国产蔷薇科苹果亚科的花粉形态

对国产蔷薇科（Ｒｏｓａｃｅａｅ）苹果亚科（Ｍａｌｏｉｄｅａｅ）１６属１８种及１变型进行了植物花粉形态的光学显微镜和扫描电镜观察。本亚科花粉呈单粒存在,花粉近球形至长球形,极面观常呈三裂圆形,赤道面观椭圆形至圆形。本亚科的花粉在全科中是最大的,极轴为１８．６２～４５．６５μｍ,赤道轴为１８．３６～４０．８μｍ。最大花粉见于Ｃｒａｔａｅｇｕｓ ｐｉｎｎａｔｉｆｉｄａ,为（２８．８５～４５．６５）μｍ     

Typification of some Maloideae (Rosaceae) commonly cultivated in Norden

In connection with a contribution of various genera of Maloideae (Rosaceae) to "Flora Nordica" lectotypes are designated for Crataegus sanguinea, C. punctata, Pyrus japonica (‵ Chaenomeles japonica ), Crataegus pyrifolia (‵ Photinia pyrifolia ), and Pyrus floribunda (‵ Photinia floribunda ) . A lectotype and an epitype is selected for Mespilus flabellata (‵ Crataegus flabellata ) . — Flora Nordica note no. 23.     

Floral morphology of Maloideae (Rosaceae) and its systematic relevance

Flowers of 169 species of Rosaceae subfamily Maloideae, which were chosen to represent the taxonomic and geographic diversity of the group, were studied to ascertain their morphological variation and its systematic relevance. We describe and illustrate variation in size, indumentum, color, and macroscopic structural features. Most maloid species have syncarpous flowers with two to five carpels in which the ovary is at least three-quarters inferior, whereas species of other Rosaceae subfamilies have apocarpous or unicarpellate flowers with superior ovaries. However, maloid flowers show significant variation in the degree of carpel connation and of ovary adnation to the hypanthium. Cotoneaster, Heteromeles, and Pyracantha are completely apocarpous, and Dichotomanthes is perigynous with a completely superior ovary. Thus, no one floral character is sufficient to separate the Maloideae from other subfamilies of Rosaceae. Differences among their flowers support our recognition of Malus, Pyrus, and Sorbus as separate genera. Further, we argue for removal of Docyniopsis and Eriolobus from Malus, division of Sorbus into several genera, and union of Aronia, Photinia, and Stranvaesia. No floral characters support the traditional dichotomy of the subfamily into tribes Crataegeae and Sorbeae.     

S-allele diversity in Sorbus aucuparia and Crataegus monogyna (Rosaceae: Maloideae)

RT-PCR was used to obtain the first estimates from natural populations of allelic diversity at the RNase-based gametophytic self-incompatibility locus in the Rosaceae. A total of 20 alleles were retrieved from 20 Sorbus aucuparia individuals, whereas 17 alleles were found in 13 Crataegus monogyna samples. Estimates of population-level allele numbers fall within the range observed in the Solanaceae, the only other family with RNase-based incompatibility for which estimates are available. The nucleotide diversity of S-allele sequences was found to be much lower in the two Rosaceae species as compared with the Solanaceae. This was not due to a lower sequence divergence among most closely related alleles. Rather, it is the depth of the entire genealogy that differs markedly in the two families, with Rosaceae S-alleles exhibiting more recent apparent coalescence. We also investigated patterns of selection at the molecular level by comparing nucleotide diversity at synonymous and nonsynonymous sites. Stabilizing selection was inferred for the 5' region of the molecule, while evidence of diversifying selection was present elsewhere.     

