Ethylene and the geotropic response of lateral branches in peanuts (Arachis hypogaea L.)

The prostrate growth habit of runner-type peanut plants changedwhen treated with the ethylene-releasing compound CEPA: thehorizontal branches became plagiotropically oriented and theplant assumed a bushy form. Treatment with CEPA caused a markedincrease in ethylene evolution for about a week, which thendecreased to the level of the control. Nevertheless, the branchesmaintained their newly assumed plagiotropic orientation. Ethylene evolution from isolated branch tips correlated withtheir age and orientation, being highest in old plagiotropicand lowest in old diatropic branches. Light intensity and qualitywhich caused plagiotropic orientation of branches also causedan increase in ethylene evolution, while ethylene evolutionwas lowest under light conditions favouring diatropic orientation.Along with the changes to plagiotropic orientation by CEPA,an increase in GA-like substances and a decrease in growth inhibitorswas observed in extracts from treated plants. (Received October 7, 1975; )     

Plasmon divergence in peanuts (Arachis hypogaea): A third plasmon and locus affecting growth habit

Summary In a series of reciprocal crosses between peanut (Arachis hypogaea L.) cultivars from different regions and known testers, the cultivar HG1 from India was shown to have a third plasmon type, designated [G]. HG1 also has a third locus, Hb₅ , which interacts with the plasmons and the loci described earlier. In the [G] plasmon, Hb₁ and Hb₅ are additive: plants having three or four dominant alleles have a trailing habit while the other nuclear genotypes produce in [G] erect plants. In the [V4] plasmon, Hb₂ and Hb₅ are complementary, [V4] Hb₂-, Hb₅-plants being trailing, the others erect. In the [G] plasmon, Hb₂ and Hb₅ are complementary, while in the [O] plasmon they are additive.     

The influence of plant growth habit on calcium nutrition of groundnut (Arachis hypogaea L.) pods

In field experiments in India and Niger runner and bunch groundnut cultivars were compared for their pod distribution pattern and its relevance to the calcium (Ca) supply for pod development. Bunch cultivars produced sixty to eighty percent of their pods within 5 cm of the tap root. Runner cultivars explored a radius of up to 30 cm for pod production and exploited the soil area in a more homogeneous manner than bunch types. The available soil volume per pod was 19 to 27 cm³ for bunch types and 43 to 46 cm³ for runner types, varying the potential for Ca competition between pods. Computation of the soil Ca content needed to satisfy pod Ca requirements showed that much higher concentrations were needed for the bunch cultivars than for the runners. No significant differences in Ca content of pods existed between bunch and runner cultivars. However, in the runner cultivars, the Ca content of the more widely dispersed pods in outer zones was greater than that of the more densely populated inner pod zones. Regression analysis of shelling percentage across a range of environments showed that the shelling percentage of runners declined less rapidly than did the shelling percent of bunch types, indicating that runners were more efficient in exploiting Ca at lower soil Ca availability than the bunch types.Approved as ICRISAT Journal Article No. 1372.     

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.     

Diniconazole's effect on peanut (Arachis hypogaea L.) growth and development

Greenhouse nutrient solution studies demonstrated that diniconazole will decrease peanut (Arachis hypogaea L.) shoot growth when either root or shoot applied. Root growth and development were decreased by root and, to a lesser extent, by shoot uptake of diniconazole. Diniconazole is apparently xylem translocated, but not phloem translocated. Concentrations of 200 ppb ES isomer of diniconazole in nutrient solution (root uptake) increased specific leaf weight and starch deposits in the leaf. Field applications of 193 g ES isomer ha^–1 of diniconazole reduced main stem height by 33%, leaf area index by 16%, and total vegetative dry weight by 19%, but had no effect on average leaf size. Decreased germination of seeds from plants treated with 1435 g ha^–1 diaminozide was associated with increased seed dormancy. Seed dormancy was counteracted by either ethylene gas or storage for 150 days after harvest. Soil applications of diniconazole were more effective than foliar appliations in reducing vine growth. Diniconazole's ER isomer is a broad spectrum fungicide that reduced damage (when compared to the control) bySclerotium rolfsii andRhizoctonia solani. The reduced damage by these diseases was thought to be the primary reason for the significant pod yield increase (when compared to the control) observed with the diniconazole treatments. In drought-stressed plots, populations of the two-spotted spider mite (Tetranychus urticae) were increased by diniconazole.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee by the University of Georgia or the U.S. Department of Agriculture and does not imply UGA or USDA approval to the exclusion of other products or vendors that also may be suitable.     

