Geotropic Responses and Pod Development in Gynophore Explants of Peanut (Arachis hypogaea L.) Cultured In Vitro

Peanut gynophore explants cultured in vitro on a defined mediumshow a positive geotropic response in both light and dark whenplanted either horizontally, or vertically with the tip pointingupwards. The growth following the initial curvature dependedon age of the gynophores and on the levels of growth substancesin the medium. In the dark and in presence of 0·01–0·1p.p.m. kinetin, naphthalene acetic acid at concentrations of0·1 p.p.m. and lower promoted gynophore elongation. Athigher concentrations elongation was promoted to a lesser extentin younger explants, caused enlargement of the ovary and formationof pods. Young explants generally elongated more than olderones and pod formation took place inside the medium, while inolder ones it took place above the medium. In the light, theinitial positive geotropic response was followed by elongationbut without any enlargement of the ovary. Decapitation of gynophores1·5–2·0 mm below their tip, removing theovary but leaving most of the intercalary meristem, had no effecton the geotropic response and elongation. The initial geotropicresponse and elongations of explants in vitro was not dependenton the presence of the ovary but on the meristem proximal toit. Changes in growth substances balance during gynophore developmentseem to affect geotropic response, elongation and pod formationin the peanut.     

Micropropagation in Peanut (Arachis hypogaea L.)

Multiple shoots in Arachis hypogaea L. could be induced from the de-embryonated cotyledons (DC), embryo-axes (EA) and mature whole seeds (MWS) in MS medium supplemented with different levels of benzylaminopurine (BAP). DC was the most suitable explant with 57.9 % induction and more than 40 shoots per explant in 31.6 % of cases. Though EA and MWS had high percent induction at or above 30 mg dm^–3 BAP, only 10 – 14 shoots per explant were observed. In DC, multiple shoots were confined to the proximal end and in EA they originated from the axillary bud region. Histological studies on DC confirmed the origin of shoots from the region of attachment with the embryo. Shoots could be rooted in MS medium containing 2 g dm^–3 charcoal and 200 mg dm^–3 casein hydrolysate. Sixty percent of the rooted plantlets could be established in the field.     

Pod Formation and Its Geotropic Orientation in the Peanut, Arachis hypogaea L., in Relation to Light and Mechanical Stimulus

Gynophore elongation, pod formation and pod orientation in thepeanut plant (Arachis hypogaea L.) were studied in relationto the effects of light and dark conditions, mechanical stimulus,and growth substances. It was found that the proembryos controlgynophore elongation, probably by secretion of growth regulatorswhich stimulate cell division in the intercalary meristem locatedproximal to the ovules. The stimulus of pod production causesthe development of the proembryo into a mature embryo simultaneouslywith the growth of pod tissues and the cessation of gynophoreelongation. Darkness was found to be an essential factor forthe induction of pod formation. Pod formation did not occurin any of the treatments performed in the light, including theapplication of different growth substances on the ovary. A mechanicalstimulus is needed, in addition to darkness, for the normalthickening and diageotropic orientation of the pod, caused bya higher growth rate of the basal proximal side of the pod.The two ovules are always located on the upper wall of the diageotropicallyoriented pod (ventral suture). A possible mechanism which causessuch an orientation is discussed.     

Pod development of groundnut (Arachis hypogaea L.) in solution culture

Normal pods (containing seed) of groundnut (Arachis hypogaea L.) (cv. TMV-2) were successfully raised in darkened, aerated, nutrient solution, but not in the light. The onset of podding was evident 7 to 8 d after gynophores were submerged in the darkened nutrient solution. An examination of pods and submerged portions of gynophore surfaces by scanning electron microscopy showed the presence of two distinctly different protuberances: unicellular root-hair-like structures that first developed from epidermal cells of the gynophores and developing pods; and branched septate hairs that developed later from cells below the epidermal layer. The septate hairs became visible only after the epidermal and associated unicellular structures had been shed by the expanding gynophore and pods. Omission of Mn and Mg from the podding environment increased pod and seed weight, whilst omission of Zn reduced pod and seed weight.     

Peanut agglutinin from callus and cell suspension cultures of Arachis hypogaea L.

