AFLP分析江西省4个斑点叉尾鮰养殖群体遗传多样性

本文运用AFLP分子标记技术,对江西省4个斑点叉尾鮰(Ictalurus punctatus)养殖群体(GZ、XJ、PYA和PYB)进行遗传多样性分析。结果表明,在64对引物组合中,E3/M2、E4/M7、E3/M8和E5/M5引物从4个群体72个体中共扩增出179个位点,其中多态位点为109,占60.89%。其中,PYA、GZ、XJ和PYB群体的多态位点比例(P)分别为56.54%、56.47%、56.32%和56.14%。Shannon多样性指数(I)分别为0.2890、0.3003、0.2896和0.2852,平均杂合度(H)分别为0.1935、0.2027、0.1938和0.1898。4个群体间的遗传分化系数(Gst)为0.1314,说明群体间发生了一定程度的遗传分化,但分子方差分析(AMOVA)显示,群体的遗传变异90.98%来源于群体内的个体间,9.02%来源于群体间。聚类分析也表明,4个群体所产生的遗传分化主要也来源于群体内。本研究为斑点叉尾鮰种质资源的调查和保护提供参考,为斑点叉尾鮰优良品种的选育提供科学依据。     

基于微卫星标记的斑点叉尾鮰家系鉴定技术及应用

研究旨在建立准确、高效且经济的斑点叉尾鮰(Ictalures punctatus)家系亲缘鉴定体系, 以期为斑点叉尾鮰的遗传评估及家系育种提供科学依据。选用10对具有较高多态性SSR标记, 建立两个5重PCR反应体系。应用建立的斑点叉尾鮰家系亲缘鉴定体系对来源于13个全同胞家系和8个半同胞家系的333尾个体进行亲权鉴定。结果表明: 10个位点平均等位基因数为9.8、平均观测杂合度0.8591、平均期望杂合度0.8092、平均多态信息含量0.7845; 3种情况下的累积排除概率分别为: 0.99996806、0.99833267和0.99999998; 验证群体的鉴定结果与系谱高度一致, 真实鉴定率达到99.1%, 子代与父母本三者之间配对平均LOD值介于13.30—24.70, 且置信度均达到95%。研究选择的微卫星位点等位基因数目较多, 多态性较高, 可以快速、准确地对斑点叉尾鮰混养群体进行家系鉴定。     

斑点叉尾鮰套肠症的病原学初步研究

本研究从2例垂死的患败血症并肠套叠的斑点叉尾鮰血液、肝脏及脑组织中分离到2种类型的致病性细菌菌株,经对细菌进行形态观察、生理生化测试和16S rDNA序列分析,分别鉴定为嗜水气单胞菌和荧光假单胞菌;攻毒实验证实它们确为斑点叉尾鮰病鱼的病原。根据药敏实验的结果,及时对病区斑点叉尾鮰进行治疗,连续用药3-5天,发病的叉尾鮰即停止死亡。根据研究结果,文章对斑点叉尾鮰肠套叠发生的原因进行了的分析,提出了不同的观点。     

斑点叉尾鮰Cbx基因家族的全基因组鉴定与进化分析

利用Cbx家族基因高度保守的Chromo结构域氨基酸序列作为种子序列,检索斑点叉尾鮰(Ictalurus punetaus)基因组注释的蛋白数据库,共鉴定分离出14个Cbx基因。并在全基因组水平对斑点叉尾鮰Cbx基因家族进行了保守结构域序列、进化、基因结构、染色体定位的系统分析。本研究中鉴定出的斑点叉尾鮰Cbx家族基因蛋白序列与已知的人类、小鼠、鸡、斑马鱼等物种Cbx蛋白序列构建系统进化树。根据系统进化树分析结果,14个斑点叉尾鮰Cbx基因分成两个亚族,5个隶属于Hp1s亚族,9个隶属于PcGs亚族。Cbx基因主要分布于斑点叉尾鮰7条染色体中,且呈不均匀分布。本研究对于后续斑点叉尾鮰Cbx基因家族深入的功能验证及分子作用机制研究具有重要的意义,也为日益丰富的水产基因组资源的挖掘利用提供了参考。     

