production Efficiency of Juglans regia in Gongshan Derung and Nu Autonomous County

We applied water releasing from rootstocks technique and Juglans sigillata in Yangbi was pruned in the shape of opened-heart or round-heart shape. By bal- anced fertilization, survival rate of grafted walnuts can be improved. We reviewed technologies to enhance walnut quality and production efficiency in Gongshan Derung and Nu Autonomous County for reference.

Two new diarylheptanoids from the pericarps of Juglans regia L.

Two new cyclic diarylheptanoids juglanin A （1） and juglanin B （2） were isolated from the pericarps of Juglans regia L. Their structures were elucidated by various spectroscopic methods including 2D NMR techniques （COSY, HMQC, HMBC, NOESY） and HR-ESIMS.

In vitro antibacterial and free radical scavenging activity of green hull of Juglans regia

Abstract Antioxidant supplements from plants are vital to count the oxidative damage in cells. We assessed the antioxidants and antibacterial activity of green hull of Juglans regia in this study. According to our results the maximum antibacterial activity was observed in ethanolic extract when compared to other extract. So, the ethanolic extract was studied for antioxidant activity which exhibited high antiradical activity against DPPH, hydroxyl, and nitric oxide radicals. In conclusion, green hull of J. regia showed strong reducing power activity and total antioxidant capacity. The results justify the therapeutic application of plant in the indigenous system of medicine.

Anti-diabetes Agents——I:Tetralone Derivative from Juglans regia

A new compound, 4-hydroxy-a-tetralone-4-O-b-D-[6-O-(3,4,5-trihydroxybenzoyl) glucopyranoside (1), together with a known compound, 4-hydroxy-a-tetralone (2), has been isolated from the roots of Juglans regia. 2 showed moderate bioactivity against protein tyrosine phosphatase 1B (PTP1B).

Two new glucosides from the pellicle of the walnut (Juglans regia)

A newα-tetralonyl glucoside,6'-O-acetyl-juglanoside E(1),and a new dihydrophaseic acid glucoside,dihydrophaseic acid 1-O-(6-O-acetyl)-glucopyranoside(2),together with two known ones,juglanoside E(3)and dihydrophaseic acid(4),were isolated from the pellicle of the walnut(Juglans regia).The structures of the new compounds were elucidated by comprehensive spectroscopic analysis,including IR,HRESIMS,1D and 2D NMR data.

Key chemical composition of walnut(Juglans regia.L)Oils generated with different processing methods and their cholesterol-lowering effects in HepG2 cells

We systematically evaluated fatty acids and triacylglycerol composition,as well as tocopherol,phytosterol,and phenolics,in walnut oil and compared the cholesterol-lowering effects of oil processed with different methods(cold pressing,roast-pressing,hexane extraction,subcritical butane extraction,and supercritical CO_(2) extraction).The different methods did not affect the lipid composition of walnut oil.The tocopherol(41.11 mg/100 g)and total phenolic content(TPC,4.26 mg/100 g)of roast-pressed walnut oil and the phytosterol contents of subcritical butane-extracted walnut oil(106.51 mg/100 g)were higher than those of other tested oils.Walnut oil significantly decreased cholesterol synthesis by downregulating the expression of HMGCR,SREBP-2,and CYP51 genes,and increased cholesterol efflux by upregulating the expression of ABCG1,thus significantly reducing total cholesterol and triacylglycerol.Phytosterols and TPC in walnut oil were responsible for lowering cholesterol;the optimal concentration of phytosterols was 10μg/mL,and that of TPC was 12.5×10^(-3)μg/mL.Through process optimization,a new processing method for walnut oil based on biological evaluation was preliminarily established.