Population structure at the S-locus of Sorbus aucuparia L. (Rosaceae: Maloideae)

Low sequence divergence within functional alleles is predicted for the self-incompatibility locus because of strong negative frequency-dependent selection. Nevertheless, sequence variation within functional alleles is essential for current models of the evolution of new mating types. We genotyped the stylar self-incompatibility RNase of 20 Sorbus aucuparia from a population in the Pyrenees mountains of France in order to compare alleles found there to those previously sampled in a Belgian population. Both populations returned 20 different alleles from samples of 20 individuals, providing maximum-likelihood estimates of 24.4 (95% CI 20-34) alleles in each. Ten alleles occurred in both samples. The maximum likelihood (ML) estimate of the overlap in the alleles present in both populations was 16, meaning that an estimated eight alleles are private to each population, and a total of 32 alleles occur across the two populations examined. We used Fisher's (1961) missing plot method to estimate that 40 alleles occur in the species. In accord with population genetics theory, we observed at most one synonymous sequence difference between copies of alleles sampled from the different populations and no variation within populations. Phylogenetic analysis shows that nearly every allele in S. aucuparia arose prior to divergence of this species from members of three different genera of the Rosaceae subfamily, Maloideae. Lack of observable sequence variation within alleles, coupled with the slow pace of allelic relative to taxonomic diversification, implies that finding intermediate stages in the process of new allele creation will be difficult in this group.     

Phytoalexin induction in the sapwood of plants of the Maloideae (Rosaceae): Biphenyls or dibenzofurans

Following fungal inoculation or natural infection, five biphenyl phytoalexins (aucuparin and its 2′ and 4′ oxygenated derivatives) were induced variously in the sapwood of Aronia, Chaenomeles, Eriobotrya, Malus(three spp.) and of Sorbus aucuparia. By contrast, 14 dibenzofuran phytoalexins were induced variously in sapwood of Cotoneaster (7 spp.), Crateagus, Cydonia, Mespilus, Photinia, Pseudocydonia, Pyracantha, Pyrus and two Sorbus spp. (S. chamaemespilum and S. domestica). These were five cotonefurans, three eriobofurans, five pyrufurans and a 2,3,4,7,8-pentaoxygenated dibenzofuran trimethyl ether. No plant has yet been found to produce both types of phytoalexin, although o-hydroxybiphenyls are theoretically precursors of the dibenzofurans. The ability to synthesize either biphenyls or dibenzofurans appears to be genus-specific, except in the case of Sorbus. In 18 of the 38 species tested, these phytoalexins were accompanied by constitutive antifungal phenolics, most of which appeared to be released from bound (glycosidic) forms during the infection process. These were identified variously as hydroquinone, p-hydroxyacetophenone, acetovanillone, 5,7-dihydroxychromone, chrysin, sakuranetin and naringenin. Woody members of the subfamilies Prunoideae and Spiraeoideae failed to yield any phytoalexins on induction, but did contain constitutive antifungal compounds. The limited frequency of the phytoalexin response within the family as a whole is considered in relation to the accumulation of constitutive antifungal agents in these plants.     

黑龙江苹果亚科5属14种植物导管分子形态结构研究

利用扫描电子显微镜对黑龙江苹果亚科5属14种植物导管分子的管腔微形态结构特征进行了比较研究。结果显示:(1)该亚科植物导管分子的管腔长度、宽度及端壁斜度角有较大的差别。(2)孔纹导管在该亚科植物种中均存在,网纹导管和螺纹导管仅见于苹果属和花楸属中。(3)导管分子管壁除苹果属及山楂属中的毛山楂、辽宁山楂外均有螺纹加厚。(4)纹孔的排列方式为互列式、对列式及互列、对列同时存在。(5)在所观察的植物中花楸、山荆子、无毛山楂导管端壁具单穿孔板和梯状穿孔板,其余种的导管端壁仅具单穿孔板。(6)导管纹孔膜残留现象普遍存在。研究表明,导管分子管腔的微形态结构特征,可为该亚科植物的系统演化提供形态学依据;导管分子微形态结构特征与其所处的环境存在一定的适应性。     

Chloroplast DNA haplotype variation and population differentiation in Sorbus aucuparia L. (Rosaceae: Maloideae)

