青藏高原东北部植物染色体数目和多倍性研究

对青藏高原东北高山冰缘地区和相邻低海拔地区５９种多年生草本被子植物进行了染色体计数。其中,４５个种的染色体记数为首次报道,并确定其倍性。对分布于高山冰缘地区和冰缘以下不同海拔地区植物染色体的多倍性进行分析研究。     

三个鲫品系DNA含量的比较研究

采用流式细胞术 (FCM)对红鲫、彭泽鲫、异育银鲫进行红血球DNA含量的检测分析比较 ,以鉴定它们的倍性。结果显示 ,红鲫红血球的DNA含量是 3 0pg ,彭泽鲫是 4 7pg ,异育银鲫是 4 8pg。显而易见 ,彭泽鲫的DNA含量是二倍体红鲫的 1 57倍 ,异育银鲫的DNA含量是红鲫的 1 6倍。采用肾细胞直接制作染色体的方法进行红鲫、彭泽鲫、异育银鲫的染色体倍性鉴定 ,结果红鲫的染色体数目是 10 0 ,为二倍体 (2n =10 0 ) ,彭泽鲫的染色体数目是 162 ,为三倍体 (3n =162 ) ,异育银鲫的染色体数目是 156— 162 ,为三倍体 (3n =156— 162 )。研究证明 :不同品系鲫的DNA含量高低与染色体的倍性有显著的正相关性     

基于液氮研磨法的流式细胞术检测马铃薯倍性的研究

染色体组倍性鉴定是马铃薯种质资源评价的重要内容,流式细胞仪能够快速、准确地对细胞核DNA含量进行测定,从而广泛用于检测植物染色体组倍性。建立适于马铃薯倍性鉴定的高通量流式细胞术体系,对马铃薯育种工作提供依据。以20份马铃薯合作88孤雌诱导后代为材料,用液氮研磨法制备叶片细胞核悬液,并将其与传统刀片切碎法制备的细胞核悬液进行比较,对已知四倍体马铃薯合作88和二倍体马铃薯IVP101进行染色体倍性测定,结果发现这两种方法在倍性测定结果之间无明显差异,但是液氮研磨法操作简单、耗时少。基于液氮研磨法的流式细胞术可快速、准确检测其倍性。另外,在液氮研磨法中,对细胞核悬液染色时间的长短(从15 min到12 h)并不会影响倍性测定结果,从而方便研究人员在实际操作中灵活选择染色时间。     

S基因在甘蓝EDFs上的高分辨率荧光原位杂交定位

植物细胞壁及细胞质的存在和植物染色体所具有的高浓缩特性,限制高效率原位杂交定位在植物细胞内的进行。针对小型染色体芸薹属植物采用常规方法DNA制备纤维的效果不佳的特点,新建制备方法：利用减数分裂前期的染色体为材料,在硅化的玻片上先后通过蛋白酶解和乙醇：乙酸（3：1）的适当处理,采用移动界而法制备EDFs。制备的EDFs比未经伸长处理的染色体在经向和横向方面分别取得较高程度的伸长与膨胀,长度可达到89-257μm,比相应地中期染色体增长30107倍,分辨率可达42．853．0kb。利用SRK和SCR两种探针同时在甘蓝粗线期染色体和EDFs上进行了原位杂交,首次鉴定了S基因座在其单倍体基因组中单拷贝性。在杂交信号检测中尽管未经过信号放大,但仍然可以观察到清晰的绿色信号;经荧光显微镜观察,在单一的EDF上发现两个相距1μm的SCR和SRK的信号点,由此得出局部分辨率为4kb的最高伸长度。     

