贵州几种常见杜鹃花的随机扩增多态性DNA(RAPD)研究

采用RAPD方法对贵州7个常见杜鹃花基因型进行分析,建立了它们的指纹图谱。从60个随机引物中筛选出的10个有效引物共产生49条DNA片段,大小分布在0．1～3．0kh之间,其中28个条带具有遗传多态性,约占总数的57．14％,平均每个引物扩增的DNA带数为4．9条。7个杜鹃花的遗传相似性分析表明,各基因型之间的J相似性系数分布在0．63～0．90之间．平均相似性系数为0．765。应用NTSYSpc软件进行聚类．将聚类结果转化为7个杜鹃花基因型之间的遗传关系树型图。7个杜鹃花基因型明显地聚成A、B两大类,A类包括：1号(锈叶杜鹃)、6号(红花露珠杜鹃)和7号(露珠杜鹃)3个基因型;B类包括：2号(大白杜鹃)、4号(杜鹃)、5号(红马缨杜鹃)和3号(桃叶杜鹃)4个基因型。     

结合分子手段和形态分析验证大白杜鹃与马缨杜鹃的自然杂交

中国西南地区是世界杜鹃属(Rhododendron)植物的分布和分化中心,开展杜鹃属自然杂交研究可为分类修订和新品种选育提供依据。本文以贵州百里杜鹃自然保护区(百里保护区)和云南石宝山分布的大白杜鹃(Rhododendron decorum)、马缨杜鹃(R.delavayi)及两种间疑似自然杂交后代和人工杂交后代个体为研究材料,通过形态特征比较、核基因间隔序列ITS以及叶绿体基因片段trnL-trn F、rbcL和trnH-psb A测序特征分析,发现疑似自然杂交后代与人工杂交后代形态特征介于大白杜鹃与马缨杜鹃之间;4个DNA片段序列均能区分大白杜鹃和马缨杜鹃,同一物种的不同居群在叶绿体基因片段rbcL、trnH-psb A序列存在差异位点;所有人工杂交后代个体和1个石宝山疑似杂交个体均以大白杜鹃为母本,所有百里保护区疑似杂交个体和6个石宝山疑似杂交个体以马缨杜鹃为母本。本研究证实了大白杜鹃与马缨杜鹃在百里保护区和云南石宝山存在自然杂交现象,杂交为双向且自然杂交后代绝大多数以马缨杜鹃为母本。     

探讨种间传粉在杜鹃花属自然杂交物种形成中的作用

自然杂交是物种形成的一个途径, 在植物进化中起着重要的作用。自然杂交主要通过种间的基因交流, 花粉传递则是基因交流的主要途径。马缨花(Rhododendron delavayi)、大白花杜鹃(R. decorum)、迷人杜鹃(R. agastum)和露珠杜鹃(R. irroratum)是在云南广泛分布的杜鹃花种类, 马缨花与大白花杜鹃形态上区别明显, 而它们的可能杂交种迷人杜鹃和露珠杜鹃在形态上基本介于二者之间。本文对这4种杜鹃花的开花物候和访花昆虫的种类进行了观察,并进行了其繁育系统和种子萌发的实验。我们发现马缨花的花期从3月初至5月底, 迷人杜鹃与露珠杜鹃花期基本一致, 为3月初至4月初, 二者同大白花杜鹃基本不存在花期重叠, 大白花杜鹃的花期为4月中旬至5月底。4种杜鹃花的开花期不同年份稍有变化, 其单花开花周期都在一周以上。4种杜鹃花的传粉昆虫虽然种类和数量上有所不同, 但都以膜翅目和双翅目昆虫为主, 中华蜜蜂(Apis cerana cerana)是其共有的传粉昆虫。繁育系统研究发现, 除露珠杜鹃外, 其余3种自花不育, 而种间杂交不存在任何生殖障碍, 可以产生萌发率很高的种子。通过分析4种杜鹃花开花物候重叠、共有传粉昆虫及种间杂交可育等现象, 探讨了传粉昆虫和异花授粉的机制在自然杂交物种形成中的作用及杂交种的适应能力。     

基于ITS序列探讨杜鹃花属马银花组的系统发育

以杜鹃花属叶状苞亚属Rhododendron　subg. Therorhodion (Maxim.) Gray 的叶状苞杜鹃R. redowskianum Maxim.为外类群,使用PAUP4.0b8软件对马银花亚属sub g. Azaleastrum Planch.的马银花组sect. Azaleastrum (Planch.) Maxim. 7种1 变种和长蕊杜鹃组sect. Choniastrum Planch. 2种及2个相关的单型亚属（异蕊杜鹃 亚属subg. Mumeazalea Max     

盐碱胁迫对4种杜鹃属植物种子萌发和幼苗生长的影响

为研究杜鹃属植物的耐盐耐碱性及筛选耐盐耐碱种,在组培条件下观测不同浓度NaCl、NaHCO3处理下对马银花(Rhododendron ovatum)、满山红(R.mariesii)、映山红(R.simsii)和云锦杜鹃(R.fortunei)种子萌发和幼苗生长的影响.研究结果表明:盐、碱胁迫对杜鹃花种子萌发和幼苗生长有...     

