植物耐热相关基因研究进展

植物受到高温胁迫时,会激活某些特定基因的表达,从而增强植物的耐热性。近年来,随着生物技术的不断发展,植物耐热相关基因被相继克隆并转化植物体。本文对植物耐热的分子机制、相关基因的克隆、耐热性基因工程研究进展进行了综述,并提出了植物耐热基因工程的研究方向。     

丹参的生物技术

本文综述了丹参的生物技术,包括离体培养克隆增殖丹参试管苗、人工诱导丹参多倍体、利用丹参细胞培养生产活性成分以及农杆菌转化丹参获得再生植物、利用转化的组织和器官培养生产丹参中的活性成分等.     

生物技术用于黄瓜遗传育种

“十五”期间,生物技术在黄瓜遗传育种上的应用更加广泛,分子标记辅助育种、单倍体育种以及黄瓜基因工程改良取得了重要进展。本文综述了黄瓜基因分子标记、遗传图谱构建、基因定位、基因克隆与表达、品种DNA指纹图谱分析、分子技术鉴定病害、单倍体和三倍体培养、遗传转化体系建立及基因工程改良方面的最新进展,并讨论了存在的问题和前景。     

甘薯生物技术研究进展

新兴的生物技术为甘薯这一古老的农作物带来了新的发展契机。细胞大规模培养、体细胞融合、基因转导等技术的研究和应用 ,可望从根本上改变甘薯传统的生产和育种模式。本文综合近年来国内外甘薯体细胞胚胎发生、原生质体培养和基因工程等方面的研究进展 ,对影响甘薯体胚发生体系及原生质体再生体系建立的诸多因素进行了详细论述 ,讨论了甘薯基因工程研究的应用潜力和目前存在的一些问题。     

无核荔枝果实形成差异表达基因cDNA的克隆

采用抑制差减杂交技术(Suppression Subtractive Hybridization,SSH)分离与海南无核荔枝果实形成相关的差异表达基因的cDNA片段,为克隆相关基因提供研究基础。分别以无核荔枝的有核幼果为driver;无核幼果为tester,建立差减cDNA文库。经Reverse Northern Dot-Blot筛选该文库,共获得61个阳性克隆,随机选取17个克隆进行测序,共获得10条非重复序列,对其中较长的7个序列进行同源分析,结果表明:有6个序列在荔枝中为首次报道。     

甘薯生物技术研究进展

新兴的生物技术为甘薯这一古老的农作物带来了新的发展契机。细胞大规模培养、体细胞融合、基因转导等技术的研究和应用,可望从根本上改变甘薯传统的生产和育种模式。本文综合近年来国内外甘薯体细胞胚胎发生、原生质体培养和基因工程等方面的研究进展,对影响甘薯体胚发生体系及原生质体再生体系建立的诸多因素进行了详细论述,讨论了甘薯基因工程研究的应用潜力和目前存在的一些问题。     

枯草杆菌克隆体系的研究

为了重组基因能良好地表达,需要发展多种克隆体系。本文综述了枯草杆菌作为克隆载体的优点,枯草杆菌中天然质粒的筛选,异源质粒的引入,一系列重组质粒的构建,噬菌体载体的发展,DNA分子与转化的关系,原生质体的转化及外源基因在枯草杆菌体系中的表达等方面的研究概况。     

枯草杆菌克隆体系的研究

为了重组基因能良好地表达,需要发展多种克隆体系。本文综述了枯草杆菌作为克隆载体的优点,枯草杆菌中天然质粒的筛选,异源质粒的引入,一系列重组质粒的构建,噬菌体载体的发展,DNA分子与转化的关系,原生质体的转化及外源基因在枯草杆菌体系中的表达等方面的研究概况。     

利用生物技术生产紫杉醇的研究进展

概述了利用植物细胞大量培养,发挥农杆菌转化的发根培养,产紫杉醇真菌培养及基因工程等生物技术生产抗癌新药紫杉醇的研究现状,并对各种途径的应用前景进行展望。     

荔枝生物技术研究进展（综述）

从荔枝的组织培养、花药培养和原生质体培养方面综述荔枝生物技术的研究概况,并提出该领域存在问题及发展方向。     

荔枝和龙眼遗传转化体系研究进展(综述)

综述近年来利用荔枝、龙眼不同品种和类型的外植体进行组织培养及植株再生取得的新成果,同时对建立荔枝、龙眼遗传转化体系的研究新进展进行了报道,并对其研究前景作以分析及展望。     

桂西南早熟荔枝实生资源遗传多样性的ISSR分析

利用ISSR标记技术对83份早熟荔枝(品种)单株遗传多样性进行分析。筛选出多态性高的10条IS-SR引物,共扩增出128条DNA条带,其中多态性带107条,多态性百分率为83.59%,表明桂西南早熟荔枝实生资源遗传多样性较丰富;用NTSYS软件计算出这83份材料的DICE相似系数在0.64～0.95之间,遗传亲缘关系较近;用UPGMA方法构建分子树状图,在相似系数0.75时,可将栽培品种与桂西南早熟实生单株区分开。各地区资源混杂聚类在一起,不能按地区单独聚类。     

