菠菜根尖细胞有丝分裂同步化诱导

本研究以菠菜（Spinacia oleracea L.）根尖分生组织为材料，采用羟基脲（HU）和甲基胺草磷（APM）结合的双阻断法对菠菜根尖细胞进行处理，结合显微镜观察和统计学分析结果，对有丝分裂中期同步化诱导作了探讨，并对中期染色体分离也作了初步研究。在试验中分别设置了羟基脲（HU）和甲基胺草磷（APM）的不同浓度梯度，并对甲基胺草磷（APM）设置了作用时间梯度，以研究其最佳同步化诱导效果。结果表明，经1.25 mmol/L HU、10μmol/L APM处理菠菜根尖细胞，能够使细胞有丝分裂中期指数(Met.I)达40%。     

VHZ对玉米分生组织毒害的细胞及生化分析

研究了微管解聚型三唑类化合物VHZ对玉米分生组织的影响,从细胞学及生物化学水平分析了VHZ的毒害机理.结果表明,VHZ能够诱导玉米根尖分生组织细胞前期、中期的同步化以及染色体变异(染色体桥、染色体滞后、染色体凝集).临界浓度和时间分别为20 μmol/L和12 h.免疫荧光标记检测表明,同步化细胞的形成以及染色体结构变异与纺锤丝的功能受到抑制有关.2D/SDS-PAGE检测发现,经VHZ处理后玉米根尖蛋白有两种组分消失,四种蛋白质组分含量有不同程度的降低,这些蛋白质组分可能对VHZ的防御机制有重要作用.     

胺磺灵诱导小麦根尖染色体结构的变异

用不同浓度的胺磺灵(Oryzalin)处理小麦种子,观察小麦根尖细胞染色体结构的变异情况。结果表明,胺磺灵的不同处理浓度及处理时间均能引起染色体的异常分裂,在光学显微镜下检测到桥、多极染色体、环状染色体、滞后染色体、染色体加倍、染色体凝集、微核等异常现象,以染色体加倍、微核的发生频率最高;处理时间对染色体结构变异的影响明显高于处理浓度。     

三氮苯类除草剂对水稻染色体结构、蛋白质含量及组分的影响

比较研究了不同浓度三氮苯类除草剂对水稻幼苗生长、叶绿素及可溶性蛋白质含量、根尖分生组织染色体结构、分生组织和叶绿体蛋白质组分的影响。结果表明,在0.1 mg /L Atrazine处理水稻后培养1周。幼苗高度由(10.8±1.7) cm（对照）降至 (8.2±0.7) cm,叶绿素含量由(1.07±0.013) mg/g FW（对照）降至(0.97±0.013) mg/g FW,     

磷酰胺除草剂APM诱导洋葱根尖分生组织细胞异常有丝分裂和蛋白质组分变化

研究了不同浓度APM(4～6 μmol/L)和不同处理时间(4～6 h)对洋葱根尖细胞有丝分裂的影响.结果表明,当用5.6 μmol/L APM处理洋葱分生组织16 h后,中期细胞有丝分裂指数(Met.Ⅰ)从0.8(对照)分别提高至5.0、5.2.结果也同时表明,当APM浓度超过4 μmol/L时,严重影响细胞有丝分裂.在根尖细胞中,多极分裂细胞(尤其是3～4级),中期染色     

不同除草剂加倍玉米单倍体的效率

通过比较3种除草剂加倍玉米单倍体的效率,提出了利用除草剂加倍玉米单倍体的新方法。以先玉335、中农大4号和8607×8609三个基因型诱导的单倍体籽粒为材料,利用20、40、80和160 μmol L^-1浓度的甲基胺草磷、炔苯酰草胺和氟乐灵作为加倍药剂,在单倍体植株生长到三叶期和五叶期时,用滴心法处理幼苗,选择有花粉的单株自交,收获后调查果穗加倍率;采用细胞学方法观察单倍体的染色体数目和花粉的活性。结果表明,20~160 μmol L^-1的3种除草剂对玉米单倍体加倍均有效果,加倍率在3.42%~26.32%之间。甲基胺草磷、炔苯酰草胺和氟乐灵的加倍率分别为4.29%~26.32%、3.85%~20.81%和3.42%~17.61%;其中80 μmol L^-1甲基胺草磷的加倍效果最佳,使用80 μmol L^-1甲基胺草磷处理3个杂交种的单倍体,平均加倍率分别为25.02%、20.13%和14.99%。方差分析表明,3个基因型间的单倍体加倍率均呈极显著差异,可见使用甲基胺草磷、炔苯酰草胺、氟乐灵可以提高玉米单倍体的加倍频率,但不同基因型单倍体对除草剂的敏感性存在差异。     

