Relationships betweenOryza species (Poaceae) based on 5S DNA sequences

Relationships between 9Oryza species, covering 6 different genomes, have been studied using hybridization and nucleotide sequence information from the5S Dna locus. Four to five units of the major size class of 5S DNA in each species, 55 units in all, were cloned and sequenced. Both hybridization and sequence data confirmed the basic differences between the A and B, C, D genome species suggested by morphological and cytological data. The 5S DNA units of the A genome species were very similar, as were the ones from the B, C, and D genome-containing species. The 5S DNA ofO. australiensis (E genome) grouped with the B, C, D cluster, while the units ofO. brachyantha (F genome) were quite different and grouped away from all other species. 5S DNA units fromO. minuta, O. latifolia, O. australiensis, andO. brachyantha hybridized strongly, and preferentially, to the genomic DNA from which the units were isolated and hence could be useful as species/genome specific probes. The 5S DNA units fromO. sativa, O. nivara, andO. rufipogon provided A genome-specific probes as they hybridized preferentially to A genome DNA. The units fromO. punctata andO. officinalis displayed weaker preferential hybridization toO. punctata DNA, possibly reflecting their shared genome (C genome).     

A biosystematic study of theOryza meyeriana complex (Poaceae)

To determine the taxonomic status and to clarify the biosystematic relationships of wild rice species, i.e.,Oryza granulata andO. meyeriana in theO. meyeriana complex (Poaceae), a series of intraspecific and interspecific hybridization experiments, genomic analyses through meiotic pairing, and morphological studies were conducted. Hybridization results demonstrate comparatively high crossability with about 34–39% of seed set, and very limited reproductive isolation betweenO. granulata andO. meyeriana. Chromosome pairing in the parental species and their F₁ hybrids indicate very high genomic affinity between the two taxa. Morphological analyses of the parental accessions and their intra- and interspecific hybrids show a large variation among the samples included, but no appreciable grouping was observed. The traditionally used character, i.e., spikelet length, does not contribute significantly to the grouping of the samples included. Based on the facts that the two taxa have negligible reproductive barriers and share almost identical genomes, the authors believe thatO. granulata andO. meyeriana do not warrant separate taxonomic status, and recommend that they be combined asOryza granulata.     

Seed morphology ofEuphorbia sectionTithymalopsis (Euphorbiaceae) and related species

Light and scanning microscopies were used to evaluate the sectional boundary of 17 species included by various authors inEuphorbia sectTithymalopsis. Based on seed shape, surface ornamentation, and mucilage formation, five seed morphological types were recognized in North American sectionTithymalopsis and related species. These results did not provide added support for recent treatment of the sectTithymalopsis s.s. However, a close relationship was suggested among species of theTithymalopsis subsectionCorollatae. In addition, including species from subsectionsInnocuae, Ipecacuanhae, andSphaerorhizae within sectTithymalopsis could not be justified, based on seed morphological data.     

Chloroplast DNA variation in diploid and polyploid species of Bromus (Poaceae) subgenera Festucaria and Ceratochloa

Summary Chloroplast DNA (cpDNA) restriction endonuclease patterns are used to examine phylogenetic relationships between Bromus subgenera Festucaria and Ceratochloa. Festucaria is considered monophyletic based on the L genome, while Ceratochloa encompasses two species complexes: the B. catharticus complex, which evolved by combining three different genomes, and the B. carinatus complex, which is thought to have originated from hybridization between polyploid species of B. catharticus and diploid members of Festucaria. All species of subgenus Ceratochloa (hexaploids and octoploids) were identical in chloroplast DNA sequences. Similarly, polyploid species of subgenus Festucaria, except for B. auleticus, were identical in cpDNA sequences. In contrast, diploid species of subgenus Festucaria showed various degrees of nucleotide sequence divergence. Species of subgenus Ceratochloa appeared monophyletic and phylogenetically closely related to the diploid B. anomalus and B. auleticus of subgenus Festucaria. The remaining diploid and polyploid species of subgenus Festucaria appeared in a distinct grouping. The study suggests that the B. catharticus complex must have been the maternal parent in the proposed hybrid origin of B. carinatus complex. Although there is no direct evidence for the paternal parent of the latter complex, the cpDNA study shows the complex to be phylogenetically very related to the diploid B. anomalus of subgenus Festucaria.     

