琥珀中的甾萜化合物是高等植物分泌的次生代谢物^([1])。因不同植物分泌出的次生代谢物不同,这些丰富的甾萜化合物可作为解译琥珀古植物来源的化学指纹^([2])。但是,现有关于琥珀或树脂化石的化学分类难以区分出琥珀古植物来源的种属,...琥珀中的甾萜化合物是高等植物分泌的次生代谢物^([1])。因不同植物分泌出的次生代谢物不同,这些丰富的甾萜化合物可作为解译琥珀古植物来源的化学指纹^([2])。但是,现有关于琥珀或树脂化石的化学分类难以区分出琥珀古植物来源的种属,甚至较为粗略层次的分类指标(如生物分类系统中的门、科等)都未见系统研究^([3-6])。本研究借用了生物化学领域中常用的比较代谢组学研究思路^([7-8]),以顶空固相微萃取与全二维气相色谱-飞行时间质谱联用为技术手段,系统分析了来自古裸子植物(始新世柏科、白垩纪南洋杉科)和古被子植物(中新世龙脑香料、中新世豆科植物)琥珀中的甾萜化合物^([9]),鉴定的次生代谢物包括83种单萜、186种倍半萜、84种二萜和43种正构烷烃。通过保留指数校正及与国际标准NIST质谱数据库比对,明确了其中大部分次生代谢物的结构及其化学名称。在化学分类前,我们先测试了样品的镜质体反射率和最大热解峰温(T_(max)),证明本文选取的四类琥珀样品具有非常相似的热成熟度;再利用多元统计法从鉴定的396种甾萜化合物中提取出了四条琥珀古植物来源分类标准:(1)根据单萜和二萜的相对含量可区分裸子植物琥珀和被子植物琥珀;(2)10种化学分类标志物可用于区分出两种裸子植物琥珀,包括柏科和南洋杉科;(3)被子植物琥珀中,豆科琥珀和龙脑香料的化学超类存在差异,豆科琥珀的主要成分是倍半萜和二萜,而龙脑香料的主要成分是单萜和倍半萜;(4)其它特殊的化学成分可将豆科琥珀的古植物源鉴定到属级别(Hymenaea mexicana and Hymenaea protera)。由于古植物次生代谢物成分是由植物的基因组控制,本文揭示的化学分类标志具备遗传基础[10-12],研究结果全面建立了古树脂植物次生代谢物数据库,为古植物及古环境研究提供数据基础。展开更多
China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of ce...China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of central and south-western China allowed their persistence through the late Neogene climate fluctuations.One of these relict lineages is Dipteronia,an oligotypic tree genus with a fossil record extending to the Paleocene.Here,we investigated the genetic variability,demographic dynamics and diversification patterns of the two currently recognized Dipteronia species(Dipteronia sinensis and D.dyeriana).Molecular data were obtained from 45 populations of Dipteronia by genotyping three cpDNA regions,two single copy nuclear genes and 15 simple sequence repeat loci.The genetic study was combined with niche comparison analyses on the environmental space,ecological niche modeling,and landscape connectivity analysis.We found that the two Dipteronia species have highly diverged both in genetic and ecological terms.Despite the incipient speciation processes that can be observed in D.sinensis,the occurrence of long-term stable refugia and,particularly,a dispersal corridor along Daba Shan-west Qinling,likely ensured its genetic and ecological integrity to date.Our study will not only help us to understand how populations of Dipteronia species responded to the tectonic and climatic changes of the Cenozoic,but also provide insight into how Arcto-Tertiary relict plants in East Asia survived,evolved,and diversified.展开更多
Gnetophytes are a key group of plant for understanding seed plant phylogeny,partly because of their unique and elusive morphology,such as xylem with vessels,phloem with chaperones,reticular veins,and double fertilizat...Gnetophytes are a key group of plant for understanding seed plant phylogeny,partly because of their unique and elusive morphology,such as xylem with vessels,phloem with chaperones,reticular veins,and double fertilization(Endress,1996).In particular,the ovule bears a membranous integument,the upper part of which extends beyond the seed envelope to form a micropylar tube.Therefore,gnetophytes occupy a unique evolutionary position in the phylogeny of seed plants and apparently represent a transition between angiosperms and other gymnosperms(Ran et al.,2018).Modern gnetophytes consist of only three families:Ephedraceae,Gnetaceae,and Welwitschiaceae,and each family contains only one genus.Ephedraceae(Ephedra L.)are the earliest diverging group of Gnetales,with a total of 70 extant species,and usually occur in cold and arid places in Asia,Europe,northern Africa,western North America and South America(Price,1996;Yang et al.,2017b).展开更多
