Rhododendrons in Indian Himalayan Region: Diversity and Conservation

The genus Rhododendron of Indian Himalayan Region (IHR) has been enumerated in the present paper. A total of 87 species, 12 subspecies and 8 varieties of Rhododendrons recorded in IHR, among these 6 species and one subspecies are reported from Western Himalaya. The maximum concentration of 86% observed in Arunachal Pradesh (75 species). The species of Rhododendrons exhibit significant diversity in habit and broad range of distribution from the altitude of 800-6000 m. and the best range is observed in 3001-3500 m altitudes. In analysis revealed 20 taxa are endemic, 30 are rare, 24 are threatened / endangered, 3 are vulnerable and 47 taxa have to be assessed. The major threats to rhododendrons are deforestation and unsustainable extraction for firewood and incense by local people has been discussed.

Adaptability of Rhododendrons in high altitude habitats

Tree species dominate many ecosystems throughout the world and their response to climate,in light of global warming,is a matter of primary concern.This review describes past and ongoing research in Rhododendron,an ecologically important and well-adapted genus of more than 1000 species,occupying diverse habitats.Research to date indicates survival ability and mechanisms,with an emphasis on cold tolerance.The capability of longdistance gene flow in these species increases their genetic variability which in turn enhances their adaptability to newer niches as well as to environmental gradients(mainly temperature).Attempts to explain the molecular basis of morphological and behavioural changes in Rhododendron against cold-induced damage has been made.Gradual advances in‘omics’have led to an enriched genomic resource dissecting the role and interaction of multiple molecular factors participating in cold adaptability.However,fewer genetic studies are available on species with an inherent or a default cold-tolerance ability.Considering this fact,understanding specific features of an adapted species can provide insights on overriding the effects of desiccation and determining phase transitions in other plants as well.We propose to integrate ecological and evolutionary studies with functional genomics to improve predictions of tree responses to their environment.

RAD-seq data reveals robust phylogeny and morphological evolutionary history of Rhododendron

Rhododendron is famous for its high ornamental value.However,the genus is taxonomically difficult and the relationships within Rhododendron remain unresolved.In addition,the origin of key morphological characters with high horticulture value need to be explored.Both problems largely hinder utilization of germplasm resources.Most studies attempted to disentangle the phylogeny of Rhododendron,but only used a few genomic markers and lacked large-scale sampling,resulting in low clade support and contradictory phylogenetic signals.Here,we used restriction-site associated DNA sequencing(RAD-seq)data and morphological traits for 144 species of Rhododendron,representing all subgenera and most sections and subsections of this species-rich genus,to decipher its intricate evolutionary history and reconstruct ancestral state.Our results revealed high resolutions at subgenera and section levels of Rhododendron based on RAD-seq data.Both optimal phylogenetic tree and split tree recovered five lineages among Rhododendron.Subg.Therorhodion(cladeⅠ)formed the basal lineage.Subg.Tsutsusi and Azaleastrum formed cladeⅡand had sister relationships.CladeⅢincluded all scaly rhododendron species.Subg.Pentanthera(cladeⅣ)formed a sister group to Subg.Hymenanthes(cladeⅤ).The results of ancestral state reconstruction showed that Rhododendron ancestor was a deciduous woody plant with terminal inflorescence,ten stamens,leaf blade without scales and broadly funnelform corolla with pink or purple color.This study shows significant distinguishability to resolve the evolutionary history of Rhododendron based on high clade support of phylogenetic tree constructed by RAD-seq data.It also provides an example to resolve discordant signals in phylogenetic trees and demonstrates the application feasibility of RAD-seq with large amounts of missing data in deciphering intricate evolutionary relationships.Additionally,the reconstructed ancestral state of six important characters provides insights into the innovation of key characters in Rhododendron.

