块根紫金牛ISSR-PCR反应体系的建立与优化

采用正交和单因素试验设计方法,研究Mg2+、dNTP、引物、TaqDNA聚合酶、模板DNA、退火温度及循环次数对ISSR-PCR扩增效果的影响,建立块根紫金牛ISSR-PCR反应体系和扩增程序,即25 ul的体系中含Mg2+ 2.0 mmol/L,dNTP0.15 mmol/L,引物1.0μmol/L,TaqDNA聚合酶1.0U,模板DNA50ng,10×Buffer 2.5μl.适宜的扩增程序是94℃预变性5 min,94℃变性30s,56.6℃退火45s,70℃延伸2.0 min;45个循环;72℃延伸7min,4℃保存.采用正交和单因素试验可快速建立ISSR-PCR反应体系.该体系稳定、可靠,可用于块根紫金牛遗传多样性分析.     

广西特有植物小花异裂菊ISSR-PCR反应体系的建立

以小花异裂菊的叶片为材料,采用正交和单因素试验研究Mg2+、dNTP、TaqDNA聚合酶、引物、模板DNA浓度对ISSR-PCR扩增效果的影响。建立了适宜于小花异裂菊的ISSR-PCR反应体系,即25μL的体系中含Mg2+1.5 mmol/L,dNTP 0.20 mmol/L,TaqDNA聚合酶1.5 U,引物0.8μmol/L,模板DNA 50 ng,10×Buffer 2.5μL。该体系稳定、可靠,为利用ISSR分析小花异裂菊遗传多样性等工作奠定了良好的基础。     

毛竹ISSR-PCR反应体系的建立与优化

采用正交和单因素试验设计方法,研究Mg²⁺、dNTP、引物、TaqDNA聚合酶、模板DNA浓度及退火温度对毛竹ISSR-PCR扩增效果的影响。毛竹ISSR-PCR反应体系为:25μL的体系中含Mg²⁺1.5 mmol/L,dNTP 0.25 mmol/L,引物1.0μmol/L,TaqDNA聚合酶1.0 U,模板DNA 30 ng,10×Buffer2.5μL。扩增程序为94℃预变性5 min,94℃变性45 s,54℃退火60 s,72℃延伸1.5 min,40个循环;72℃延伸7 min,4℃保存。该体系稳定、可靠,可用于毛竹遗传多样性分析。     

黄枝油杉ISSR-PCR反应体系的建立与优化

先运用正交设计进行初步筛选,再用单因素设计逐一优化对ISSR-PCR扩增效果有影响的Mg2+、Taq DNA聚合酶、dNTP、引物、模板DNA、循环次数及退火温度.建立了黄枝油杉的最佳反应体系和程序,即25μL体系中含2.0mmol/L的Mg2+、1.5U Taq DNA聚合酶、0.10mmol/L的dNTP、1.0μmol/L的引物、30ng的模板DNA以及2.5μL10×PCR buffer,其余的用灭菌的ddH2O补够25μL.扩增程序:94℃预变性5min;94℃变性30s,48～56℃(不同的引物,其退火温度不同,根据具体引物而定)退火45s,72℃延伸90s,以上3个步骤循环50次;最后72℃延伸7min;扩增产物放在4℃冰箱中保存.该体系和程序稳定性良好,结果可靠,可用于黄枝油杉遗传多样性分析.     

枣ISSR扩增体系的建立

以冬枣DNA为研究对象,利用单因素试验,分析了Mg2+浓度、dNTP浓度、Taq酶含量、引物浓度、模板DNA含量以及退火温度对ISSR-PCR扩增的影响,经优化建立了枣属植物最适ISSR-PCR反应体系,25μL反应液中包含1×PCR Buffer、2.0 mmol/L Mg2+、0.25 mmol/L dNTP、1.5 UTaq酶、1.25μmol/L引物和50 ng模板,最适退火温度为58℃。PCR反应体系的建立为应用ISSR标记技术开展枣种群遗传变异分析和构建遗传图谱奠定基础。     