Identifying Litchi (Litchi chinensis Sonn.) Cultivars and Their Genetic Relationships Using Single Nucleotide Polymorphism (SNP) Markers

Litchi is an important fruit tree in tropical and subtropical areas of the world. However, there is widespread confusion regarding litchi cultivar nomenclature and detailed information of genetic relationships among litchi germplasm is unclear. In the present study, the potential of single nucleotide polymorphism (SNP) for the identification of 96 representative litchi accessions and their genetic relationships in China was evaluated using 155 SNPs that were evenly spaced across litchi genome. Ninety SNPs with minor allele frequencies above 0.05 and a good genotyping success rate were used for further analysis. A relatively high level of genetic variation was observed among litchi accessions, as quantified by the expected heterozygosity (He = 0.305). The SNP based multilocus matching identified two synonymous groups, ‘Heiye’ and ‘Wuye’, and ‘Chengtuo’ and ‘Baitangli 1’. A subset of 14 SNPs was sufficient to distinguish all the non-redundant litchi genotypes, and these SNPs were proven to be highly stable by repeated analyses of a selected group of cultivars. Unweighted pair-group method of arithmetic averages (UPGMA) cluster analysis divided the litchi accessions analyzed into four main groups, which corresponded to the traits of extremely early-maturing, early-maturing, middle-maturing, and late-maturing, indicating that the fruit maturation period should be considered as the primary criterion for litchi taxonomy. Two subpopulations were detected among litchi accessions by STRUCTURE analysis, and accessions with extremely early- and late-maturing traits showed membership coefficients above 0.99 for Cluster 1 and Cluster 2, respectively. Accessions with early- and middle-maturing traits were identified as admixture forms with varying levels of membership shared between the two clusters, indicating their hybrid origin during litchi domestication. The results of this study will benefit litchi germplasm conservation programs and facilitate maximum genetic gains in litchi breeding programs.     

Genetic variation of wild litchi (<Emphasis Type="Italic">Litchi chinensis</Emphasis> Sonn. subsp. <Emphasis Type="Italic">chinensis</Emphasis>) revealed by microsatellites

Understanding the amount and distribution of genetic diversity in natural populations can inform the conservation strategy for the species in question. In this study, genetic variation at eight nuclear microsatellite loci was used to investigate genetic diversity and population structure of wild litchi (Litchi chinensis Sonn. subsp. chinensis). Totally 215 individuals were sampled, representing nine populations of wild litchi. All eight loci were polymorphic, with a total of 51 alleles. The expected heterozygosity in the nine populations ranged from 0.367 to 0.638 with an average value of 0.526. Inbreeding within wild litchi populations was indicated by a strong heterozygote defect. Significant bottleneck events were detected in the populations from Yunnan and Vietnam, which could be responsible for lower levels of genetic diversity in these populations. Measures of genetic differentiation (F _ST = 0.269) indicated strong differentiation among wild litchi populations. Significant correlation was found between genetic differentiation and geographical distance (r = 0.655, P = 0.002), indicating a strong isolation by distance in these populations. Bayesian clustering suggested genetic separation among three regional groups, namely, the western group, the central group and the eastern group. Some conservation strategies for wild litchi populations were also proposed based on our results.     

荔枝胚败育过程中内源激素与蛋白质含量的变化

连续3年(1999-2001年)对典型的荔枝焦核品种桂味、糯米糍和大核品种黑叶、怀枝花后10-40d的幼胚和胚乳内源激素、多酚含量及蛋白质动态变化进行研究。结果表明,焦核品种幼胚及胚乳中的IAA、GAs和ABA含量低于大核品种;多酚类物质含量在胚中低于大核品种,胚乳中则高于大核品种;胚和胚乳中的蛋白质含量均低于大核品种。蛋白质电泳结果显示,22．5、28．5和45kD这3类蛋白质在怀枝和黑叶的胚蛋白质代谢过程中表现出较高的稳定性,桂味和糯米糍胚蛋白质中的28．5kD蛋白质也有相似的特性。     

荔枝与龙眼种质资源研究进展

荔枝和龙眼是中国著名的南亚热带果树。本文分别就荔枝、龙眼种质资源在起源与分布、分类与鉴定等方面取得的研究进展进行了综述。荔枝和龙眼的分类研究大体经历了3个阶段:根据形态特征进行分类、应用同工酶分析和DNA分子标记进行分类。形态特征常常受到环境条件的影响,而同工酶分析可以检测到的多态性位点十分有限。应用分子标记研究荔枝、龙眼种质资源的遗传多样性克服了前述2种研究方法的不足。目前,荔枝和龙眼的品种选育仍然以实生选种和芽变选种为主。为了实现对荔枝、龙眼果实品质和农艺性状的改良,建议在分子水平上进一步深入地探讨荔枝、龙眼种质资源的遗传多样性;同时通过应用分子标记辅助选择技术提高荔枝和龙眼杂交育种的效率。     

