山羊草属异源多倍体植物基因组进化的ＲＡＰＤ分析

和２４个随机引物对山羊草属（Ａegilops L.)异源多倍体物种对其祖先二倍体物进行ＲＡＰＤ分析,对扩增出的３１３条带进行聚类分析发现,含Ｄ基因组的多倍体与二倍体祖先Ａe.squarrosa(DD)在聚类图上聚为一支;除Ａe.juvenalis(DDMMUU)聚到上一支外,含Ｕ基因组的多倍 与二倍体祖先Ae.umbellulata(ＵＵ）在聚类图上聚为另一支;多倍体与其他二倍体均不聚在一起,表明多倍体分别与Ａe.squarrosa(DD)、Ae.umbellulata(UU)具有较近的亲缘关系,这说明多倍体开之后,Ｄ和Ｕ基因组变化较小,而其他基因组则发生了较大的变化。     

山羊草属异源多倍体物种核rDNA ITS区的进化

本文测定了山羊草属Aegilops 3个组中异源多倍体物种的核rDNA ITS区序列,并用邻接法进行了聚类分析。结果表明,多倍体物种的ITS区序列长度为559∽606bp,其中ITS1、ITS2分别有变异位点51、42个,且存在多态位点。多倍体种均与各自的某一祖先种构成稳定分支,说明在杂交-多倍化后,这些多倍体的ITS区在同步进化的作用下已向着其某一祖先种的ITS区进化。对于sect．Vertebrata的异源多倍体物种来说,其ITS区主要向其祖先种Ae．umbellulata(UU)的ITS区进化,这与山羊草属的细胞遗传学研究结果基本一致。在sect．Cylindropyrum和sect．Polyeides中,Ae．cylindrica(CCDD)朝着Ae．caudata (CC)进化;Ae．ventricosa(DDMvMv)朝着Ae．comosa(MM)进化;Ae．vavilovii(DDMMSS)朝着Ae．crassa (DDMM)进化。     

序列消除与异源多倍体植物基因组的进化

经杂交后多倍化形成的异源多倍体植物,被认为在其形成的早期阶段经历了DNA序列消除过程。发生消除的序列既涉及到高拷贝的序列也有低拷贝的序列,而且大多数情况下倾向于消除来自其中一个亲本的序列。序列消除的模式因基因组组成和物种的不同而有差异,并且可能受到细胞质的影响。尽管序列消除的分子机制还不是很清楚,但很多证据已表明非同源染色体之间的互作不是主要的原因。目前认为,序列消除增加了非同源染色体之间的差异,为多倍化后在减数分裂过程中快速恢复二倍化的染色体配对模式提供了物质基础,这样更有利于多倍体在自然界快速稳定。     

芸薹属多倍体植物基因组进化的RAPD分析

多倍化是促进高等植物发生进化的重要力量。为了更清楚地了解多倍体在形成之后其基因组是如何进化的,利用38个随机引物对芸薹属Brassica L.禹氏三角（U’Triangle）中的多倍体物种及其祖先二倍体物种进行了研究。根据扩增出的273条带计算了遗传距离,并用UPGMA法进行了聚类分析。结果发现,二倍体物种B.campestris（AA）与B.oleracea（CC）的亲缘关系比与B.nigra（BB）的要近;异源多倍体B.napus（AACC）比起其二倍体祖先之一B.campestris（AA）与另一个     

植物异源多倍体进化中基因表达的变化

多倍化是植物物种进化的主要动力, 异源多倍体植物在形成早期发生着快速的基因表达变化。本文概述了异源多倍体植物中基因表达变化的特点, 包括基因的沉默、激活和部分同源基因表达水平的变化, 探讨了基因表达变化的分子机制和生物学意义, 并对研究中的问题进行了分析和展望。     

植物异源多倍体进化中基因表达的变化

多倍化是植物物种进化的主要动力,异源多倍体植物在形成早期发生着快速的基因表达变化。本文概述了异源多倍体植物中基因表达变化的特点,包括基因的沉默、激活和部分同源基因表达水平的变化,探讨了基因表达变化的分子机制和生物学意义,并对研究中的问题进行了分析和展望。     

山羊草属五个基本基因组系统发育的RAPD分析

利用ＲＡＰＤ技术,从ＯＰＥ、ＯＰＦ、ＯＰＧ、ＯＰＵ、ＯＰＸ、ＯＰＹ和ＯＰＺ共７组随机引物中筛选出２８个能产生基因组特异带的稳定引物,对山羊草属（ＡｅｇｉｌｏｐｓＬ．）的５个基本基因组及普通小麦“中国春”的ＤＮＡ进行随机扩增,根据扩增的４８８条ＤＮＡ片段绘制出系统发育图。普通小麦ＡＢＤ基因组与Ｓ基因组亲缘关系最近,Ｃ与Ｕ基因组具有比较近的亲缘关系,Ｄ基因组与其它基因组的亲缘关系比较远     