Intra-specific chloroplast DNA (cpDNA) variation was studied in Sorbus aucuparia L., an entomophilous, mid-or early successional tree producing fleshy fruits. Eight PCR-amplified fragments of the chloroplast genome were screened for restriction fragment length polymorphisms, using one or two 4 bp-cutter restriction endonucleases. cpDNA variation was investigated on two geographical scales: (1) among four regions in France and Belgium; and (2) within the Belgian region. A total of 150 individuals from six populations were analysed. Fourteen polymorphisms were detected in six of the cpDNA fragments. All polymorphisms probably resulted from insertions or deletions, and allowed the identification of 12 haplotypes. The level of genetic differentiation computed on the basis of haplotype frequencies was similar on the two geographical scales considered (G(STc) = 0.286 among regions, G(STc) = 0.259 among populations within the Belgian region). These values are much lower than those obtained in nine previously studied temperate tree species, which are all wind-pollinated, late-successional species producing dry fruits. These results might primarily be accounted for by the contrasting life history traits of S. aucuparia. In order to obtain insights into the relative contribution of pollen and seeds to gene flow, G(STc) was also compared with previously obtained G(ST) estimates based on allozyme data.     

Pericarp anatomy of wild roses (Rosa L., Rosaceae)

The pericarp anatomy of representatives of all subgenera and sections of the genus Rosa was studied. All species have the same basic pericarp structure: it is composed of inner and outer endocarps, mesocarp and exocarp formed by the epidermis and hypodermis. The differences concern mainly the thickness of particular layers, and the shape and size of their cells. Cells of the endocarp and mesocarp are thick-walled. The only exception is Rosa rugosa mesocarp, which is composed of rather thin-walled cells with a large lumen. The endocarp structure of Rosa achenes resembles the drupe of the genus Prunus s.l. and drupelets of Rubus species.     

Phylogeny of subtribe Pyrinae (formerly the Maloideae, Rosaceae): Limited resolution of a complex evolutionary history

Generic relationships in the Pyrinae (equivalent to subfamily Maloideae) were assessed with six chloroplast regions and five nuclear regions. We also plotted 12 non-molecular characters onto molecular phylogenies. Chloroplast DNA trees are incongruent with those from nuclear regions, as are most nuclear regions with one another. Some of this conflict may be the result of hybridization, which occurs between many genera of Pyrinae in the present and may have occurred in the past, and duplication of nuclear loci. Sequence divergence between genera of Pyrinae, which is significantly less than that between genera of another large clade in Rosaceae, the Rosoideae, is concentrated in terminal branches, with short internal branches. This pattern is consistent with an ancient, rapid radiation, which has also been hypothesized from the fossil record. Even with about 500,000 bp of sequence, our results resolve only several small groups of genera and leave much uncertainty about phylogenetic relationships within Pyrinae.     

A variable minisatellite sequence in the chloroplast genome of Sorbus L. (Rosaceae: Maloideae).

The chloroplast genome is now known to be more variable than was once thought. Reports of RFLP (restriction fragment length polymorphism) and sequence variation, as well as variation in chloroplast microsatellites, are common. Here, data are presented on the variability of a minisatellite sequence in the chloroplast genome of Sorbus species. RFLP analysis of a PCR product comprising the region between the trnM and rbcL genes of nine Sorbus species identified seven size variants. Sequencing revealed the observed size polymorphism to be due to differences in the number of copies of an imperfect 9-bp motif. A more intensive survey of the variability of the minisatellite was undertaken in populations of Sorbus aucuparia. The potential uses of such regions in chloroplast DNA are discussed and a possible mechanism for the evolution of the minisatellite is presented.     

The origin of the apple subfamily (Maloideae; Rosaceae) is clarified by DNA sequence data from duplicated GBSSI genes

For 70 yr the leading hypothesis for the origin of the Maloideae has involved wide hybridization between ancestors of two other subfamilies. The basis of this hypothesis is that Maloideae have a base chromosome number of 17, whereas other Rosaceae are mostly x = 7, 8, or 9. To investigate this hypothesis we cloned and sequenced approximately 1.8 kilobases from the 5' portion of granule-bound starch synthase (GBSSI, or waxy) genes for 89 clones from 32 Rosaceae genera. Previous studies demonstrate the presence of two copies in all Rosaceae (GBSSI-1 and GBSSI-2) and four in Maloideae (GBSSI-1A, GBSSI-1B, GBSSI-2A, and GBSSI-2B). Parsimony and maximum likelihood analyses nest Gillenia, a genus of the southeastern United States with a base chromosome number of 9, within either Maloideae GBSSI-1 or GBSSI-2. Monophyly of Maloideae plus Gillenia is well supported by bootstrap values, loss of the sixth intron in all GBSSI-1 sequences, intron alignability between genera, and numerous nonmolecular characters. Our results falsify the wide-hybridization hypothesis and are consistent with a polyploid origin involving only members of a lineage that contained the ancestors of Gillenia. Under this hypothesis, the subfamily originated in North America, and the high Maloideae chromosome number arose via aneuploidy from x = 18.     