利用RAPD技术鉴定海南荔枝品种光明

应用RAPD标记对6份无性系材料进行检验,20个引物对6份材料均扩增出完全相同的125条带,不具多态性,证明6份材料遗传基础高度相似。利用30个引物对光明和其他42份材料的基因组进行多态性分析,多态性位点为212个,占总数的80、83％,显示多态性较高。光明和其他荔枝品种间的相似系数均较高,与大丁香的相似系数（0．884）最高。在相似系数0．78水平上,可将供试材料分成4大类,这些类型与成熟期有一定相关,光明属于第3类。光明不具特征谱带,但可用少数引物组合将其和很多品种区别开,如利用AP09、AM16和AK17即可将光明从其他荔枝材料中鉴别出来。     

龙眼和荔枝卷叶蛾类种群动态及其群落结构

调查结果显示,在广西南宁市和崇左市的部分龙眼和荔枝园中,危害龙眼和荔枝的卷叶蛾类有3科20种,其中龙眼园的卷叶蛾类有3科16种,荔枝园有2科17种,2类果园发生的种类有所不同。20种中,9种过去尚未见报道。龙眼园和荔枝园卷叶蛾类群落结构的均匀度指数较低,分别为0.298 2和0.406 3,说明在群落中有某种卷叶蛾的种群数量相当大,各种类数量分布不均一,有某个种群数量相当大。2类果园卷叶蛾类群落的多样性相比,荔枝园要高于龙眼园。龙眼园卷叶蛾类的优势种为三角新小卷蛾Olethreutes leucaspisMeyrick(优势度指数d=0.813 2),荔枝园分别为三角新小卷蛾(d=0.722 6)和灰白条小卷蛾Dudua aprobola(Meyrick)(d=0.102 8)。2类果园种群数量较大的种类均为三角新小卷蛾、灰白条小卷蛾和圆角卷蛾Ebodo cellerigeraMeyrick。各月份卷叶蛾类发生的总数量均以龙眼园高于荔枝园。     

基于叶片解剖特征分析三种无患子科果树的亲缘关系

采用石蜡切片和组织离析法,对3种无患子科果树的10份种质叶片横切及表皮解剖特征进行观察,并采用聚类分析对其亲缘关系进行初步研究。结果表明：10份试材均为异面叶,叶横切结构分为表皮、叶肉和叶脉3部分。中脉厚度总体上龙眼最大、龙荔次之、荔枝最小,差异显著。荔枝的中脉横切面为圆三角形,龙眼近似半圆形,龙荔则近似扁圆形。不同试材的叶片、上表皮和下表皮、栅栏组织及海绵组织的厚度分别为175.23~318.84、11.18~25.13、7.49~20.43、50.01~124.59和84.0~173.64μm,栅栏组织细胞有2~3层。此外,叶脉突起度、栅栏组织与海绵组织厚度之比、叶片组织结构紧密度和叶片组织结构疏松度分别为2.65~5.77、0.52~0.82、28.89％~39.95％和44.89％~55.57％。荔枝的表皮细胞较小、多边形,垂周壁为弧形,下表皮无表皮毛,气孔器呈长椭圆形;龙眼的表皮细胞较大、不规则形,垂周壁深波状,下表皮具表皮毛,气孔椭圆形或近圆形;龙荔的表皮细胞与龙眼相近,但垂周壁为波状。聚类分析显示,10份试材首先聚为两大类,其中第一类是荔枝属,第二类是龙眼属;然后又分为4个亚类,三月红和龙荔各自单独聚为一个亚类。     

Bacterial cellulose production from the litchi extract by Gluconacetobacter xylinus

Although litchi has both nutrient and edible value, the extremely short preservation time limited its further market promotion. To explore processed litchi products with longer preservation time, litchi extract was selected as an alternative feedstock for production of bacterial cellulose (BC). After 2 weeks of static fermentation, 2.53 g/L of the BC membrane was obtained. The trace elements including magnesium (Mg) and sodium (Na) in the litchi extract were partly absorbed in the BC membrane, but no potassium (K) element was detected in it, curiously. Scanning electron microscope (SEM) photographs exhibited an ultrafine network nanostructure for the BC produced in the litchi extract. Analysis of the fourier-transform infrared spectroscopy (FTIR) confirmed the pellicles to be a cellulosic material. Interestingly, X-ray diffraction (XRD) results showed the BC membrane obtained from litchi extract had higher crystallinity of 94.0% than that from HS medium. Overall, the work showed the potential of producing high value-added polymer from litchi resources.