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。     

冀鲁豫花生育成品种的遗传多样性分析

以冀鲁豫三省不同地域的41个花生育成品种为材料,利用SSR分子标记结合田间表型鉴定、聚类分析等方法对其遗传多样性进行了研究。结果表明,21对SSR引物对41个花生育成品种进行了扫描,共检测到52个等位变异,每个位点2～4个,平均2.5个,Shannon信息指数变幅为0.21～1.40,平均为0.73,聚类分析显示在阈值为5.54可将供试品种分为3大类群7个亚类。不同品种9个农艺性状变异系数在13.16%～186.49%之间,基于农艺性状的聚类分析结果显示在阈值为5.48时可以将供试品种分为6大类群11个亚类,各大类群间品种的农艺性状表现各具特点。     

Growth promotion and yield enhancement of peanut (Arachis hypogaea L.) by application of plant growth-promoting rhizobacteria

Although plant growth-promoting rhizobacteria (PGPR) have been reported to influence plant growth, yield and nutrient uptake by an array of mechanisms, the specific traits by which PGPR promote plant growth, yield and nutrient uptake were limited to the expression of one or more of the traits expressed at a given environment of plant–microbe interaction. We selected nine different isolates of PGPR from a pool of 233 rhizobacterial isolates obtained from the peanut rhizosphere on the basis of ACC-deaminase activity. The nine isolates were selected, initially, on the basis of germinating seed bioassay in which the root length of the seedling was enhanced significantly over the untreated control. All the nine isolates were identified as Pseudomonas spp. Four of these isolates, viz. PGPR1, PGPR2, PGPR4 and PGPR7 (all fluorescent pseudomonads), were the best in producing siderophore and indole acetic acid (IAA). In addition to IAA and siderophore-producing attributes, Pseudomonas fluorescens PGPR1 also possessed the characters like tri-calcium phosphate solubilization, ammonification and inhibited Aspergillus niger and A. flavus in vitro. P. fluorescens PGPR2 differed from PGPR1 in the sense that it did not show ammonification. In addition to the traits exhibited by PGPR1, PGPR4 showed strong in vitro inhibition to Sclerotium rolfsii. The performances of these selected plant growth-promoting rhizobacterial isolates were repeatedly evaluated for 3 years in pot and field trials. Seed inoculation of these three isolates, viz. PGPR1, PGPR2 and PGPR4, resulted in a significantly higher pod yield than the control, in pots, during rainy and post-rainy seasons. The contents of nitrogen and phosphorus in soil, shoot and kernel were also enhanced significantly in treatments inoculated with these rhizobacterial isolates in pots during both the seasons. In the field trials, however, there was wide variation in the performance of the PGPR isolates in enhancing the growth and yield of peanut in different years. Plant growth-promoting fluorescent pseudomonad isolates, viz. PGPR1, PGPR2 and PGPR4, significantly enhanced pod yield (23–26%, 24–28% and 18–24%, respectively), haulm yield and nodule dry weight over the control in 3 years. Other attributes like root length, pod number, 100-kernel mass, shelling out-turn and nodule number were also enhanced. Seed bacterization with plant growth-promoting P. fluorescens isolates, viz. PGPR1, PGPR2 and PGPR4, suppressed the soil-borne fungal diseases like collar rot of peanut caused by A. niger and PGPR4 also suppressed stem rot caused by S. rolfsii. Studies on the growth patterns of PGPR isolates utilizing the seed leachate as the sole source of C and N indicated that PGPR4 isolate was the best in utilizing the seed leachate of peanut, cultivar JL24. Studies on the rhizosphere competence of the PGPR isolates, evaluated on the basis of spontaneous rifampicin resistance, indicated that PGPR7 was the best rhizoplane colonizer and PGPR1 was the best rhizosphere colonizer. Although the presence of growth-promoting traits in vitro does not guarantee that an isolate will be plant growth promoting in nature, results suggested that besides ACC-deaminase activity of the PGPR isolates, expression of one or more of the traits like suppression of phytopathogens, solubilization of tri-calcium phosphate, production of siderophore and/or nodulation promotion might have contributed to the enhancement of growth, yield and nutrient uptake of peanut.     

