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For a quadratic Markov branching process (QMBP), we show that the decay parameter is equal to the first eigenvalue of a Sturm–Liouville operator associated with the partial differential equation that the generating function of the transition probability satisfies. The proof is based on the spectral properties of the Sturm–Liouville operator. Both the upper and lower bounds of the decay parameter are given explicitly by means of a version of Hardy’s inequality. Two examples are provided to illustrate our results. The important quantity, the Hardy index, which is closely linked to the decay parameter of the QMBP, is deeply investigated and estimated.

The transfer of mitochondrial DNA to the nuclear genome gives rise to the nuclear DNA sequences of mitochondrial origin (NUMTs), considered as a driving force in genome evolution. In this study, NUMTs in 23 bat genomes were investigated and compared systematically. The results showed that NUMTs existed in 22 genomes except for Noctilio leporinus, suggesting that mitochondrial fragment insertion in the nuclear genome was a common event in bat genomes. However, remarkable variations in NUMTs number, cumulative length, and proportion in the nuclear genome were discovered across bat species. Further orthologous NUMT loci analysis of the Phyllostomidae family indicated that the NUMTs insertion events in bat genomes were homoplasy-free. The NUMTs were mainly inserted into the intergenic regions, particularly, co-localized with repetitive sequences (especially transposable elements). However, several NUMTs were inserted into genes, some of which were in the exon region of functional genes. One NUMT in the genome of Pteropus alecto surprisingly matched with cDNA of ATP8B3 that provided evidence of NUMTs with coding function. Phylogenic analysis on NUMTs originating from COXI and COXII loci highlighted 2 clusters of Yinpterochiroptera and Yangochiroptera for Chiroptera. Seven NUMTs from Rhinolophus ferrumequinum were amplified, and the sequencing results confirmed the reliability of the NUMT analysis. One of them was polymorphic for the presence or absence of the NUMT insertion, and each genotype of NUMT loci showed a distinct regional distribution pattern. The information obtained in this study provides novel insights into the NUMT organization and features in bat genomes and establishes a basis for further studying of the evolution of bat species.

Spinach (Spinacia oleracea Linnaeus, 1753) is an ideal material for studying molecular mechanisms of early-stage sex chromosome evolution in dioecious plants. Degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) technique facilitates the retrotransposon-relevant studies by enriching specific repetitive DNA sequences from a micro-dissected single chromosome. We conducted genomic subtractive hybridization to screen sex-biased DNA sequences by using the DOP-PCR amplification products of micro-dissected spinach Y chromosome. The screening yielded 55 male-biased DNA sequences with 30 576 bp in length, of which, 32 DNA sequences (12 049 bp) contained repeat DNA sequences, including LTR/Copia, LTR/Gypsy, simple repeats, and DNA/CMC-EnSpm. Among these repetitive DNA sequences, four DNA sequences that contained a fragment of Ty3-gypsy retrotransposons (SP73, SP75, SP76, and SP77) were selected as fluorescence probes to hybridization on male and female spinach karyotypes. Fluorescence in situ hybridization (FISH) signals of SP73 and SP75 were captured mostly on the centromeres and their surrounding area for each homolog. Hybridization signals primarily appeared near the putative centromeres for each homologous chromosome pair by using SP76 and SP77 probes for FISH, and sporadic signals existed on the long arms. Results can be served as a basis to study the function of repetitive DNA sequences in sex chromosome evolution in spinach.

Asparagus setaceus is an important ornamental plant and is important to study the sex chromosome evolution in genus Asparagus. Here the complete chloroplast (cp) genome sequence of A. setaceus was determined. The cpDNA is 156,978 bp in length, contains a large single copy region of 85,311 bp and a small single copy region of 18,641 bp, which was separated by a pair of inverted repeat regions of 26,513 bp each. The cp genome contains 132 genes, including 88 protein-coding genes, 6 ribosomal RNA genes, and 38 transfer RNA genes. Phylogenetic analysis indicates that A. setaceus is closely related to Asparagus officinalis and Asparagus schoberioides.

