甜菜DAMD-PCR体系的建立及优化

为了建立甜菜DAMD扩增体系,以期利用DAMD引物应用于甜菜品种指纹图谱的构建及分子标记辅助育种。本实验利用单因素变量的方法对甜菜DAMD体系进行优化。同时选用12个甜菜品种,利用优化的体系对25条DAMD引物进行扩增。获得甜菜的最适DAMD体系:总体积为20μL,包含模板DNA 10~80 ng、0.75 U的DNA聚合酶、0.2μL的d NTPs(2.5 mmol/L each)以及2.0μL的引物(10μmol/L)。同时25条引物均扩增出了清晰条带,除了个别引物多态性较差外,其余引物多态性都非常的丰富,其中引物62H(-)就可以把实验中用到的12个甜菜品种全部区分开。由此可见,DAMD引物的扩增效率很高,并且扩增结果稳定,条带清晰,非常适合甜菜品种指纹图谱的构建及遗传多样性分析。     

橄榄SRAP-PCR体系的建立和优化

以橄榄品种为材料,采用L16（45）的正交试验设计,对影响PCR反应的Taq酶量、Mg2+浓度、模板DNA含量、dNTPs浓度和引物浓度5个因素进行了SRAP-PCR扩增反应条件优化研究,并利用反应体系对11个橄榄品种进行了SRAP-PCR扩增。结果表明：在20μl体系中,Taq酶1.5U、Mg2+2.5 mmol/L、模板DNA 60ng、dNTPs 0.2 mmol/L和引物0.15μmol/L时的扩增效果最好;利用该体系,SRAP标记引物对Me5- Em2在11个橄榄品种中可以扩增出7条清晰的多态性条带。     

砂仁及其混伪品益智仁的ISSR分子鉴别

为创建砂仁及其主要混伪品益智仁的ISSR分子鉴别方法,以UBC818为引物,对影响ISSR-PCR反应体系的引物、dNTPs、DNA模板、Taq DNA聚合酶和Mg2+浓度进行5因素4水平正交优化试验,并在此基础上筛选阳春砂ISSR引物及砂仁正伪品的鉴别引物。结果表明,20μL阳春砂ISSR-PCR最佳反应体系包括引物0.5μmol/L、dNTPs 0.25 mmol/L、DNA模板40 ng、Taq DNA聚合酶1.2 U、Mg^2+2.0 mmol/L;从52条ISSR引物中筛选出10条阳春砂ISSR引物,从6条阳春砂和益智的共同引物中,筛选出扩增条带清晰、多态性强的砂仁正伪品的鉴别引物UBC808,利用UBC808对15份样品进行验证试验,结果表明鉴别体系稳定性好,可用于砂仁与益智仁的快速、准确鉴别。     

牡丹杂交品系SRAP-PCR反应体系优化及引物筛选

通过研究牡丹杂交新品系的遗传多样性,解决其在牡丹品种分类体系中位置的问题。利用正交设计,从Mg2+、dNTPs、引物浓度、DNA聚合酶和不同模板DNA浓度5种因素4个水平来优化牡丹杂交品系SRAP-PCR反应体系,对引物进行筛选。建立牡丹杂交品系SRAP-PCR反应最佳体系(25 μL)为： 2.0 mmol/L Mg2+、1.5 U Taq酶、0.25 mmol/L dNTPs、2 ng/μL模板DNA、0.25 μmol/L引物;运用试验结果从100对引物中筛选出扩增条带清晰、多态性丰富的SRAP引物30对。优化体系的建立及引物的筛选,可为利用SRAP标记技术研究牡丹杂交品系的遗传多样性及亲缘关系提供技术基础和理论依据。     

红毛丹SRAP反应体系优化及多态性标记筛选

为建立成熟可靠的红毛丹SRAP-PCR扩增检测技术体系,本研究首先采用单因素实验设计,对反应体系中的DNA模板、Mg2+、d NTPs、Taq DNA聚合酶和引物浓度等5个主要影响因素,设置不同的水平梯度,筛选出适宜的因子范围;在此基础上,进一步采用L16(45)正交设计,建立了红毛丹SRAP-PCR最佳反应体系:20μL体系中包含DNA模板20 ng、d NTPs 0.25 mmol/L、引物0.6μmol/L、r Taq酶1.0 U、Mg2+2.5 mmol/L。并利用优化的反应体系,从116对SRAP引物组合中筛选出37对扩增条带清晰、产物多态性较好的引物。本研究建立的SRAP-PCR体系及筛选的引物,将为红毛丹从分子水平进行种质资源遗传多样性分析、品种指纹图谱构建等研究提供基础。     

