Allozyme Diversity and Population Structure in Korean Populations of Cymbidium goeringii (Orchidaceae)

Cymbidium goeringii (Orchidaceae). Mean observed population heterozygosity (H _op=0.181), expected heterozygosity (H _eP=0.240), and total genetic diversity (H _T =0.351) were all higher than average values for species with similar life-history characteristics. A considerable deficit of heterozygotes relative to Hardy–Weinberg expectations was detected (77% of fixation indices were positive) with a mean F _IS of 0.278. On average, 90% of the total genetic diversity was found within populations (mean G _ST = 0.098). An indirect estimate of the number of migrants per generation (Nm=2.30, calculated from G _ST , Nm=8.48, calculated from the frequencies of unique alleles) indicated that gene flow has been extensive in C. goeringii. Results of a spatial autocorrelation analysis based on allele frequencies of 16 populations revealed a trend with respect to the distance classes (0<63 km, six significant positive values; beyond that distance, 12 significant negative values). It is highly probable that C. goeringii has a history of relative large, continuous populations that had greater chance for gene movement among adjacent populations via large numbers of small seeds, following the last Ice Age. Factors contributing to the high levels of genetic diversity found within populations of C. goeringii include its large and continuous populations, its long-lived perennial habit, its widespread geographical distribution, and its ability for relatively long distance seed movement by wind. Received 18 June 1998/ Accepted in revised form 18 November 1998     

杂交兰ChCAO基因的克隆及其在叶艺品系中的表达特征

【目的】叶绿素酸酯a加氧酶（CAO）是叶绿素b形成过程中的关键酶,为探究CAO基因在杂交兰叶艺形成中的调控作用,并为进一步研究杂交兰叶艺形成机理提供重要依据。【方法】该研究以杂交兰‘紫妍氏’（K21）及其叶艺品系‘中透紫妍氏’（K21-3）为试验材料,运用RT-PCR和RACE技术从叶片中克隆获得ChCAO基因;对ChCAO进行结构特征、理化性质、序列比对以及系统进化关系等分析;并利用qRT-PCR法对ChCAO在不同组织及叶艺品系叶片中的表达特性进行分析。【结果】结果表明,ChCAO基因编码区长1 608 bp,编码535个氨基酸,ChCAO与墨兰CAO亲缘关系最近,并与其他兰科植物CAO聚为一类。qRT-PCR结果显示,ChCAO基因表达具有组织特异性,在叶中相对表达量最高,根中相对表达量最低;此外,ChCAO在K21绿叶和K21-3绿叶区域叶片中的相对表达量显著高于K21-3叶艺区域叶片中的相对表达量。构建该基因的VIGS沉默载体转化烟草,发现沉默ChCAO后烟草叶片呈黄化状态,叶片中的叶绿素含量及ChCAO基因的相对表达量也显著降低,由此推测ChCAO基因的沉默表达可能导致叶绿素含量降低,叶片黄化,初步明确了杂交兰ChCAO基因的功能。     

大花蕙兰多倍体的高效诱导

以大花蕙兰‘红瀑布’无菌苗丛芽为材料、秋水仙素为诱变剂,采用不同的处理浓度、时间诱导大花蕙兰体细胞加倍。通过形态学和细胞学观察、统计等方法对其进行倍性鉴定。结果表明：秋水仙素浓度0.05%,处理时间24 h的条件下,诱导率高达28.2%;多倍体苗外部形态、叶绿体数目、气孔数目和大小与二倍体差异大,加倍后的细胞核明显变大,染色体倍数增加。     

墨兰花朵发育和衰老生理的初步研究

目的：了解墨兰花朵的发育和衰老生理,为控制黑兰花期提供科学依据。方法：测定不同发育期的墨兰花瓣的干重／鲜重、呼吸速率、过氧化物酶活性及可溶性糖含量。结果：黑兰花朵在由花蕾发育到衰老的过程中,上述指标呈现出一定的变化规律。     

蕙兰病株根部内生细菌种群变化

为了研究褐斑病与蕙兰根部内生细菌群落结构和多样性的关联,从野生蕙兰健株和褐斑病株根部分离出内生细菌112株,采用核糖体DNA扩增片段限制性酶切分析(ARDRA),研究了健株和病株内生细菌多样性与群落结构。将内生细菌纯培养物扩增近全长的16S rDNA,并用ARDRA (Amplified Ribosomal DNA Restriction Analysis) 对所分离的菌株进行分型,根据酶切图谱的差异,将健株中的内生细菌分成8个ARDRA型,病株分成13个ARDRA型。并选取代表性菌株进行16S rDNA序列测定。结果表明,健株分离出内生细菌6个属,优势菌群为Bacillus;病株分离出11个属,优势菌群为 Mitsuaria和Flavobacterium。通过回接兰花植物和初步拮抗实验发现,从病株分离出的H5号菌株 (Flavobacterium resistens)使兰花产生病症,而健株中的B02 (Bacillus cereus) 和B22号菌株 (Burkholderia stabilis) 对菌株H5有拮抗作用。     