Perfect syncarpy in apple (Malus x domestica 'Summerland McIntosh') and its implications for pollination, seed distribution and fruit production (Rosaceae: Maloideae)

BACKGROUND AND AIMS: The gynoecium of the domestic apple, Malus x domestica, has been assumed to be imperfectly syncarpic, whereby pollination of each stigmatic surface can result in fertilization within only one of the five carpels. Despite its implied effect on fruit quantity and quality, the resulting influence of flower form on seed set and distribution within the apple fruit has seldom been investigated. Instead, poor fruit quality is usually attributed to problems with pollination, such as low bee numbers and/or ineffective pollinators within apple agro-ecosystems. The objective of this study was to determine the true nature of gynoecial structure and its influence on fruit production in the apple cultivar 'Summerland McIntosh'. METHODS: A stigma-excision method was used to determine the effects of uneven pollination among the five stigmas on fruit quantity (as measured by fruit set), and quality (seed number and distribution). In addition, flowers were examined microscopically to determine pollen tube pathways. KEY RESULTS: Fruit set, seed number, seed distribution, and the microscopic examination of flower gynoecial structure reported in this study indicated that the gynoecium of the cultivar Summerland McIntosh is perfectly syncarpic and not imperfectly syncarpic as previously thought. CONCLUSIONS: Pollination levels among the five stigmas need not be uniform to obtain full seed development within Summerland McIntosh fruit; even if one stigmatic surface is adequately pollinated, a full complement of seeds is likely. The importance of perfect syncarpy in recognizing true causes of poor fruit quality in apple is discussed.     

Polyunsaturated and Very‐Long‐Chain Fatty Acids Are Involved in the Adaptation of Maloideae (Rosaceae) to Combined Stress in the Mountains

One of the mechanisms of plant adaptation to combined stress under conditions of altitudinal zonation is changing the lipid fatty acid (FA) composition. The main changes in the FA composition occurred in the outer cell layers of the pericarp, but not in the parenchyma. Adaptation was found to be species‐specific. In Cydonia oblonga Mill . and Malus domestica Borkh ., the ratio of polyunsaturated 18:2 and 18:3 lipid FAs changed with increasing height, while a constitutive level of the unsaturation index (UI) and low contents of very‐long‐chain fatty acids (VLCFAs) were maintained. Mespilus germanica L. was characterized by a higher level of VLCFAs due to the high content of 20:0. The sum of VLCFAs in medlar increased by up to 16 % with changing altitude, which was accompanied by the changes in the ultrastructure of chloroplasts and a noticeable decrease in the UI. We attribute the differences in the adaptive strategies in C. oblonga, M. domestica and M. germanica to specific structural features of the pericarp peel. Despite different adaptation mechanisms, the studied species can grow equally successfully at the altitudes from 300 to 1200 m.     

Phylogenetic relationships in Maloideae (Rosaceae): evidence from sequences of the internal transcribed spacers of nuclear ribosomal DNA and its congruence with morphology

We used sequences from both internal transcribed spacers (ITS) and a small portion of the 5.8S gene of nuclear ribosomal DNA (nrDNA) for phylogenetic reconstruction of 19 genera of Maloideae and four potential outgroups from the Rosaceae. Parsimony analyses indicate that Maloideae are not monophyletic; Vauquelinia, which is traditionally placed in Spiraeoideae, and two genera of the Maloideae, Eriobotrya and Rhaphiolepis, form a well-supported clade that is the sister to the remainder of the subfamily. Although our ITS phylogenetic hypothesis is highly resolved, there is considerable homoplasy, and support, as indicated by bootstrap values and decay indices, is relatively weak for all groups except four: Eriobotrya-Rhaphiolepis-Vauquelinia, Crataegus-Mespilus, Amelanchier-Peraphyllum-Malacomeles, and Cydonia-Pseudocydonia. Our DNA sequence data do not support a broad interpretation of Sorbus. Intergeneric hybridization, which is prevalent in Maloideae, occurs between genera that are far removed from one another on our most-parsimonious trees. We infer an overall phylogeny from separate analyses of ITS DNA sequences and recently published morphological and wood anatomical studies of Maloideae and from analyses after pooling these data sets. The four most strongly supported clades of the ITS phylogeny appear in the phylogeny based on pooled data.     