不同生境三种杜鹃属植物花特征比较

生境影响植物花部特征的分化.为探究不同人为干扰强度生境是否影响杜鹃花特征分化和资源分配,以及不同颜色杜鹃花分布情况,该研究以百里杜鹃保护区高、中、低人为干扰强度生境的马缨杜鹃、迷人杜鹃和露珠杜鹃为实验材料,采用五点取样法统计不同生境杜鹃花的植株数量,游标卡尺测量花部特征,光学显微镜统计花粉数,海洋光谱仪测定花色的反射光...     

基于ITS序列探讨杜鹃属的亚属和组间系统关系

首次报道了 15种杜鹃属 (Rhododendron)植物、1种杜香属 (Ledum)植物和Cassiopefastigiata的内转录间隔区(ITS) (包括 5 .8S)序列。加上从GenBank下载的 13种杜鹃属植物和Bajiariaracemosa的ITS序列 ,以C .fastigiata和B .racemosa为外类群 ,用最大简约法对杜鹃属的亚属和组间的系统关系进行了分析。结果表明 :1)杜鹃属是一个单系类群 ,叶状苞亚属为杜鹃属的基部类群 ;2 )杜香属确应归并到杜鹃属中 ,且与有鳞杜鹃亚属有较近的亲缘关系 ;3)有鳞杜鹃亚属和杜香构成一个单系分支 ,该分支是其余无鳞杜鹃花的姐妹群 ;4 )由无鳞杜鹃花组成的一个分支的内部支持率较低 ,其中常绿杜鹃亚属和映山红亚属均为内部支持率很高的单系类群 ,而羊踯躅亚属和马银花亚属均为多系类群 ;5 )在马银花亚属中 ,长蕊杜鹃组和马银花组均分别得到强烈支持 ,马银花组与异蕊杜鹃亚属可能构成姐妹群关系 ,异蕊杜鹃亚属和马银花组组成的一个分支可能与映山红亚属构成姐妹群关系。     

基于ITS序列探讨杜鹃属的亚属和组间系统关系

首次报道了15种杜鹃属(Rhododendron)植物、1种杜香属(Ledum)植物和Cassiope fastigiata的内转录间隔区(ITS) (包括5.8S)序列.加上从GenBank下载的13种杜鹃属植物和Bajiaria racemosa的ITS序列,以C. fastigiata和B. racemosa为外类群,用最大简约法对杜鹃属的亚属和组间的系统关系进行了分析.结果表明: 1)杜鹃属是一个单系类群,叶状苞亚属为杜鹃属的基部类群; 2)杜香属确应归并到杜鹃属中,且与有鳞杜鹃亚属有较近的亲缘关系; 3)有鳞杜鹃亚属和杜香构成一个单系分支,该分支是其余无鳞杜鹃花的姐妹群; 4)由无鳞杜鹃花组成的一个分支的内部支持率较低,其中常绿杜鹃亚属和映山红亚属均为内部支持率很高的单系类群,而羊踯躅亚属和马银花亚属均为多系类群; 5)在马银花亚属中,长蕊杜鹃组和马银花组均分别得到强烈支持,马银花组与异蕊杜鹃亚属可能构成姐妹群关系,异蕊杜鹃亚属和马银花组组成的一个分支可能与映山红亚属构成姐妹群关系.     