斑点叉尾鮰源普通变形杆菌的分离、鉴定及药敏特性

【目的】对患病斑点叉尾鮰进行病原菌分离、鉴定及药敏实验,为斑点叉尾鮰肠道坏死病的防控提供参考。【方法】从患病斑点叉尾鮰病灶、肝、脾和肾分离纯化病原菌,经理化特性测定及16S rRNA基因序列分析对其进行鉴定,开展人工感染试验,并利用纸片扩散法进行药敏特性分析。【结果】分离菌株k1为本次引发斑点叉尾鮰病害的致病菌,其对斑点叉尾鮰的LD50为2.82×10~5 CFU/g。菌株k1理化特性与普通变形杆菌Proteus vulgaris基本一致,16S rRNA基因序列与普通变形杆菌相似性最高,综合判定分离菌株为普通变形杆菌。分离菌株k1对环丙沙星、头孢唑林及头孢拉定等12种抗生素高度敏感,对苯唑西林、阿莫西林及痢特灵等7种抗生素耐药。【结论】分离菌株k1是斑点叉尾鮰病原菌,养殖时可选用庆大霉素及氟苯尼考等药物进行防控。     

斑点叉尾鮰鱼油脂成分分析

采用铁锅炼制提取斑点叉尾鮰内脏鱼油,然后加酸使其甲酯化,以气相色谱/质谱法分析鱼油中的脂肪酸.结果斑点叉尾鮰内脏纯油脂中鱼油达到99%.从鱼油中共鉴定出15种成分,有饱和脂肪酸及不饱和脂肪酸,还有少量烷烃类物质.不饱和脂肪酸含量为76.40%,其中多不饱和脂肪酸为18.03%,以C18∶ 2(16.23%)为主,单不饱和脂肪酸为58.37%,以C18∶ 1(54.88%)为主.饱和脂肪酸含量为20.91%,主要有C16∶ 0 (15.84%)和C18∶ 0(4.29%),多是低于C18以上的中长链脂肪酸.因此斑点叉尾鮰油脂可作功能性脂肪酸的重要膳食来源.     

基于重组毕赤酵母的斑点叉尾鮰β-防御素表达

β-防御素是斑点叉尾鮰Ietalurus punetaus抵御病原微生物侵染的首要蛋白质免疫因子,其一级结构包含氨基端24个氨基酸组成的信号肽和羧基端43个氨基酸组成的成熟肽,该成熟肽赋予β-防御素的生物学活性。文中首次构建了产斑点叉尾鮰β-防御素的毕赤酵母Pichiapastoris重组菌株,实现了基于真核表达的斑点叉尾鮰β-防御素的生物合成。首先通过RT-PCR从斑点叉尾鮰皮肤中分离β-防御素成熟肽基因"IPBD",将其与表达载体p PICZαA连接并转入毕赤酵母X-33后,获得重组毕赤酵母菌株;经含1 000μg/m L博来霉素的培养基筛选,获得高拷贝重组菌株。以BMM培养基(无氨基氮源培养基)替代BMMY培养基(含氨基氮源培养基),对重组菌株的发酵培养条件进行优化,确定其产斑点叉尾鮰β-防御素的最适条件为:28℃、250 r/min、1.0%甲醇诱导表达96 h。重组菌株产物经镍离子亲和层析获得分子量为5.98k Da的纯化蛋白,基于MALDI-TOF-TOF的质谱分析证明该纯化蛋白为重组IPBD。抑菌活性测定结果表明重组IPBD对革兰氏阳性的金黄色葡萄球菌Staphylococcus aureus、单增李斯特菌Listeria monocytogenes以及革兰氏阴性的铜绿假单胞菌Pseudomonas aeruginosa的抑菌率分别为69.6%、71.6%和65.8%。本研究为鱼类来源天然小分子抗菌肽的开发提供了可参考的重组DNA技术。     

