Advances in Pollen Mediated Genetic Transformation

植物遗传转化技术是植物科学基础理论与应用研究的有力武器,已成为植物遗传改良的重要途径之一。但是、目前遗传转化所采用的受体系统,大都需要体外培养和植株再生过程,才能获得转基因植株。其中、基因型限制和遗传变异是该技术不可逾越的两大障碍。花粉管通道法可省去转化体的离体培养,不过、多数植物受花器结构的限制而难以经花柱注射ＤＮＡ,只能向子房注射,并不是真正的“花粉管通道”。又由于此法外源基因的导入发生在授粉之后,因此该方法亦不属于花粉遗传转化。利用小孢子胚胎发生体系进行遗传转化与利用花粉作为外源ＤＮＡ的媒介,继而、通过授粉受精获得转基因种子,是目前花粉遗传转化的两个重要方面和活跃的研究方向。前者仍需要离体再生系统,后者则可以利用植物自身的再生机制,本文称之为花粉介导法（ｐｏｌｅｎ－ｍｅｄｉａｔｅｄｔｒａｎｓｆｏｒｍａｔｉｏｎ）。该方法通过自然的胚胎发育过程获得转基因子代,避免了组织培养过程中的遗传变异和转基因植株的嵌合现象。可望成为简便快速的植物遗传转化体系。目前对花粉介导的遗传转化进行专门评述的文献较少,本文对该领域的研究分三个层次进行了综述。一、外源基因转化方法小孢子或由小孢子形成的胚状体是很有潜力的遗传转化受体     

Genetic and Genomic Resources of Small Millets

Small millets are very promising agricultural entity to ensure global food security. They gained remarkable importance in agriculture due to their resilience to climatic changes and increasing demand for nutritious food and feed. The genetic variability in the core and mini-core germplasm of small millets was characterized for nutritional composition and capacity to tolerate abiotic stresses that can be infused in breeding programs. Other than the foxtail millet, availability of genomic information in small millets is far below the mark for use in marker-assisted breeding and other genetic improvement programs. The genome sequence of foxtail millet has recently triggered a plethora of post-genomic analysis and envisaged foxtail millet as a model organism for the C₄ grasses and bioenergy research. Recent developments in the next-generation sequencing technologies enabled us, with the simultaneous discovery of high-throughput markers and multiplexed genotyping of germplasm, to speedup marker-assisted breeding. In this context, an in-depth analysis of the wealth of diverse germplasm resources and future perspectives of integrating genomics in genome-wide marker-trait association and breeding in small millets is worthy.     

地中海地区稻种资源的籼粳分类及遗传多样性

利用SSR标记及程氏综合指数法分析了109份从地中海引进的水稻种质资源的遗传多样性和籼粳类型,同时利用籼粳测交法分析了其中37份资源的籼粳亲和性.结果表明,大部分引进的水稻种质属粳稻类型,基于SSR聚类、程氏综合指数法分析所确定的粳型品种数分别占引进种质的80.73%和77.98%,基于籼粳亲和性分类所确定的粳型品种数占供试37份资源的75.68%.地中海稻种资源具有较高的遗传多样性,平均有效等位基因数为3.84个,Nei多样性指数平均值为0.482,其中籼稻群与粳稻群的Nei多样性指数分别为0.459和0.340,籼稻遗传多样性高于粳稻.研究结果对于科学引进、合理保存和有效利用国外水稻种质改良国内水稻品种具有指导意义.     

月季遗传资源的评价与利用

国产蔷薇属植物82种,约占世界总数的41%.在近200种蔷薇属植物中,只有15种参与了现代月季的形成,新的遗传资源的引入是月季抗性育种的关键.现代月季品种达25000多个,但在欧洲苗圃销售的不到3000个,而以丰花月季为主.月季抗病遗传资源的研究主要针对黑斑病、白粉病和根结线虫.分子标记已广泛应用于月季亲缘关系分析、遗传图谱的构建和品种的鉴定.蔷薇果含有丰富的Vc和药用价值.     