Diallel analysis in groundnut (Arachis hypogaea L.)

Summary An 8 × 8 full diallel experiment based on 4 bunch plus 4 spreading types of groundnut (Arachis hypogaea L.) was conducted over three environments. For both number of pods and pod yield, additive, nonadditive and reciprocal cross effects were detected and these were also influenced by changes in environments. For number of pods additive genetic variance was predominant whereas it was approximately equal to non-additive genetic variance for pod yield. Graphical analysis revealed the presence of strong non-allelic interaction for number of pods whereas for pod yield absence of dominance and/or presence of non-allelic interaction was evident.Part of Ph.D. Thesis of the first author     

Boron mobility in peanut (Arachis hypogaea L.)

In most plant families, boron (B) is phloem immobile. For plants such as peanut which bury their fruit, the mechanism for B delivery and the B source for fruit and seed growth remains enigmatic. Therefore, this study aimed to establish evidence of B retranslocation in peanut and to identify its importance in plant development. In a sand culture experiment, the increase in B contents in new organs after B withdrawal and the corresponding decline in B contents in older organs was evidence of B redistribution. In a foliar ¹⁰B experiment, the ¹⁰B abundance of treated-leaves decreased and ¹⁰B was detected in leaves and flowers formed after the application of foliar B. Application of ¹⁰B to the roots for a period also provided evidence for the retranslocation of ¹⁰B accumulated during the first growth period. The ¹⁰B abundance in older plant parts declined and ¹⁰B appeared in new organs (flowers, pegs, leaves) that had developed after the ¹⁰B supply had been replaced by ¹¹B. In the fourth experiment, foliar application of B reduced hollow heart, a symptom of B deficiency in seeds, in cv. TAG 24 from 39 to 8% and in Tainan 9 from 63 to 18%. These experiments all provide evidence for B retranslocation in peanut, but further work on the relative importance of the xylem and phloem pathways for B loading into the fruit is needed.     

Inadequate iron supply and high bicarbonate impair the symbiosis of peanuts (Arachis hypogaea L.) with different Bradyrhizobium strains

In the present study, we examined the effects of iron deficiency in an acid solution and in an alkaline solution containing bicarbonate on the growth and nodulation of peanuts inoculated with different bradyrhizobial strains or supplied with fertilizer nitrogen.Inadequate iron supply in acid solution decreased the number of nodule initials, nodule number and nodule mass. Alleviating the iron deficiency increased acetylene reduction but not bacteroid numbers in nodules. Nitrogen concentrations in shoots of inoculated plants increased as iron concentrations in solution increased when determined at day 30 but not at day 50. Higher iron concentrations in solution were required for maximum growth of plants reliant on symbiotic nitrogen fixation than for those receiving fertilizer nitrogen.Adding bicarbonate to the solution with 7.5 M Fe markedly depressed nodule formation. This effect was much more severe than that of inadequate iron supply alone. Bicarbonate also decreased nitrogenase activity but did not decrease bacteroid concentrations in nodules.Both NC92 and TAL1000 nodulated peanuts poorly when bicarbonate was present. However, an interaction between iron concentrations in acid solutions and Bradyrhizobium strains on nodulation of peanuts was observed. Alleviating iron deficiency increased the number of nodule initials and nodules to a much greater extent for plants inoculated with TAL1000 than for plants inoculated with NC92.     