Structural characterization of four Rhododendron spp.chloroplast genomes and comparative analyses with other azaleas

Azalea is a general designation of Rhododendron in the Ericaceae family.Rhododendron not only has high ornamental value but also has application value in ecological protection,medicine,and scientific research.In this study,we used Illumina and PacBio sequencing to assemble and annotate the entire chloroplast genomes(cp genomes)of four Rhododendron species.The chloroplast genomes of R.concinnum,R.henanense subsp.lingbaoense,R.micranthum,and R.simsii were assembled into 207,236,208,015,207,233,and 206,912 bp,respectively.All chloroplast genomes contain eight rRNA genes,with either 88 or 89 protein-coding genes.The four cp genomes were compared and analyzed by bioinformatics,and the phylogenetic analysis based on chloroplast genomes of 26 species of Ericaceae,Actinidiaceae,and Primulaceae under Ericales was conducted.A comparison of the linear structure of cp genomes of four Rhododendron showed that there were substantial sequence similarities in coding regions,but high differences in non-coding regions.A phylogenetic analysis,based on chloroplast whole genome sequences,showed that all Rhododendron species are in the clade Ericaceae.This study provides valuable genetic information for the study of population genetics and evolutionary relationships in Rhododendron and other azalea species.

Projecting the potential distribution and analyzing the bioclimatic factors of four Rhododendron subsect.Tsutsusi species under climate warming

Tsutsusi is one of the eight subgenera of the Rhododendron genus.Four Tsutsusi species,R.indicum,R.simisii,R.oldhamii,and R.schlippenbachii,have high ornamental and medicinal values,resulting in an increasing market demand.These species thrive in cool and humid environments and are widely distributed in Europe and Asia.Whether global climate warming will affect the distribution of these valuable resources remains unclear.Thus,this study analyzed the climatic suitability of these species for the first time on the basis of 1552 geographical distribution points and 19 bioclimatic factors using the maximum entropy model.The results show that a suitable distribution area for all four species would decrease under climate warming.The main bioclimatic factors affecting their distribution are the mean temperature of the coldest quarter for R.indicum,the mean diurnal range for R.simisii,and precipitation of the warmest quarter for R.oldhamii and R.schlippenbachii.In addition,the contribution of the temperature-related bioclimatic factors to the distribution of R.indicum and R.simisii is higher than that of the associated precipitation-related climatic factors;in contrast,the contribution of precipitation-related bioclimatic factors to the distribution of R.oldhamii and R.schlippenbachii is higher than that of the temperature-related climatic factors.These results provide references for the introduction,conservation,sustainable development,and utilization of these four species in the future,and may also provide information with regards to other Rhododendron species.

Ecosystem Service Value Assessment of Wutong Mountain Rhododendron moulmainense Ecological Landscape Forest in Shenzhen City in 2021

Taking Wutong Mountain Rhododendron moulmainense ecological landscape forest in Shenzhen City as an example,the value of the forest was assessed by constructing an ecological service value assessment system and accounting method.The assessment results showed that the total ecosystem service value of R.moulmainense ecological landscape forest was 13.195 billion yuan,and the top three services included the value of forestry products,the value of biodiversity maintenance and the value of leisure and recreation,indicating that the ecosystem service of Wutong Mountain R.moulmainense ecological landscape forest in Shenzhen has great ecological and economic value,especially in forestry products,biodiversity maintenance,and leisure and recreation.

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。

高温胁迫对桃叶杜鹃幼苗生理生化指标的响应

为探明桃叶杜鹃生长适宜的温度,以桃叶杜鹃(Rhododendron annae Franch.)幼苗为试验材料,采用人工模拟气候鉴定法,设置对照(22℃)、模拟高温(30和38℃),对不同温度条件下桃叶杜鹃叶片丙二醛(MDA)、脯氨酸(Pro)、可溶性蛋白质、可溶性糖和叶绿素含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性进行研究。结果表明,与对照相比,桃叶杜鹃幼苗的MDA、Pro和可溶性蛋白质含量和SOD、CAT和POD活性均随温度升高而增加,叶绿素含量随温度升高而降低,可溶性糖含量则表现为在30℃条件下小幅增加,38℃条件下下降的趋势。说明桃叶杜鹃幼苗不耐高温胁迫,22℃条件是其较适宜的生长温度。