西瓜种质资源主要植物学性状的遗传多样性及相关性分析

以我国西瓜、甜瓜种质资源中期库内1200份西瓜种质为材料,对果实重量、果肉颜色、中心糖、种子千粒重等12项主要植物学性状进行遗传多样性和相关性分析。多样性分析结果表明:我国西瓜资源12项植物学性状多样性指数平均值为1.70,种子千粒重多样性指数最大为2.37,果实形状多样性指数最小为1.02,其中果皮底色、果皮覆纹颜色、果肉颜色、果实重量、果实中心糖、种子千粒重性状数据分布较为分散。数量性状变异系数平均值为31.8,变异幅度均比其平均值大1～3倍。相关性分析结果表明:果实形状和果形指数、果肉颜色和果实中心糖、果肉颜色和种子千粒重、果皮厚度和硬度4对性状相关性极显著。种子千粒重和果实中心糖、果实重量和果皮厚度、果实重量和果皮硬度、覆纹颜色和形状4对性状相关性显著。     

黑龙江省抗寒李资源花粉形态的比较观察

对31个寒地李资源进行了电镜扫描,在测量极轴、赤道轴,条脊宽、穿孔径、穿孔频率后,分析出31个李品种花粉粒大小属于小至中等,31个李品种大多为长球形（比值2～1.14）,个别品种牛心李、长李17号、吉林六号为超长球形（比值>2）, 均有3条沿极轴走向的等间距的发芽沟,发芽沟的有开张、半开张、不开张3种。31个李品种的外壁纹饰可以分为七种类型,大多数李品种的纹饰是条脊平行或分枝多穿孔纹饰,云状纹饰品种少为矮甜李、龙园秋李,脑纹状纹饰只有延吉李。根据极轴、赤道轴、条脊宽、穿孔径、穿孔频率5项指标,采用最远距离法对31个李品种进行聚类分析,牛心李与其它30个李品种亲缘较远。     

Staining Germinating Pollen and Pollen Tubes

Germinating pollen on stigmas and pollen tubes in styles of Antirrhinum, Brassica, Oenothera, Raphanus, Rosa, solatium and Tagetes spp. were prepared for examination as follows: The styles were fixed in ethyl alcohol-acetic acid 3:1 for 1 hr, and hydrolyzed at 60°C for 5 to 60 min (depending on the species) in 45% acetic acid. The stigma with its attached strand(s) of stigmatoid tissue was then dissected out under a stereoscopic microscope, placed in a few drops of a staining solution made by dissolving 150 mg of safranin O and 20 mg of aniline blue in 25 ml of hot 45% acetic acid. After 5-15 min in this stain, the tissue was placed in a fresh drop of stain on a microscope slide and gently squashed under a cover glass. Because of a gradual precipitation of the aniline blue component, the stain had to be filtered regularly before use. However, a staining solution could be kept at room temperature for several weeks.     

复粒稻种质资源及其遗传育种利用

水稻(Oryza sativa)是世界上最重要的粮食作物之一, 也是单子叶植物发育分子生物学研究的理想模式植物。穗部形态是影响水稻产量的重要因素, 也是当前水稻遗传改良和发育生物学研究的热点之一。复粒稻是发生于水稻穗粒部的一种突变体材料, 在形态上可分为小穗簇生型和颖壳多雌型两种, 有自然突变、杂交变异和理化诱变等多种来源途径。作为一种特异的水稻种质资源, 复粒稻在水稻新材料创建、复粒型新品种选育、改善杂交制种结实性及探讨单子叶植物成花机理等方面具有重要的研究价值, 对创造复粒新型育种材料、提高穗着粒密度及穗粒数、有效缩短穗长度、改良水稻植株性状及提高产量等都具有重要意义。该文综述了复粒稻的资源类型、来源途径、遗传分析、基因定位及其育种利用价值等方面的研究进展, 并提出了今后的研究方向, 以期为水稻遗传育种提供参考。     

中俄茄子种质资源遗传多样性研究

利用25对SSR分子标记和24个表型性状对105份中俄茄子材料进行遗传多样性分析。表型变异分析结果表明:24个表型性状在中俄材料间均表现出了不同程度的多样性,但是同一性状在中俄材料中多样性不同;主成分分析可将24个表型性状概括为果形因子、颜色因子、果实外观因子、叶片形态因子、果萼刺和花药条纹6个指标,其中果实特征占主要成分;利用UPGMA法进行聚类,遗传相似系数在0.4~0.8之间,平均值0.6。25对多态性SSR标记,扩增出122个条带,含有等位基因82个,其中有效等位数24.8个,PIC值为0.3~0.7。分子聚类的遗传相似系数在0.5~1之间,平均值是0.7。表型聚类和分子标记聚类的结果相似,105份茄子种质资源间的类群划分与地理来源之间没有直接关系,但与茄子的果实性状有一定的相关性。     

印度植物遗传资源保护与对外交流管理

印度拥有高等植物17500种,是世界著名的八大栽培作物起源中心之一。植被可分为8个区系,即喜马拉雅西部、喜马拉雅东部、阿萨姆地区、印度河平原、恒河平原、德干高原、马拉巴尔海岸和安达曼群岛。已建立6种原生境保护形式和229个基因库,长期保存植物遗传资源35万份,中期保存17．6万份。以科研为目的资源引进由印度植物遗传资源国家局（NBPGR）统一管理,对外提供由国家生物多样性总局（NBA）统一管理。     