Fungal populations in the rhizosphere of peanut (Arachis hypogaea L.)

Summary A comparison of fungal populations in the rhizospheres of eight varieties of peanut grown in a red lateritic soil amended with farmyard manure was made by the dilution-plate technique. There was a marked increase in fungi in the rhizospheres of TMV 2, TMV 4, Pollachi Red and EC 1698, the increase was smaller in Spanish Improved and RS 1 while very little rhizosphere effect was shown by TMV 3 and Pondicherry 8. Age of the plant had a significant influence on numbers of fungi in the rhizosphere. High R/S ratios were obtained when the plants were 30 days old, at which time attained maximum vegetative growth and started to flower. The ratios gradually decreased after that age until the plants were three months old when there was again a small increase. This later rise in fungal populations is interpreted to be due to an increase in microbial activity around dead or senescent roots. No correlation could be established between numbers of root nodules produced by a variety and its rhizosphere effect. Preferential stimulation of certain fungi in the rhizosphere of some of the varieties was noticed.     

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.     

Some characteristics of symbiotic nitrogen fixation,yield, protein and oil accumulation in irrigated peanuts (Arachis hypogaea L.)

Summary The potential of peanuts for symbiotic nitrogen fixation is considerable and under optimal edaphic and climatic conditions it reached 222 kg N₂/ha, which was 58% of the nitrogen accumulated in the plants. The effect of the Rhizobium inoculation on crude protein accumulation in the yield (kg/ha) was 3–4 times greater than its effect on the yield of pods and hay. There was an inverse relationship between the protein and oil content in the kernels.Seasonal changes in nitrogenase activity in the nodules were determined by the acetylene reduction method during two growing seasons. Under favorable conditions the specific activity of the nitrogenase reached a very high level (up to 975 moles C₂H₂ g dry wt nod/h) and the total activity (moles C₂H₄/plant/h) was also high in spite of the relatively poor nodulation (weight and number). The high activity was drastically reduced (to 75 moles C₂H₄ g dry wt nod/h) due to exceptionally hot and dry weather, which occurred in the middle of the second half of the growing season. It appears that N₂-fixation (nitrogenase activity) is more sensitive to these unfavorable conditions, than is nodule growth. Maximum nitrogenase activity was observed during the podfilling stage; until 50–60 days after planting, nitrogenase activity was very low.     

Utility of EST-derived SSR in cultivated peanut (Arachis hypogaea L.) and Arachis wild species

Background  

Lack of sufficient molecular markers hinders current genetic research in peanuts (Arachis hypogaea L.). It is necessary to develop more molecular markers for potential use in peanut genetic research. With the development of peanut EST projects, a vast amount of available EST sequence data has been generated. These data offered an opportunity to identify SSR in ESTs by data mining.     

Light,dark and growth regulator involvement in groundnut (Arachis hypogaea L.) pod development

Gynophore elongation and pod formation were studied in peanut plants (Arachis hypogaea L.) under light and dark conditions in vivo. The gynophores elongated until pod formation was initiated. Pod (3–20 mm length) development could be totally controlled by alternating dark (switched on) and light (switched off) conditions, repeatedly. Gynophore elongation responded conversely to light/dark conditions, compared to pods. In this study we aimed to correlate the light/dark effects with endogenous growth substances. The levels of endogenous growth substances were determined in the different stags of pod development. Gynophores shortly after penetration into the soil, ‘white’ gynophores, released twice the amount of ethylene as compared to the aerial green ones, or to gynophores bearing pods. Ethylene inhibitors had no effect on the percent of gynophores that developed pods, but affected pod size which were smaller compared to the control. A similar level of IAA was extracted from gynophore tips of green gynophores, ‘white’ gynophores and pods. ABA levels differed between the three stages and were highest in the green gynophores and lowest in the pods.     

