Comparative Embryo Sac Morphology at Anthesis of Cultivated and Wild Species of Arachis

Introgression of germplasm from wild to cultivated species ofArachis is severely impeded because abortion processes oftenoccur as a prepeg-, peg-(gynophore), or postpeg-elongation event.A comparative study of embryo sac morphology at anthesis wasundertaken to determine if observable differences were presentthat could possibly explain abortion prior to peg tip swellingfollowing soil penetration. Two wild Arachis species (A. duranensisand A. stenosperma) plus A. hypogaea cultivars NC 6 and Argentinewere studied. Differences in starch grain concentration andcytoplasmic stranding organization were observed between A.hypogaea cultivars and the wild Arachis species. These differencesprobably have a significant impact on energy availability atsyngamy and the subsequent early cell division of the embryo.An improper energy balance could contribute to the onset ofabortion in interspecific hybrids. Modification in egg apparatusorganization among all species was also observed which may accountfor low percentages of seed recovery resulting from interspecifichybridization attempts. Embryo sac morphology, interspecific hybridization, Arachis hypogaea L., Arachis species, light microscopy, scanning electron microscopy, embryo abortion, fertilization incompatibility, peanuts, groundnut     

Molecular and Cytogenetic Characterization of Wild Musa Species

The production of bananas is threatened by rapid spreading of various diseases and adverse environmental conditions. The preservation and characterization of banana diversity is essential for the purposes of crop improvement. The world''s largest banana germplasm collection maintained at the Bioversity International Transit Centre (ITC) in Belgium is continuously expanded by new accessions of edible cultivars and wild species. Detailed morphological and molecular characterization of the accessions is necessary for efficient management of the collection and utilization of banana diversity. In this work, nuclear DNA content and genomic distribution of 45S and 5S rDNA were examined in 21 diploid accessions recently added to ITC collection, representing both sections of the genus Musa. 2C DNA content in the section Musa ranged from 1.217 to 1.315 pg. Species belonging to section Callimusa had 2C DNA contents ranging from 1.390 to 1.772 pg. While the number of 45S rDNA loci was conserved in the section Musa, it was highly variable in Callimusa species. 5S rRNA gene clusters were found on two to eight chromosomes per diploid cell. The accessions were genotyped using a set of 19 microsatellite markers to establish their relationships with the remaining accessions held at ITC. Genetic diversity done by SSR genotyping platform was extended by phylogenetic analysis of ITS region. ITS sequence data supported the clustering obtained by SSR analysis for most of the accessions. High level of nucleotide diversity and presence of more than two types of ITS sequences in eight wild diploids pointed to their origin by hybridization of different genotypes. This study significantly expands the number of wild Musa species where nuclear genome size and genomic distribution of rDNA loci is known. SSR genotyping identified Musa species that are closely related to the previously characterized accessions and provided data to aid in their classification. Sequence analysis of ITS region provided further information about evolutionary relationships between individual accessions and suggested that some of analyzed accessions were interspecific hybrids and/or backcross progeny.     

Occurrence of Erysiphe cichoracearum Perithecia on Wild Lactuca Species

Perithecia of Erysiphe cichoracearum (powdery mildew) were found on several, but not all, accessions of Lactuca serriola, L. saligna, L. aculeata and L. serriola × L. sativa hybrid. Their occurrence varied between Lactuca species and different accessions of the same species. Perithecia were globular, had a mean diameter of 125.5 μm and contained an average 13–14 asci. Asci had mean dimensions of 55.0 × 26.1 μm and each contained two ascospores which measured an average 17.4 × 10.6 μm. There were however significant differences in the dimensions of spores and other structures obtained from different Lactuca accessions.     

甘薯近缘野生种资源的杂交亲和性评价及利用

甘薯近缘野生种与甘薯栽培品种的杂交结实率研究表明,甘薯栽培品种与不同倍性I．trifida的平均杂交结实率为9．33％,其中与六倍体I．trifuta杂交结实率最高,与二倍体I．trifida杂交结实率最低;与四倍体I．1ittoralis杂交的平均结实率为4．22％;与I．leucantha杂交的平均结实率为0．75％。甘薯与近缘野生种杂交,其后代的结薯性出现广泛的分离,甘薯与六倍体I．frifida的杂交后代结薯率高于与其它低倍体的野生种。在甘薯栽培品种与近缘野生种的杂交后代中选出了一些优良的杂种后代。利用六倍体I．trifida与甘薯栽培品种杂交和回交,从其后代中选育出了苏渝303和渝苏297等甘薯品种。     

