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排序方式: 共有1097条查询结果,搜索用时 15 毫秒
1.
对辽宁西部半干旱地区深松中耕对作物产量影响及作用机理的研究表明,深松打破了犁底层,减小了土壤容重及穿透阻力,增加了表层及亚表层土壤的孔隙度.深松土壤水分人渗可达80cm,大豆根系深度增加3.6~4.0cm,大豆产量和水分利用效率分别增加27.7~34.5%和16.1%,在干旱年份玉米增产7.9%.  相似文献   
2.
玉米根ABA结合蛋白的亚细胞定位及动力学性质   总被引:9,自引:0,他引:9  
以玉米(Zea maysL.)根或胚芽鞘为材料,经匀浆、分级离心得到胞质部分和膜部分(微粒体),进一步用6.2% (W/W ) Dextran T500 和PEG 3350 两相系统制备质膜,用1% 和8% (W /W) Dextran T70 梯度离心制备液泡膜. 电镜鉴定及多种标志酶检测表明,制备获得了高纯度正向型质膜和富含液泡膜的组分,其它内膜的污染很少. 用微量放射配体结合(MRLB)实验证明,玉米根微粒体的ABA专一性结合位点主要分布在液泡膜和质膜上,这两种膜组分与ABA 的特异结合活性分别为2485.4 fm ol/m g protein 和1257.3 fm ol/m g pro-tein,玉米根段胞质部分结合活性最低(差一个数量级).质膜上ABA-BP与ABA 的结合平衡解离常数(KD)为1.57 nm ol/L.  相似文献   
3.
This study analyzes population structure and linkage disequilibrium (LD) among 187 commonly used Chinese maize inbred lines, representing the genetic diversity among public, commercial and historically important lines for corn breeding. Seventy SSR loci, evenly distributed over 10 chromosomes, were assayed for polymorphism. The identified 290 alleles served to estimate population structure and analyze the genome-wide LD. The population of lines was highly structured, showing 6 subpopulations: BSSS (American BSSS including Reid), PA (group A germplasm derived from modern U.S. hybrids in China), PB (group B germplasm derived from modern U.S. hybrid in China), Lan (Lancaster Surecrop), LRC (derivative lines from Lvda Reb Cob, a Chinese landrace) and SPT (derivative lines from Si-ping-tou, a Chinese landrace). Forty lines, which formerly had an unknown and/or miscellaneous origin and pedigree record, were assigned to the appropriate group. Relationship estimates based on SSR marker data were quantified in a Q matrix, and this information will inform breeder’s decisions regarding crosses. Extensive inter- and intra-chromosomal LD was detected between 70 microsatellite loci for the investigated maize lines (2109 loci pairs in LD with D′ > 0.1 and 93 out of them at P < 0.01).This suggests that rapidly evolving microsatellites may track recent population structure. Interlocus LD decay among the diverse maize germplasm indicated that association studies in QTLs and/or candidate genes might avoid nonfunctional and spurious associations since most of the LD blocks were broken between diverse germplasm. The defined population structure and the LD analysis present the basis for future association mapping. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
4.
The decoupling of the retention time of easily degradable and persistent substances relieves the degradation process from inhibitors and increases the biogas yield. Anaerobic digestion of maize silage was investigated in a pilot‐scale plant with a coupled ultrafiltration membrane. The aim of the study was the evaluation of the influence of the membrane‐based relief of the degradation process and the increase of the retention time of persistent substances. For that purpose, the fermenter content was separated into solid and liquid fractions. The solid fraction was recirculated to the fermenter for longer retention time and higher substrate degradation rates. The fermentation process was improved by the removal of the liquid fraction and adding volatile fatty acids. The results showed an increase of the biogas yield by 7.2% in comparison to the anaerobic digestion without membrane filtration.  相似文献   
5.
Probst C  Cotty PJ 《Fungal biology》2012,116(4):503-510
Aflatoxins are highly carcinogenic mycotoxins frequently produced by Aspergillus flavus. Contamination of maize with aflatoxins imposes both economic and health burdens in many regions. Identification of the most important etiologic agents of contamination is complicated by mixed infections and varying aflatoxin-producing potential of fungal species and individuals. In order to know the potential importance of an isolate to cause a contamination event, the ability of the isolate to produce aflatoxins on the living host must be determined. Aflatoxin production in vitro (synthetic and natural media) was contrasted with in vivo (viable maize kernels) in order to determine ability of in vitro techniques to predict the relative importance of causal agents to maize contamination events. Several media types and fermentation techniques (aerated, non-aerated, fermentation volume) were compared. There was no correlation between aflatoxin production in viable maize and production in any of the tested liquid fermentation media using any of the fermentation techniques. Isolates that produced aflatoxins on viable maize frequently failed to produce detectable (limit of detection = 1 ppb) aflatoxin concentrations in synthetic media. Aflatoxin production on autoclaved maize kernels was highly correlated with production on viable maize kernels. The results have important implications for researchers seeking to either identify causal agents of contamination events or characterize atoxigenic isolates for biological control.  相似文献   
6.