倍性复杂植物的2种倍性鉴定方法的建立及应用(专题约稿）

研究以猕猴桃属内不同植物的幼嫩叶片为材料,利用流式细胞术和全基因组SNP(single nucleotide polymorphism)位点杂合子等位基因深度比率(heterozygous allele depth ratio)分布2种方法进行猕猴桃倍性鉴定。对取样叶片的生长状态、防止细胞核黏连的PVP(聚乙烯吡咯烷酮)浓度、滤网目数及过滤次数、不同倍性样本全基因组SNP分型的参数调整等因素进行探索。结果表明,流式细胞术检测中取未展开的幼嫩叶片获得完整细胞核的数目最多;5%PVP对减少细胞核之间的黏连最适宜;500目滤网过滤3次效果最好。SNP的分型主要与模拟基因组的组装质量和过滤识别SNP的参数设置有关。流式细胞术鉴定倍性的关键技术是使用未展开的幼嫩叶片以保证足够数量的完整细胞核及减少细胞核之间的黏连。同一植物材料的染色体倍性在60Co-γ辐照处理前后未发生改变。全基因组SNP位点杂合子频率分布图判断的倍性与流式细胞术鉴定结果一致。2种鉴定结果可以相互验证,使倍性的判断变得更加准确,为加快猕猴桃育种提供了基础。     

雌雄异株植物性别鉴定的研究进展

雌雄异株植物为研究植物的性别决定和进化提供了一个模式体系,由于不同性别的植物具有不同的经济价值,所以其性别鉴定的研究不仅具有重要的理论意义,而且具有极为重要的实践价值。从外部形态、生理生化指标、染色体组型、同工酶、特异蛋白质分子、分子标记等方面,对近15年来国内外有关雌雄异株植物性别鉴定研究的进展作了总结,并对各种鉴定方法的优缺点进行了评价,同时对其研究发展趋势作了展望。     

染色体数据的挖掘及其在植物多样性进化研究中的利用

多倍化（或全基因组加倍）是植物物种形成的重要途径,现存的被子植物可能都发生过一次甚至多次多倍化事件。多倍化传统的定义是染色体数目相对于祖先类群呈整倍性增加。其中最常用的研究方法是核型分析,核型能够提供物种的基本细胞学参数,包括染色体数目、倍性水平、核型不对称性、核型变异系数等。目前核型研究的趋势表现出从物种基本核型参数分析逐渐演化到多类群、多学科交叉融合的特点：一方面植物核型分析从种群、物种、科属的类群到生命之树,探讨染色体核型在各支系的进化特征、趋势以及驱动植物系统进化的细胞学机制;另一方面探讨和分析区域或生态系统植物区系的染色体谱或倍性等细胞学特征,可以探究区域地质环境变化或生态环境对染色体倍性等的影响,或通过区域染色体谱的构建,分析区域植物区系的形成和进化历史。因而,植物核型研究为系统发育、分子系统进化、生命之树以及植物区系地理的起源和演化研究提供了新思路。越来越多的新方法、新手段在植物核型分析与多倍化研究中得到运用,从而揭示了植物类群或植物区系的染色体进化以及细胞地理特征。今后植物细胞学研究趋势会向多学科交叉融合,整合各研究领域证据,从不同水平角度综合分析植物核型多样性形成的原因及意义,从而更加全面地认识和理解植物物种多样化与物种形成原因。     

染色体数据的挖掘及其在植物多样性进化研究中的利用

多倍化(或全基因组加倍)是植物物种形成的重要途径,现存的被子植物可能都发生过一次甚至多次多倍化事件。多倍化传统的定义是染色体数目相对于祖先类群呈整倍性增加。其中最常用的研究方法是核型分析,核型能够提供物种的基本细胞学参数,包括染色体数目、倍性水平、核型不对称性、核型变异系数等。目前核型研究的趋势表现出从物种基本核型参数分析逐渐演化到多类群、多学科交叉融合的特点:一方面植物核型分析从种群、物种、科属的类群到生命之树,探讨染色体核型在各支系的进化特征、趋势以及驱动植物系统进化的细胞学机制;另一方面探讨和分析区域或生态系统植物区系的染色体谱或倍性等细胞学特征,可以探究区域地质环境变化或生态环境对染色体倍性等的影响,或通过区域染色体谱的构建,分析区域植物区系的形成和进化历史。因而,植物核型研究为系统发育、分子系统进化、生命之树以及植物区系地理的起源和演化研究提供了新思路。越来越多的新方法、新手段在植物核型分析与多倍化研究中得到运用,从而揭示了植物类群或植物区系的染色体进化以及细胞地理特征。今后植物细胞学研究趋势会向多学科交叉融合,整合各研究领域证据,从不同水平角度综合分析植物核型多样性形成的原因及意义,从而更加全面地认识和理解植物物种多样化与物种形成原因。     