Light, dark and growth regulator involvement in groundnut (Arachis hypogaea L.) pod development

Gynophore elongation and pod formation were studied in peanut plants (Arachis hypogaea L.) under light and dark conditions in vivo. The gynophores elongated until pod formation was initiated. Pod (3–20 mm length) development could be totally controlled by alternating dark (switched on) and light (switched off) conditions, repeatedly. Gynophore elongation responded conversely to light/dark conditions, compared to pods. In this study we aimed to correlate the light/dark effects with endogenous growth substances. The levels of endogenous growth substances were determined in the different stags of pod development. Gynophores shortly after penetration into the soil, white gynophores, released twice the amount of ethylene as compared to the aerial green ones, or to gynophores bearing pods. Ethylene inhibitors had no effect on the percent of gynophores that developed pods, but affected pod size which were smaller compared to the control. A similar level of IAA was extracted from gynophore tips of green gynophores, white gynophores and pods. ABA levels differed between the three stages and were highest in the green gynophores and lowest in the pods.Abbreviations ABA abscisic acid - AOA aminooxyacetic acid - ELISA enzyme linked immunosorbent assay - Ethrel 2-chloroethanephosphonic acid - GC gas chromatography - HPLC High Performance Liquid Chromatography - IAA indole-3-acetic acid - NAA naphthalene acetic acid - RIA radioimmunoassay - STS silver thiosulfhate - TIBA 2,3,6-triiodobenzoic acid     

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。     

Root turnover of groundnut (Arachis hypogaea L.) in soil tubes

Five groundnut cultivars were grown in transparent tubes of pasteurized loam compost in growth-chamber conditions. Weekly tracings were made of all the roots visible through the walls of the tubes. White roots were assessed as living, and brown or decayed roots as dead; this correlated with microscopical assessments of root viability based on cytoplasmic staining with neutral red followed by plasmolysis.For all five cultivars, root laterals began to die 3–4 weeks after plants were sown. Death of root laterals progressed down the soil profile with time, while new roots were produced successively deeper from the extending taproot. The half-life of individual roots was calculated as 3.7–4.4 weeks for all cultivars, based on assessments of the roots that died up to plant maturity (14–20 weeks, depending on cultivar). At maturity, 73–83% of the cumulative length of root systems had died. The onset and rate of root death were not related to onset of flowering or pod-filling; instead, the peak times of root death at different distances down the root system were related to earlier (3–5 week) peak times of root production in those regions. The net result of root turnover was that, despite continued new root production, the maximum length of living (white) roots of each cultivar was recorded at 2–4 weeks after sowing. Death of the earliest formed root laterals was also observed in the first five weeks after sowing of groundnut in an experimental field plot in Malawi. Progressive root turnover is considered to be a normal feature of groundnut, perhaps representing an energy-economy strategy.     

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。     

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.     

花生镉污染研究进展

花生既是世界主要的油料作物,又是重要的植物蛋白来源和食品加工原料．随着花生直接食用和食品加工的不断增加,国际上对花生籽粒Cd含量问题越来越关注．我国是世界上重要的花生生产国和出口国．近年来,花生Cd含量偏高已经成为制约我国出口贸易的重要因素．本文从花生籽粒Cd富集能力、花生Cd含量的种内差异、籽粒中Cd的分布规律、影响花生籽粒Cd积累的机制和降低花生籽粒Cd含量技术等方面,对花生Cd污染研究的现状与问题进行了论述．指出在花生cd污染控制方面有2种策略可以考虑,一是降低花生对土壤Cd的吸收;二是控制Cd向籽粒的迁移富集．为此需要从3个方面加强对花生籽粒Cd积累机制的研究,即花生根系活性特征参数及其与籽粒Cd积累的关系;花生果荚Cd吸收机制及其对籽粒Cd含量的贡献;花生植株体内Cd迁移机制及其与籽粒Cd含量的关系．