Summary Synthesis of peanut agglutinin was induced in callus and cell suspension cultures of cotyledons of peanut (Arachis hypogaea L.). The lectin was synthesised in cultures through several passages. Biosynthesis of peanut agglutinin was regulated by the type and concentration of exogenous growth regulators and was positively correlated to the growth of the cultures, indicating that the agglutinin may have a role to play during cell growth. Movement of agglutinin from the cells into the medium not only facilitated easy isolation of the lectin but also provided a clue that it may probably serve as a defence molecule. The synthesized lectin purified from culture, was found to be biologically active, and was found to be comparable with the lectin from seeds, in terms of its electrophoretic mobility.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - EDTA ethylenediamine-tetraacetic acid - HAU(s) haemagglutination unit(s) - IEF isoelectric focusing - KN kinetin - LS Linsmaier and Skoog (1965) medium - M_m medium promoting minimum growth of cells - M_X medium promoting maximum growth of cells - NAA naphthalene-1-acetic acid - PBS phosphate buffered saline - PMSF phenylmethylsulfonylfluoride - PNA peanut agglutinin - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - SHAA specific haemagglutination activity - TCA trichloroacetic acid     

AhNCED1基因转化花生研究

构建转化AhNCED1基因花生(Arachis hypogaea L.)过表达载体35S::AhNCED1::GUS,用OD600=0.8的LBA4404农杆菌液浸染汕油523,抗性芽诱导率达100%.PCR检测89株筛选苗,43株呈阳性,GUS检测阳性率为50%.转基因植株地上部分ABA含量增加;PEG胁迫10 h,转基因植株叶片AhNCEDl蛋白表达增强,内源ABA水平积累,超氧化物水平降低.     

Histological Changes of the Peanut (Arachis hypogaea) Gynophore and Fruit Surface During Development, and their Potential Significance for Nutrient Uptake

Histological changes in gynophores and fruits of Arachis hypogaeaL.cv. White Spanish were examined, utilizing scanning electronmicroscopy as well as light microscopy. The epidermis of theabove ground parts of gynophores is characterized by the presenceof stomata, lenticels and multicellular trichomes. Below groundportions of the same plant organ exhibit unicellular root-hair-likestructures. These protuberances of the epidermal cells can reacha very high density and length (up to 0.75mm) . Identical structurescan be found on the developing pod and are most prominent atthe reproductive stages R5-R6. In later developmental stagesthe hairs degenerate and the presence of large lenticels becomesthe obvious external feature of the pod. It is suggested thatthe substantial increase in surface area due to the hairs maywell be an anatomical adaptation for nutrient and water uptake. Arachis hypogaea, peanut fruit development, nutrient uptake     

花生转基因研究进展

花生是世界上重要的油料和经济作物之一,是人们生活的植物脂肪和蛋白质来源。现代生物技术的不断发展为花生育种和种质创新提供了新的技术手段, 它可以直接将来自不同种属的异源目的基因插人到花生基因组, 使花生表达目标性状, 实现花生品种的遗传改良。近年来, 国内外花生转基因研究取得了重大进展。文章综述了花生转基因在抗虫、抗病、抗非生物逆境和品质改良等方面的最新进展,并总结了近年来人们对农杆菌介导法、基因枪法和不依赖组织培养的转化法等主要的花生遗传转化方法的改进和探索。     

花生根部性状的遗传分析

利用花生RIL群体,分析了11个花生根部性状的遗传力,估算基因对数及性状间的相互关系,根据偏度系数(g1)和峰度系数(g2)估算控制性状的基因互作情况。结果表明:11个性状都是受多基因控制的数量性状,在RIL群体中基因型间的差异均表现为连续变异和明显的超亲分离。侧根干重的遗传力最高达0.60,其次是侧根鲜重,为0.58,而其他性状的遗传力均较低。控制主根长性状的多基因间存在互作,互作方式为重叠作用;控制主根粗(3cm)性状的基因间也存在一定的重叠作用,但是作用不明显;控制其他性状的基因都存在互作,表现为互补作用,但互补作用的强弱有差异。主根粗(1cm)、主根粗(3cm)、主根干重、主根鲜重、侧根干重和侧根鲜重之间都显著或极显著相关;根体积与主根粗(1cm)、主根粗(3cm)、侧根干重和侧根鲜重显著或极显著相关。     

Distribution of Lectins in the Jumbo Virginia and Spanish Varieties of the Peanut, Arachis hypogaea L

