海洋双RNA病毒(MABV)vp2e和vp3基因在昆虫细胞中的高效表达

海洋双RNA病毒(Marinebirnavirus,MABV)可引起多种海洋鱼贝的腹水病等病症。利用RT-PCR技术得到了MABVY-6株系A片段的cDNA,进而克隆了病毒的外壳蛋白VP2e的抗原决定簇区642bp片段(vp2e)和另一结构蛋白VP3编码区序列。通过转座作用构建了重组杆状病毒表达载体,在昆虫细胞中对VP2e和VP3进行了表达。SDS-PAGE检测和薄层扫描表明,VP2e和VP3与增强型绿色荧光蛋白(enhancedgreenfluorescenceprotein,EGFP)融合蛋白表达量分别占整个昆虫细胞蛋白的15.8%和8.2%。用HisTag单抗和MABV病毒多抗对表达的VP2e融合蛋白进行Westernblot检测,结果表明表达产物具有很好的抗原性。同样,用HisTag单抗和VP3多抗对表达的VP3融合蛋白进行的Westernblot检测,证明融合蛋白表达正确,并且表达产物可溶,易于纯化。实验结果为该病毒结构蛋白和MABV疫苗研究提供了基础。     

昆虫几丁质酶的分类、功能分析、重组表达及酶学性质的研究进展

昆虫几丁质酶及其类似蛋白在昆虫生长和发育阶段起到重要调节作用。最近几年,运用新的生物技术对昆虫几丁质酶的结构,时空表达,和组织特异性表达以及生物学功能进行了深入研究,取得了许多新的成果。本文就昆虫几丁质酶基因的结构特征,几丁质酶生理功能、重组表达特点、酶活测定方法及影响酶活性因素等方面进行讨论与综述。     

猪圆环病毒2d亚型衣壳蛋白在昆虫细胞中的表达

为了在昆虫细胞中表达猪圆环毒病2型(Porcine circovirus type 2,PCV2)衣壳蛋白,本研究设计合成引物从临床病料中扩增获得猪圆环病毒(Porcine circovirus,PCV)山东株衣壳蛋白基因缺失核定位区的序列,并进行序列分析.将该片段克隆到杆状病毒供体载体pFastBac-1上,然后转化大肠杆菌(Escherichia coli) DH 10-Bac感受态细胞,获得重组穿梭杆粒,将该杆粒转染到sf9昆虫细胞中,观察重组杆状病毒致细胞病变效应,并采用PCR、间接免疫荧光实验、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)和Western blot鉴定衣壳蛋白的表达情况.结果表明,扩增获得的猪圆环病毒山东株属于PCV2d亚型,与我国目前使用的商品化疫苗株(PCV2a及PCV2b亚型)在160～180 aa抗原位点有差异.成功构建了重组供体质粒pFastBac l-PCV2d-Cap和重组穿梭杆粒Bacmid-PCV2d-Cap,获得的重组杆状病毒在昆虫细胞中成功表达了约24 kD的PCV2d-Cap,该蛋白可以与猪圆环病毒阳性血清及His标签抗体发生反应,证明具有良好的反应原性.本研究是我国首次采用杆状病毒系统表达PCV2d亚型衣壳蛋白,为制备PCV2d亚单位疫苗以及酶联免疫吸附测定(enzyme linked immunosorbent assay,ELISA)试剂盒、防范PCV2d亚型流行提供了理论依据.     

海洋双RNA病毒(MABV) VP2和VP3基因在昆虫细胞中的高效表达

海洋双RNA病毒(Marine birnavirus, MABV) 可引起多种海洋鱼贝的腹水病等病症。利用RT-PCR技术得到了MABV Y-6株系A片段的cDNA，进而克隆了病毒的外壳蛋白VP2e的抗原决定簇区642 bp片段(vp2e)和另一结构蛋白VP3编码区序列。通过转座作用构建了重组杆状病毒表达载体，在昆虫细胞中对VP2e 和VP3进行了表达。SDS-PAGE检测和薄层扫描表明，VP2e和VP3与增强型绿色荧光蛋白(enhanced green fluorescence protein, EGFP)融合蛋白表达量分别占整个昆虫细胞蛋白的15.8％和8.2％。用His Tag单抗和MABV病毒多抗对表达的VP2e融合蛋白进行Western blot检测，结果表明表达产物具有很好的抗原性。同样，用His Tag单抗和VP3多抗对表达的VP3融合蛋白进行的Western blot检测，证明融合蛋白表达正确，并且表达产物可溶，易于纯化。实验结果为该病毒结构蛋白和MABV疫苗研究提供了基础。关键词: 海洋双RNA病毒； VP2e; VP3; 杆状病毒表达系统; 表达纯化     