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.     

Uptake and partitioning of cadmium by cultivars of peanut (Arachis hypogaea L.)

Cadmium has been found to accumulate in peanut (Arachis hypogaea) kernels to levels exceeding the current maximum permitted concentration in Australia of 0.1 mg kg^-1. Little is known of the mechanisms of Cd uptake into kernels by cultivars of peanut, so the aims of the experiments reported here were to determine if Cd is absorbed directly through the pod wall or via the main root system, and if differences exist between cultivars in this respect. Split-pot soil and sand/nutrient solution experiments were performed with two cultivars of peanut (cv. NC7 and Streeton) known to accumulate Cd to different levels in the kernel. The growth medium was separated into pod and root zones with Cd concentrations in each zone varied. In confirmation of previous field trial results, cv. NC7 had higher concentrations of Cd in kernels, given the same Cd levels in the external medium (solution or soil). Despite total Cd uptake by cv. NC7 being similar to cv. Streeton, cv. NC7 appeared to retain more Cd in the roots and translocate less Cd to shoots. Results from both soil and sand/solution culture indicated that the dominant path of Cd uptake by peanut was via the main root system, with direct pod uptake contributing less than 5% of the total Cd in the kernel. There was little difference between cultivars in this characteristic. This indicates that unlike Ca nutrition of peanuts, agronomic techniques to manage Cd uptake will require modification of soil to the full depth of root exploration, rather than just the surface strata where pods develop. Cadmium concentrations in testa were up to an order of magnitude higher than in the kernel, indicating that blanching of kernels would be effective in reducing Cd in the marketed product. This revised version was published online in June 2006 with corrections to the Cover Date.     

Response of two peanut (Arachis hypogaea L.) cultivars to boron and calcium

The response of two peanut cultivars (Tainan 9 and SK 38) to applications of six boron (B) rates (H₃BO₃ at 0, 0.12, 0.25, 0.5, 1 and 2 kg B ha^–1) at two calcium levels [nil (-Ca) or CaSO₄ at 100 kg Ca ha^–1 (+Ca)] to a B-deficient Oxic Paleustult was studied in a pot experiment. Without added Ca, both cultivars had low seed yields and gave only small responses to B. Similarly, without added B, both cultivars had low seed yields and did not respond to Ca. But, with added Ca or B, they responded strongly to B and Ca, respectively. In both cultivars, deficiencies of Ca or B depressed seed dry weight by depressing seed size by over 75%. Boron deficiency further depressed seed dry weight by decreasing the number of seeds per plant by decreasing the number of seeds per pod in Tainan 9, and the number of pods per plant in SK 38. Seed dry weight was depressed more than pod dry weight, so that both Ca and B deficiencies severely depressed the shelling %. With added Ca, tainan 9 responded to lower levels of B than SK 38, reaching maximum seed dry weight at 0.12 kg B ha^–1. At this low level of B. SK 38 yielded only half the seed dry weight of Tainan 9. But SK 38 continued to respond to increasing levels of B to 2 kg ha^–1, producing a maximum seed yield 40% higher than Tainan 9. The results indicate that where all other nutrients are adequate, SK 38 will yield better than Tainan 9 on soils with high B, but worse on soils with low B. The implications of these findings for the selection of peanut cultivars are discussed.     

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.     

Leaflet development, induction time, and medium influence somatic embryogenesis in peanut (Arachis hypogaea L.)

Factors affecting somatic embryogenesis in peanut (Arachis hypogaea L.) using leaflet explants of seedlings obtained from aseptically germinated embryo axes were evaluated. Somatic embryogenesis was influenced by developmental stage, leaflet size, induction medium, and time on induction medium. Leaflets that were 5–7 mm long had a greater embryogenic response than smaller or larger leaflets. Percent embryogenesis and mean number of embryos were related to the developmental stage of germinating seedlings. A greater response was obtained if leaflets were folded and closely appressed. Preselection of leaflets increased percent embryogenesis from 21% up to 67%. As leaflets unfolded, embryogenesis decreased; open leaflets lost the potential for embryogenesis. The optimal induction conditions were a 7-day incubation period on Murashige and Skoog medium with 136 μm 2,4-dichlorophenoxyacetic acid and 0.93 μm kinetin. Somatic embryos germinated to form plants that exhibited a normal morphology. Received: 29 December 1997 / Revision received: 9 April 1998 / Accepted: 24 April 1998     