矮秆已被广泛用于改良作物的抗倒伏性状,培育理想株型,从而提高作物产量。玉米矮秆突变体K123d由自交系K123自然突变产生。本研究比较该突变体与野生型主要农艺性状差异及其对赤霉素的敏感性;用K123d与株高不同的3个自交系分别构建F1、BC和F2群体,分析矮秆性状的遗传模式;以K169/K123d-F2为定位群体,采用集团分离分析法(BSA),运用SSR标记定位矮秆基因d123;参照br-2序列信息分段设计特异引物,同源克隆d123。结果表明,与野生型相比K123d株高降低35.59%,穗位高降低、节间缩短、叶片较直立,但结实率差,对赤霉素敏感;在F2群体和BC1群体中,正常植株与矮秆植株分离比例分别符合3∶1和1∶1,说明矮秆性状受1对隐性基因控制;其矮秆基因d123定位于第一条染色体上SSR标记umc1278和bnlg1564之间,遗传距离分别为12.8 c M和7.3 c M;同源克隆显示d123与br-2存在12个碱基替换,其中第4个外显子编码的一个谷氨酸被替换为赖氨酸。由此可见,矮秆突变体K123d为br-2的一个突变类型,对矮化育种具有进一步研究利用价值。  相似文献   
7.
Recombination at the Rp1 locus of maize.   总被引:11,自引:0,他引:11  
Summary The Rp1 locus of maize determines resistance to races of the maize rust fungus (Puccinia sorghi). Restriction fragment length polymorphism markers that closely flank Rp1 were mapped and used to study the genetic fine structure and role of recombination in the instability of this locus. Susceptible progeny, lacking the resistance of either parent, were obtained from test cross progeny of several Rp1 heterozygotes. These susceptible progeny usually had non-parental genotypes at flanking marker loci, thereby verifying their recombinational origin. Seven of eight Rp1 alleles (or genes) studied were clustered within about 0.2 map units of each other. Rpl G, however, mapped from 1–3 map units distal to other Rp1 alleles. Rp5 also mapped distally to most Rp1 alleles. Other aspects of recombination at Rp1 suggested that some alleles carry duplicated sequences, that mispairing can occur, and that unequal crossing-over may be a common phenomenon in this region; susceptible progeny from an Rp1 A homozygote had recombinant flanking marker genotypes, and susceptible progeny from an Rp1 DlRp1 F heterozygote showed both possible nonparental flanking marker genotypes.  相似文献   
8.
RFLP markers and predicted testcross performance of maize sister inbreds   总被引:1,自引:0,他引:1  
 Inbreds selfed from the same F2 or backcross population are referred to as sister inbreds. In some situations, maize (Zea mays L.) sister inbreds may not have testcross data available for best linear unbiased prediction (BLUP) of single-cross performance. This study evaluated the usefulness of BLUP and restriction fragment length polymorphism (RFLP)-based coefficients of coancestry ( f ) in predicting the testcross performance of sister inbreds. Parental contributions (p) were estimated from 70 RFLP loci for 15 inbreds that comprised three sister inbreds selfed from each of five F2 populations. Estimates of p were subsequently used to calculate RFLP-based f. Grain yield, moisture, and stalk lodging data were obtained for 2265 single crosses tested by Limagrain Genetics in multilocation trials from 1990 to 1995. Performance of the sister inbreds when crossed to several inbred testers was predicted from the performance of the tested single crosses and RFLP-based f. Correlations between predicted and observed performance, obtained with a delete-one cross-validation procedure, were erratic and mostly low for all three traits. Correspondence was poor between ranks for predicted and observed general combining ability of the sister inbreds. The results suggested that the proportion of the genome derived by a sister inbred from a given parental inbred does not solely determine its testcross performance. The failure of BLUP and RFLP-based f to consistently predict testcross performance indicated that actual field testing will continue to be necessary for preliminary evaluation of sister inbreds. Received : 17 March 1997 / Accepted : 18 April 1997  相似文献   
9.
Two cDNA clones corresponding to anaerobically induced maize mRNAs were found to have homology to a previously identified maize pyruvate decarboxylase gene. DNA sequencing and RFLP mapping indicate that these cDNAs represent two additional maize pdc genes. Each of the clones is approximately 85% identical in predicted amino acid sequence to the other two. All three clones are induced by hypoxic stress, but with different levels and kinetics of induction.  相似文献   
10.
Molecular-marker loci were used to investigate the adaptation differences between highland and lowland tropical maize. An F2 population from the cross of two inbred lines independently derived from highland and lowland maize germplasm was developed, and extracted F3:4 lines were phenotype in replicated field trials at four thermally diverse tropical testing sites, ranging from lowland to extreme highland (mean growing season temperature range 13.2–24.6°C). Traits closely related with adaptation, such as biomass and grain yield, yield components, days from sowing to male and female flowering, total leaf number, plant height and number of primary tassel branches (TBN), were analyzed. A large line × environment interaction was observed for most traits. The genetic basis of this interaction was reflected by significant, but systematic, changes from lowland to highland sites in the correlation between the trait value and genomic composition (designated by the proportion of marker alleles with the same origin). Joint analysis of quantitative trait loci (QTLs) over sites detected 5–8 QTLs for each trait (except disease scores, with data only from one site). With the exception of one QTL for TBN, none of these accounted for more than 15% of the total phenotypic variation. In total, detected QTLs accounted for 24–61% of the variation at each site on average. For yield, yield components and disease scores, alleles generally favored the site of origin. Highland-derived alleles had little effect at lowland sites, while lowland-derived alleles showed relatively broader adaptation. Gradual changes in the estimated QTL effects with increasing mean site temperature were observed, and paralleled the observed patterns of adaptation in highland and lowland germplasm. Several clusters of QTLs for different traits reflected the relative importance in the adaptation differences between the two germplasm types, and pleiotropy is suggested as the main cause for the clustering. Breeding for broad thermal adaptation should be possible by pooling genes showing adaptation to specific thermal regimes, though perhaps at the expense of reduced progress for adaptation to a specific site. Molecular marker-assisted selection would be an ideal tool for this task, since it could greatly reduce the linkage drag caused by the unintentional transfer of undesirable traits. Received: 10 October 1998 / Accepted: 9 April 1999  相似文献   
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