文摘琥珀中的甾萜化合物是高等植物分泌的次生代谢物^([1])。因不同植物分泌出的次生代谢物不同,这些丰富的甾萜化合物可作为解译琥珀古植物来源的化学指纹^([2])。但是,现有关于琥珀或树脂化石的化学分类难以区分出琥珀古植物来源的种属,甚至较为粗略层次的分类指标(如生物分类系统中的门、科等)都未见系统研究^([3-6])。本研究借用了生物化学领域中常用的比较代谢组学研究思路^([7-8]),以顶空固相微萃取与全二维气相色谱-飞行时间质谱联用为技术手段,系统分析了来自古裸子植物(始新世柏科、白垩纪南洋杉科)和古被子植物(中新世龙脑香料、中新世豆科植物)琥珀中的甾萜化合物^([9]),鉴定的次生代谢物包括83种单萜、186种倍半萜、84种二萜和43种正构烷烃。通过保留指数校正及与国际标准NIST质谱数据库比对,明确了其中大部分次生代谢物的结构及其化学名称。在化学分类前,我们先测试了样品的镜质体反射率和最大热解峰温(T_(max)),证明本文选取的四类琥珀样品具有非常相似的热成熟度;再利用多元统计法从鉴定的396种甾萜化合物中提取出了四条琥珀古植物来源分类标准:(1)根据单萜和二萜的相对含量可区分裸子植物琥珀和被子植物琥珀;(2)10种化学分类标志物可用于区分出两种裸子植物琥珀,包括柏科和南洋杉科;(3)被子植物琥珀中,豆科琥珀和龙脑香料的化学超类存在差异,豆科琥珀的主要成分是倍半萜和二萜,而龙脑香料的主要成分是单萜和倍半萜;(4)其它特殊的化学成分可将豆科琥珀的古植物源鉴定到属级别(Hymenaea mexicana and Hymenaea protera)。由于古植物次生代谢物成分是由植物的基因组控制,本文揭示的化学分类标志具备遗传基础[10-12],研究结果全面建立了古树脂植物次生代谢物数据库,为古植物及古环境研究提供数据基础。
基金co-supported by the National Natural Science Foundation of China(Grant No.31470311)the Ph.D.Programs Foundation of the Ministry of Education of China(Grant No.20136101130001).
文摘China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of central and south-western China allowed their persistence through the late Neogene climate fluctuations.One of these relict lineages is Dipteronia,an oligotypic tree genus with a fossil record extending to the Paleocene.Here,we investigated the genetic variability,demographic dynamics and diversification patterns of the two currently recognized Dipteronia species(Dipteronia sinensis and D.dyeriana).Molecular data were obtained from 45 populations of Dipteronia by genotyping three cpDNA regions,two single copy nuclear genes and 15 simple sequence repeat loci.The genetic study was combined with niche comparison analyses on the environmental space,ecological niche modeling,and landscape connectivity analysis.We found that the two Dipteronia species have highly diverged both in genetic and ecological terms.Despite the incipient speciation processes that can be observed in D.sinensis,the occurrence of long-term stable refugia and,particularly,a dispersal corridor along Daba Shan-west Qinling,likely ensured its genetic and ecological integrity to date.Our study will not only help us to understand how populations of Dipteronia species responded to the tectonic and climatic changes of the Cenozoic,but also provide insight into how Arcto-Tertiary relict plants in East Asia survived,evolved,and diversified.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0704)the National Natural Science Foundation of China(Grant No.42272029).
文摘Gnetophytes are a key group of plant for understanding seed plant phylogeny,partly because of their unique and elusive morphology,such as xylem with vessels,phloem with chaperones,reticular veins,and double fertilization(Endress,1996).In particular,the ovule bears a membranous integument,the upper part of which extends beyond the seed envelope to form a micropylar tube.Therefore,gnetophytes occupy a unique evolutionary position in the phylogeny of seed plants and apparently represent a transition between angiosperms and other gymnosperms(Ran et al.,2018).Modern gnetophytes consist of only three families:Ephedraceae,Gnetaceae,and Welwitschiaceae,and each family contains only one genus.Ephedraceae(Ephedra L.)are the earliest diverging group of Gnetales,with a total of 70 extant species,and usually occur in cold and arid places in Asia,Europe,northern Africa,western North America and South America(Price,1996;Yang et al.,2017b).