国家Ⅱ级重点保护野生植物驼峰藤的研究进展

通过对专著、文献和多个网络资源数据库(植物志、标本、图像等)分析考证,及赴部分产地的野外实地考察,对珍稀濒危植物驼峰藤(Merrillanthus hainanensis Chun et Tsiang)的分类地位、形态特征、标本记录与保存、产地与生境、濒危的野外生存现状等情况进行了综述,以期为该保护物种的生存和发展和保护提供参考。自1933年采集到标本和1941年命名驼峰藤以来,至今已有80多年的历史,研究表明它的分布区范围从原广东、海南省扩展到中国大陆西南部和中南半岛部分地区(缅甸和柬埔寨),部分原有记载分布点已无法找到野生植株,导致其濒危的主要原因是生境的破坏和质量下降,广东中山五桂山脉或许是目前发现的最大野生种群保存地,文中就其保护措施提出了相关建议。     

Cryptic Variation between Species and the Basis of Hybrid Performance

Crosses between closely related species give two contrasting results. One result is that species hybrids may be inferior to their parents, for example, being less fertile [1]. The other is that F1 hybrids may display superior performance (heterosis), for example with increased vigour [2]. Although various hypotheses have been proposed to account for these two aspects of hybridisation, their biological basis is still poorly understood [3]. To gain further insights into this issue, we analysed the role that variation in gene expression may play. We took a conserved trait, flower asymmetry in Antirrhinum, and determined the extent to which the underlying regulatory genes varied in expression among closely related species. We show that expression of both genes analysed, CYC and RAD, varies significantly between species because of cis-acting differences. By making a quantitative genotype-phenotype map, using a range of mutant alleles, we demonstrate that the species lie on a plateau in gene expression-morphology space, so that the variation has no detectable phenotypic effect. However, phenotypic differences can be revealed by shifting genotypes off the plateau through genetic crosses. Our results can be readily explained if genomes are free to evolve within an effectively neutral zone in gene expression space. The consequences of this drift will be negligible for individual loci, but when multiple loci across the genome are considered, we show that the variation may have significant effects on phenotype and fitness, causing a significant drift load. By considering these consequences for various gene-expression–fitness landscapes, we conclude that F1 hybrids might be expected to show increased performance with regard to conserved traits, such as basic physiology, but reduced performance with regard to others. Thus, our study provides a new way of explaining how various aspects of hybrid performance may arise through natural variation in gene activity.     

四种野生百合核型分析

对南川百合(Lilium rosthornii Diels)、青岛百合(L.tsingtauense Gilg)、山丹(L.pumilum DC.)和岷江百合(L.regaleWilson)等4种野生百合进行了染色体数目观察和核型分析。结果表明,核型除山丹为3A外,其余3种材料核型均为3B。核型公式分别为:南川百合2n=2x=24=4m(4SAT)+2sm+6st+12t;青岛百合2n=2x=24=8m(4SAT)+2sm(2SAT)+14t;山丹2n=2x=24=2m(2SAT)+6sm(2SAT)+4st(4SAT)+12t;岷江百合2n=2x=24=2m(2SAT)+2sm+6st+14t。核型不对称系数分别是81.68%、76.09%、80.34%和82.26%。其中,南川百合和青岛百合为国内首次报道。     

中国葡萄属植物野生种多样性分析

中国是葡萄属植物的主要起源地之一,也是世界葡萄属植物种类最多、遗传资源最丰富的国家之一,起源于中国的葡萄属植物共有40种、1亚种、13变种。本研究根据《葡萄种质资源描述规范和数据标准》,选择多项性状指标作为形态鉴定参数,对起源于中国的葡萄属植物23个种的生物学性状、植物学特征、农艺性状等进行鉴定,分析其遗传多样性特点。结果表明,中国葡萄属植物的主要物候期,嫩梢新梢的绒毛、颜色,叶片的形状、颜色、锯齿,果实大小、颜色、香型和花器官等形态性状都有丰富的变化,表现出丰富的多样性。上述研究结果将为葡萄属植物的分类鉴定提供依据,也将为葡萄属植物演化研究和育种利用提供参考。根据本研究结果,建议对目前使用的《葡萄种质资源描述规范和数据标准》作进一步修订和完善,以适应我国野生葡萄资源多样性评价研究。     

湖南野生食用菌物种多样性研究

本次报道湖南野生食用菌资源265种,这是近40年来的考察研究结果.这些种类中包括子囊菌10种,担子菌255种,许多种类具有重要的利用和开发意义.对每个种的生态特征和利用价值均进行了简单介绍.     

