兴安落叶松Ty1-copia型逆转座子逆转录酶序列的克隆及生物信息学分析

为深入了解兴安落叶松的基因组构成及其逆转座子基因的特征,本研究克隆了其逆转座子逆转录酶序列,并进行了生物信息学分析。根据Tyl-copia型逆转座子逆转录酶的保守序列设计简并引物,并利用PCR技术获得了26条逆转座子逆转录酶序列。这些序列去除引物后的核苷酸长度范围为237~251 bp,序列间相似度为55.9%~90.9%,可被分为6个家族。氨基酸预测结果显示,有3条序列存在移框突变,9条序列存在终止密码子突变。系统进化分析显示,所克隆的17条没有发生终止密码子突变的序列分别与处于不同进化阶段的其他植物的Tyl-copia型逆转录酶具有共同的起源。研究结果证实兴安落叶松含有类型丰富的Tyl-copia型逆转座子,可为该物种逆转座子基因资源的开发和利用提供依据。     

毛竹WUSCHEL-related homeobox(WOX)基因家族鉴定及表达分析

WOX基因家族是植物特有的转录因子家族,在干细胞分裂和分化的维持中发挥着关键作用。虽然在模式植物拟南芥和水稻中,WOX基因家族的功能已有深入的研究,但是毛竹Ph WOX基因家族的表达模式和功能仍属未知。本研究系统地分析毛竹Ph WOX基因家族,首先在毛竹基因组数据库进行检索获取毛竹WOX基因家族,鉴定出毛竹基因组编码5个Ph WOX基因。通过遗传进化和基因结构分析,毛竹Ph WOX基因家族分为现代/WUS进化分支和古老进化分支。有趣的是毛竹Ph WOX基因家族在根、茎、叶和笋中广泛表达,并且在竹笋的发育过程中动态表达。本研究首次分析毛竹Ph WOX基因家族的功能,揭示了毛竹Ph WOX基因家族具有独特的进化模式和多样的表达模式,为后续探索毛竹发育的分子机制奠定基础。     

兴安落叶松Ty3-gypsy类逆转座子逆转录酶的多样性分析

为分析兴安落叶松(Larix gmelinii Rupr.)逆转座子的特点及其多样性与系统进化关系,本研究利用兼并-PCR技术克隆了27条Ty3-gypsy型逆转座子逆转录酶基因序列。这些核苷酸序列长度变化范围为376~417 bp,同源性范围为55.9%~91.4%,具有较高的异质性。系统聚类分析发现,这27条核苷酸序列被分为7个组。翻译成氨基酸后,其中有8条序列出现了终止密码子突变,有2条序列出现了移框突变。将其氨基酸序列与已登录的其它物种的Ty3-gypsy型逆转座子逆转录酶进行聚类分析发现,兴安落叶松的Ty3-gypsy型逆转座子与枣、黄瓜、可可树等同类型的逆转座子逆转录酶有较近的亲缘关系。以上研究表明兴安落叶松的逆转座子具有高度的多样性,可为分析兴安落叶松基因组构成及遗传多样性提供实验依据。     

高等植物线粒体基因组进化分析

线粒体是进行呼吸代谢、为生命活动提供能量的细胞器;其基因组相对独立于核基因组,表现为半自主遗传特性。植物线粒体基因组较大,基因组重排、重复序列重组,以及基因获得/缺失/转移/重复等频繁发生,很大程度影响其基因的正常功能行使;同时,也增加了研究其基因功能及其基因组进化的难度。新一代测序技术降低了测序成本,数据库中测序基因组数据激增。其中,也包括大量已获得的植物细胞器——线粒体和叶绿体的基因组序列。本文使用公用数据库的线粒体基因组序列,通过对高等植物线粒体DNA序列、结构、功能基因丢失/迁入、DNA片段水平转移、重复序列及RNA编辑等方面比较分析,试图从某些侧面揭示植物线粒体基因组复杂的进化特征与过程,为解析植物线粒体基因组的进化、探讨细胞质雄性不育机制提供新证据。     

毛竹茎秆快速生长相关基因PeHSD1的功能探究

毛竹是中国最重要的经济竹种,也是世界上生长速度最快的物种之一。研究毛竹快速生长机制对促进林木类植物快速生长的研究有重要意义。本研究通过毛竹全长均一化cDNA文库的筛选得到一个使模式植物拟南芥出现类似抑制生长表型的基因,该基因为11β-羟类固醇脱氢酶家族基因PeHSD1。11β-羟类固醇脱氢酶家族基因是糖皮质激素的代谢酶,是糖皮质激素水平的关键调节器和催化剂。本研究首先对PeHSD1进行了基因结构和遗传进化分析,发现PeHSD1基因与拟南芥同源基因最相近。通过在模式植物拟南芥中过表达这个基因发现过表达植株出现矮小、叶片卷曲等表型。有趣的是毛竹PeHSD1基因在毛竹根、茎、和笋等各个组织中广泛表达,并且在毛竹竹秆快速生长过程中动态表达。本研究首次分析了PeHSD1基因的功能,揭示了毛竹PeHSD1基因具有独特的功能和多样的表达模式,为后续探索毛竹茎秆快速生长的分子机制提供了依据。     