Sequencing a Juglans regia×J.microcarpa hybrid yields high-quality genome assemblies of parental species

Members of the genus Juglans are monecious wind-pollinated trees in the family Juglandaceae with highly heterozygous genomes,which greatly complicates genome sequence assembly.The genomes of interspecific hybrids are usually comprised of haploid genomes of parental species.We exploited this attribute of interspecific hybrids to avoid heterozygosity and sequenced an interspecific hybrid Juglans microcarpa×J.regia using a novel combination of single-molecule sequencing and optical genome mapping technologies.The resulting assemblies of both genomes were remarkably complete including chromosome termini and centromere regions.Chromosome termini consisted of arrays of telomeric repeats about 8 kb long and heterochromatic subtelomeric regions about 10 kb long.The centromeres consisted of arrays of a centromere-specific Gypsy retrotransposon and most contained genes,many of them transcribed.Juglans genomes evolved by a whole-genome-duplication dating back to the Cretaceous-Paleogene boundary and consist of two subgenomes,which were fractionated by numerous short gene deletions evenly distributed along the length of the chromosomes.Fractionation was shown to be asymmetric with one subgenome exhibiting greater gene loss than the other.The asymmetry of the process is ongoing and mirrors an asymmetry in gene expression between the subgenomes.Given the importance of J.microcarpa×J.regia hybrids as potential walnut rootstocks,we catalogued disease resistance genes in the parental genomes and studied their chromosomal distribution.We also estimated the molecular clock rates for woody perennials and deployed them in estimating divergence times of Juglans genomes and those of other woody perennials.

Gene flow among wild and cultivated common walnut(Juglans regia)trees in the Qinling Mountains revealed by microsatellite markers

Patterns of gene flow and gene introgres sion can be used to assess the risk of genetic pollution of wild forest trees from widespread cultivated trees.A comprehensive understanding of the genetic relationships and levels of gene flow among wild and cultivated common walnut(Juglans regia)has become an urgent issue.Using twelve microsatellite markers,we investigated the genetic diversity and gene flow between cultivated and wild trees of J.regia in the Qinling Mountains,China.A high level of genetic variation was detected in both cultivated and wild trees.The mean number of alleles per locus was 17.5.Observed heterozygosity(HO)and expected heterozygosity(HE)were 0.777 and 0.800,respectively.Pollination of mother trees was not by nearest neighbors,and a paternity of 60.7%of offspring evaluated could not be assigned to a local,sampled tree.Pollen flow from cultivated trees to wild trees was infrequent(5.4%),and selfing rates ranged from zero to 25.0%.Male parents were located from 0 to 1005 m from their female partners,with an average pollination distance of 285.1 m.These results are discussed in light of the cultivated species’diversity,outlining the frequent spontaneous genetic contributions from the wild to the cultivated compartment.In addition,the pollen flow parameters provide useful information about the dynamics of pollen movement within J.regia populations.

Effect of Fertilizer Application on the Yield of Walnut (Juglans regia L.)

[Objectives] This study was conducted to explore the fertilization ratio of walnut, so as to provide a basis for rational fertilization of walnut. [Methods] Under the condition of gravelly yellow soil in Chaotian District, Guangyuan City, the orthogonal design of L_9(3~4) was used to test the fertilization ratio of nitrogen, phosphorus and potassium fertilizers. [Results] The effects of nitrogen, phosphorus and potassium fertilizers on walnut yield ranked as phosphate fertilizer>potassium fertilizer>nitrogen fertilizer. The different treatments had great effects on the yield of walnut, and for the land with gravelly yellow soil, the suitable annual fertilization amount of walnut was urea 1 200 g/plant + calcium superphosphate 1 500 g/plant + potassium sulfate 940 g/plant. [Conclusions] This study provides a theoretical basis for rational fertilization of walnut in Sichuan Province.

Isolation and Characterization of Novel Microsatellite Markers in Walnut (<i>Juglans regia</i>L.)

Thirteen microsatellite markers were isolated and characterized from Juglans regia L. Successful polymorphism of the 13 primer pairs was observed in various genotypes of J. regia. The number of polymorphic alleles ranged from 2 to 4 (with an average of 4.35). The polymorphic information content values ranged from 0.47 to 0.88 (with an average of 0.69). TC/AG and GAA/CTT class of repeats were the most abundant di-nucleotide and tri-nucleotide repeats, respectively.