6种野生草莓的核型分析

以五叶草莓等6种野生草莓为试材,采用常规压片法对其进行了核型分析。结果表明,6种野生草莓的核型公式分别为:五叶草莓2n=2x=14=12m+2sm、黄毛草莓2n=2x=14=8m+6sm、绿色草莓2n=2x=14=10m+2sm+2st、东北草莓2n=2x=14=8m+6sm、森林草莓2n=2x=14=6m+8sm、西南草莓2n=4x=28=16m+12sm,6种野生草莓的核型类型均为"2A"型。供试6种野生草莓的进化顺序可能为:五叶草莓、绿色草莓、东北草莓、黄毛草莓、西南草莓、森林草莓。     

云南48种木兰科野生植物资源遗传多样性研究

为了解云南省木兰科（Magnoliaceae）野生植物资源的遗传多样性,利用ISSR分子标记技术对48种木兰科野生植物资源进行研究。结果表明,10对引物共扩增出151条带,均为多态性条带,多态性条带百分率为100%。总的观测等位基因数（N_a）为2.000 0,有效等位基因数（N_e）为1.564 5,Nei’s基因多样性指数（H）0.337 9,Shannon’s信息指数（I）为0.510 1。总的基因多样性指数（H_t）为0.368 0,属间基因多样性指数（D_st）为0.251 9,占68.4%,基因分化系数（G_st）为0.684 0,基因流（N_m）为0.231 0。UPGMA聚类分析将48种木兰科植物划分为7个类群,各类群并非按照属聚在一起,而是不同属植物相间分布,长喙厚朴（Magnolia rostrata）、素黄含笑（Michelia flaviflora）和球花含笑（M.sphaerantha）可能为云南省木兰科植物中的原始种。48种木兰科野生植物总体具有较高的遗传多样性,但属间遗传变异较高,基因流较小,存在遗传漂变的风险,聚类结果与刘玉壶的分类系统存在分歧,这从分子水平为木兰科植物间的起源、进化与分类提供了重要依据。     

马铃薯栽培种和野生种叶肉原生质体紫外线辐射效应

4个马铃薯栽培种和4个野生种叶肉原生质体黑暗中进行紫外线辐射处理。观察了不同剂量紫外线照射对原生质体分裂生长的影响。S.demissum,S.tuberosum,S.bulbocastum,S.phureja和S.brevidens最低失活剂量分别为8min,5.5min,4.0min,2.0min和15min。３种紫外线照射方式中,“15w,60cm”照射方式失活效果最好。刚分离的原生质体对紫外线最敏感,随着原生质体培养进程,其紫外线抗性逐渐增强。基因型、倍性水平、原生质体体积对原生质体紫外线失活剂量有影响。     

花期追施氮肥对菜用大豆AC10生理指标及产量影响的研究

选用激光诱变育成的菜用大豆品种AC10,通过在开花初期追施不同的氮素水平,研究其对主要生理指标及产量和产量构成因素的影响。结果表明：花期追施适量氮肥,能明显提高菜用大豆品种AC10植株花后叶面积指数、叶绿素含量、光合速率和荚果可溶性糖含量,从而提高鲜豆荚产量,其中以每公顷追施75．0kg-112．5kg尿素,单株鲜豆荚产量达到92．15g～90．37g,比对照增产8．0％～7．1％;但过量追施氮肥,影响植株生长．造成减产,当每公顷追施尿素达150kg时,单株鲜豆荚产量为81．19g,比对照减产5．1％。     

云南野生稻资源及其保护

云南野生稻生态类型丰富,且具有抗白叶枯病、抗稻瘟病、耐旱、耐寒等栽培稻不具有或已经消失的遗传基因,是水稻品种改良的优良基因库。然而,随着人类社会经济活动对生态环境影响的加剧,这一宝贵的战略性生物资源正面临着快速消失的危险。为了加强云南野生稻资源的保护,近年来,我们对云南野生稻资源开展了原生境保护(物理隔离方式和主流化方式)及非原生境保护(种质库、种质圃、细胞库和DNA库)等保护技术研究,明确了各种保护方法的优缺点和适用性,保护了云南野生稻的多样性和丰富度,为改良栽培稻储备了丰富的基因源。     

全球变化与野生物种:观测和预测

由于人类活动的影响,世界正在变暖。迅速的全球变化很可能对野生物种产生巨大影响,同时伴随着城市化、农垦和造林实践所引起的自然生境的丧失和破坏。观测和预测的气候变化对野生物种的影响着眼于4个方面：生活史的时间、物种分布与种群格局、迁移对策以及重要地点。许多物种可能因气候的变化而灭绝,而气候变化所造成的野生物种分布的变化很可能对人类产生长期久远的影响。     