中国西南地区鹿药属4种15居群核型研究

对产于中国西南部的鹿药属（Maianthemum）4种植物进行了细胞学研究,包括染色体数目,多倍化,非整倍性和随体染色体,以及核型不对称性和核型进化。结果表明：1）除了在云南丽江采集的Maianthemum tatsienensis染色体数目为2n=72之外,其余的居群全为2n=36;2）核型在居群间存在变异,特别是在具中部染色体和近中部染色体的数目以及随体染色体的数目和位置上。此外,M．nanchuanense和M．szechuanicum的核型是首次报道,B染色体也是首次在该属中发现。我们推测鹿药属的进化方式包括频繁的染色体畸变以及不同水平上的多倍化,而中国西南部是该属的分化中心。     

水晶兰属植物的染色体

对国产水晶兰属植物水晶兰（Monotropa uniflroa L．）和毛花松下兰（M．hypopitys var．hirsutea Roth）的花粉母细胞减数分裂进行了观察,它们的减数分裂中期Ⅰ的染色体数目均为n=24。结合前人所做的研究,确定该属的染色体基数为x=8,并对该属的染色体基数和倍性变异与地理分布区的关系进行了初步探讨。通过对鹿蹄草亚科和水晶兰亚科的染色体基数比较,结合两个亚科的生长习性和花药开裂方式的不同,作者赞同哈钦松系统将水晶兰亚科作为科的处理。     

Ploidy reduction and genome segregation in cultured carrot cell lines. I. Prophase chromosome reduction

Cytological analysis of different carrot cell lines in culture has shown various cytogenetic anomalies generating new levels of ploidy and novel chromosome numbers. Polyploidy may be considered a reservoir of variability that can be released in the form of distinct new segregants of different ploidy. Mechanisms alternative to mitosis (reductional grouping, prophase chromosome reduction) operate from a polyploid state (possibly reached by means of endopolyploidy, endomitosis, nuclear fusion, or restitution nuclei) to generate new levels of ploidy and novel chromosome numbers necessary for selection to operate in vitro. The segregational phenomena require chromosome recognition in haploid set complements and abnormal behaviour of mitoses; the resulting chromosome variability suggests that chromosomes are arranged, in the resting nuclei, in an orderly and predictable manner.The knowledge of the molecular events governing these mechanisms, and how to control them, would be of great help for future applications of plant cell culture.     

Karyotypes,Banding Patterns and the Evolution of Different Ploidy Wheats

Karyotypes and Giemsa N banding patterns of 13 species of different ploidy wheats have been studied by means of a new method of preparing mitotic chromosome sample in plant. Chromosomes of all diploids and Emmer are metacentric chromosomes, while submetacentric chromosomes occur only in T. timopheevii and T. aestivum. The number of satellite chromosome in the polyploid wheats is not the case of the amount of diploid. Diploid species do not show any N-bands except for T. speltoides. The banding pattern of T. timopheevii is different from that of Emmer. According to the results, authors consider: 1. In the evolution of polyploid wheats, certain variances arise frmn morphological and structural variation of chromosomes; 2. T. speltoides is of importance to the evolution of polyploid wheats and may not only involve the origin of the B genome but also the G genome; 3. The origin of the B genome perhaps is polyphyletic, i.e. 2 or more amphidiploids included T. speltoides crossing each other result in the present of B genome by recombination or chromosome substitution, and 4. T. dicoccoide and T. timopheevii may have evolved from a common ancestor.     