Evolution of Ac and Dsl elements in select grasses (Poaceae)

We present data on evolution of the Ac/Ds family of transposable elements in select grasses (Poaceae). An Ac-like element was cloned from a DNA library of the grass Pennisetum glaucum (pearl millet) and 2387 bp of it have been sequenced. When the pearl millet Ac-like sequence is aligned with the corresponding region of the maize Ac sequence, it is found that all sequences corresponding to intron II in maize Ac are absent in pearl millet Ac. Kimura's evolutionary distance between maize and pearl millet Ac sequences is estimated to be 0.429±0.020 nucleotide substitutions per site. This value is not significantly different from the average number of synonymous substitutions for coding regions of the Adh1 gene between maize and pearl millet, which is 0.395±0.051 nucleotide substitutions per site. If we can assume Ac and Adh1 divergence times are equivalent between maize and pearl millet, then the above calculations suggest Ac-like sequences have probably not been strongly constrained by natural selection. The level of DNA sequence divergence between maize and pearl millet Ac sequences, the estimated date when maize and pearl millet diverged (25–40 million years ago), coupled with their reproductive isolation/lack of current genetic exchange, all support the theory that Ac-like sequences have not been recently introduced into pearl millet from maize. Instead, Ac-like sequences were probably present in the progenitor of maize and pearl millet, and have thus existed in the grasses for at least 25 million years. Ac-like sequences may be widely distributed among the grasses. We also present the first 2 Dsl controlling element sequences from teosinte species: Zea luxurians and Zea perennis. A total of 10 Dsl elements had previously been sequenced from maize and a distant maize relative, Tripsacum. When a maximum likelihood network of genetic relationships is constructed for all 12 sequenced Dsl elements, the 2 teosinte Dsl elements are as distant from most maize Dsl elements and from each other, as the maize Dsl elements are from one another. Our new teosinte sequence data support the previous conclusion that Dsl elements have been accumulating mutations independently since maize and Tripsacum diverged. We present a scenario for the origin of Dsl elements.     

Relationships between seven species ofVulpia (Poaceae)

Seven species ofVulpia were subjected to morphological and protein studies using principal component and cluster analysis and theJaccard's Similarity Coefficient. Studies showed all species were uniform and distinct from each other. Species of sect.Loretia were very dissimilar from those of sect.Monachne and sect.Vulpia. The latter section comprises taxa of high mutual affinity.     

Aulonemia yanachagensis (Poaceae: Bambusoideae: Bambuseae): A new species from central Peru

Aulonemia yanachagensis is described from cloud forests at 2600–3000 m elevation in the Parque Nacional Yanachaga-Chemillén Prov. Oxapampa, Dept. Pasco, Peru. It differs from all other congeners in its combination of prominent sheath auricles, with abundant radiate fimbriae, small foliage leaf blades, and awnless spikelets.     

中国禾本科植物新资料(I)

报道了2种禾本科植物,曲序黄花茅[Anthoxanthum flexuosum（Hook.f.）Veldkamp]在西藏的新分布,外来物种弗吉尼亚须芒草（Andropogon virginicus L.）在江西的归化,并提供了它们详细的形态学描述、图版、分布及生境等信息。此外,还讨论了弗吉尼亚须芒草的潜在入侵危险。     

赖草属植物的分类现状及主要存在的问题

赖草属(Leymus Hochst.)为禾本科(Poaceae)小麦族(Triticeae)中的一个有重要经济价值的属,属内多数种类是优良牧草,有些种类具有耐寒、耐旱、耐碱等特性,是农业良种繁育、畜牧业牧草改良利用的重要基因资源。该属在分类学上是一个疑难属,在属的界限、属下组系的划分,以及类群间演化关系上问题较多。对赖草属分类学问题进行了综述,为赖草属植物资源的开发利用和保护提供资料。     

Relationships between five species ofLolium (Poaceae)

Morphological analysis and electrophoresis of seed proteins of fiveLolium species disclosed that they form two distinct groups corresponding to those recognized from compatibility data.Lolium temulentum andL. remotum of the self-pollinated group were shown to be distinct but closely related species. Morphological intergradation and high similarities between protein profiles ofL. perenne, L. multiflorum andL. rigidum (cross-pollinated species) suggest little genetic differentiation between these taxa. This implies that treatment at the infraspecific level might better accomodate the data.     