氧化油脂对斑点叉尾鮰生长、体色和抗氧化能力的影响

为考察正常及氧化鱼油、豆油、混合油脂(鱼油﹕豆油=1﹕1)对斑点叉尾鮰(Ictalurus punctatus)生长性能、体色和肝脏抗氧化能力的影响, 设计6组等氮等脂饲料, 分别添加6%鱼油、6%豆油、3%鱼油+3%豆油、6%氧化鱼油、6%氧化豆油、3%氧化鱼油+3%氧化豆油, 饲喂6组初始体重(150.5±4.2 g)的斑点叉尾鮰8周, 每组3个重复, 每个重复14尾鱼。结果表明, 摄食6%鱼油、6%豆油、3%鱼油+3%豆油饲料的斑点叉尾鮰在增重率、饲料系数、肌肉组成、体色和肝脏抗氧化指标上均无显著差异(P>0.05); 摄食3组氧化油脂饲料后, 鱼体增重率和肌肉粗脂肪含量降低(P<0.05), 饲料系数和背部、尾部皮肤b*(黄度值)增加(P<0.05), 肝脏丙二醛(MDA)和血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆红素(TBIL)和直接胆红素升高(DBIL)(P<0.05), 肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、还原型谷胱甘肽降低(GSH)(P<0.05), 而肌肉色度值(L*、a* 、b*)和肌肉水分、粗蛋白质、灰分含量无显著差异(P>0.05)。以上结果表明, 6%氧化油脂(鱼油、豆油或混合油脂)导致斑点叉尾鮰生长性能下降、皮肤黄度增加、肝脏抗氧化能力受损; 豆油可替代斑点叉尾鮰饲料中鱼油的使用, 而不会对生长产生负面影响。     

斑点叉尾鮰病毒实时荧光LAMP检测方法的建立

斑点叉尾鮰病毒(Channel catfish virus, CCV)属于大DNA病毒, 是一种能引起斑点叉尾鮰(Letalurus punetaus)病毒性疾病的重要病原。研究以编码产物为磷酸激酶的CCV ORF77基因为靶标, 设计了能识别靶基因上的8个独立区域的6条特异引物, 利用基于环介导等温扩增技术(Loop-mediated isothermal amplification, LAMP)建立了用于CCV的实时荧光LAMP快速检测方法。结果显示, 建立的实时荧光LAMP检测方法在63℃恒温反应45min条件下, 反应大约12min后出现明显的峰值, 最低检测限度为100个拷贝的病毒质粒DNA, 检出时间为35min; 并且具有良好的特异性, 与白斑综合症病毒(WSSV)、传染性皮下及造血组织坏死病毒(IHHNV)、锦鲤疱疹病毒(KHV)、真鲷虹彩病毒(RSIV)、传染性脾肾坏死病毒(ISKNV)和新加坡石斑鱼虹彩病毒(SGIV)等常见水生动物病原DNA均没有交叉反应; 同一样品于试验内及试验间重复性试验发现, 20个平行样品的扩增曲线基本重合, 表现出良好的重复性。通过对实际样品的检测结果显示, 实时荧光LAMP检测方法能够特异性的检出CCV。因此, 研究建立的CCV实时荧光LAMP检测方法操作简单、检测快速、特异性好、灵敏度高、结果可靠, 能为斑点叉尾鮰养殖现场和实验室的斑点叉尾鮰疱疹病毒病病原的快速诊断和实时监测方面提供技术支撑。     

斑点叉尾鮰巨噬细胞移动抑制因子(MIF)基因多态性及表达分析

巨噬细胞移动抑制因子(MIF)是一类主要由T细胞产生、负责机体在环境协迫和炎症反应中进行免疫应答的细胞因子。根据斑点叉尾鮰MIF基因EST序列,应用RACE技术克隆了MIF 3'UTR和5'UTR序列,利用Genome Walking技术克隆了MIF启动子序列,通过特异PCR克隆MIF内含子序列,并对多个体MIF基因组序列进行多态性分析,利用荧光定量PCR研究MIF的组织分布。结果显示,斑点叉尾鮰MIF基因组序列共3 918 bp,其中编码区348 bp,编码115个氨基酸,5'UTR为70 bp,3'UTR为434 bp,启动子为1 382 bp,共有2个内含子,分别为243 bp和1 441 bp。MIF基因组序列中包含4个重复单元序列和60个多态性位点,其中共有6个SNP位于转录因子结合位点上。斑点叉尾鮰MIF mRNA在肠中表达量最高,肌肉中表达量最低。     

Phylogeny and biogeography of Croton alabamensis (Euphorbiaceae), a rare shrub from Texas and Alabama, using DNA sequence and AFLP data