檀香科半寄生植物叶绿体基因组比较与进化分析

檀香科植物具有极高的观赏价值与经济价值,其中大多数为半寄生物种,包括兼性半寄生与专性半寄生类型,在半寄生类植物系统发育研究中具有重要的地位。本研究以檀香科12个半寄生物种叶绿体基因组序列为研究对象,分析其基因组基本特征、基因组比较以及系统进化关系。结果表明：(1)基因组特征分析方面：与典型的被子植物叶绿体基因组相比,檀香科半寄生物种叶绿体基因组略有缩短。檀香科物种密码子偏好性与其他陆生植物一致,密码子第三位更偏好A或T。重复序列和SSR序列鉴定结果表明,槲寄生属物种与其他物种在序列数目和长度上存在差异。(2)基因组比较分析发现,部分檀香科植物IR区域扩张引起了LSC-IR边界改变,IR-SSC区域差异是边界处基因区域倒置的结果。此外,部分蛋白编码基因(ndh, infA, matK,rpl33和ccsA)被假基因化或完全缺失。(3)基于叶绿体全基因组序列构建的系统发育树揭示了檀香科物种之间的进化关系,结果显示檀香科半寄生物种叶绿体基因组可能以谱系特异性方式进化。本研究结果为檀香科种间鉴别、SSR分子标记开发、系统发育和叶绿体基因组进化提供了理论基础。     

华山松叶绿体基因组特征分析

叶绿体基因组凭借稳定的结构、高度保守的序列在植物遗传结构、比较基因组学和系统发育进化等研究中发挥着重要作用。为明确南系华山松叶绿体基因组的大小、结构、基因组成及近缘种的关系和分类地位,本研究以南系华山松为研究对象,采用2×CTAB法提取南系华山松叶绿体基因组DNA,建立测序文库,进行浅层基因组测序、组装、SSR检测、序列对比、共线性分析以及系统发育树构建。结果表明,南系华山松叶绿体基因组全长116 879 bp,GC含量为38.16%。南系华山松叶绿体基因组共编码136个基因。其中,蛋白编码基因77个,tRNA基因55个,rRNA基因4个,具有2～5份拷贝的基因共有14个(均属于tRNA基因),具有1个内含子的基因共有12个。经叶绿体基因组序列比对发现,南系华山松与新疆五针松的相似性最高,达98.852%;与欧洲云杉的相似性最低,仅为57.588%。运用最大似然法基于GTR+F+R2模型构建系统发育树,可将20种松科植物分为4类,其中,南系华山松与北系华山松虽聚为一类,但两者之间的支持率处于较低水平,仅为55%。此外,南系华山松与北系华山松叶绿体基因组序列存在碱基替换和插入缺失,编码基因数量和种类存在异同,说明南北系华山松间叶绿体基因组存在明显差异。本研究可为南系华山松遗传结构和华山松群体遗传研究提供理论依据。     

毛竹β-1,3-葡聚糖酶基因的克隆及序列分析(英文)

β-1,3-葡聚糖酶是一种植物病程相关蛋白,在植物抵御病害中有重要作用。本研究以毛竹为实验材料,利用RACE技术,克隆毛竹β-1,3-葡聚糖酶基因的外显子序列,并在β-1,3-葡聚糖酶基因的编码区两端设计引物,以毛竹基因组DNA为模版扩增该基因的内含子序列。序列结果表明,该基因全长1693bp,包含两个外显子和一个内含子,命名为PheGLU(GenBank登录号GU238236)。该基因包含1个996bp的开放阅读框,编码332个氨基酸,相对分子质量为3.541×104Da,其等电点pI为6.389,是一个酸性蛋白且分泌到胞外;其中,该蛋白的二级结构中包含35.15%的α-螺旋,21.82%的β-转角,43.03%的延伸链和无规则卷曲等;三级结构同源建模预测显示,它与大麦β-1,3-葡聚糖酶(PDB number:1ghsA)具有80.4%的同源性;聚类分析显示,该基因序列与已报道的其它植物具有较的高氨基酸序列同源性。本研究为进一步鉴定毛竹β-1,3-葡聚糖酶基因的抗真菌病害能力奠定了基础。     

串联重复序列在玉米基因组中的特征及分布

串联重复序列(tandem repeats, TRs)在玉米基因组中广泛存在,对维持染色体结构和调节基因表达起到重要作用。从Phytozome (http://www.phytozome.net/)下载玉米全基因组序列和基因注解(Gene annotation)数据,然后使用串联重复序列分析工具(Phobos)检测TRs的密度变化、模体类型及其在基因内与基因间的位置分布情况。研究表明,5'UTR和启动子中的TRs密度最高,内含子(Intron)和编码区(CDS)中TRs密度相对较低。同时TRs主要分布于CDS两端,这可能与内含子剪接有关;在基因间隔区,串联重复序列的分布明显偏向于靠近基因。本研究对串联重复序列在植物基因组中的特征及作用及有借鉴作用。     

CITES监管植物习志野叶绿体基因组结构特征及系统发育分析

利用二代测序技术Illumina平台对CITES附录监管物种习志野(Tephrocactus geometricus)进行叶绿体全基因组测序与组装,并对其基因组结构特征及系统进化关系进行分析。结果表明,习志野叶绿体基因组具备典型的环状四分体结构,全长116 183 bp,包含72个蛋白编码基因、6个rRNA基因和30个tRNA基因。习志野叶绿体基因组共编码16 119个密码子,编码亮氨酸(Leu)的最多;共发现微卫星位点259个,其中最多的是单核苷酸重复序列186个。采用ML法构建系统进化树,习志野与巨人柱属的巨人柱(Carnegiea gigantea)亲缘关系最近。本研究为习志野的分子标记开发、系统发育关系研究、叶绿体转化技术、濒危机制的解析等提供了基础数据参考,同时也丰富了仙人掌科植物的叶绿体基因组遗传信息。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...