金银花ISSR-PCR反应体系的建立与优化

以金银花叶片基因组DNA为模板,通过单因素试验,研究了退火温度、Taq DNA 聚合酶的用量及模板DNA、引物、dNTPs、Mg2+浓度等6种因素对ISSR－PCR扩增的影响,建立了适合于金银花ISSR-PCR反应体系和扩增程序,即在20 μL反应体系中,内含1×PCR反应缓冲液（Mg2＋free）、1.5 U Taq DNA 聚合酶、0.15 mmol·L-1 dNTPs、0.4 μmol·L-1引物、1.5 mmol·L-1 MgCl2、60 ng模板DNA。确定了适宜的退火温度为49.9 ℃。扩增程序为94 ℃预变性5 min ;35个循环为94 ℃变性30 s,49.9 ℃退火30 s,72 ℃延伸1.5 min;最后72 ℃延伸7 min,4 ℃保存。利用优化反应体系,从100条ISSR引物中筛选出10条稳定性和重复性高的引物;以这10条引物对22个金银花品种基因组DNA扩增,共扩增出108条带,其中多态性条带96条,多态性条带比率为88.9%。金银花ISSR反应体系的建立为利用ISSR标记技术进行金银花品种鉴别、分类、种质资源遗传多样性分析奠定了良好基础。     

正交设计优化青蒿SRAP-PCR反应体系及引物筛选

为了建立青蒿的SRAP最佳扩增体系,并筛选出SRAP多态性引物,本研究以青蒿叶片DNA为模板,采用正交试验设计,以Mg^2+、dNTP Mix、Taq DNA聚合酶、引物和DNA模板5种因素5个水平,对青蒿SRAP反应体系进行研究。结果表明,青蒿SRAP-PCR最佳反应体系为:引物0.6μmol/L、Mg^2+2.0 mmol/L、模板DNA 5.1 ng、Taq DNA聚合酶2.0 U、dNTPs 0.25 mmol/L,总体积为25μL。各因素对扩增反应均有不同影响,其中引物浓度的影响最大,dNTPs的影响最小。运用该体系对不同种质资源的青蒿进行验证,证明该体系稳定可靠,并在30个引物组合中筛选出了25对扩增条带清晰,多态性丰富的引物组合。这一结论为今后利用SRAP标记技术进行青蒿分子遗传学研究提供了科学依据。     

二月兰SSR-PCR反应体系的优化及引物筛选

为建立适合二月兰的SSR-PCR反应体系,采用正交试验设计方法对影响二月兰SSR反应体系的5个因素(DNA模板、Mg~(2+)、d NTPs、引物和Taq聚合酶)进行优化试验,筛选出每个因素的最佳水平。结果表明,10μL反应体系中,Mg~(2+)浓度2.0 mmol/L,d NTPs浓度0.4 mmol/L,引物浓度0.6μmol/L,DNA模板量20 ng,Taq聚合酶量0.6 U。以3份二月兰基因组DNA为模板,利用优化后的SSR-PCR反应体系进行引物筛选,从50对SSR引物中成功筛选出扩增条带清晰、具有多态性的引物有12对,证明该反应体系具有较好的稳定性和通用性。研究建立和优化的二月兰SSR-PCR反应体系,为进一步利用SSR标记技术开展二月兰分子生物学研究提供了理论依据和技术参考。     

药用菊花SSR-PCR反应体系优化及引物筛选

为进一步开发利用药用菊花种质资源和开展分子标记辅助选择育种,本研究利用L25(56)正交设计对影响药用菊花SSR-PCR反应的模板DNA、Mg2+、d NTPs、Taq酶、引物等5个因素进行优化,并对SSR引物进行筛选。结果建立了药用菊花SSR-PCR最佳反应体系(20μL):模板DNA 60 ng,正、反向引物0.25μmol/L,d NTPs 0.3 mmol/L,Mg2+3.0 mmol/L,Taq酶1.5 U。运用优化后的反应体系,从136对引物中成功筛选出了扩增条带清晰、多态性丰富的SSR引物57对,大多数条带大小集中在100~500 bp,不同引物扩增的条带数为5~15条。优化的SSR-PCR反应体系在多个药用菊花品种遗传多样性研究中得到了验证,获得了稳定性、重复性良好和多态性丰富的扩增图谱。该体系的建立可为今后利用SSR标记对药用菊花种质鉴定、遗传多样性分析、系统发育研究、遗传图谱构建、基因定位和分子标记辅助育种等研究提供了依据。     

仁用杏ISSR分析体系的正交优化

本研究以仁用杏丰仁为试材,采用经改良的CTAB法提取实验材料幼叶基因组DNA.利用正交设计法,从Mg~(2+)浓度、dNTPs浓度、引物浓度、Taq/DNA聚合酶及模板DNA用最5种因素4水平出发,构建和优化仁用杏ISSR-PCR反应体系,并采用直观分析和方差分析相结合的方法分析正交实验结果,最终建立了仁用杏ISSR-PCR最佳反应体系总体积20μL:1.5 U Taw DNA聚合酶、2.0 mmol/L MgCl_2、0.15 mmol/L dNTPs、0.35μmol/L引物、30～60 ng模板DNA.在优化体系的基础上筛选出 13个扩增稳定、多态性丰富的ISSR引物,并通过梯度PCR试验,确定每个引物的最适退火温度.经对最佳反应体系和程序进行了验证,结果显示该体系具有扩增稳定性.     

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.     

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.     

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.     

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.