Croton alabamensis (Euphorbiaceae s.s.) is a rare plant species known from several populations in Texas and Alabama that have been assigned to var. texensis and var. alabamensis, respectively. We performed maximum parsimony, maximum likelihood, and Bayesian analyses of DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) and 5.8S regions and chloroplast trnL-trnF regions from collections of the two varieties of C. alabamensis and from outgroup taxa. C. alabamensis emerges alone on a long branch that is sister to Croton section Corylocroton and the Cuban endemic genus Moacroton. Molecular clock analysis estimates the split of C. alabamensis from its closest relatives in sect. Corylocroton at 41 million years ago, whereas the split of the two varieties of C. alabamensis occurred sometime in the Quaternary. Amplified fragment length polymorphism (AFLP) analyses were performed using two selective primer pairs on a larger sampling of accessions (22 from Texas, 17 from Alabama) to further discriminate phylogenetic structure and quantify genetic diversity. Using both neighbour joining and minimum evolution, the populations from the Cahaba and Black Warrior watersheds in Alabama form two well-separated groups, and in Texas, geographically distinct populations are recovered from Fort Hood, Balcones Canyonlands, and Pace Bend Park. Most of the molecular variance is accounted for by variance within populations. Approximately equal variance is found among populations within states and between states (varieties). Genetic distance between the Texas populations is significantly less than genetic distance between the Alabama populations. Both sequence and AFLP data support the same relationships between the varieties of C. alabamensis and their outgroup, while the AFLP data provide better resolution among the different geographical regions where C. alabamensis occurs. The conservation implications of these findings are discussed.     

Newcastle disease virus in double-crested cormorants in Alabama, Florida, and Mississippi.

In order to understand the epidemiology of Newcastle disease (ND) outbreaks in double-crested cormorants (Phalacrocorax auritus), a study was conducted on wintering migratory cormorants (P. a. auritus) in Alabama and Mississippi (USA) and non-migratory cormorants (P. a. floridanus) that breed in Florida (USA). Antibodies against ND virus were detected by the hemagglutination-inhibition method in sera from 86 of 183 (47%) migratory cormorants over-wintering in eight roosting sites in Alabama and Mississippi between November, 1997 and April, 1999. Titers ranged from 5 to 40. Antibody prevalences in sera collected from females in early winter (November and December) (26%) and late winter (February and March) (56%) were significantly different (P = 0.0007). None of 45 serum samples from 1- to 7-wk-old nestlings from 11 colonies in Florida during the 1997-98 and 1998-99 breeding seasons was positive. However, antibodies were detected in yolk samples from 98 of 126 (78%) eggs collected in these same colonies. Titers ranged from 4 to 256. The prevalence of antibodies in eggs collected from fresh-water colonies (63% prevalence, n = 30) and salt-water colonies (82% prevalence, n = 96) was significantly different (P = 0.041). ND virus was not isolated from tissues of 18 cormorants and cloacal and tracheal swabs from 202 cormorants collected in Alabama and Mississippi; virus was also not isolated from cloacal and tracheal swabs from 51 nestlings from Florida.     

Demographic Clusters Identified within the Northern Gulf of Mexico Common Bottlenose Dolphin (Tursiops truncates) Unusual Mortality Event: January 2010 - June 2013

A multi-year unusual mortality event (UME) involving primarily common bottlenose dolphins (Tursiops truncates) was declared in the northern Gulf of Mexico (GoM) with an initial start date of February 2010 and remains ongoing as of August 2014. To examine potential changing characteristics of the UME over time, we compared the number and demographics of dolphin strandings from January 2010 through June 2013 across the entire GoM as well as against baseline (1990-2009) GoM stranding patterns. Years 2010 and 2011 had the highest annual number of stranded dolphins since Louisiana’s record began, and 2011 was one of the years with the highest strandings for both Mississippi and Alabama. Statewide, annual numbers of stranded dolphins were not elevated for GoM coasts of Florida or Texas during the UME period. Demographic, spatial, and temporal clusters identified within this UME included increased strandings in northern coastal Louisiana and Mississippi (March-May 2010); Barataria Bay, Louisiana (August 2010-December 2011); Mississippi and Alabama (2011, including a high prevalence and number of stranded perinates); and multiple GoM states during early 2013. While the causes of the GoM UME have not been determined, the location and magnitude of dolphin strandings during and the year following the 2010 Deepwater Horizon oil spill, including the Barataria Bay cluster from August 2010 to December 2011, overlap in time and space with locations that received heavy and prolonged oiling. There are, however, multiple known causes of previous GoM dolphin UMEs, including brevetoxicosis and dolphin morbillivirus. Additionally, increased dolphin strandings occurred in northern Louisiana and Mississippi before the Deepwater Horizon oil spill. Identification of spatial, temporal, and demographic clusters within the UME suggest that this mortality event may involve different contributing factors varying by location, time, and bottlenose dolphin populations that will be better discerned by incorporating diagnostic information, including histopathology.     