长白山杜鹃花属种间杂交亲和性的研究

为了探索长白山杜鹃花属种间杂交的亲和性及种间杂交在种质创新中的可行性,以5种长白山杜鹃花属植物为试材,进行种间正反杂交,并对杂种胚进行离体培养.结果表明,杜鹃花属种间正反杂交亲和力有显著差异,以牛皮杜鹃为母本,与迎红杜鹃、白花迎红杜鹃、亚布力杜鹃杂交有较高的亲和性,与母本的自然授粉坐果率无显著差异,分别为92.55％、94.14％、92.42％,杂种胚的萌发率分别为13.60％、11.59％、4.12％;杂种苗生长势微弱,呈白化状态,有败育迹象,经继代培养2～3次后,生长势得到一定的恢复,且分化率明显高于牛皮杜鹃种胚苗,但植株的颜色仍是黄绿色.而反交时,坐果率明显降低,坐果率最高的组合为亚布力杜鹃×牛皮杜鹃,为36.51％;与迎红杜鹃的杂交坐果率为6.52％;而与大字杜鹃的杂交坐果率为0,但反交时亚布力×牛皮杜鹃的种胚萌发率极显著地高于正交,为39.81％,而且种胚苗生长健壮,无需继代,可直接进行炼苗移栽.

基于层次分析法的西安露地栽培杜鹃花品种综合评价

采用层次分析法(AHP)对西安地区栽培的30个杜鹃花(Rhododendron simsii Planch.)品种进行综合评价。根据选定指标的评价结果,将30个品种分为4个等级:一级(≥4.75分),共4个品种;二级(4.00～4.50分),共10个品种;三级(3.50～3.75分),共11个品种;四级(<3.50分),共5个品种。综合评价结果与杜鹃花实际种植性能相一致,为西安杜鹃花品种选育和应用提供了科学依据。

镇安木王国家森林公园野生杜鹃花资源调查

1分布区概况木王国家森林公园,位于陕西省商洛市镇安县杨泗乡境内,西部木王国有林场境内,距镇安县城78km,距西安市156km,总面积3616hm2,最低海拔1350.0m,最高海拔2601.6m。2003年12月被国家林业局批准建立为国家级森林公园,堪称"天然氧吧",素有"千山杜鹃"、"杜鹃故里"的美誉。森林覆盖率高达98.3%,年平均降雨量1100mm。植被繁茂,原始森林葱郁。

兴安杜鹃总黄酮抗氧化活性

为考察兴安杜鹃(Rhododendron dauricum L.)总黄酮对·OH、超氧阴离子自由基和亚硝酸盐的清除作用,以及对亚硝胺合成的阻断作用,采用超声波提取法,以95%(V/V)乙醇浸提兴安杜鹃叶和茎样品,紫外可见分光光度法测定兴安杜鹃提取物的总黄酮含量。结果表明,兴安杜鹃提取物对·OH、亚硝酸盐和超氧阴离子均有清除作用,对亚硝胺的合成具有阻断作用,且随着浓度的增大,清除或合成阻断作用增加。兴安杜鹃提取物对超氧阴离子的清除效果优于对·OH和亚硝酸盐的清除效果,叶提取物的清除作用强于茎提取物的清除作用。

头花杜鹃和千里香杜鹃叶中挥发油的化学成分分析

分析比较青海互助北山林场中头花杜鹃(Rhododendron capitatum Maxim.)和千里香杜鹃(Rhododendron thymifolium Maxim.)叶中挥发油的化学成分及异同。采用水蒸气蒸馏法对头花杜鹃和千里香杜鹃叶的挥发油进行气相色谱-质谱(GC-MS)分析,并结合Kovats保留指数对其主要成分进行定性分析。鉴定出头花杜鹃叶中40种挥发性化学成分,含量最高的分别是β-蒎烯(29.02%)、α-蒎烯(28.31%)、柠檬烯(7.45%)。千里香杜鹃叶中鉴定出24种挥发性化学成分,含量最高的分别是β-蒎烯(19.92%)、α-蒎烯(19.81%)、月桂烯(4.21%)。头花杜鹃和千里香杜鹃叶中的挥发油在成分构成上比较相似,但在相对含量上差异较大。