Fluctuating Selection,Egg Banks and Population Genetic Structure in Cyclically Parthenogenetic Species

Associations between neutral genetic markers and genes under selection have been suggested to explain the population genetic structure of neutral genes in cyclically parthenogenetic freshwater invertebrates. A simulation model was constructed in order to analyse the extrapolated consequences of observed fluctuations in genotype frequencies in Daphnia, in the presence of egg banks. When of sufficient depth and magnitude, egg banks in combination with fluctuating selection were shown to maintain genetic variation within populations indefinitely. The level of equilibrium diversity increased with the depth and magnitude of the banks, and with intensity of selection. The same threshold was responsible for genetic differentiation between populations, which was independent of migration rate, and which was attained very rapidly following initial Hardy–Weinberg equilibrium. In the absence of selection, egg banks increased the effective size of local populations, thereby decreasing genetic differentiation at migration-drift equilibrium. These results suggest that egg banks are crucial to the genetic structure in the presence of fluctuating selective pressures, but more data are needed if this knowledge is to be used in an improved general understanding of the genetic structure of cyclically parthenogenetic species.     

花灌木种质资源及其遗传多样性研究

综述了国内外关于花灌木种质资源在形态学、细胞学、酶、DNA等水平的多样性研究,探讨了目前花灌木种质资源遗传多样性研究中存在的一些问题和建议。     

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。     

Pollen Organs and Seeds with Eucommiidites Pollen

The characteristic Mesozoic pollen genus Eucommiidites is described from pollen organs and seeds recovered in Cretaceous strata of North America and Europe. The pollen organs are from the lowermost Upper Cretaceous (Cenomanian) of Texas and are referred to Erdtmanitheca texensis gen. et sp. nov. They are spherical heads, composed of numerous, densely crowded, radiating pollen sacs that contain abundant well-preserved pollen. Combined LM, SEM and TEM investigations show that the pollen grains each have a distinct distal colpus flanked by two lateral colpi in an equatorial position. Pollen wall ultrastructure is gymnospermous with a thick lamellate inner layer (endexine) and an outer layer (ektexine) composed of a granular inner part and a homogeneous outer part. The endexine is thickened in the region of the colpi. Small seeds from the Lower Cretaceous (upper Berriasian to Valanginian) of Bornholm, Denmark contain abundant Eucommiidites pollen in their micropyles. The seeds are referred to Erdtmanispermum balticum gen. et sp. nov. They are ovoid, and weakly triangular in transverse section and gradually taper at the apex into an elongated tube. The megaspore membrane is granular and well developed, and apparently surrounded by three separate tissues interpreted as nucellus, a thin inner integument and a sclerified outer envelope. Eucommiidites pollen in the micropyles of the seeds has a laminated endexine and an ektexine comprising two homogeneous parts separated by a granular layer. Réévaluation of other seeds known to contain Eucommiidites pollen indicates that they share significant similarities with Erdlmanispermum and that they may have been produced by closely related plants. Comparison of “Eucommiidites plants” with other seed plants suggests that they are probably most closely related to the anthophytes comprising Bennettitales, Pentoxylales, Gnetales and angiosperms.     

Genetic variation for aerial dispersal behavior in the Banks grass mite

Banks grass mites, Oligonychus pratensis (Banks), exhibit a behavior that facilitates their dispersal as aerial plankton over long distances. The propensity to display this behavior and its latency varies among individual mites. Some of this variation can be attributed to genetic differences among individuals. Mother-daughter resemblance and bi-directional selection were used to estimate the genetic component of latency of the aerial dispersal behavior in a wild population collected from corn plants. Mother-daughter regression analysis suggested that up to 10% of variation in initiation of aerial dispersal behavior was attributable to an additive genetic component. Subsequent selection for shorter and longer latency resulted in significant divergence between selected lines after 9 generation, but the response was not symmetrical. Realized heritability for shorter latency was 0.09, while that for longer latency was not different from 0. This response to selection was consistent with results of the mother-daughter analysis, and the response asymmetry may explain the high variability in the mother-daughter regression. In both their natural habitat and in a corn agroecosystem, mites survive by using a succession of temporarily available hosts. Aerial dispersal behavior by Banks grass mites facilitates colonization of new hosts. The genetic basis and selection response of behavior initiating aerial dispersal is consistent with its role in mites population dynamics in this setting.     

菊花种质资源与遗传改良研究进展

本文对菊花(Dendranthema morifolium)种质资源的调查、搜集、研究与评价、菊花杂交育种、诱变育种和生物技术育种等方面取得的成果进行了综述,并对目前存在的问题及今后的发展方向进行了探讨。