新疆贝母DNA提取及ISSR-PCR体系的建立与优化

目的:从新疆贝母干叶片中提取高质量的DNA,建立ISSR-PCR体系并进行优化。方法:通过改进的CTAB法提取基因组DNA;综合利用单因素实验和L9(34)正交实验2种方法,对镁离子、dNTP、模板DNA含量、TaqDNA聚合酶量、引物浓度等因素进行优化,并采用温度梯度筛选引物的退火温度。结果:新疆贝母20μL ISSR-PCR最适反应体系dNTP为0.3 mmol/L,Mg2+为2.0 mmol/L,模板浓度为40～100 ng/(20μL),引物为1.2 mmol/L,Taq DNA聚合酶为1.0 U/20μL,引物UBC 859的最适退火温度为50.7℃。结论:此提取方法得到的DNA纯度高,ISSR-PCR扩增效果显著,为新疆贝母种质资源鉴定、遗传多样性分析奠定研究基础。     

水葫芦苗ISSR-PCR体系的优化与引物筛选

以改良CTAB法提取水葫芦苗基因组DNA为模板,利用正交设计试验对影响ISSR-PCR反应体系的5个因素(TaqDNA聚合酶,dNTP,引物,模板及Mg~(2+))进行了优化筛选。经极差分析和方差分析,最终建立了水葫芦苗ISSR-PCR的最佳反应体系。结果表明,总体积20μL的反应体系中各因素浓度分别为:TaqDNA聚合酶0.025 U/μL、Mg~(2+)1.5 mmol/L、dNTP 1.0 mmol/L、引物0.5μmol/L、模板DNA 1.5 ng/μL。通过筛选得到10条扩增条带清晰的ISSR引物,并通过梯度PCR确定了各引物的最适退火温度。在此基础上对循环次数进行优化,最终确定最佳循环次数为40次。     

文冠果ISSR反应体系的建立及优化

为了建立文冠果ISSR-PCR最佳反应体系,从而为文冠果遗传多样性研究提供理论依据,从定西巉口林场文冠果人工林内选取健康嫩叶为试验材料,通过单因子试验研究了影响ISSR-PCR反应各因素的浓度,分析因子包括模板DNA用量、退火温度、dNTP浓度、Mg2+浓度、引物浓度及TaqDNA聚合酶用量等。通过研究,找出了各因子合适的条件,建立并优化了文冠果ISSR反应体系,即20μL总反应体系含模板DNA约30 ng,Mg²⁺2.5 mmol/L,引物0.2μmol/L,dNTP 0.20 mmol/L,Taq聚合酶1 U。试验结果表明,在此反应体系下可得到多样性好、条带清晰的图谱。     

柑桔SRAP和ISSR分子标记技术体系的建立与优化

通过对PCR反应程序、反应体系(DNA模板量、PCR反应体积、Mg2 浓度、dNTP浓度、Taq酶用量、引物量)、电泳检测方法的系统优化,建立了柑桔SRAP-PCR和ISSR-PCR体系;以此进行大规模引物筛选,从而建立了柑桔SRAP和ISSR分子标记技术体系.SRAP-PCR:25μL体系,模板DNA25ng,Tris-HCl10 mmol/L,KCl50 mmol/L,Mg2 1.2 mmol/L,dNTP 120 μmol/L,Taq酶1.5U,引物0.4μmol/L,反应程序为94℃预变性5min,35个循环(94℃ 30s,47℃ 1min,72℃ 1min),72℃延伸10min;ISSR-PCR:25μL体系,模板DNA25ng,Tris-HCl10mmol/L,KCl50mmol/L,Mg2 1.6 mmol/L,dNTP200μmol/L,Taq酶1 U,引物0.8μmol/L.筛选出稳定性好、多态性高的24对SRAP引物和13条ISSR引物.     

酥瓜(Cucumis melo var. conomon Group)ISSR-PCR反应体系建立与优化

利用正交设计L_(16)(4~5),对酥瓜ISSR-PCR反应体系的5个影响因素(引物,d NTPs,Taq DNA聚合酶,Mg2+和模板DNA)在4个水平上进行优化试验,并在36℃~56℃范围内摸索退火温度,建立适合酥瓜ISSR-PCR反应体系,结果表明,在20μL反应体系中,含有引物0.2μmol/L、d NTPs 0.3 mmol/L、Taq DNA聚合酶1.2 U、Mg2+1.0 mmol/L、DNA模板70 ng、10×Buffer 2.0μL为最佳反应体系,ISSR-PCR扩增程序中最佳退火温度为52.5℃。该体系为酥瓜种质资源的遗传多样性分析评价提供了帮助。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.