Background The transfer of chloroplast DNA into nuclear genome is a common process in plants. These transfers form nuclear integrants of plastid DNAs (NUPTs), which are thought to be driving forces in genome evolution, including sex chromosome evolution. In this study, NUPTs in the genome of a dioecious plant Asparagus officinalis L. were systematically analyzed, in order to investigate the characteristics of NUPTs in the nuclear genome and the relationship between NUPTs and sex chromosome evolution in this species. Results A total of 3155 NUPT insertions were detected, and they represented approximated 0.06% of the nuclear genome. About 45% of the NUPTs were organized in clusters. These clusters were derived from various evolutionary events. The Y chromosome contained the highest number and largest proportion of NUPTs, suggesting more accumulation of NUPTs on sex chromosomes. NUPTs were distributed widely in all of the chromosomes, and some regions preferred these insertions. The highest density of NUPTs was found in a 47 kb region in the Y chromosome; more than 75% of this region was occupied by NUPTs. Further cytogenetic and sequence alignment analysis revealed that this region was likely the centromeric region of the sex chromosomes. On the other hand, the male-specific region of the Y chromosome (MSY) and the adjacent regions did not have NUPT insertions. Conclusions These results indicated that NUPTs were involved in shaping the genome of A. officinalis through complicated process. NUPTs may play important roles in the centromere shaping of the sex chromosomes of A. officinalis, but were not implicated in MSY formation. Electronic supplementary material The online version of this article (10.1186/s12870-019-1975-8) contains supplementary material, which is available to authorized users.

The primers used for amplification of the RT sequences of lineages in spinach. (DOC 42 kb)

Table S1. The detailed information of NUPTs in the nuclear genome of A. officinalis. (DOCX 44 kb)

Topological layout and consensus sequence of satellite DNAs. (DOC 1441 kb)

∆(8)-sphingolipid desaturase catalyzes the C8 desaturation of a long chain base, which is the characteristic structure of various complex sphingolipids. The genes of 20 ∆(8)-sphingolipid desaturases from 12 plants were identified and functionally detected by using Saccharomyces cerevisiae system to elucidate the relationship between the biochemical function and evolution of this enzyme. Results showed that the 20 genes all can encode a functional ∆(8)-sphingolipid desaturase, which catalyzes different ratios of two products, namely, 8(Z) and 8(E)-C18-phytosphingenine. The coded enzymes could be divided into two groups on the basis of biochemical functions: ∆(8)-sphingolipid desaturase with a preference for an E-isomer product and ∆(8)-sphingolipid desaturase with a preference for a Z-isomer product. The conversion rate of the latter was generally lower than that of the former. Phylogenetic analysis revealed that the 20 desaturases could also be clustered into two groups, and this grouping is consistent with that of the biochemical functions. Thus, the biochemical function of ∆(8)-sphingolipid desaturase is correlated with its evolution. The two groups of ∆(8)-sphingolipid desaturases could arise from distinct ancestors in higher plants. However, they might have initially evolved from ∆(8)-sphingolipid desaturases in lower organisms, such as yeasts, which can produce E-isomer products only. Furthermore, almost all of the transgenic yeasts harboring ∆(8)-sphingolipid desaturase genes exhibit an improvement in aluminum tolerance. Our study provided new insights into the biochemical function and evolution of ∆(8)-sphingolipid desaturases in plants.

Asparagus setaceus is an important ornamental plant and is important to study the sex chromosome evolution in genus Asparagus. Here the complete chloroplast (cp) genome sequence of A. setac...

Spinach (Spinacia oleracea L.) is a diploid dioecious plant with a pair of homomorphic sex chromosomes X and Y. Plant DNA methylation, a known process for genome epigenetic modification, regulates gene expression in plants. To explore the effects of DNA methylation on spinach growth and sexual development, spinach seeds were treated with the demethylating reagent 5-azaC. The resulting phenotypes were then investigated, including germination percentage, root length, plant height, flowering time, and sexual phenotype. Results showed that 5-azaC at a low concentration (30 µM) only slightly influenced spinach development but promoted seed germination. The germination percentage, root length, and plant height negatively correlated with 5-azaC at 100–1000 µM. The flowering time significantly reduced at all four treatments with 5-azaC. In addition, 5-azaC influenced the sexual phenotype of spinach and remarkably increased the percentage of monoecious individuals. These results may suggest that vegetative and reproductive growth are both epigenetically regulated by DNA methylation.

We prove that there exists a unique quasi-stationary distribution for the minimal birth–death process with exit boundary. A spectral representation for the quasi-stationary distribution is also obtained.