Pathogenicity of four Phytophthora Species on Wild Cherry and Italian Alder Seedlings

Inoculation tests were carried out in the greenhouse on wild cherry (Prunus avium) and Italian alder (Alnus cordata) seedlings, to determine their susceptibility to certain Phytophthora species (P. citrophthora, P. alni, P. megasperma and P. cinnamomi) that are commonly present in the soil. Host susceptibility was evaluated in accordance with a disease index, with the lesion length after stem inoculation, and with a root system disease index. Wild cherry was found to be highly susceptible to P. citrophthora, and was also found to be susceptible to P. alni, although to a lesser extent. Italian alder was very susceptible to P. alni, but had only low susceptibility to P. citrophthora. The other Phytophthora species caused only modest symptoms. The danger to alder and wild cherry is all the greater because these trees not only share the same pathogens, but also commonly planted together in mixed stands. The results will now have to be confirmed by using a more natural inoculation method.     

四种野生报春花种子萌发生物学特性

以多脉报春Primula polyneura、钟花报春P. sikkimensis、桔红灯台报春P. bulleyana 和粉被灯台报春P. pulverulenta 的种子为材料,研究其形态及光照、GA3 对种子萌发的影响。结果表明,4 种报春花种子形态各异,钟花报春种子质量最大,千粒重达0.458 g,粉被灯台报春种子质量最小,千粒重为0.192 g。光照处理及不同浓度GA3 处理对4 种报春花种子萌发的影响存在差异。光照对多脉报春的萌发效果最好,其次为钟花报春与桔红灯台报春,对粉被灯台报春无明显促进作用。光照条件下,400 mg·L^-1 GA3 处理对桔红灯台报春和粉被灯台报春的萌发效果较好,发芽率显著提高,发芽持续时间缩短;钟花报春萌发适宜的GA3浓度为200 mg·L^-1。     

Genetic Basis of Mating Preferences in Wild House Mice

This paper reviews work conducted over the last several yearson the effect of genetic differences within the t-complex ofwild house mice on female mating preference. Wild mice are polymorphicfor a mutation within the t complex on chromosome 17. About25% of wild mice are heterozygous (+/t) for a t-haplotype andthe remainder are +/+. These t-haplotypes have a number of deleteriouseffects when homozygous and hence t/t individuals are rarelyfound in wild populations. We have examined preferences of +/+and +/t females for males of both genotypes. We have found that+/t, but not +/+ females have strong preferences for +/+ males.These preferences can be modified by a variety of factors includingestrous condition of the female (the preferences are strongeramong estrous than diestrous females) and the dominance statusof the male (when forced to choose, females give priority tomale dominance status over t complex genotype in choosing males).The restiction of preference to +/t females indicates that geneson t haplotypes modulate these preferences. Because t haplotypesinclude the major histocompatibility complex (MHC) of the mousewe designed a study to ascertain whether the preferences of+/t females were associated with the MHC. Results of the studyindicate that the preferences are independent of the MHC. Furtherwork testing females carrying a partial t-haplotype (t^w18) indicatesthat the genes for mating preference are localized in the regionof the t complex distal to the MHC. A large number of t haplotypesare found in wild mouse populations. Females that are themselves+/t when forced to choose between 2 +/t males (one carryinga haplotype that is the same as their own and one carrying ahaplotype that is different) prefer males carrying t-haplotypesthat differ from their own. Finally, we conclude that matingpreference may only be a weak force regulating the frequencyof t-mutations in wild mouse populations. The impact of matingpreference on population genetics of genes within this regionis muted because of the great importance of male dominance rankin determining mating patterns within interacting social groups.     

狗尾草属野生近缘种的染色体鉴定

对来自多个国家和地区的10个种(青狗尾草S.viridis,法氏狗尾草S.faberii,轮生狗尾草S.verticillata、S.verticillifor-mis,金色狗尾草S.glauca、S.pumila、S.grisebachii、S.leucopila、S.parviflora、S.queenslandica等)50份狗尾草材料进行了染色体计数及倍性鉴定。发现狗尾草属中的青狗尾草均为二倍体,金色狗尾草S.glauca有四倍体和八倍体,轮生狗尾草S.verticillata有二倍体和四倍体,法氏狗尾草S.faberii为四倍体,S.pumila有二倍体和四倍体,S.grisebachii为二倍体,S.leucopila为二倍体,S.queenslandica为四倍体。本研究中对S.grisebachii、S.leucopila、S.queenslandica3个种是首次染色体倍性观察。发掘近缘种的有益基因是作物育种的重要途径之一,本研究搜集的谷子近缘野生种对谷子远缘杂交育种和谷子起源进化分析有重要意义。