North American black-fruited hawthorns. II. Floral development of 10- and 20-stamen morphotypes in Crataegus section Douglasii (Rosaceae: Maloideae)

Crataegus section Douglasii exhibits variation in stamen number per flower typical for the genus throughout North America. To understand the developmental basis for this variation we studied the early floral ontogeny of the three taxa in section Douglasii: C. douglasii (both Pacific northwest and the upper Great Lakes basin), C. rivularis, and C. suksdorfii. Crataegus suksdorfii, like all known diploid Crataegus, has ≈20 stamens; the two other taxa have ≈10 stamens, a condition associated only with polyploidy. In all taxa petal primordia and a whorl of five pairs of stamen primordia develop from five common primordia. The 10-stamen∗∗∗ condition results from loss of two whorls of five stamens that are subsequently formed in C. suksdorfii. Loss of these two whorls in the 10-stamen taxa is the result of neither a smaller floral apex at initiation, nor a smaller flower at anthesis. Stamen number variability, particularly in C. douglasii and C. rivularis, is the result predominantly of fewer than two stamen primordia developing between adjacent petal primordia. Pollen production in C. douglasii is half that in C. suksdorfii because of the reduction in stamen number. The results are presented and discussed in terms of morphogenetic explanations of meristic variation.     

Fine Structure of Cellular Inclusions in Pericarp Cells of Polysiphonia deusta (Ceramiales, Rhodophyta)

The ultrastructure of cytoplasmic inclusions in pericarp cells(cystocarpic plant) of Polysiphonia deusta shows five structuraltypes of inclusions; (1) membrane-bounded crystalloid inclusionsthat are composed of tetragonally packed fibrils, each 8 nmdiam., spaced 17.5 nm between centres; (2) membrane-boundedcrystalloid-like inclusions with incomplete structure; (3) unboundedcrystalline body without a distinct crystal lattice pattern;(4) membrane-limited fibrillar inclusions; (5) fibrillogranularstructure. The membranes of the first two inclusions were coveredwith ribosomes and seem to be elements of endoplasmic reticulum. Polysiphonia deusta, pericarp cells, cellular inclusions     

Decaploidy in Fragaria iturupensis (Rosaceae)

The strawberry genus, Fragaria (Rosaceae), has a base chromosome number of x = 7. Cultivated strawberries (F. ×ananassa nothosubsp. ananassa) are octoploid (2n = 8x = 56) and first hybridized from F. chiloensis subsp. chiloensis forma chiloensis × F. virginiana subsp. virginiana. Europe has no known native octoploid species, and only one Asian octoploid species has been reported: F. iturupensis, from Iturup Island. Our objective was to examine the chromosomes of F. iturupensis. Ploidy levels of wild strawberry species, include diploid (2n = 2x = 14), tetraploid (2n = 4x = 28), pentaploid (2n = 5x = 35), hexaploid (2n = 6x = 42), octoploid (2n = 8x = 56), and nonaploid (2n = 9x = 63). Artificial triploid (2n = 3x = 21), tetraploid, pentaploid, octoploid, decaploid (2n = 10x = 70), 16-ploid, and 32-ploid plants have been constructed and cultivated. Surprisingly, chromosome counts and flow cytometry revealed that F. iturupensis includes natural decaploid genotypes with 2n = 10x = 70 chromosomes. This report is the first of a naturally occurring decaploid strawberry species. Further research on F. iturupensis and exploration on northern Pacific islands is warranted to ascertain the phylogeny and development of American octoploid species.