Classical forward genetic analysis relies on construction of complicated progeny populations and development of many molecular markers for linkage analysis in genetic mapping, which is both time- and cost-consuming. The recently developed MutMap is a new forward genetic approach based on high-throughput next-generation sequencing technologies. It is more efficient and affordable than traditional methods. Moreover, new extended methods based on MutMap have been developed: MutMap+, which is based on self-crossing; MutMap-Gap, which is used to recognize the causative variations occurring in genome gap regions; QTL-seq, a method similar to MutMap for mapping quantitative trait loci. These methods are free from constructing complicated mapping population, genetic hybridization and linkage information. They have greatly accelerated the identification of genetic elements associated with interested phenotypic variation. Here, we review the basic principles of MutMap, and discuss their future applications in next generation sequencing-based forward genetic mapping and crop improvement.

Chromosome evolution is a fundamental aspect of evolutionary biology. The evolution of chromosome size, structure and shape, number, and the change in DNA composition suggest the high plasticity of nuclear genomes at the chromosomal level. Repetitive DNA sequences, which represent a conspicuous fraction of every eukaryotic genome, particularly in plants, are found to be tightly linked with plant chromosome evolution. Different classes of repetitive sequences have distinct distribution patterns on the chromosomes. Mounting evidence shows that repetitive sequences may play multiple generative roles in shaping the chromosome karyotypes in plants. Furthermore, recent development in our understanding of the repetitive sequences and plant chromosome evolution has elucidated the involvement of a spectrum of epigenetic modification. In this review, we focused on the recent evidence relating to the distribution pattern of repetitive sequences in plant chromosomes and highlighted their potential relevance to chromosome evolution in plants. We also discussed the possible connections between evolution and epigenetic alterations in chromosome structure and repatterning, such as heterochromatin formation, centromere function, and epigenetic-associated transposable element inactivation.

In this study, 17 male-specific amplified fragment length polymorphism (AFLP) markers were identified between male and female Humulus scandens plants. BLAST analysis revealed that 7 of the 17 sex-linked sequences were highly similar to retrotransposons. Two stable male-specific sequence-characterized amplified regions (SCAR) markers were developed. These AFLP and SCAR markers are novel molecular probes that can be used efficiently to identify the genetic gender of H. scandens and may provide a basis for further investigations on the evolution of sex chromosomes.

Asparagus officinalis L. is a dioecious plant. A region called the M-locus located on a pair of homomorphic L5 chromosomes controls sexual dimorphism in asparagus. This study aims to conduct microd...

∆8-sphingolipid desaturase is characterized by its ability to catalyze desaturation at the C8 position of the long-chain base of sphingolipids in plants. No previous studies have been conducted on genes encoding Δ8-sphingolipid desaturases in the woody plant Populus tomentosa. In this study, three genes that encode Δ8-sphingolipid desaturase were isolated from P. tomentosa. Among these genes, PtD8A and PtD8B showed high sequence similarity; whereas PtD8C exhibited large sequence divergence. RT-PCR results showed that PtD8A and PtD8B were expressed in all tissues detected, whereas PtD8C was not expressed in roots. Heterologous expression in yeast revealed that PtD8A/B/C were functional Δ8-sphingolipid desaturases, and can catalyze the C18-phytosphingenine desaturation to produce 8(Z)- and 8(E)-C18-phytosphingenine. However, the conversion rate and ratios of the two products differed. Compared with control cells, transgenic yeasts expressing PtD8A/B/C exhibited enhanced aluminum tolerance. Our findings further elucidated the biochemical functions and evolutionary history of Δ8-sphingolipid desaturases in plants. Candidate genes for breeding new poplar germplasm resources with enhanced tolerance ability to aluminium were also provided.

In this paper, we deal with multidimensional backward stochastic equations (BSDES) driven by continuous semi-martingale. We first obtain the existence of solution for this kind of BSDES with locally Lipschitz coefficient, which generalizes the corresponding results in Khaled Bahlali.

Spinach has long been used as a model for genetic and physiological studies of sex determination and expression. Although trisomic analysis from a cross between diploid and triploid plants identified the XY chromosome as the largest chromosome, no direct evidence has been provided to support this at the molecular level. In this study, the largest chromosomes of spinach from mitotic metaphase spreads were microdissected using glass needles. Degenerate oligonucleotide primed polymerase chain reaction was used to amplify the dissected chromosomes. The amplified products from the Y chromosome were identified using the male-specific marker T11A. For the first time, the largest spinach chromosome was confirmed to be a sex chromosome at the molecular level. PCR products from the isolated chromosomes were used in an in situ probe mixture for painting the Y chromosome. The fluorescence signals were mainly distributed on all chromosomes and four pair of weaker punctate fluorescence signal sites were observed on the terminal region of two pair of autosomes. These findings provide a foundation for the study of sex chromosome evolution in spinach.