高粱属植物的地理分布

为探讨高粱属(Sorghum Moench)的系统发育关系,通过野外调查及查阅标本和文献资料,对高粱属植物的地理分布进行了整理和研究。高粱属植物约有29种,分布于全世界热带到温带地区,其中澳大利亚22种,亚洲15种,非洲9种,欧洲3种,地中海2种,美洲6种。中国有5种,分布在东北、西南到华南各省(区)。高粱属有5亚属,仅高粱亚属(subgen.Sorghum)延伸至新世界,其他亚属均分布在旧世界,高粱亚属覆盖非洲并扩散到全世界热带到温带地区;拟高粱亚属(subgen.Parasorghum)分布在非洲、亚洲、澳大利亚;有柄高粱亚属(subgen.Stiposorghum)主要分布在澳大利亚,个别种分布到亚洲;多毛高粱亚属(subgen.Chaetosorghum)分布在澳大利亚;异高粱亚属(subgen.Heterosorghum)分布在澳大利亚和亚洲。这表明澳大利亚东北部是高粱属的现代分布中心和多样化中心,非洲东北部和热带亚洲是否是高粱属的起源地尚需确证。     

禾本科燕麦属植物的地理分布

为探讨燕麦属(Avena L.)植物的地理分布,通过野外调查及查阅标本和文献资料,对燕麦属植物的地理分布进行整理和研究。结果表明,燕麦属植物约有29种,主要分布在欧洲、地中海地区、北非、西亚、东亚和美洲。中国有4种,分布于华北、西北、西南各省(区)的高海拔地区。燕麦属下分7个组,分别是多年生燕麦组[sect.Avenotrichon(Holub)Baum]、偏凸燕麦组(sect.Ventricosa Baum)、耕地燕麦组(sect.Agraria Baum)、软果燕麦组(sect.Tenuicarpa Baum)、埃塞俄比亚燕麦组(sect.Ethiopica Baum)、厚果燕麦组(sect.Pachycarpa Baum)和真燕麦组(sect.Avena)。其中,埃塞俄比亚燕麦组分布在埃塞俄比亚、沙特阿拉伯、也门,其他6个组分布在欧洲、地中海、西北非洲、西亚、东亚和美洲地区。地中海、西北非洲、西亚地区分布有除埃塞俄比亚燕麦组之外的所有6个组,因此推断该地区可能是燕麦属的现代分布中心和多样性中心,而燕麦属的起源地尚需确证。     

Comparative seed morphology and character evolution in the genus Lysimachia (Myrsinaceae) and related taxa

Summary We investigated seed morphology in 34 species of the genus Lysimachia and in 14 species and two subspecies of six additional genera (Anagallis, Ardisiandra, Asterolinon, Glaux, Pelletiera, Trientalis), which have been shown to be closely related to, or are placed within Lysimachia in previous molecular studies. We studied seed shape, seed coat structure, and seed coat surface patterns. Three major types of seed shape were identified: (1) sectoroid, (2) polyhedral, and (3) coarsely rugose with concave hilar area. In addition, seeds may be keeled or winged. The outer layer of the seed coat is either sponge-like and adhering only loosely to the inner seed coat or it is thin and tightly adhering to the underlying tissue. Seed surface patterns can be divided into six main types: (1) reticulate, (2) tuberculate, (3) vesiculose, (4) colliculate, (5) undulate, or (6) poroid-alveolate. Seed surface patterns are mostly congruent with molecular phylogenetic relationships. A reticulate surface pattern is diagnostic of, e.g. Lysimachia subgenera Palladia and Hawaiian Lysimachiopsis. Mapping seed characters onto a recent phylogenetic tree, reveals that they provide potentially synapomorphic character states for various subclades of Lysimachia. Salient examples include a rugose seed shape, which turns out to be synapomorphic for the clade comprising the genus Pelletiera plus Asterolinon linum-stellatum and a sponge-like outer seed coat layer, which characterizes a clade with Lysimachia vulgaris, L. thyrsiflora, and L. terrestris, with an analogue that apparently evolved in parallel in Trientalis europaea. We also discuss possible habitat factors that may have favored the independent evolution of particular seed types such as winged seeds in various lineages.     