果皮和种皮微形态特征在杜鹃花属系统学研究中的应用

采用扫描电子显微镜对国产杜鹃花属Rhododendron6个亚属的代表种和近缘类群杜香属Ledum杜香L.palustre的果皮和种皮微形态特征进行观察,对杜鹃花属植物果皮微形态特征进行了系统描述,并通过比较现存杜鹃花属植物和种子化石,新发现一些居间的种子类型。结果表明,果皮和种皮微形态特征具有一定的系统学意义。叶状苞亚属subgen.Therorhodion的叶状苞杜鹃R.redowskianum的果实有短而疏的刺毛,无气孔,种子为无翅类,扁平,外围轮廓长椭圆形。杜鹃亚属subgen.Rhododendron植物果皮为百合花杜鹃型,具有鳞片,气孔器散生于指状突起之间,与叶表皮的微形态特征一致,其种子为百合花杜鹃型,表面具宽而浅的沟,呈脑纹状,有别于无鳞类杜鹃花。常绿杜鹃亚属subgen.Hymenanthes果皮为云锦杜鹃型,其角质层表面不规则,无表皮毛,偶见气孔;种子为云锦杜鹃型。映山红亚属subgen.Tsutsusi果皮为岭南杜鹃型,密生长表皮毛,角质层致密;种子为南边杜鹃型和岭南杜鹃型。微形态特征与“常绿杜鹃亚属和(国产)映山红亚属均为内部支持率很高的单系类群”的分子系统发育研究结果一致。马银花亚属subgen.Azaleastrum的马银花组sect.Azaleastrum和长蕊杜鹃组sect.Choniastrum微形态区别明显,支持各自为独立的单系类群。羊踯躅亚属subgen.Pentanthera的羊踯躅R.molle果皮特征明显,可与其他亚属区分,但种子类型更接近常绿杜鹃亚属。本研究结合分子系统发育资料和叶表皮微形态特征讨论了一些近缘类群的系统发育关系;研究结果支持将腺萼马银花处理为独立的种。     

GA3浸种处理对五种晚花杜鹃种子萌发的影响

晚花杜鹃(late flower Rhododendron)是一类花期较晚的杜鹃品种,具有较高的观赏价值,被广泛应用于庭院种植和园林绿化。随着旅游以及经济发展的需要,开发和利用晚花杜鹃资源显得非常迫切。自然条件下晚花杜鹃萌发率相对较低,因此为提高晚花杜鹃萌发率,探究不同浓度赤霉素(GA_3)处理对五种杜鹃种子萌发的影响,该文以五种晚花杜鹃(小白杜鹃、大白杜鹃、桃叶杜鹃、长蕊杜鹃和九龙山杜鹃)为实验材料,通过不同浓度(0、300、400、500、600、700 mg·L~(-1))的GA_3对五种晚花杜鹃种子进行24 h浸种处理,测定其发芽指数、发芽势、发芽率以及成苗率等指标,分别确定五种杜鹃种子萌发的最适GA_3浓度,并对相同处理下五种杜鹃种子的萌发率和成苗率进行比较。结果表明:(1) GA_3浸种对五种晚花杜鹃种子萌发具有促进作用,在适当GA_3浓度下五种杜鹃种子的发芽指数、发芽势和发芽率均显著高于对照组,萌发时滞、萌发高峰期和持续萌发时间均较对照组浓度相对缩短。(2)大白杜鹃、桃叶杜鹃和九龙山杜鹃种子在GA_3浓度为600 mg·L~(-1)处理时各项萌发指标相对较好;长蕊杜鹃以GA_3浓度为700 mg·L~(-1)浸种处理萌发效果相对较好;小白杜鹃以GA_3浓度为400和700 mg·L~(-1)处理最好。因此,在杜鹃的栽培中,可以采用赤霉素GA_3处理法提高种子发芽率,缩短萌发时间。     

Morphological and molecular evidence of natural hybridization between two distantly related Rhododendron species from the Sino-Himalaya

Rhododendron (Ericaceae) is a large woody genus in which hybridization may play an important role in evolution and speciation, particularly in the Sino-Himalayan region, where many interfertile species often occur sympatrically. Natural hybridization between Rhododendron delavayi Franch. (=  R. arboreum ssp. delavayi ) and Rhododendron decorum Franch., which belong to different subsections of subgenus Hymenanthes, was investigated. Material of R. delavayi and R. decorum and their putative hybrids was collected from the wild. On the basis of morphology, chloroplast DNA, nuclear ribosomal DNA, and AFLP profiles, hybrids and parental species were identified. Hybridization occurred in both directions, but was asymmetrical, with R. delavayi as the major maternal parent in the hybrid zone. Most of the hybrids possessed intermediate phenotypes, and amongst the 15 hybrids detected were six F1s, two F2s, one first-generation backcross to R. delavayi , and two first-generation backcrosses to R. decorum . This indicates that, if Rhododendron underwent rapid radiation in this region, it did so in spite of permeable species barriers.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 119–129.     

