花生衰老进程的研究

通过对鲁花11号和辐8707 2个高产花生品种的衰老进程研究表明：花生衰老具有地上部（叶片）渐进衰老和整株衰老的双重特点。花生从始花至花后60d左右为地上部（叶片）渐进衰老期：此期主茎高、侧枝长、分枝数、主茎、侧枝绿叶数、叶面积、茎、叶干重迅速增加,并接近或达到最大值,主茎及侧枝基部叶片逐渐由下向上开始衰老死亡,饱果开始出现,根系活力、固氮酶活性逐渐升高至接近最大值,始花后60－90d为整株缓衰期,此期地上部茎叶生长基因停止,逐渐开始衰老死亡,主茎、侧枝绿叶数开始减少,生殖体（荚果）干重迅速增长,根系活力、固氮酶活性缓慢降低;始花后90d以后称为整株速衰期,此期主茎、侧枝绿叶迅速减少,地上部迅速衰老死亡,生殖体（荚果）干重缓慢增长,根系活力、固氮酶活性迅速降低。地上部（叶片）渐进衰老期与开花及大量荚果形成相对应,整株缓衰期伴随着荚果迅速增重,整株速衰期与荚果缓慢增重一致。     

Role of carbohydrate moieties in peanut (Arachis hypogaea) peroxidases.

The activities of a cationic (C.PRX) and an anionic peroxidase isolated from peanut (Arachis hypogaea)-cell suspension culture were drastically reduced when they were deglycosylated with glycopeptidase F or oxidized by 10 mM-periodate. In contrast with the controls, the deglycosylated or the oxidized peroxidases were much more susceptible to proteolytic degradation. In radiolabelling experiments with [35S]methionine, the non-glycosylated C.PRX was synthesized in the tunicamycin-treated cultures and secreted into the medium. Examination of the C.PRX polypeptides by SDS/polyacrylamide-gel electrophoresis followed by fluorography showed that the non-glycosylated form had an Mr of approx. 31,000, which is about 78% of that of the glycosylated form. Our results suggest that carbohydrates may not be essential for peroxidase secretion, but that stabilization of the peroxidase molecules and acquisition by these isoenzymes of a catalytically active conformation is linked directly or indirectly to glycosylation.     

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.     

Pterocarpenes elicited by Aspergillus caelatus in peanut (Arachis hypogaea) seeds

The substituted pterocarpenes named aracarpene-1 (1) and aracarpene-2 (2) were isolated from wounded peanut seeds challenged by a strain of Aspergillus caelatus. The structures of these putative phytoalexins were determined by interpretation of NMR and MS data. The aracarpenes were investigated for their antifungal and antibacterial activities as well as antioxidant, anti-inflammatory, and cytotoxic activities in mammalian cells. Aracarpene-2 demonstrated high antibacterial properties against tested gram-positive and gram-negative bacteria, whereas aracarpene-1 displayed low antibacterial properties against the same bacteria. Both compounds had no antifungal activity against Aspergillus flavus. Together with peanut stilbenoids that are also produced in the challenged seeds, these compounds may represent a class of low-molecular weight peanut metabolites with a defensive role(s) against pathogenic microorganisms.     

A simplified methodology for purification of peanut (Arachis hypogaea) agglutinin

The agglutinin from peanut (Arachis hypogaea) was readily isolated by affinity chromatography on acid-treated Sepharose 6B. The recovered lectin (50 mg/100 g seeds) appeared as a single band of Mr 32,000 on gel electrophoresis and its specific haemagglutination titre on desialylated human A red blood cells was very high (2(15)).     

Immunochemical studies on the specificity of the peanut (Arachis hypogaea) agglutinin.