Inference of individual ploidy level using codominant markers

A significant portion of plant species are polyploids, with ploidy levels sometimes varying among individuals and/or populations. Current techniques to determine the individual ploidy, e.g., flow cytometry, chromosome counting or genotyping‐by‐sequencing, are often cumbersome. Based on the genotypic probabilities for polysomic inheritance under double‐reduction, we developed a model to estimate allele frequency and infer the ploidy status of individuals from the allelic phenotypes of codominant genetic markers. The allele frequencies are estimated by an expectation‐maximization algorithm in the presence of null alleles, false alleles, negative amplifications and self‐fertilization, and the posterior probabilities are used to assign individuals into different levels of ploidy. The accuracy of this method under different conditions is evaluated. Our methods are freely available in a new software package, ploidyinfer , for use by other researchers which can be downloaded from http://github.com/huangkang1987/ploidyinfer .     

Ploidy doubling by in vitro culture of excised protocorms or protocorm-like bodies in <Emphasis Type="Italic">Phalaenopsis</Emphasis> species

Endopolyploidy was observed in the protocorms of diploid Phalaenopsis aphrodite subsp. formosana with ploidy doubling achieved by in vitro regeneration of excised protocorms, or protocorm-like bodies (PLBs). Thirty-four per cent of the PLBs regenerated from the first cycle of sectioned protocorms were found to be polyploids with ploidy doubled once or twice as determined by flow-cytometry. The frequency of ploidy doubling increased as the sectioning cycles increased and was highest in diploid followed by the triploid and tetraploid. Regeneration of the endopolyploid cells in the tissue of the protocorms or PLBs is proposed as the source of the development of ploidy doubled plantlets. The frequency of ploidy doubling was similar in seven other Phalaenopsis species, although the rate of increase within cycles was genotype specific. In two species, a comparison of five parameters between 5-month-old diploid and tetraploid potted plants showed only the stomata density differed significantly. The flowers of the tetraploid plant were larger and heavier than those of the diploids. This ploidy doubling method is a simple and effective means to produce large number of polyploid Phalaenopsis species plants as well as their hybrids. The method will be beneficial to orchid breeding programs especially for the interspecific hybridization between varieties having different chromosome sizes and ploidy levels.     

‘金星无核’葡萄短节间突变体的遗传变异和内源激素水平分析

以秋水仙素处理‘金星无核’葡萄获得的短节间突变体植株‘3-2D-05’和‘金星无核’植株新抽枝梢嫩叶、梢尖和茎段为材料,利用高效液相色谱(HPLC)法测定了新抽枝梢不同部位内源GA3、IAA及ABA的含量及比值差异;采用细胞流式仪分析两种材料叶细胞染色体倍性,并通过RAPD和SSR两种标记对两种植株进行分子鉴定,以明确...     

Ploidy variation of pronamide-treated maize calli during long term culture

Summary Anther-derived calli of corn were treated with 10 M pronamide for 2, 3 and 4 days. The ploidy level of the calli was then evaluated using flow cytometry, at different times after the treatment. Untreated haploid calli did not change in ploidy level for 97 days but by 466 days, there were up to 50% diploid or higher ploidy cells thus showing that spontaneous doubling may occur during corn calli subculture with this genotype. Pronamide treatment did increase the percentage of diploid and tetraploid cells and by 466 days, all of the lines showed an additional change toward higher ploidy levels. This change may be due to spontaneous chromosome doubling or to differential cell cycle times of cells with different ploidy levels. The ploidy level of plants regenerated from the cultures was determined by counting the guard cell chloroplast numbers and the correlation with the ploidy level of the cultures was r²=0.84. These studies show that pronamide treatments can increase haploid maize callus chromosome numbers and that spontaneous chromosome doubling can occur with time in maize callus.     