Peanut lectin was purified from seed meal of the Spanish and Jumbo Virginia varieties of peanut (Arachis hypogaea L.) by affinity chromatography on lactose coupled to Sepharose 4B. Polyacrylamide gel isoelectric focusing resolved the lectin preparation from Jumbo Virginia seeds into seven isolectins (pI 5.7, 5.9, 6.0, 6.2, 6.3, 6.5, and 6.7). Seed meal from the Spanish variety contained six isolectins which were indistinguishable from the pI 5.7, 5.9, 6.2, 6.3, 6.5, and 6.7 isolectins from Jumbo Virginia. Quantitative, lactose-specific hemagglutination was used to examine the lectins in tissues of both peanut varieties. In young (3- to 9-day-old) seedlings of each variety, more than 90% of the total amount of lectins detected in the plants was in the cotyledons. Most of the remainder was in hypocotyls, stems, and leaves; young roots contained no more than 4 micrograms of lectin per plant. Lectins were present in all nonroot tissues of 21- to 30-day-old seedlings, except 27-day-old Spanish hypocotyls. As cotyledons of each variety senesced, several of the more basic isolectins decreased to undetectable levels, but the acidic isolectins remained until at least 15 days after planting. Some of the seed isolectins and several apparently new lactose-binding lectins were also identified in affinity-purified extracts of 5-day-old roots and hypocotyls. Rabbit antibodies raised against the Jumbo Virginia seed isolectin preparation reacted with seed, cotyledon, and hypocotyl lectin preparations from both varieties. Analysis of seed lectin preparations from seven varieties of A. hypogaea and of a related species (A. villosulicarpa) indicated that isolectin composition in Arachis may be a characteristic of both the species and the subspecies (botanical type) to which the variety belongs.     

龙生型花生的遗传多样性

龙生型花生(Arachis hypogaea var.hirsute)是中国引进最早、种植最早的花生类型。经过不断地自然选择和人工选择,形成了许多各具特色的地方品种,并逐渐形成了次生中心。本实验对15份龙生型花生资源在植物学性状和品质性状及分子水平上进行了系统研究。结果表明:龙生型花生在植物学性状和品质性状上具有丰富的遗传多样性,在分子水平上差异也较大。变异系数在5.10~34.60之间,多样性指数在1.17~2.04之间,同时两者的变化趋势相反。基于植物学性状和品质性状上的聚类分析在阀值为6.5将龙生型花生分为两大类,一类主要包括广西的品种,另一类包括其它省份的品种;基于AFLP分析的聚类结果在阀值为0.39处分为5类,一类主要包括广西的品种,其它4类包括其它省份的品种。     

Embryo Rescue in Wide Crosses in Arachis. 2. Embryo Development in Cultured Peg Tips of Arachis hypogaea

Embryo rescue techniques in Arachis are potentially importantfor recovering interspecific hybrids which have the propensityto abort. Pegs are commonly produced in interspecific crosses,but either they fail to reach the soil because growth is arrested,or pods are produced but embryo development is never re-initiated.Peg tips, with the ovule and embryo, of A. hypogaea L. cv. ‘NC6’, were used to determine whether peg tips can be usedas nurse tissue for in vitro culture of embryos. Tissues werecollected 1, 2, 3 and 4 d after self-pollination, after whichpeg meristems were removed from half the pegs, and culturedon five media combinations. Continued reproductive developmentwas observed for embryos cultured at all four collection days;however, the highest frequency of growth was observed in 1-d-oldtissues. Evidence is presented that meristematic activity mayrestrict embryo growth in the 2- to 4-d-old embryos and, oncethe sequence of events is initiated to slow embryo growth, itis not easily reversed in vitro. Achievements of embryo growthto multicellular, globular stages (stages 1–1 or 1–2)encourage the development of methods to recover very young embryosthrough tissue-culture techniques. Embryo culture, morphology, interspecific hybridization, Arachis hypogaea, comparative light and scanning electron microscopy, peanuts, groundnuts     