苹果蠹蛾颗粒体病毒(CpGV)GP37蛋白在Bac-to-Bac系统中的表达和亚细胞定位

苹果蠹蛾颗粒体病毒(Cydia pomonella granulovirus,CpGV)是防治苹果蠹蛾最重要的生物药剂之一,为探寻苹果CpGV GP37蛋白的增效机制,本研究利用Bac-to-Bac杆状病毒表达系统,将苹果CpGV gp37基因和绿色荧光蛋白基因(egfp)以N端或C端融合的方式插入苜蓿银纹夜蛾核多角体病毒(Autographa californica multiple nucleocapsid NPV,AcMNPV)基因组中,获得重组的杆状病毒质粒(bacmid),转染昆虫细胞Sf9,然后进行Western blot检测。结果显示,检测到GP37和EGFP的融合蛋白(vAcEGFPGP37、vAcGP37EGFP)和非融合蛋白(vAcGP37、vAcEGFP)都得到了高效表达;用激光共聚焦显微镜观察蛋白的亚细胞定位情况,融合GP37的EGFP主要聚集在细胞质中,没有融合GP37的EGFP遍布整个细胞,说明CpGV GP37蛋白定位于细胞质中。本实验研究了CpGV GP37蛋白的真核表达,为该蛋白的后续研究提供了条件;而该蛋白的亚细胞定位研究,不仅为CpGV GP37蛋白增效机制的研究提供了基础资料,同时丰富了杆状病毒GP37蛋白的相关理论。     

球孢白僵菌基因组候选效应子的预测与分析

球孢白僵菌(Beauveria bassiana)是一种广泛应用的生防菌株,效应子在其对寄主昆虫侵染过程中发挥着重要作用。为高通量地筛选球孢白僵菌的效应子,本研究根据球孢白僵菌全基因组信息,利用SignalP、TMHMM、TargetP和Protcomp等生物信息学软件和预测程序对球孢白僵菌中10 364个蛋白序列进行分泌蛋白预测。结果表明,共分析到940个分泌蛋白,包含了185个碳水化合物活性酶家族蛋白。其中碳水化合物结合模块(CBM)40个,碳水化合物酯酶(CE)23个,糖苷水解酶(GH)92个,糖基转移酶(GT)4个,多糖裂解酶(PL)2个,辅助功能酶(AA)24个。进一步将上述分泌蛋白与胞外酶数据库进行比对分析、半胱氨酸含量分析、多个串联重复序列分析、病原寄主互作数据库进行比对及剔除大于300个氨基酸序列的蛋白,共获得18个候选效应子,其中11个为功能未知的假定蛋白,其余为胞外蛋白、细胞壁蛋白、几丁质酶蛋白等。本研究结果为进一步探究效应子在病原菌与昆虫寄主中的互作奠定了理论基础,并为其他病原菌效应子的预测及分析提供了技术参考。     

植物翻译控制肿瘤蛋白研究进展

翻译控制肿瘤蛋白(TCTP)广泛存在于各类真核生物中,是一类在进化上高度保守的同源蛋白家族。植物TCTP具有促进细胞增殖、分化和再生、对抗生物或非生物胁迫等功能,其表达受转录和翻译水平的调节,调控机理较复杂。本文从TCTP的发现与命名、研究领域与分布、植物TCTP基因的结构特点、表达特性及功能等方面进行了简要综述,旨在全面了解植物TCTP的生理生化功能,以期为进一步研究其调控机理,调控植物生长发育和培育抗逆新品种提供一定的理论参考。     