Garden asparagus (Asparagus officinalis), an important vegetable cultivated worldwide, can also serve as a model dioecious plant species in the study of sex determination and sex chromosome evolution. However, limited DNA marker resources have been developed and used for this species. To expand these resources, we examined the DNA sequences for simple sequence repeats (SSRs) in 163,406 scaffolds representing approximately 400 Mbp of the A. officinalis genome. A total of 87,576 SSRs were identified in 59,565 scaffolds. The most abundant SSR repeats were trinucleotide and tetranucleotide, accounting for 29.2 and 29.1% of the total SSRs, respectively, followed by di-, penta-, hexa-, hepta-, and octanucleotides. The AG motif was most common among dinucleotides and was also the most frequent motif in the entire A. officinalis genome, representing 14.7% of all SSRs. A total of 41,917 SSR primers pairs were designed to amplify SSRs. Twenty-two genomic SSR markers were tested in 39 asparagus accessions belonging to ten cultivars and one accession of Asparagus setaceus for determination of genetic diversity. The intra-species polymorphism information content (PIC) values of the 22 genomic SSR markers were intermediate, with an average of 0.41. The genetic diversity between the ten A. officinalis cultivars was low, and the UPGMA dendrogram was largely unrelated to cultivars. It is here suggested that the sex of individuals is an important factor influencing the clustering results. The information reported here provides new information about the organization of the microsatellites in A. officinalis genome and lays a foundation for further genetic studies and breeding applications of A. officinalis and related species.

Male and female spinach (Spinacia oleracea L, 2n = 12) were karyotyped by chromosome measurements and subjected to fluorescence in situ hybridization with 45s rDNA The chromosome complement comprised two long nearly subtelocentrics, two short subtelocentrics, two acrocentrics, and six submetacentrics. The X and Y chromosomes were not distinguished by morphological analysis; thus, six obvious 45s rDNA sites were labeled with Texas red and clearly observed as red signals on three pairs of chromosomes. Among the three pairs of signal sites, a pair of the largest one was located on the short arms of chromosome 5, which is a satellite chromosome. Another prominent signal site was found on the short arms of chromosomes 2 and 6. However, from single images with 45s rDNA (red) of male or female spinach, weak 45s rDNA sites labeled with Texas red were observed on chromosomes 1 and 3. The weak 45s rDNA signals site were located on the large arm of chromosome 3 of both male and female spinach. Interestingly, differe...

ƒIn this paper, we study the one-dimensional backward stochastic equations driven by continuous local martingale. We establish a generalized the comparison theorem for any solutions where the coefficient is uniformly Lipschitz continuous in z and is equi-continuous in y.

Ion implantation, as a new biophysically mutagenic technique, has shown a great potential for horticultural plant breeding. Up to date, little is known about the mutation mechanism of ion implantation at the DNA level. To reveal the mutation effect of Fe+ ion implantation on Baiyangdian red lotus, the random amplified polymorphic DNA (RAPD) was used, and then the bands of mutants and the control in the radiation-sensitive sites were cloned to be sequenced for comparing their DNA sequences. The results indicated that the total base mutation rate of mutants was 0.87%, and there was different in the six mutants. The types of base changes included base transition, transversion, deletion, and insertion. Among the 159 base changes detected, the frequency of single base substitutions (61.01%) was higher than that of base deletions and insertions (38.99%), and the frequency of base transitions (44.65%) was 2.7 times of that of the base transversions (16.35%). The transitions between C and T accounted for largest proportion, A→G transitions and A→T transversions were also present at high frequency. Adenine, thymine, guanine or cytosine could be replaced by any of other three bases, except that there was no C → G substitution. However, thymine was more sensitive to the irradiation than other bases. In our study, we found many purine bases around the purine mutational sites, and many pyrimidine bases around the pyrimidine mutational sites. These will further help us to understand the mechanism of mutagenesis by ion implantation.

Suppression of recombination is the prerequisite for plant sex chromosome evolution from a pair of autosomes. Recombination suppression around the locus controlling sex determination results in sex chromosome degeneration and differentiation. Important events such as repetitive sequence accumulation, heterochromatize, and DNA methylation have relation to recombination suppression. Accumulation of repetitive DNA sequence, including transposable elements and satellite DNA, leads to primitive sex chromosome differentiated on morphological and molecular structure, and also gives rise to chromosome heterochromatize, and thus recombination between sex chromosomes was suppressed. Here, we re-viewed the advances in this field, meanwhile, the function of DNA methylation in recombination suppression was analyzed.