ATP Synthesis in Cell-Free Extracts of Peanut (Arachis hypogaea L.) Seeds

Cell-free extracts of peanut (Arachis hypogaea L., cv. Shulamit)seeds, incubated with various substrates, synthesized ATP. Significantsynthesis occurred in the presence of AMP + PEP, NADH₂ + PEPand NAD + PEP. When the activities were examined in extractsprepared with 0.3 M mannitol, the rates were 0.6, 0.1 and 0.04nmol min^–1 mg^–1 protein, respectively. The activitiesunder such conditions were linear with time up to 90 min incubationat 30 °C. In the presence of PEP + NADH₂ there was a higherspecific activity in extracts from non-dormant seeds than fromdormant seeds. No such difference was found when PEP + AMP orNAD + PEP was used as the substrate. The temperature dependenceof the activity showed a relatively high energy of activation(Ea) for AMP + PEP and a low one if NADH₂ + PEP or NAD + PEPwas used as substrate. In buffer extracts of seeds ATP was synthesizedin the presence of the above-mentioned substrate combinationsbut the rate of activity exhibited a lag phase at the earlytime of incubation, after which higher rates of activities (ascompared with mannitol extracts) were obtained. The activitieswere Co⁺-dependent, with a K_m of about 0.7 mM. In the bufferextracts relatively high activities of adenylate kinase (EC2.7.4.3 [EC] (AK) and pyruvate kinase (EC 2.7.1.50 [EC] ) (PK) were found.AK was stimulated by ethephon (ethylene). This effect is temperature-dependentand occurs in both directions: in the presence of ADP (ATP +AMP) as well as if ATP + AMP is used as substrate to synthesizeADP. PK is Co⁺-dependent, and unaffected by ethephon. Both activitieswere stimulated by malonate. Key words: Adenylate Kinase, Arachis hypogaea, ATP synthesis, Peanut, Pyruvate kinase, Seed     

Reassociation Kinetics and Cytophotometric Characterization of Peanut (Arachis hypogaea L.) DNA

The base composition of peanut (var. NC-17) DNA determined from thermal denaturation profiles showed an average guanine plus cystosine content of 34% which was in close approximation to 36% guanine plus cytosine calculated from the buoyant density. Buoyant density also indicated the absence of satellite DNA. The genome size, 2.0 × 10⁹ base pairs, as determined by reassociation kinetics of the single copy DNA was close to the genome size determined by cytophotometry, 2.1 × 10⁹ base pairs. Peanut DNA averaging 450 to 600 base pairs long, reassociated in phosphate buffer and fractionated by hydroxylapatite, indicated a DNA genome composition of 36% nonrepetitive or single copy DNA; reassociation in formamide and followed by optical methods indicated the repetitive DNA possesses highly repeated, intermediately repeated and rarely repeated components of DNA with DNA sequences repeated on the average about 38,000, 6,700, and 200 times each. Different criteria of reassociation in formamide revealed further subdivisions of these four separate components of DNA. The DNA of above mentioned NC-17 variety compared to Florigiant variety showed no differences in thermal denaturation profiles, buoyant density, or in genome size.     

De Novo Synthesis of Isocitritase in Peanut (Arachis hypogaea L.) Cotyledons

Germination of peanut seed is accompanied by a rapid increase in isocitritase (isocitrate lyase, EC 4.1.3.1) during the first 4 days. The presence of cycloheximide (50 μg/ml) during water imbibition inhibited the increase in isocitritase activity. Actinomycin D conversely did not inhibit isocitritase activity until the second day of imbibition while RNA synthesis was inhibited. Germination of peanut seed in ¹⁴C-reconstituted amino acids followed by fractionation of a 20 to 35% ammonium sulfate preparation on a Sephadex G-200 column (57-fold purification) showed that the active enzymic fraction coincided with a large peak of radioactivity. Germination of peanut seed in 45% D₂O followed by enzyme purification and CsCl equilibrium centrifugation revealed that all the enzyme from D₂O seed had a higher density than normal isocitritase. These data indicate that isocitritase in peanut seed is synthesized de novo.     

花生LEC1基因的克隆及表达研究

通过构建花生未成熟种子cDNA文库,结合大规模EST测序,从花生中克隆了LEC1基因2个成员的全长cDNA序列.序列分析表明,花生中LEC1的2个成员的序列在B结构域高度保守,属于LEC1型HAP3亚基.不同植物中LEC1基因在B结构域以外的序列差异很大.利用花生cDNA芯片和半定量RT-PCR对花生LEC1进行表达研究表明,LEC1在种子中高水平表达,在种子发育的不同时期表达有差异.     

花生防御素基因的克隆及原核表达

定基础.