Co-located quantitative trait loci mediate resistance to Agrobacterium tumefaciens, Phytophthora cinnamomi,and P.pini in Juglans microcarpa×J.regia hybrids

Soil-borne plant pathogens represent a serious threat that undermines commercial walnut(Juglans regia)production worldwide.Crown gall,caused by Agrobacterium tumefaciens,and Phytophthora root and crown rots,caused by various Phytophthora spp.,are among the most devastating walnut soil-borne diseases.A recognized strategy to combat soil-borne diseases is adoption of resistant rootstocks.Here,resistance to A.tumefaciens,P.cinnamomi,and P.pini is mapped in the genome of Juglans microcarpa,a North American wild relative of cultivated walnut.Half-sib J.microcarpa mother trees DJUG 31.01 and DJUG 31.09 were crossed with J.regia cv.Serr,producing 353 and 400 hybrids,respectively.Clonally propagated hybrids were genotyped by sequencing to construct genetic maps for the two populations and challenged with the three pathogens.Resistance to each of the three pathogens was mapped as a major QTL on the long arm of J.microcarpa chromosome 4D and was associated with the same haplotype,designated as haplotype b,raising the possibility that the two mother trees were heterozygous for a single Mendelian gene conferring resistance to all three pathogens.The deployment of this haplotype in rootstock breeding will facilitate breeding of a walnut rootstock resistant to both crown gall and Phytophthora root and crown rots.

Acaricidal Activity of Extracts of Juglans regia L. on Tetranychus urticae Koch （Acari： Tetranychidae）

Two-spotted spider mite （Tetranychus urticae Koch） （Acari： Tetranychidae） is a very serious pest worldwide, causing considerable damage to vegetables, flowers and fruit crops. The application of plant extracts to control insects can be an effective alternative. In this study, the efficacy of an extract from Juglans regia L. （Juglandecaea） was tested as an alternative to conventional acaricides. Using two different methods, bioassays were used to determine the effects of varying concentrations J. regia （1%, 3%, 6%, 12%） of the extracts. Experiments were carried out using 3 cm diameter leaf disks of Phaseolus vulgaris L. In addition, the effects of the extract on mite reproduction and oviposition were investigated. As a result, in the leaf dipping method, the 12% concentration of the extract caused the highest mortality of nymph （90%） and adult （83.00%） stages. For the spraying method, the mortality of adults at the same concentration was 100%. In bioassays at lower concentrations, the adult mites laid lower numbers of eggs in comparison to the untreated mites. The highest effect occurred at concentration of 12% and the lowest effect was at 1%. The extract was no observed ovicidal effect.

不同施肥处理对‘渝城1号’核桃产量、品质和土壤肥力的影响

以‘渝城1号’核桃为研究对象,设置单施复合肥、单施有机肥、施用核桃配方肥及不施肥4个处理,测定不同施肥处理时核桃产量、品质及核桃园土壤理化性质、微生物数量等,对核桃配方肥的应用效果进行评价。结果表明:施复合肥、有机肥及核桃配方肥均能提高核桃产量,其中,施用核桃配方肥的增产效果最好,经济效益最高,该施肥处理比不施肥的收益提高88.1%。相比于不施肥,施用核桃配方肥时核桃果实的蛋白质及脂肪总量显著提高,油酸、亚油酸、α-亚麻酸等不饱和脂肪酸占比增加,硬脂酸、棕榈酸等饱和脂肪酸占比下降。施用复合肥能促进核桃园土壤有效氮、磷、钾质量分数的增加,但会引起土壤pH及有机质质量分数下降。施用有机肥和核桃配方肥均能促进土壤有机质和有效养分质量分数增加。施用核桃配方肥后,土壤总微生物量增加,固氮菌、解磷菌、解钾菌、纤维降解菌等功能微生物数量均显著增多,土壤脲酶、磷酸酶、蔗糖酶、过氧化氢酶等活性大幅升高。施用核桃配方肥能显著提升核桃的产量和品质,更利于土壤养分转化和果园可持续经营。