Garden asparagus (Asparagus officinalis L.) is a dioecious species whose male and female flowers are found in separate unisexual individuals. A region called the M-locus, located on a pair of homomorphic sex chromosomes, controls sexual dimorphism in asparagus. To date, no sex determining gene has been isolated from asparagus. To identify more genes involved in flower development in asparagus, subtractive hybridization library of male flowers in asparagus was constructed by suppression subtraction hybridization. A total of 107 expressed sequence tags (ESTs) were identified. BLASTX analysis showed that the library contained several genes that could be related to flower development. The expression patterns of seven selected genes believed to be involved in the development of asparagus male flower were further analyzed by semi-quantitative or real-time reverse-transcription polymerase chain reaction (RT-PCR). Results showed that AOEST4-5, AOEST12-40, and AOEST13-38 were strongly expressed in the male flower stage, whereas no transcript level of AOEST13-38 was detected in the female flower stage. The expression levels of AOEST13-87, AOEST13-92, AOEST13-40, and AOEST18-87 in the male flower stage were also higher than those in the female flower stage, although these transcripts were also expressed in other tissues. The identified genes can provide a strong starting point for further studies on the underlying molecular differences between the male and female flowers of asparagus.

DNA methylation has been implicated in the regulation of gene expression, genome imprinting, and chromatin remodeling in eukaryotes. In this study, we analyzed possible alterations in levels and patterns of cytosine methylation in male and female spinach plants after treatment with demethylation agent 5-azacytidine (5-azaC) using two methods: (1) direct determination of 5-methylcytidine (5 mC) amounts in genomic DNA by high-performance liquid chromatography (HPLC) separation and quantification of nucleosides and (2) methylation-sensitive inter-simple sequence repeat (MS-ISSR) technique. HPLC analysis revealed that the DNA methylation events in male and female spinach leaves markedly decreased upon 30 μM 5-azaC treatment, and the methylation level gradually decreased with the increase in 5-azaC concentration. To study the altered DNA methylation patterns in spinach after 5-azaC treatment, untreated and 500 μM 5-azaC-treated samples were analyzed by MS-ISSR assay. A total of 385 informative profiles were resolved using 35 ISSR primer sets. MS-ISSR analysis showed various altered methylation patterns between untreated and 5-azaC-treated spinach plants. These alterations were mainly demethylation events, which were largely consistent with the HPLC results. Both HPLC and MS-ISSR analyses showed that the changes in DNA methylation levels and patterns were similar in male and female spinach leaves, which implies that sex was not the main factor influencing DNA methylation levels and patterns in the vegetative organs of spinach. This study could provide a molecular basis of the altered DNA methylation induced by 5-azaC, and lay a foundation for further investigation of the relationship between methylation and sex determination and development in this dioecious plant spinach.

To identify rapidly a number of genes probably involved in sex determination and differentiation of the dioecious plant Asparagus officinalis, gene expression profiles in early flower development for male and female plants were investigated by microarray assay with 8,665 probes. In total, 638 male-biased and 543 female-biased genes were identified. These genes with biased-expression for male and female were involved in a variety of processes associated with molecular functions, cellular components, and biological processes, suggesting that a complex mechanism underlies the sex development of asparagus. Among the differentially expressed genes involved in the reproductive process, a number of genes associated with floral development were identified. Reverse transcription-PCR was performed for validation, and the results were largely consistent with those obtained by microarray analysis. The findings of this study might contribute to understanding of the molecular mechanisms of sex determination and differentiation in dioecious asparagus and provide a foundation for further studies of this plant.

Ion implantation, as a new biophysically mutagenic technique, has shown a great potential for horticultural plant breeding. Up to date, little is known about the mutation mechanism of ion implantation at the DNA level. To reveal the mutation effect of Fe+ ion implantation on Baiyangdian red lotus, the random amplified polymorphic DNA (RAPD) was used, and then the bands of mutants and the control in the radiation-sensitive sites were cloned to be sequenced for comparing their DNA sequences. The results indicated that the total base mutation rate of mutants was 0.87%, and there was different in the six mutants. The types of base changes included base transition, transversion, deletion, and insertion. Among the 159 base changes detected, the frequency of single base substitutions (61.01%) was higher than that of base deletions and insertions (38.99%), and the frequency of base transitions (44.65%) was 2.7 times of that of the base transversions (16.35%). The transitions between C and T accounted for largest proportion, A→G transitions and A→T transversions were also present at high frequency. Adenine, thymine, guanine or cytosine could be replaced by any of other three bases, except that there was no C → G substitution. However, thymine was more sensitive to the irradiation than other bases. In our study, we found many purine bases around the purine mutational sites, and many pyrimidine bases around the pyrimidine mutational sites. These will further help us to understand the mechanism of mutagenesis by ion implantation.