利用RNAi技术研究水稻瘤矮病毒P8蛋白在病毒装配中的作用

水稻瘤矮病毒(Rice gall dwarf virus,RGDV)是呼肠孤病毒科(Reoviridae)植物呼肠孤病毒属(Phytoreovirus)的一个成员,由介体电光叶蝉(Recilia dorsalis)和黑尾叶蝉(Nephotettix cincticeps)以持久增殖型方式传播。其基因组编码6个结构蛋白和6个非结构蛋白。已知结构蛋白P8是病毒外层衣壳的主要成分,但其在病毒侵染介体细胞过程中的功能尚未弄清。本研究利用体外合成的ds RNA诱导的RNA干扰(RNA interference,RNAi)技术,研究RGDV P8蛋白在病毒侵染电光叶蝉培养细胞中的功能。通过免疫荧光标记技术对ds P8处理后的电光叶蝉培养细胞进行RGDV侵染观察,发现ds P8处理不仅抑制了P8在细胞内的正常表达,同时也抑制了病毒在细胞内的积累。随后通过SDS-PAGE凝胶电泳和Western blot分别检测病毒的ds RNA基因组和病毒蛋白水平的变化,发现ds P8处理显著降低了病毒双链RNA(double-stranded RNA,ds RNA)基因组的合成水平和病毒P8蛋白的表达量。由此推测RGDV P8蛋白参与了病毒粒体的组装过程和病毒在介体昆虫细胞内的有效增殖和侵染过程。本研究结果为利用RNAi技术控制水稻瘤矮病的传播提供了重要的理论依据。     

一个棉铃虫触角特异表达基因cDNA片段的克隆

摘要：昆虫触角嗅觉感器的主要功能是识别空气中的挥发性气味分子，它们直接与外界环境接触，外界环境中许多分子对昆虫细胞具有毒性，昆虫触角中必定存在某种机制分解这些毒性物质以及多余的气味刺激物。利用差异显示PCR的方法分离得到了3条棉铃虫(Helicoverpa armigera )触角专一性的mRNA片段，在GenBank中进行同源搜索表明，克隆A4-1与昆虫谷胱甘肽-S-转移酶基因家族具有很高的同源性。Northern杂交表明，克隆A4-1在棉铃虫触角中专一性表达，并且在雄蛾触角中的表达量明显比雌虫中高，这与棉铃虫性外激素结合蛋白基因的表达相似。根据该基因在昆虫触角中的表达情况以及已经报道的谷胱甘肽-S-转移酶在昆虫中所起的作用，推测该基因与性外激素的分解有关，同时可能参与触角中毒性分子的分解。     

香鱼Wap65-2在昆虫杆状病毒系统中的表达及其与补体C3的相互作用验证

Wap65-2 (Warm temperature acclimation related 65 kD protein-2)是至今仅在鱼类中发现的糖蛋白,与鱼类温度、细菌感染、重金属等胁迫等紧密相关。近年来其在鱼类抗细菌免疫反应中的作用引起广泛关注。本研究主要利用昆虫细胞杆状病毒载体系统(baculovirus expression vector system, BEVS)表达重组香鱼(Plecoglossus altivelis) Wap65-2成熟肽(recombinant ayu mature Wap65-2, rPaWap65-2m),建立真核生物表达具有生物活性rPaWap65-2m的制备方法。首先克隆获得香鱼Wap65-2基因的重组杆粒,将重组杆粒转染草地夜蛾(Spodoptera frugiperda)卵巢细胞(Sf9)获得病毒储液,用高滴度P3代病毒储液继续感染Sf9细胞,Western blot技术检测培养基中的重组蛋白。在最佳条件下无血清悬浮扩大培养,收集培养基上清,再经阴离子交换层析柱和镍亲和层析柱纯化获得rPaWap65-2m。采用His-tag pulldown技术验证rPaWap65-2m与血清补体C3 (complement 3)蛋白之间的相互作用。结果表明,P3代病毒储液感染Sf9细胞后,Western blot结果表明r PaWap65-2m以非N-连接糖基化形式表达并分泌至培养基上清。感染复数(multiplicity of infection, MOI)为5且感染72 h后,重组蛋白表达条件最佳。经纯化的rPaWap65-2m纯度大于93%,可用于后续实验。pulldown实验显示rPaWap65-2m蛋白与C3蛋白相互作用。综上,本研究获得了具有生物活性的rPaWap65-2m蛋白,并验证了r PaWap65-2m蛋白与血清中补体C3的相互作用,为后续免疫相关功能研究奠定了基础。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.