Natural hybridization origin of <Emphasis Type="Italic">Rhododendron agastum </Emphasis>(Ericaceae) in Yunnan,China: inferred from morphological and molecular evidence

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. The assumed parents, Rhododendron delavayi Franch. and R. decorum Franch., are morphologically distinct, and the putative hybrid species, R. agastum Balf. f. et W. W. Smith, has an intermediate morphology. We used the main morphological characters, sequences of the nuclear ribosomal DNA ITS region, and the chloroplast DNA trnL-F intronspacer to analyze the three species, and compared these morphological and molecular data with an artificial hybrid between R. decorum (♀) × R. delavayi (♂). From the results, we conclude that R. agastum is a natural hybrid between a female R. delavayi and a male R. decorum.     

水分胁迫下扶芳藤幼苗保护酶活性和渗透调节物质的变化

扶芳藤(Euonymus fortunei(Turcz.)Hand.-Mazz)作为北方城市园林的新优攀援藤本和地被植物越来越受到重视,新品系的抗逆性筛选工作迫在眉睫。本文采用聚乙二醇(PEG-6000)模拟水分胁迫的方法,测定其生理指标,研究水分胁迫对扶芳藤不同品系幼苗叶片保护酶活性和渗透调节物质的影响,旨在摸索出这些生理指标与植物抗旱性的关系。研究结果表明,随着模拟干旱时间的延长,扶芳藤幼苗叶片中相对含水量(RWC)逐步下降,保护酶活性上升,脯氨酸和可溶性糖含量急剧上升,并且抗旱性强的品系保护酶活性和渗透调节物质含量较高。     

三种冬青属树种的耐涝性和耐旱性评价

通过致死性干旱和致死性水涝处理,用生理生态方法,对冬青(Ilexchinensis)、绿冬青(I.viridis)和无刺枸骨(I.cornatavar.fortunei)进行抗逆性研究。耐涝性结果表明随淹水时间延长,3种受淹冬青体内的游离脯氨酸和丙二醛含量增加,净光合速率下降;比较而言,绿冬青上述受淹反应出现早,无刺枸骨出现迟,而冬青介于二者之间;绿冬青耐涝约1周,无刺枸骨耐涝2周以上,冬青耐涝介于二者之间,在江南水乡推广利用,耐涝方面不会成为限制因素。耐旱结果表明随干旱的逐渐加重,3种冬青体内的游离脯氨酸含量呈上升趋势,比较而言,绿冬青上升的峰值出现早,冬青和无刺枸骨的上升峰值出现迟;绿冬青耐旱约15d,无刺枸骨耐旱约25d,冬青介于二者之间。3种冬青均有一定的抗逆性,其中无刺枸骨对水胁迫的适应能力最强,冬青次之,而绿冬青相对较弱。     

Unusual patterns of hybridization involving a narrow endemic Rhododendron species (Ericaceae) in Yunnan, China

? Premise of the study: One potential threat to rare species is genetic swamping caused by hybridization, but few studies have quantified this threat. Rhododendron cyanocarpum is a narrow endemic species that occurs sympatrically with potentially interfertile congeners throughout its range within Yunnan, China. We searched the entire distribution of R. cyanocarpum for hybrids and examined the patterns of hybridization to assess potential threat from hybridization. ? Methods: In a comprehensive field survey, we detected only one instance of hybridization involving R. cyanocarpum, with R. delavayi, at Huadianba near Dali. Material of both species and putative hybrids was examined using morphology, chloroplast DNA, nuclear ribosomal DNA, and Bayesian analysis of AFLP profiles. ? Key results: Of 10 putative hybrids, two were F(1)(')s and at least seven were F(2)(')s. Four backcrosses to R. delavayi were detected among material with R. delavayi-like morphology within the hybrid zone. Backcrosses to R. cyanocarpum were not detected. Therefore F(2)(')s outnumbered all other classes within the hybrid zone, a situation not previously confirmed for plants and extremely rare generally. Hybridization was asymmetrical, with R. delavayi as the maternal parent in all but one of the hybrids detected. ? Conclusions: Although natural hybridization is common in Rhododendron, it is rare in R. cyanocarpum and is apparently not accompanied by backcrossing toward R. cyanocarpum. Hence, there is no immediate risk of genetic swamping, unless habitat disturbance increases and changes the patterns of hybridization. Our study is the first to report a plant hybrid zone dominated by F(2) hybrids. This pattern might contribute to species barrier maintenance.     