花生幼叶为外植体的植株再生系统的建立

本文报道利用花生成熟胚幼叶为外植体获得高频植株再生的方法,为花生转基因提供有效的受体系统。通过诱导培养基TDZ、BA、NAA的浓度以及种子萌发时问、继代培养基种类五个因素不同水平的正交试验,筛选出了分化高频发生的最佳组合为：MS培养基中应含有TDZ 1．0／μmol／L、BA0．4μmol／L、NAA5．0μmol／L,种子萌发4d,继代培养基为MS0。本研究表明,五因素中诱导培养基TDZ浓度为诱导花生幼叶分化的主要影响因素,其次为继代培养基、种子萌发时问,而诱导培养基中BA和NAA的浓度作用较小。试管苗生根后移栽田间,可正常开花结果。     

Genetic relationships among three chlorophyll-deficient mutants in peanut,Arachis hypogaea L.

Summary The genetic relationships of three chlorophyll-deficient mutant peanuts, lutescens (lu), aureus (au), and virescent (v) were studied under field and greenhouse conditions. The F₁ plants from crosses between these mutants produced phenotypically normal green. In F₂, aureus X virescent segregated 675 normal green : 225 virescent : 45 aureus : 15 virescent aureus : 64 seedling lethal, and lutescens X virescent segregated 45 normal green : 15 virescent : 3 lutescens : 1 seedling lethal. (Lutescens peanuts were seedling lethal in the field.) As previously reported, the F₂ of aureus X lutescens gave 225 normal green : 15 aureus :15 lutescens : 1 seedling lethal. The three chlorophyll-deficient factors (au, lu, and v) show independent inheritance. The recessive combinations from the parental types between aureus and virescent and between aureus and lutescens would produce plants with a combination of their respective parental characteristics, but the recessive combination between lutescens and virescent was nearly albino. The v-au and lu-au seedlings have a longer life span than the v-lu seedling has. The genotypes for the three mutants are tentatively identified as lutescens VV Au ₁ Au ₁ Au ₂ Au ₂ lu ₁ lu ₁ lu ₂ lu ₂ L ₁ L ₁ L ₂ L ₂, aureus VV au₁au₁ au₂au₂ Lu₁Lu₁ Lu₂Lu₂ L₁L₁ l₂l₂, and virescent vv Au₁Au₁ Au₂Au₂ lu₁lu₁ Lu₂Lu₂ l₁l₁ L₂L₂.     

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。     

Ontogenetic changes in growth and net photosynthetic rate of two peanut (Arachis hypogaea L.) cultivars

The ontogenetic changes in growth, and the diurnal changes in net photosynthetic rate (P_N) and stomatal conductance were studied in two peanut cultivars of different habit groups. Significant cultivar differences were noticed: the prostrate cv. M 13 was found superior to the erect cv. J 11 in all the parameters studied. Specific leaf mass and the rates of gross photosynthesis and respiration were higher in cv. M 13 than in cv. J 11. In vegetative phase, the maximum P_N was in cv. J 11, but in pod filling phase, it was in cv. M 13. The differences in growth and P_N of the cultivars were significant after the onset of reproductive sink. Therefore, the screening for higher P_N has to be made at the pod-filling phase, and between 09.00 and 10.00 of the day (at optimum temperature).     

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。     

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.     

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.     

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     

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．     

Effect of foliar application of phosphorus on RNA and DNA under salt-stress in peanut plants (Arachis hypogaea L.)

Summary Peanut (Arachis hypogaea L., var. TMV-2) plants were raised in sand cultures salinized with sodium chloride at 0.4% on air dry weight basis. Phosphate was sprayed to the drip point, once daily for five days from 20th to 25th day and from 30th to 35th day. Shoot apices and mature leaves were harvested for nucleic acid analyses at 30th and 40th day, receiving one and two sets of sprays respectively. Salinity decreased RNA and DNA levels which were partially restored by foliar application of phosphate.