基于均匀设计优化牛皮杜鹃嫩叶直接再生芽苗及植株再生体系(英文)

[Objective] The experimental was aimed to screen the optimum regeneration shoot induction media and rooting media for tender leaves of Rhododendron chrysanthum Pall.[Method] The tender leaves of Rhododendron chrysanthum Pall were taken as explants to select the optimum bud induction media and rooting media through uniform design and the screening results were verified.[Result] The optimum media for regeneration shoot of Rhododendron chrysanthum Pall contained 1/4 MS,3.70 mg/L ZT, 0.02 mg/L IAA and 1.00 mg/L KT and its induction rate was 95.5% and the rooting media contained modified MS, 0.10 mg/L IAA and 0.07 mg/L NAA and its rooting rate was 98%. [Conclusion] Through this experiment, regeneration systems for regeneration shoot and regenerated plant from tender leaves of Rhododendron chrysanthum Pall were created successfully.

液-质联用分析锦锈杜鹃叶黄酮类成分

[目的]采用高效液相色谱—电喷雾离子阱质谱技术对锦锈杜鹃叶中的黄酮类化合物进行分析和鉴定。[方法]色谱条件为:Wa-ters C18色谱柱(4.6 mm×250 mm,5μm);流动相A相为水(含浓度0.1%甲酸),流动相B相为无水甲醇;梯度洗脱程序:0～24 min,31%～42%B;24～30 min,42%～50%B;30～35 min,50%～60%B;35～40 min,60%B;进样量20μl;流速为0.7 ml/min;柱温30℃;检测波长356 nm。质谱条件为:电离源:电喷雾离子源;负离子模式扫描;干燥气温度:350℃;干燥气体积流量(N2):10 L/min;雾化气压力275.8 KPa;毛细管电压:3.5 KV,毛细管出口电压100 V;质量扫描范围:m/z 200～700。使用ESI离子源,负离子模式下采集数据。[结果]通过与文献数据和部分标准品对照,推断出锦锈杜鹃叶中含有5个黄酮类化合物,分别是金丝桃苷、异槲皮苷、广寄生苷、槲皮苷、槲皮素。[结论]液质联用技术具有快速、准确、有效的特点,是一种相对较好的定性测定方法。其对锦锈杜鹃叶中的黄酮类化合物进行分析和鉴定,为今后锦锈杜鹃的应用提供了一定的理论依据。

不同激素处理对锦绣杜鹃开花时期的影响

采用不同浓度的GA3、6-BA、KT、GA3+6-BA、GA3+KT处理锦绣杜鹃(Rhododendron pulchrum Sweet)花蕾,研究其对锦绣杜鹃花蕾形态指标、开花时期、开花质量的影响。结果表明,上述激素处理均可使花蕾发育进程显著加快,开花时期提前,花朵体积增大,但对花期长短没有影响或影响较小;其中,GA3+KT促进效果最好,1 500 mg/L GA3+15 mg/L KT可使开花提前45 d左右,其次为GA3+6-BA,1 500 mg/L GA3+15 mg/L 6-BA处理可使开花提前33 d左右,而这两种混合液处理效果都显著优于单纯GA3处理;促进效应还与激素的浓度有关,1 500 mg/L GA3促进效应显著优于1 000 mg/L GA3的处理,无论是混合液还是单纯GA3处理,1 500 mg/L GA3促进效应显著优于1 000 mg/L GA3的处理。结构的观察显示,GA3+KT混合液处理显著促进了子房的发育进程,使子房膨大速度加快,提前形成胚珠,并发育至成熟,但对花药的发育进程没有影响或影响不显著,开花后的花药不开裂、不散粉,花粉粒处于四分体时期。