EMS诱变甘蔗茎尖分生组织的初步研究

为探索EMS对离体培养的甘蔗茎尖进行化学诱变的合适浓度和时间组合,以‘新台糖22’和‘粤糖93-159’甘蔗茎尖分生组织为材料,研究不同浓度(24、48、72μmol/L)、不同时间(2、4 h)诱变处理对茎尖分生组织的成活率、鲜重增重量、分化率及分化成苗情况的影响。结果表明:诱变处理后2个基因型的甘蔗茎尖分生组织成活率、每克鲜重增重量、分化率以及成苗的数量和质量都随着EMS处理浓度的升高和处理时间的延长而下降,2个基因型甘蔗茎尖经诱变处理后半分化EMS浓度均小于半致死浓度。综合成活和分化情况,适合‘新台糖22’茎尖分生组织的EMS诱变处理为48μmol/L处理2 h或24μmol/L处理4 h;适合‘粤糖93-159’茎尖分生组织的EMS诱变处理为72μmol/L处理2 h或48μmol/L处理4 h。     

高Fe2+胁迫下水稻幼苗根尖铁的分布及细胞超微结构变化

以耐性水稻(Oryza sativa L.)品种Azucena为实验材料,研究高Fe2+胁迫下,0～10mm段幼苗根尖铁的分布,以及根尖细胞亚显微结构变化情况.结果表明,400μmol/L Fe2+处理下,0～2mm段根尖铁含量最高;随着Fe2+浓度的升高,根尖边缘细胞(BC)铁含量呈递增趋势.电镜观察发现,400μmol/L Fe2+处理下,BC内出现大量碎片,受损明显,而根冠细胞主要表现为细胞壁增厚、细胞内出现许多小液泡.     

硫酸铜对大麦根尖细胞有丝分裂的影响及其致畸效应

为了研究硫酸铜对大麦根尖细胞的畸变效应,采用不同浓度的硫酸铜(0.05g/L、0.10gL、0.25g/L、0.50g/L和1.00g/L)分别处理大麦根尖,统计分析了大麦根尖细胞的有丝分裂指数、微核千分率和染色体畸变率。结果表明,不同浓度的硫酸铜均能使大麦根尖细胞有丝分裂指数明显增加0.10g/L硫酸铜处理有丝分裂指数最大,为9.64%而前期、中期和末期分裂指数均高于对照,后期分裂指数与对照之间差异不显著。在浓度低于0.10g/L时,细胞微核千分率随硫酸铜处理浓度的升高而增加,但随着硫酸铜浓度的进一步升高反而呈下降趋势。硫酸铜还能诱导染色体产生多种类型的畸变在浓度低于0.25g/L时,染色体畸变率随硫酸铜处理浓度的升高而增加,然而随着硫酸铜浓度的进一步升高染色体畸变率呈下降趋势,但均明显高于对照。     

大蒜对纳米金引起蚕豆根尖细胞微核拮抗作用的研究

为了研究大蒜提取液拮抗纳米金对蚕豆根尖细胞的遗传毒性效应,以100μg/m L纳米金溶液对蚕豆根尖进行染毒处理,分别以浓度为0～1 g/m L的大蒜提取液作为拮抗效应物。利用蚕豆根尖细胞微核检测技术,研究不同浓度大蒜对纳米金处理下蚕豆根尖细胞有丝分裂行为的影响。试验结果表明,纳米金具有一定的遗传毒性,且随着大蒜提取液浓度的不断增加,蚕豆根尖细胞有丝分裂指数、微核率和染色体畸变率均呈现显著减少的趋势(P0.05),表明大蒜提取液对纳米金引起的蚕豆根尖细胞毒害作用具有一定的拮抗作用,且最适拮抗浓度为0.25 g/m L。同时,试验结果还表明,高浓度的大蒜提取液对蚕豆根尖细胞的有丝分裂具有一定的抑制作用。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.