Suppression of recombination is the prerequisite for plant sex chromosome evolution from a pair of autosomes. Recombination suppression around the locus controlling sex determination results in sex chromosome degeneration and differentiation. Important events such as repetitive sequence accumulation, heterochromatize, and DNA methylation have relation to recombination suppression. Accumulation of repetitive DNA sequence, including transposable elements and satellite DNA, leads to primitive sex chromosome differentiated on morphological and molecular structure, and also gives rise to chromosome heterochromatize, and thus recombination between sex chromosomes was suppressed. Here, we re-viewed the advances in this field, meanwhile, the function of DNA methylation in recombination suppression was analyzed.

In dioecious plants, the important differences of male and female individuals exist in the genome, so it is very significant to do a comparative study on the sex differences with the DNA markers. In this article, Random Amplification Polymorphic DNA (RAPD) technology was used to increase the Humulus scandens female and male genome teams. The results show that two of the 100 primers, S1519 and S2142, respectly produced a sex-linked band only found in tested males, with the length of 1207 bp and 762 bp. These fragments were cloned and sequenced and then aligned with the GenBank database by BLAST, finding that they are abundant in AT (individually 64%, 54.7%), and no sequence was significantly similar. The RAPD markers were then converted into male-linked SCAR (Sequence Characterized Amplified Regions) markers.

Multiple-PCR was conducted to establish a stable PCR system for identifying the three Wx genes in wheat. Two pairs of primers were employed to amplify Wx-A1, Wx-B1, and Wx-D1 genes of wheat, with the target sequences of 230 bp/265 bp, 854 bp, and 204 bp, respectively. The results showed that Wx-A1, Wx-B1, and Wx-D1 can be detected simultaneously in a single reaction. This method proved to be repeatable and low cost for evaluation of wheat quality properties in breeding program. This multiple-PCR technique can be efficiently used in marker-assisted selection for Wx genes, which will improve selection procedure for waxy wheat.

Sex-linked molecular markers are being obtained, which would be essential to be used in the screening of different sex of dioecious plants at the seedling stage. Furthermore, it is important in cloning the gene related to the sex. In this study the random amplified polymorphic DNA (RAPD) technique was employed with the objective to find markers linked to sex determination in Asparagus. A total of 100 primers were tested with the same PCR cycling procedure. A female-associated fragment with a length of about 867bp was generated with S12 primer. The fragment was cloned and sequenced, showing it is abundant in AT and contains 2 shorter open reading frames. In order to convert the RAPD marker into SCAR (sequence characterized amplified regions) marker, 24bp specific primers were constructed and used for PCR amplifying. The female-linked dominant SCAR marker was obtained, which would be efficient to identify the different sex of Asparagus officinalis L.

Lycoris longituba Y. Hsu et Q. J. Fan is a perennial, bulbiferous, herbaceous plant of the family Amaryllidaceae. It is endemic in China, with a very limited distribution, being found only at Langyashan in Anhui province, and Baohuashan and Xuyi city in Jiangsu province, all located about 50 km from one another (see figure 1 and table 1 in electronic supplementary material at http://www.ias.ac.in/jgenet/). A unique biological characteristic of this plant is that its leaves come out in spring and die in early summer, followed by flowering. Thus, its vegetative growth and reproduction are discrete, which is rare in angiosperms. With a vigorous and long scape, its flowers are diverse in both colour and floral form, and fragrant in smell, and have high ornamental value. Also called Chinese tulip, this species is ideal for ikebana, and its bulb has medicinal properties. We have collected more than 70 variants of this species in our laboratory with different floral colours and forms. Population-genetic structure is considered as spatiotemporal distribution of genetic variation (Ge 1997), and reflects evolutionary processes in populations (Hamrick and Loveless 1989). To take right measures to protect wild resources of L. longituba, it is important to study the range of genetic variation, genetic structure, diversification trend and other factors affecting genetic structure of the populations of this important and sparsely distributed species. Presently, many biochemical and DNA-based markers are used in studies of population structure. The random amplified polymorphic DNA (RAPD) method (Williams et al. 1990) is frequently applied to reveal population-genetic variation, divergence and biogeography (Schaal and Leverich 2001). A large number of studies have successfully applied this method to study genetic variation in plants owing to