龟峰山古杜鹃群落遗传多样性的ISSR研究

采用简单序列重复区间扩增多态性分子标记(Inter-simple sequence repeat,ISSR)技术,对龟峰山3个野生杜鹃(Rhododendron simsii Planch.)居群共23个种质材料进行了遗传多样性分析与评价。运用40条ISSR引物共筛选出7条扩增条带清晰、重复性好和多态性高的引物;筛选出来的7条ISSR引物共扩增出79条清晰的条带,其中多态性条带有74条,平均多态性位点比率为93.67%,等位基因数Na和有效等位基因数Ne分别为1.962 0和1.555 4,奈氏基因多样性指数h为0.330 8,香农氏信息指数I为0.499 0,表明龟峰山古杜鹃群落具有较高的遗传多样性,其中Rho-M和Rho-H两个居群之间的遗传距离小至0.069 8,亦即这两个居群之间的分化最小。试验从分子层面对古杜鹃的遗传多样性分析将对龟峰山古杜鹃种质资源的评价、保存以及杜鹃新品种的选育提供理论支撑。

基于BIB-LCJ法与SD法的杜鹃专类园春季植物景观美学评价

杜鹃(Rhododendron L.)专类园是春季景观最具特色的专类园之一,运用BIB-LCJ法(Balanced Incomplete Block design-Law of Comparative Judgment,平衡不完全区组设计-比较评判法)对湖南省森林植物园国家杜鹃园25个景观样本进行了美学评价,根据200名评价者的评价结果,得出最优及最差景观样本;同时,40名相关领域人员采用SD法(Semantic Differential,语义学解析法)对以上样本也进行了评价。综合2种评价结果,认为最优景观样本为14、1、6、20号,最差样本为9、10、25、22号。对SD法评价结果进行SD分析和因子分析,得到影响杜鹃专类园春季植物景观的因子有环境、空间、形式、美感4个方面。

基于遥感与地理信息系统的黄冈市野生杜鹃花空间分布研究

在湖北省黄冈市麻城市境内的龟峰山上生长着大面积的野生杜鹃花（Rhododendron L.）灌丛,形成了极为壮观的“花海”景观,吸引了大量游客,以杜鹃花为主题的旅游活动日趋火热。为了加强对野生杜鹃花种群的保护,全面了解大别山地区野生杜鹃花分布状况是非常必要的。利用黄冈市ETM＋遥感影像,采用监督分类的方法,以龟峰山景区的杜鹃花为典型训练样本,在地理信息系统（Geographic information system,GIS）Arc GIS 10.0平台上单独提取出杜鹃花的分布图层,分县（市）统计并与DEM数据叠加分析,了解杜鹃花在不同海拔高度、坡度及坡向的分布特征。结果显示,黄冈市的野生杜鹃花主要分布在英山、罗田、麻城3县（市）,总面积在34 562.7 hm2左右。主要集中在海拔500~1 000 m的山丘,坡度范围在15°~25°,且阳坡和阴坡上的分布差异不明显,由此推测,在黄冈市可能还存在着集中连片分布的杜鹃花种群。该结果对于认识北亚热带区域杜鹃花种群生境特征具有重要意义,也对黄冈市旅游资源的开发具有参考价值。

杜鹃基因组微卫星富集文库的构建

利用FIASCO方法(Fast Isolation by AFLP Sequences COntaining repeats)构建杜鹃(Rhododendron simsii Planch.)的(AG)n微卫星富集文库。通过菌液PCR检测,从(AG)n微卫星富集文库的356个阳性菌落中筛选了233个进行测序分析。结果表明,202个序列富含SSR位点,阳性比率达86.7%。去除杂峰、叠峰、信号弱的序列,最终筛选39个供后续引物开发使用,其中完美型SSR有22个,不完美型5个,混合型12个。磁珠富集法构建杜鹃基因组微卫星文库是一条高效可行的途径,为微卫星位点的分离、杜鹃种群遗传多样性和遗传结构的研究奠定了基础。