<Emphasis Type="Italic">Ambrosiella</Emphasis><Emphasis Type="Italic">beaveri,</Emphasis> sp. nov., Associated with an exotic ambrosia beetle, <Emphasis Type="Italic">Xylosandrus mutilatus</Emphasis> (Coleoptera: Curculionidae,Scolytinae), in Mississippi,USA

Xylosandrus mutilatus is an Asian ambrosia beetle that has recently established in Mississippi, Texas, Alabama, and possibly Florida, USA. We investigated the fungi associated with the mycangia (specialized fungus-transporting structures) of X. mutilatus in Mississippi. Mycangia consistently yielded an Ambrosiella sp. which was subsequently found to be closely related to, but distinct from, other Ambrosiella species affiliated with Ceratocystis. This Ambrosiella is described herein as Ambrosiella beaveri sp. nov. Also isolated were Geosmithia lavendula, G. obscura, and a yeast, Candida homelintoma. It is likely Ambrosiella beaveri was introduced along with the beetle into North America.     

Influenza exposure in United States feral swine populations

Swine play an important role in the disease ecology of influenza. Having cellular receptors in common with birds and humans, swine provide opportunities for mixed infections and potential for genetic reassortment between avian, human, and porcine influenza. Feral swine populations are rapidly expanding in both numbers and range and are increasingly coming into contact with waterfowl, humans, and agricultural operations. In this study, over 875 feral swine were sampled from six states across the United States for serologic evidence of exposure to influenza. In Oklahoma, Florida, and Missouri, USA, no seropositive feral swine were detected. Seropositive swine were detected in California, Mississippi, and Texas, USA. Antibody prevalences in these states were 1% in Mississippi, 5% in California, and 14.4% in Texas. All seropositive swine were exposed to H3N2 subtype, the predominant subtype currently circulating in domestic swine. The only exceptions were in San Saba County, Texas, where of the 15 seropositive samples, four were positive for H1N1 and seven for both H1N1 and H3N2. In Texas, there was large geographical and temporal variation in antibody prevalence and no obvious connection to domestic swine operations. No evidence of exposure to avian influenza in feral swine was uncovered. From these results it is apparent that influenza in feral swine poses a risk primarily to swine production operations. However, because feral swine share habitat with waterfowl, prey on and scavenge dead and dying birds, are highly mobile, and are increasingly coming into contact with humans, the potential for these animals to become infected with avian or human influenza in addition to swine influenza is a distinct possibility.     

Regional differences in production of aflatoxin B1 and cyclopiazonic acid by soil isolates of aspergillus flavus along a transect within the United States

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n = 774), which produces sclerotia that are >400 micrometer in diameter, or the S strain (n = 309), which produces numerous small sclerotia that are <400 micrometer in diameter. The S-strain isolates generally produced high levels of aflatoxin B1, whereas the L-strain isolates were more variable in aflatoxin production; variation in cyclopiazonic acid production also was greater in the L strain than in the S strain. There was a positive correlation between aflatoxin B1 production and cyclopiazonic acid production in both strains, although 12% of the L-strain isolates produced only cyclopiazonic acid. Significant differences in production of aflatoxin B1 and cyclopiazonic acid by the L-strain isolates were detected among regions. In the western half of Texas and the peanut-growing region of Georgia and Alabama, 62 to 94% of the isolates produced >10 microgram of aflatoxin B1 per ml. The percentages of isolates producing >10 microgram of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect.     

Apteragia pursglovei sp. n. (Trichostrongyloidea: trichostrongylidae) from the white-tailed deer, Odocoileus virginianus.

Two species of Apteragia were found in white-tailed deer (Odocoileus virginianus) from 152 counties in 13 southeastern states. Specimens previously reported as Skrjabinagia odocoilei were reidentified as belonging to 2 similar species of the genus Apteragia, A. odocoilei, and A. pursglovei sp. n. Apteragia pursglovei sp. n. is differentiated primarily by the length, conformation, and degree of sclerotization of the spicules. Of the 824 deer, A. odocoilei occurred in 76.5%, A. pursglovei in 13.8%, both species in 5.0%, and neither in 4.7%. Reassessment of distribution data revealed that only A. odocoilei was present in deer from 99 counties, only A. pursglovei in deer from 25 counties, and both species in deer from 28 counties. Both A. odocoilei and A. pursglovei were found in Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, and Virginia. Apteragia odocoilei also occurred in Maryland, Tennessee, West Virginia, Texas, Oklahoma, New Jersey, and the Virgin Islands.     