植物多倍体基因组的形成与进化

多倍化是植物进化变异的自然现象,也是促进植物发生进化改变的重要力量。在被子植物中,约 70％的种类在进化史中曾发生过一次或多次多倍化的过程。目前的研究结果表明,自然界绝大多数多倍体是通过未减数配子的融合而形成的,并且很多多倍体种是通过多次独立的多倍化过程而重复发生的。由多倍化所导致的重复基因在多倍体基因组中可能有三种不同的命运,即：保持原有的功能、基因沉默或分化并执行新的功能。多倍化以后,重复基因组的进化动态则主要表现在染色体重排和“染色体二倍化”、不同基因组之间的相互渗透、以及核-质之间的相互作用等方面。     

异源多倍体植物核rDNA序列的同步进化

同步进化是异源多倍体植物核rDNA序列进化的重要方式,同步进化的程度在不同植物类群中存在较大差异,有些类群中同步进化力量较强,核rDNA重复序列间已经纯合或接近纯合,有些类群中同步进化的力量较弱,可观察到序列的杂合性。同步进化的机制主要是不等交换和基因转换,并受异源多倍体形成年代、生殖方式、基因突变率等因素的影响。     

山羊草属核型分析及其与小麦属的进化关系

作者研究了山羊草属(Aegilops)中的新疆节节麦(Ae.squarrosa)、拟斯卑尔脱山羊草(Ae.speltoides)、沙融山羊草(Ae.sharonensis)、尾状山羊草(Ae.caudata)、卵圆山羊草(Ae.ovata)、偏凸山车草(Ae.ventricosa),钩状山羊草(Ae.triuncialis)、三芒山羊草(Me.triaristata)、欧山羊草(Ae.biuncialis)、柱穗山羊草(Ae.cylindrica)、可兹山羊草(Ae.kotschyi)和肥厚山羊草(Ae.crassa)的核型和部分材料的Giemsa N-带,结果表明山羊草属的C组核型为:4sm+3st;D组核型为:6m+1sm;S组的核型为:6m+1sm;M组的核型为:4m+1sm+2t。在四倍体、六倍体中,各染色体组保持着相对稳定。山羊草属S、D染色体组的核型与带型表明它们是小麦B、D染色体组的可能供体,C、M染色体组的一部分染色体带型亦与小麦B组带型相似。     

Genomic instability in phenotypically normal regenerants of medicinal plant Codonopsis lanceolata Benth. et Hook. f., as revealed by ISSR and RAPD markers

Codonopsis lanceolata Benth. et Hook. f., commonly known as bonnet bellflower, is a high-valued herb medicine and vegetable. In this study, a large number of plants were regenerated via organogenesis from immature seed-derived calli in C. lanceolata by a simple and efficient method. Compared with the mother donor plant, the regenerated plants did not exhibit visible phenotypic variations in six major morphological traits examined at the stage of one-season-maturity under field conditions. To gain insight into the genomic stability of these regenerated plants, 63 individuals were randomly tagged among a population of more than 2,000 regenerants, and were compared with the single mother donor plant by two molecular markers, the inter-simple sequence repeats (ISSR) and randomly amplified polymorphic DNA (RAPD). Apparent genomic variation was detected in the 63 regenerants, whereas preexisting heterozygosiy in the donor plant was deemed minimal by testing 30 seedlings germinated from selfed seeds of the same donor plant. The percentages of polymorphic bands (PPB) in the ISSR and RAPD analysis were respectively 15.7 and 24.9% for the 63 regenerated plants. Cluster analysis indicates that the genetic similarity values calculated on the basis of RAPD and ISSR data among the 64 plants (63 regenerated and one donor) were respectively 0.894 and 0.933, which allow classification of the plants into distinct groups. Nineteen randomly isolated bands underlying the changed RAPD or ISSR patterns were sequenced, and three of them showed significant homology to known-function genes. Detailed pairwise sequence comparison at one locus between the donor plant and a regenerant revealed that insertion of two short (24 and 19 bp) stretches of nucleotides in the regenerated plant relative to the donor plant occurred in an apparently stochastic manner.Electronic Supplementary Material Supplementary material is available for this article at     