Changes in Germination and Seedling Traits of Sesame under Simulated Drought

Drought is considered one of the leading abiotic constraints to agricultural crop production globally. Present study was conducted to assess the effects of different drought treatments (viz. Control, 10% PEG, and 20% PEG) on seed germination, germination indices, seedling traits, and drought tolerance indices of sesame. Our results showed that maximum reduction in the studied parameters was observed at higher PEG concentration (i.e., 20% PEG). As compared to control, the drought treatments viz. 10% and 20% PEG decreased the values for germination indices, such as germination percentage, coefficient of variation of germination time, germination index, and seedling vigor index. Similarly, for seedling traits, the values were decreased for root length, shoot length, root shoot ratio, root fresh weight, shoot fresh weight, root dry weight and shoot dry weight under 10% and 20% PEG treatments significantly in comparison with control. Furthermore, relative to control, the values for drought tolerance indices, such as germination drought tolerance index, root length drought tolerance index, shoot length drought tolerance index, total seedling length drought tolerance index, root fresh weight drought tolerance index, shoot fresh weight drought tolerance index, total fresh weight drought tolerance index, root dry weight drought tolerance index, shoot dry weight drought tolerance index and total dry weight drought tolerance index were also reduced under 10% and 20% PEG treatments, respectively. Our results confirms that drought impact on seed germination and seedling traits could be quantified by using different indices which can further help to design drought adaptation and mitigation strategies. Based on these results it can be concluded that germination indices, seedling traits, and drought tolerance indices have great potential to simulate drought stress impacts on different crop traits thus they should be used in all kinds of stress related studies.     

2R,3R-butanediol, a bacterial volatile produced by Pseudomonas chlororaphis O6, is involved in induction of systemic tolerance to drought in Arabidopsis thaliana

Root colonization of plants with certain rhizobacteria, such as Pseudomonas chlororaphis O6, induces tolerance to biotic and abiotic stresses. Tolerance to drought was correlated with reduced water loss in P. chlororaphis O6-colonized plants and with stomatal closure, indicated by size of stomatal aperture and percentage of closed stomata. Stomatal closure and drought resistance were mediated by production of 2R,3R-butanediol, a volatile metabolite of P. chlororaphis O6. Root colonization with bacteria deficient in 2R,3R-butanediol production showed no induction of drought tolerance. Studies with Arabidopsis mutant lines indicated that induced drought tolerance required the salicylic acid (SA)-, ethylene-, and jasmonic acid-signaling pathways. Both induced drought tolerance and stomatal closure were dependent on Aba-1 and OST-1 kinase. Increases in free SA after drought stress of P. chlororaphis O6-colonized plants and after 2R,3R-butanediol treatment suggested a primary role for SA signaling in induced drought tolerance. We conclude that the bacterial volatile 2R,3R-butanediol was a major determinant in inducing resistance to drought in Arabidopsis through an SA-dependent mechanism.     

Influence of PEG induced drought stress on molecular and biochemical constituents and seedling growth of Egyptian barley cultivars

In order to investigate the effects of drought stress on germination components of barley cultivars, a laboratory experiment was conducted in a factorial randomized complete design with four replications. The controlled experiment included ten of Egyptian barley cultivars namely; (Giza 123, 124, 125, 126, 127, 129, 130, 134, 135 and 2000) as first factor. The second factor included 4 levels of drought stress inducer by applying 0, 5, 10 and 20% of polyethylene glycol-6000 (PEG) which is equivalent to four osmotic potential levels including ?0.001, ?0.27, ?0.54 and ?1.09 MPa, respectively. The results showed that, the highest reduction was related to the drought level of 20% PEG among the barley cultivars. The best cultivars in terms of germination traits were Giza 134, Giza 127, and Giza 126 this indicate their tolerance to drought stress and Giza 130, 135, 2000 cultivars was moderately tolerance and remaining is less tolerance. The protein band 27 kDa and 78 kDa showed high intensity after stress in almost all cultivars. Those two protein bands their exciting was very clear in treated barley leaf tissue. It could be related to dehydrine and oxygen evolving enhancer protein 2 (OEE2) which involved in drought stress tolerance response. Cultivars Giza 127, 130 and 134 showed highest tolerance response under drought stress. The antioxidant enzymes PAGE pattern of Peroxidase (POX), Sodium dismutase (SOD) and Ascorbate peroxidase (APX) for Barley cultivars under drought stress revealed a high activities for Giza 126, 127, 134, 136 and 2000 under ?0.5 MPa osmotic stress by PEG in most of their isoforms. Based on similarity coefficient values the highest values were 1.0 with 100% similarly between tolerant cultivars Giza 130 and Giza 127. Similarly between the susceptible cultivars 125 and Giza 129 was 60%.These data confirmed by the growth parameters which we ranked as tolerant to drought stress.