Microsatellites reveal genetic diversity in Rotylenchulus reniformis populations

Rotylenchulus reniformis is the predominant parasitic nematode of cotton in the Mid South area of the United States. Although variable levels of infection and morphological differences have been reported for this nematode, genetic variability has been more elusive. We developed microsatellite-enriched libraries for R. reniformis, produced 1152 clones, assembled 694 contigs, detected 783 simple sequence repeats (SSR) and designed 192 SSR-markers. The markers were tested on six R. reniformis cultures from four states, Texas, Louisiana, Mississippi and Georgia, in the USA. Based on performance we selected 156 SSR markers for R. reniformis from which 88 were polymorphic across the six reniform nematode populations, showing as the most frequent motif the dinucleotide AG. The polymorphic information content of the markers ranged from 0.00 to 0.82, and the percentage of multiallelic loci of the isolates was between 40.9 and 45.1%. An interesting finding in this study was the genetic variability detected among the three Mississippi isolates, for which 22 SSR markers were polymorphic. We also tested the level of infection of these isolates on six cotton genotypes, where significant differences were found between the Texas and Georgia isolates. Coincidentally, 62 polymorphic markers were able to distinguish these two populations. Further studies will be necessary to establish possible connections, if any, between markers and level of pathogenicity of the nematode. The SSR markers developed here will be useful in the assessment of the genetic diversity of this nematode, could assist in management practices for control of reniform nematode, be used in breeding programs for crop resistance, and help in detecting the origin and spread of this nematode in the United States.     

Suppression of Rotylenchulus reniformis 122-cm Deep Endorses Resistance Introgression in Gossypium

Nine sources of resistance to Rotylenchulus reniformis in Gossypium (cotton) were tested by measuring population density (Pf) and root-length density 0 to 122 cm deep. A Pf in the plow layer less than the autumn sample treatment threshold used by consultants was considered the minimum criterion for acceptable resistance, regardless of population density at planting (Pi). Other criteria were ample roots and a Pf lower than on the susceptible control, as in pot studies. In a Texas field in 2001 and 2002, no resistant accessions had Pf less than the control but all did in microplots into which nematodes from Louisiana were introduced. An environmental chamber experiment ruled out nematode genetic variance and implicated unknown soil factors. Pf in field experiments in Louisiana, Mississippi, and Alabama were below threshold for zero, six and four of the accessions and above threshold in the control. Gossypium arboreum A2–87 and G. barbadense GB-713 were the most resistant accessions. Results indicate that cultivars developed from these sources will suppress R. reniformis populations but less than in pots in a single season.     

An AFLP-based survey of genetic diversity among accessions of sea oats (Uniola paniculata, Poaceae) from the southeastern Atlantic and Gulf coast states of the United States

Uniola paniculata, commonly known as sea oats, is a C₄ perennial grass capable of stabilizing sand dunes. It is most abundant along the Gulf of Mexico and southeastern Atlantic coastal regions of the United States. The species exhibits low seed set and low rates of germination and seedling emergence, and so extensive clonal reproduction is achieved through production of rhizomes, which may contribute to a decline in genetic diversity. To date, there has been no systematic assessment of genetic variability and population structure in naturally occurring stands in the USA. This study was conducted to assess the genetic relationship and diversity among nineteen U. paniculata accessions representing eight states: Texas, Louisiana, Mississippi, Alabama, Florida, South Carolina, North Carolina, and Virginia, using amplified fragment length polymorphism (AFLP). Twelve AFLP EcoRI+MseI primer combinations generated a wide range of polymorphisms (42–81%) with a mean of 59%. Overall, the sea oats plants exhibited a low range of genetic similarity. Florida accessions, FL-33 and FL-39, were most genetically diverse and the accessions from both Carolinas and Virginia (NC-1, NC-11, SC-15, and VA-53) harbored less genetic variability. Cluster analysis using the UPGMA approach separated U. paniculata plants into four major clusters which were also confirmed by principal coordinate analysis (PCO). Further examination of the different components of genetic variation by analysis of molecular variance (AMOVA) indicated the largest proportion of variability at the state level (47.8%) followed by the variation due to the differences among the genotypes within an accession (34.4%), and the differences among the accessions within a state (17.8%). The relationship between genetic diversity and geographic source of sea oats populations of the United States as revealed through this comprehensive study will be helpful to resource managers and commercial nurseries in identifying suitable plant materials for restoration of new areas without compromising the adaptation and genetic diversity.