The specificity of purified, peanut agglutinin has been studied immunochemically by quantitative precipitin and inhibition assays. The lectin showed substantial differences in precipitating with blood-group substances of the same specificity. Of the B substances tested, horse 4 25% completely precipitated the lectin, Beach phenol insoluble failed to interact, and PM phenol insoluble gave an intermediate reaction. The lectin did not precipitate with A1 substances, with hog gastric mucin A + H substance, or with A2 substance WG phenol insoluble. Another A2 substance, cyst 14 phenol insoluble, precipitated approximately 2/3 of the lectin. Of the H substances, Tighe phenol insoluble was inactive, JS phenol insoluble precipitated poorly, and morgan standard H precipitated about 80% of the lectin. However, first stage of Smith degradation, as well as Pl fractions obtained by mild acid hydrolysis of blood-group substances, gave products which precipitated strongly. The lectin was also completely precipitated by all precursor blood-group substances, as well as by cows 21 and 26, all having strong I-Ma, I-Ort, I-Step, and I-Da activities. Cow 18, which does not possess significant blood-group I activity, precipitated very slightly. Fractions of blood-group substances N-1 (Lea) and Tij (B) obtained by precipitation from 90 percent phenol at higher concentrations of ethanol interacted better with peanut agglutinin. These differences in activity are ascribable to a heterogeneity resulting from incomplete biosynthesis of carbohydrate side-chains of blood-group substances, particularly resulting in variations in the numbers of DGalbeta1 leads to 3DGalNAc or DGalbeta1 leads to 4DGlcNAc determinants. The agglutinin reacted with the hydatid cyst P1 glycoprotein, as well as with the previously studied antifreeze and sialic acid-free alpha1 acid glycoproteins, but not with pneumococcus type XIV polysaccharide. Inhibition of precipitation showed the lectin to be most specific for the disaccharide DGalbeta1 leads to 3DGalNAc, which is 14, 55, and 90 times as active as DGalbeta1 leads to 4DGlcNAc, DGal, and DGalbeta1 leads to 3DGlcNAc, respectively. DGalbeta1 leads to 3N-acetyl-D-galactosaminitol has approximately 1/25th the activity of DGalbeta1 leads to 3DGalNAc. Substitutions of DGlcNAc or LFuc on the DGal of active inhibitors completely blocked the activity, in line with the assumption that the combining site of the peanut lectin is a partial cavity. The oligosaccharides DGalbeta1 leads to 4DGlcNAcbeta1 leads to 6-hexane-1,2,4,5,6-pentol(s) and DGalbeta1 leads to 3[DGalbeta1 leads to 4DGlcNAcbeta1 leads to 6]N-acetyl-D-galactosaminitol showed the same inhibitory activity as DGalbeta1 leads to 4DGlcNAc, suggesting that the combining site of the peanut agglutinin may not be complementary to more than a disaccharide...     

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.     

Thidiazuron promotes high frequency regeneration of peanut (Arachis hypogaea) plants in vitro

Multiple shoots were induced on Valenciatype peanut (Arachis hypogaea L.) explants cultured in vitro on a nutrient medium supplemented with thidiazuron. Zygotic embryos excised from mature seeds were germinated on Murashige-Skoog nutrient medium, and the resulting plantlets (8 days-old) were used as a source of explants. When cultured on a nutrient medium with increasing levels of thidiazuron (0.5 to 30 mg/l), expiants from various parts of the peanut plant (except the root) produced multiple shoot primordia which subsequently developed into individual shoots. Hypocotyl and cotyledon explants produced shoots in higher numbers than other explants (20 shoots per hypocotyl explant at all thidiazuron concentrations and 15 shoots per cotyledon explant at 30 mg/l). Shoots rooted normally on a basal Murashige-Skoog medium containing charcoal and developed into healthy and fertile plants when planted in soil.Abbreviations TDZ thidiazuron - MSO Murashige and Skoog (1962) basal medium - BA 6-benzylaminopurine     

花生分子标记的研究进展

国内外对花生的研究特别是在分子水平上的研究相对水稻、油菜等农作物比较薄弱。近些年,分子标记技术迅速发展,在花生上也得到广泛的应用。本文从花生属起源、种质资源的遗传多样性、抗性基因的标记和指纹图谱等方面,综述了国内外花生分子标记的研究进展。     

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.     

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.     

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．     

Plant regeneration through somatic embryogenesis in peanut (Arachis hypogaea L.)

Somatic embryos were induced from immature cotyledons and immature embryonal axis ofArachis hypogaea L. on L-6 basal medium supplemented with NAA, picloram or 2,4-D at 5–50 mg 1^-1. Immature embryonal axis produced a higher number of somatic embryos in comparison with immature cotyledons. The highest number of responding cultures was produced on medium supplemented with NAA (50 mg 1^-1), while the highest average number of somatic embryos per culture was produced on medium with 2,4-D (10 or 20 mg 1^-1) and picloram (30 mg 1^-1) from cotyledons. The somatic embryos developed into plants on basal medium supplemented with activated charcoal and about 100 plants were successfully transferred to the field. Acknowledgement: The authors wish to thank Nuclear Agriculture Division, BARC for supplyingA. hypogaea seeds and Mr. R.M. Mudliar for photography.     

Agrobacterium tumefaciens mediated gene transfer in peanut (Arachis hypogaea L.)

Transgenic peanut plants were produced using Agrobacterium mediated gene transfer. Primary leaf explants of peanut were co-cultivated with Agrobacterium tumefaciens LBA 4404 harbouring the binary plasmid pBI 121 (conferring -glucuronidase activity and resistance to kanamycin) and cultured on regeneration medium supplemented with kanamycin to select putatively transformed shoots. They were rooted and plants were transferred to soil. Stable integration and expression of the transgenes were confirmed by NPT II assay, Southern blot hybridization and GUS assay.Abbreviations BA 6-benzyladenine - GUS -glucuronidase - IAA indole-3-acetic acid - NAA -naphthaleneacetic acid - NOS nopaline synthase - NPT II neomycin phosphotransferase II - SDS Lauryl sulfate     

Somatic embryogenesis from the axillary meristems of peanut (Arachis hypogaea L.)