禾本科植物基因组大小与种子特性的相关性分析

在检索植物C值数据库和种子数据信息库的基础上,对禾本科282种植物的基因组参数（倍性、染色体数、C值、GS值和平均每条染色体DNA含量）和种子特性（千粒重、含油量和蛋白含量）进行了统计分析。分析结果表明,禾本科植物C值在0.35～19.7 pg,大多位于1.6～3.2 pg之间,呈偏正态分布,种子千粒重在0.05～252 g,绝大多数位于0.05～20.0 g,呈偏态分布,二者平均值分别为4.14 pg和7.1 g。随着染色体倍性增加,C值在二倍体到八倍体之间显著增加,而GS值和平均每染色体DNA含量在二倍体到六倍体之间显著下降（p<0.05)。雀麦属和羊茅属随着倍性增加,C值显著增加,表现与禾本科相似的变化规律,GS值下降却不明显。相关性分析表明,禾本科植物C值与倍性、染色体数、GS值及平均每条染色体DNA含量均呈极显著正相关（p<0.01),与种子千粒重无相关性。GS值与染色体数、倍性呈极显著负相关,而与千粒重呈极显著正相关。C值与种子含油量呈显著负相关,但与种子蛋白含量之间无相关性。以上结果表明,禾本科植物在系统演化和进化过程中,主要通过倍性和染色体的增加来增大C值,可能通过某种删除或丢失机制来降低GS值,从而保持较高的适应环境能力和进化速率。     

Androgenesis,gynogenesis, and parthenogenesis haploids in cucurbit species

Haploids and doubled haploids are critical components of plant breeding. This review is focused on studies on haploids and double haploids inducted in cucurbits through in vitro pollination with irradiated pollen, unfertilized ovule/ovary culture, and anther/microspore culture during the last 30 years, as well as comprehensive analysis of the main factors of each process and comparison between chromosome doubling and ploidy identification methods, with special focus on the application of double haploids in plant breeding and genetics. This review identifies existing problems affecting the efficiency of androgenesis, gynogenesis, and parthenogenesis in cucurbit species. Donor plant genotypes and surrounding environments, developmental stages of explants, culture media, stress factors, and chromosome doubling and ploidy identification are compared at length and discussed as methodologies and protocols for androgenesis, gynogenesis, and parthenogenesis in haploid and double haploid production technologies.     

Polyploidy determines the stage of invasion: clues from Kashmir Himalayan aquatic flora

Invasive species pose a major threat to native biodiversity and ecosystem integrity in many ecologically sensitive parts of the globe. Many research efforts have so far been made mainly with a focus on morphology, physiology and reproductive biology of invasive species to explain what determines the patterns of invasion. Recently, polyploidy has been reported to significantly influence plant invasiveness. Notwithstanding the profound management and conservation implications, determining the genetic basis of plant invasiveness is a challenging task for ecologists. Variation in ploidy levels of species promises to yield some useful insights in this direction and we, therefore, aimed to test the relation between polyploidy and species invasiveness. We documented chromosome number and ploidy level of 118 alien aquatic plant species including 50 alien non-invasive and 70 alien invasive species, belonging to 64 genera and 39 families distributed across various aquatic habitats of the Kashmir Himalaya at different stages of invasion. Results yielded 47 (39.83%) diploid species, 53 (44.91%) polyploids and the remaining 18 (15.25%) species were reported to have mixed ploidy, i.e., both diploids and polyploids. The invasive plant species exhibited about 40% of intraspecific ploidy polymorphism in contrast to about 28% found in non-invasive plant species. Alien invasive species (at stage IVa, IVb and V senso Colautti and MacIsaac 2004) were found to have more polyploidy (60%) than non-invasive species (at stage II and III) having only 45.23% polyploidy. Our results depict a clear pattern that non-invasive species are disproportionately more diploids with lower ploidy ratios, while invasive plant species on the contrary exhibit higher chromosome counts, thereby being predominantly polyploids. Invasion stage III with 17 diploid species represents by far the highest relative proportion of diploid species, while invasion stage V having 16 polyploid species is highest in terms of polyploid species. Regression analysis based on the stage of invasion and the ploidy status revealed that the relative proportion of polyploids on progressing stage of invasion increases significantly (p < 0.01). These results indicate that polyploidy may be one of the potential determinants of plant invasion. The implications of these results in timely prediction and better management of invasive species are discussed.