Genetic diversity of castor bean (Ricinus communis L.) in Northeast China revealed by ISSR markers

Inter-Simple Sequence Repeat (ISSR) markers were employed to analyze the genetic diversity of Ricinus communis L. in northeastern China plants. We selected ten primers that produced clear, reproducible and multiple bands for these experiments and 179 bands were obtained across 39 genotypes. Polymorphic band ratios ranged from 100% to a minimum of 78.9% with an average of 96.4% while band numbers were comprised between 13 (UBC823) and 23 (UBC856). The results obtained from UPGMA clustering dendrogram and PCoA lead to 39 distinct castor bean accessions belonging to four major groups. We found that all groups shared a common node with 66% similarity while Jaccard's similarity coefficient ranged from 0.58 to 0.92. Compatible inference was also observed from the high values of heterozygosity (Ht = 0.3378 ± 0.0218), Nei's genetic diversity (H = 0.1765 ± 0.2090), and Shannon's information index (I = 0.4942 ± 0.1872). In addition, our data reveal a Nei's genetic differentiation index (G_ST) of 0.3452 and estimated the gene flow (Nm) at 0.9482. These findings clearly suggest a genetic diversity in castor bean germplasms from various geographic origins and contribute to our understanding of breeding and conservation of castor beans.     

Genetic diversity revealed by morphological traits and ISSR markers in 48 Okras (Abelmoschus escullentus L.)

Physiology and Molecular Biology of Plants - Okra is a widely distributed crop in the tropics, subtropics, and warmer areas of the temperate zones. Its major potential uses as a vegetable, oil and...     

粗山羊草居群间遗传分化及多样性的SSR分析

选用分布在粗山羊草14条染色体上的32对SSR引物,对来自中国河南、陕西、新疆和中东地区共147份粗山羊草材料进行遗传分化及多样性分析,结果表明在26个多态性位点中,等位基因数平均为4.15,Ne i基因多样性指数(He)平均为0.243,多态性信息含量指数(PIC)平均为0.226;居群间遗传变异差异明显,中东粗山羊草居群具有丰富的遗传变异(He=0.607,PIC=0.551),而来自陕西和河南的粗山羊草资源遗传多样性较低(He=0.055,PIC=0.047)和(He=0.024,PIC=0.021)。AMOVA分子变异分析显示,居群间遗传变异占总变异的52%,达到显著水平;河南粗山羊草和陕西粗山羊草间发生了一定的遗传分化(Fst=0.210),为研究中国粗山羊草资源的起源与分化问题提供了有用的信息与证据。     

Micropropagation in banana using high levels of cytokinins does not involve any genetic changes as revealed by RAPD and ISSR markers

Use of high levels of growth regulators during micropropagation results in undesirable clonal variability in important commercial crops such as banana. The present study investigated the effects of high levels of cytokinins on micropropagation in banana (genotype AAB), and the genetic stability of plantlets was assessed using RAPD and ISSR markers. Cytokinins, such as BA and kinetin were added to the routine shoot multiplication medium at concentrations up to 10 mg l⁻¹. After 12 weeks of culture involving three subcultures, the maximum number of shoot buds were produced in cultures receiving either 5 mg l⁻¹ BA (80 shoot buds) or 4 mg l⁻¹ kinetin (62 shoot buds). Certain morphological abnormalities observed during proliferation of shoot buds in vitro were not observed during acclimatization ex vitro. To check the genetic stability, RAPD and ISSR profiles of micropropagated plantlets obtained from different cytokinin-treatments were compared with control microplants maintained on MS medium as well as the field-grown mother plant. A total of 50 RAPD and 12 ISSR primers resulted in 625 distinct and reproducible bands. Thus a total of 17,400 bands were generated showing homogeneous RAPD and ISSR patterns. Band intensity histogram of each gel confirmed their monomorphic nature with no genetic variation in all the plantlets analysed. Based on these results a protocol for high rate shoot multiplication was worked out leading to uniform shoot production.     

Genetic diversity and structure among natural populations of Sindora glabra in Hainan Island,China as revealed by ISSR markers

Sindora glabra, one of the second-class national protective plants in China, has important ecological and commercial values. To understand the genetic diversity and structure of S. glabra, eleven natural populations from four areas of Hainan Island in China were analyzed by inter-simple sequence repeat (ISSR) markers. Thirteen primers were screened out and used to amplify 157 DNA samples. A total of 122 bands were obtained, among which 114 (93.4%) bands were polymorphic. Genetic parameters including average number of effective alleles (1.547), Nei's gene diversity (0.321), Shannon's information index (0.482), and gene differentiation coefficient (0.1944) revealed a high level of genetic diversity maintained in S. glabra populations. The variation within populations accounted for 85.6% of total variation based on analysis of molecular variance. Genetic distance analysis showed that 11 populations could be divided into three groups and populations from the same areas were classified as one group, suggesting that high genetic diversity of S. glabra was attributable to geographic isolation. Together, introduction of germplasm from distant natural distribution areas would be a sound strategy for germplasm resource conservation of S. glabra and selection of elite individuals from populations of far relationship for hybridization is of great importance for breeding improvement programs in future.     