Developmental anomalies in the plumule meristem of peanut (Arachis hypogaea L.) somatic embryos resulted in poor shoot differentiation and reduced plant recovery. Existing meristems with caulogenic potential have never been tested for embryogenesis in peanut. The present experiment was designed to test the mature zygotic embryo axis derived plumule with three meristems for somatic embryogenesis. Embryogenic masses and embryos developed from the caulogenic meristems in the axils. Exposure of 2 weeks in primary medium with 90.5 μM 2,4-D suppressed the shoot tip differentiation temporarily which then regained the ability to form the shoot on withdrawal of 2,4-D. Exposure of 4 weeks in primary medium with 90.5 μM 2,4-D suppressed the shoot tip differentiation irreversibly. No shoot formation was noted from the tips in any of the cultures which were in secondary medium with 13.6 μM 2,4-D. Development of somatic embryos directly from axillary meristems was confirmed histologically. Conversion frequency of these embryos was 11%. Thus, in this report, we describe a method to obtain somatic embryos from the determined organogenic buds of the axillary meristem, by culturing the nodal explant vertically on embryo induction medium. It also displays the possibility of obtaining both embryogenic and organogenic potential in two parts of the same explant simultaneously. The possibility of extending this approach for genetic transformation in in vivo system through direct DNA delivery or Agrobacterium injection in meristems can also be explored. Using Agrobacterium rhizogenes, we have demonstrated the possibility of gene transfer in the axillary meristems of seed-derived plumule explant.     

Mass spectrometric characterization of isoform variants of peanut (Arachis hypogaea) stem lectin (SL-I)

Matrix assisted laser desorption/ionization–time-of-flight (MALDI–TOF) mass spectrometric (MS) analysis of purified Arachis hypogaea stem lectin (SL-I) and its tryptic digests suggested it to be an isoformic glucose/mannose binding lectin. Two-dimensional gel electrophoresis of SL-I indicated six isoforms (A1–A6), which were confirmed by Western blotting and MALDI–TOF MS analysis. Comparative analysis of peptide mass spectra of the isoforms matched with A. hypogaea lectins with three different accession numbers (Q43376_ARAHY, Q43377_ARAHY, Q70DJ5_ARAHY). Tandem mass spectrometric (MS/MS) analysis of tryptic peptides revealed these to be isoformic variants with altered amino acid sequences. Among the peptides, the peptide T12 showed major variation. The ¹⁹⁹Val–Ser–Tyr–Asn²⁰² sequence in peptide T12 of A1 and A2 was replaced by ¹⁹⁹Leu–Ser–His–Glu²⁰² in A3 and A4 (T12′) while in A5 and A6 this sequence was ¹⁹⁹Val–Ser–Tyr–Val²⁰² (T12″). Peptide T1 showed the presence of ¹⁰Asn in the isoforms A1–A5 while in A6 this amino acid was replaced by ¹⁰Lys (T1′). Overall amino acid sequence as identified by MS/MS showed a high degree of similarity between A1, A2 and among A3, A4, A5. Carbohydrate binding domain and adenine binding site seem to be conserved.     

Effects of aluminium on the peanut (Arachis hypogaea L.)/ Bradyrhizobium symbiosis

The effects of low activities of the monomeric Al species, Al³⁺, Al(OH)₂ ⁺ and Al(OH)²⁺, on the peanut/Bradyrhizobium symbiosis were examined in solution culture. In flowing solution culture, growth of the host plant was depressed at activities ≥5 μM. Neither shoot dry weight, root dry weight nor root length were inhibited by 3 μM Al, an activity which reduced nodule number by 70%. Low nodule number was compensated for, at this activity, by an increase in weight per nodule. In non-flowing solution culture of similar composition, survival of a streptomycin resistant mutant of Bradyrhizobium spp. NC92 in the bulk solution or in the rhizosphere of peanut roots was unaffected by 20 μM Al. The site of infection by Bradyrhizobium was examined by scanning electron microscopy. Lateral root axils of plants exposed to ≥2 μM Al did not display the rosette of multicellular root hairs which is characteristic in normal plants. The detrimental effects of Al on nodulation appear to be related to structural changes at the site of infection which are observed at Al activities too low to cause any depression in growth of the host plant, including root length, and at activities of Al which do not affect survival of the free-living Bradyrhizobium.     

Utilizing peanut husk (Arachis hypogaea L.) in the manufacture of medium-density fiberboards

The main objective of this study was to investigate the potential of peanut husk (Arachis hypogaea L.) as a fiber–peanut mixture to produce fiberboards for general purposes. For panel production, the addition of peanut husk at various percentages to the wood fiber was the only variable. Panels produced utilizing peanut husk were compared to panels produced using 100% wood fiber. The chemical properties of peanut husk; holocellulose and lignin content, alcohol–benzene, hot and cold water, and dilute alkali (1% NaOH) solubility, were also determined. Results indicated that panels could be produced utilizing up to 30% peanut husk without affecting the usability of the panels. It was not possible to meet the minimum IB strength standards when peanut husk was added to the mixture. Higher additions resulted in panels having lower elastic and rupture moduli than the minimum requirements according to TS-EN standards.