气候变暖背景下春兰和蕙兰的适生区分布预测

为了阐明气候变暖背景下春兰(Cymbidium goeringii)和蕙兰(C. faberi)在我国的适生区分布变化情况,根据157条分布记录和19个生物气候变量,应用最大熵物种分布模型,对2070年4种温室气体排放情景下春兰和蕙兰在我国的适生区分布进行预测,并筛选影响其地理分布的主要气候因子。结果表明:(1)2070年春兰和蕙兰分布点的年均温(bio1)、最冷月最低温度(bio6)和最冷季平均温度(bio11)等均升高,气候有变暖趋势;(2)受试者工作特征曲线下面积(AUC)值在0.9—1.0之间,模型预测结果可信度较高;(3)影响春兰、蕙兰当前和2070年地理分布的限制性气候因子主要有最冷月最低温度(bio6)、最冷季平均温度(bio11)、年均降水量(bio12)和最干月份降水量(bio14);(4)气候变暖将会对春兰和蕙兰的适宜生境范围和面积产生影响。预测2070年春兰的适宜生境面积将会有所减小,而蕙兰的适宜生境面积将会增加,且整体有向北迁移的趋势。研究结果为野生春兰和蕙兰的生态风险评价和引种提供了重要依据。     

大花蕙兰生产中常见病虫害及其防治措施

本文介绍大花蕙兰生产中常见病害(疫病、软腐病、根腐病、炭疽病、叶枯病、毒素病等)和虫害(介壳虫类、粉虱、螨虫类、蚜虫、蟑螂等)的为害特征及防治方法。     

La3+对墨兰根状茎某些细胞器发育的影响

以１／２ＭＳ＋ＢＡ（１ｍｇＬ－１）＋ＮＡＡ（１ｍｇＬ－１）＋Ｌａ３＋（１０ｍｇＬ－１）培养墨兰根状茎３０ｄ后,取样观察根状茎细胞叶绿体、线粒体和细胞核的发育特点并与对照进行比较,发现：①处理组叶绿体发育较快,有较丰富的片层结构和嗜锇颗粒,而对照组的发育慢,含大型的淀粉粒,无明显的片层结构．②处理组线粒体体积较大,内含物较丰富,而对照组的较小,内含物较少。③处理组细胞核内的染色质较对照组丰富．上述结果表明,ｔａ３＋对墨兰根状茎细胞器的发育有一定的调节作用。     

CygoSTK基因在普通春兰与奇花品种‘天彭牡丹''中的表达比较

为深入研究春兰(Cymbidium goeringii)与春兰奇花品种花器官发育调控的分子机制,该研究采用同源克隆的方法,分别从普通的春兰与春兰奇花品种‘天彭牡丹’的花芽中克隆得到1个cDNA长849 bp D类MADS-box基因CygoSTK(Genbank登录号为MH917912.1)。结果表明:该基因序列在两种春兰中高度一致,包含1个长705 bp的完整ORF,编码1个由234个氨基酸残基组成的STK进化系MADS-box转录因子;结构分析表明,CygoSTK转录因子包含1个高度保守的MADS结构域(MADS domain)(1～57)和1个次级保守的K结构域(91～172),其C末端的转录激活区含有两个高度保守的基序,即AGI基序和AGⅡ基序;进一步用qPCR检测CygoSTK基因在普通的春兰与春兰奇花品种‘天彭牡丹’不同花器官中的相对表达量发现,CygoSTK基因在普通的春兰和春兰‘天彭牡丹’子房中的表达量最高,显著高于该基因在相应品种其他花器官中的表达量(LSD,P0.05)。以上结果说明CygoSTK基因在功能上有很强的保守性,主要参与春兰子房的发育。     

Argonaute 5 family proteins play crucial roles in the defence against Cymbidium mosaic virus and Odontoglossum ringspot virus in Phalaenopsis aphrodite subsp. formosana

The orchid industry faces severe threats from diseases caused by viruses. Argonaute proteins (AGOs) have been shown to be the major components in the antiviral defence systems through RNA silencing in many model plants. However, the roles of AGOs in orchids against viral infections have not been analysed comprehensively. In this study, Phalaenopsis aphrodite subsp. formosana was chosen as the representative to analyse the AGOs (PaAGOs) involved in the defence against two major viruses of orchids, Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). A total of 11 PaAGOs were identified from the expression profile analyses of these PaAGOs in P. aphrodite subsp. formosana singly or doubly infected with CymMV and/or ORSV. PaAGO5b was found to be the only one highly induced. Results from overexpression of individual PaAGO5 family genes revealed that PaAGO5a and PaAGO5b play central roles in the antiviral defence mechanisms of P. aphrodite subsp. formosana. Furthermore, a virus-induced gene silencing vector based on Foxtail mosaic virus was developed to corroborate the function of PaAGO5s. The results confirmed their importance in the defences against CymMV and ORSV. Our findings may provide useful information for the breeding of traits for resistance or tolerance to CymMV or ORSV infections in Phalaenopsis orchids.