Genetic relationship among species in the genus Sonneratia in China as revealed by inter-simple sequence repeat (ISSR) markers

Inter-simple sequence repeat (ISSR) analysis was used to establish the genetic relationship among six Sonneratia species in China. A total of 100 primers were screened, of which 11 polymorphic and informative patterns were selected to determine the genetic relationship. Four hundred and eighty five DNA bands were amplified, among which 481 bands (99.18%) were polymorphic. The average number of DNA bands amplified by each primer was 44. Similarity coefficients were calculated and a dendrogram was constructed by using UPGMA algorithm. The six Sonneratia species were divided into two major groups. Group I consisted of Sonneratia caseolaris, Sonneratia × gulngai, Sonneratia alba, and Group II included Sonneratia × hainanensis, Sonneratia ovata and Sonneratia apetala. In Group I, S. × gulngai was close to S. alba, and in Group II, S. × hainanensis was close to S. ovata. The genetic relationships estimated by the polymorphism of ISSR markers are basically in agreement with those previously inferred by morphological data. Thus, ISSR approach is a reliable marker system that can be used to study genetic relationship in the genus Sonneratia.     

Genetic diversity and population structure in Elephantopus scaber (Asteraceae) from South China as revealed by ISSR markers

Abstract

We used inter-simple sequence repeat (ISSR) markers to investigate genetic variation in eight natural populations of Elephantopus scaber from South China, including Guangdong, Hainan and Hong Kong. Eleven primers produced 247 bands across all 184 individuals, of which 243 (98.4%) were polymorphic. The average genetic diversity at the species and population levels was estimated to be 0.283 and 0.103, respectively, using mean expected heterozygosity. The average gene differentiation (F _ST) among populations was 0.725. AMOVA analysis showed that the partition of molecular variation between and within populations was 72.5% and 27.5%, respectively. The effective number of migrants among populations based on the F _ST was relatively low (N _m = 0.095). Cluster analysis based on Nei's genetic distance and the neighbour-joining method revealed the genetic relationships among the populations of E. scaber. The Mantel test indicated that there was no significant correlation between population genetic and geographic distances. The results obtained from the AMOVA analysis, the cluster analysis, and the Mantel test all suggested that fragmented local environments and human disturbance might play important roles in shaping the population structure of E. scaber.     

Genomic analysis in the genus Aegilops.

Summary Hybrids between different Aegilops species and Secale cereale were studied at metaphase I by means of a C-banding technique. On the basis of differences in the C-banding patterns of some of the chromosomes of these hybrids it was possible to carry out an accurate analysis of several types of Aegilops-Aegilops and Aegilops-Secale chromosome associations and, consequently, to establish intraspecific and intergeneric genome relationships. Genomes present in the majority of polyploid Aegilops species are shown to maintain similar patterns of evolutionary affinity to those reported for their proposed diploid parents although in some species there are differences indicating either that differentiations occurred during the evolution of the polyploid species or, on the contrary, that the diploid donors proposed are not the correct ones. On the other hand, differences in the relationships not only between the R genome and different Aegilops genomes but also among different homoeologous groups have been found.     

Genetic variation of the genus Kengyilia by ISSR markers

We investigated the genetic variation within 32 accessions distributed to 14 species and one variety by using ISSR (inter-simple sequence repeat) markers.The results showed that genetic variation was relatively higher among the accessions.A total of 593 bands were amplified by 12 ISSR primers,of which 535 bands (90.2%) were polymorphic.Eleven to 80 polymorphie bands were amplified from each prime,with an average of 44.6 bands.The interspecies GS (genetic similarity)value ranged from 0.430 to 0.866,and the average was 0.620.Cluster analysis showed that all accessions could be classified into 4 groups by ISSR markers.The different accessions in a species were clustered together,but they had genetic variation in molecular levels.There was obvious interspecies genetic variation.Species with similar morphological characteristics and from the same areas or neighboring geographical regions were clustered together and had close relationships.ISSR markers are useful in analyzing interspecies variation in Kengyilia.