In vitro shoot culture of wild Oryzae and other grass species

A method was developed for the in vitro clonal propagation of shoots from a range of wild rice and other grass species that have important genetic traits such as drought resistance and salinity tolerance. The axenic multiple shoot cultures, which were suitable for DNA and protein extraction or direct protoplast isolation, could be maintained without subculture for between 2 and 3 months or rapidly multiplied for the subsequent production of mature plants and seeds. Basal sections of the micropropagated shoots also provided novel explants for the production of highly embryogenic callus, from some species, that could be regenerated into green plants. It is envisaged that this clonal propagation technique could aid the genetic manipulation of cultivated rice by providing a means to vegetatively conserve valuable genetic resources, a technique to rapidly multiply novel hybrid material and a source of embryogenic callus that will allow the application of biotechnological techniques, such as somatic hybridization and genetic transformation, to previously unexploited species.Abbreviations BA N⁶-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - PAR photosynthetically-active radiation     

CHy-banding patterns and chromatin organization inAegilops andTriticum species (Poaceae)

The distribution of CHy-banded heterochromatin was studied in the chromosomes ofAegilops longissima, Ae. speltoides, Triticum monococcum, andT. turgidum. Interphase nuclei were measured after Feulgen staining at different thresholds of optical density; the curves so obtained indicated the relationship among the species with respect to the different fractions of the genomic DNA. The karyological and cytophotometric analyses indicate differences betweenAe. speltoides andAe. longissima, the latter species being enriched in heterochromatin. Similar results were demonstrated for the genusTriticum, in whichT. turgidum showed more heterochromatin when compared withT. monococcum. The results suggest that the B genome of the cultivated wheats possesses a type of heterochromatin that resembles the type present inAe. longissima.     

Unusual chromosome pairing and B chromosomes inBriza spicata (Poaceae)

One plant from a population ofBriza spicata (Poaceae) was found to have highly irregular meiotic behaviour. It is characterized by having a reduced chiasma frequency, a large between cell variance in chiasma frequency and the formation of multivalents involving pairs of A chromosomes. The B chromosome present in this plant also forms multivalents with a pair of A chromosomes. It is suggested that the normal control of strict bivalent pairing has broken down and homoeologous chromosomes are associating as multivalents. Furthermore, the partial homology of the B chromosome with a pair of A chromosomes is revealed.     

Comparative RFLP mapping of an allotetraploid wild rice species (Oryza latifolia) and cultivated rice (O. sativa)

The purpose of this study was to construct a comparative RFLP map of an allotetraploid wild rice species, Oryza latifolia, and to study the relationship between the CCDD genome of O. latifolia and the AA genome of O. sativa. A set of RFLP markers, which had been previously mapped to the AA genome of cultivated rice, were used to construct the comparative map. Fifty-eight F₂ progeny, which were derived from a single F₁ plant, were used for segregation analysis. The comparative RFLP map contains 149 DNA markers, including 145 genomic DNA markers from cultivated rice, 3 cDNA markers from oat, and one known gene (waxy, from maize). Segregation patterns reflected the allotetraploid ancestry of O. latifolia, and the CC and DD genomes were readily distinguished by most probes tested. There is a high degree of conservation between the CCDD genome of O. latifolia and the AA genome of O. sativa based on our data, but some inversions and translocations were noted.     

Variation of silica bodies in leaf epidermal long cells within and among seventeen species of Oryza (Poaceae)

Morphometric procedures were used with scanning electron microscopy backscattered images to study silica bodies in epidermal long cells of four different leaf veins of 17 of the 20 species of Oryza. The veins studied were midrib, large vein, small vein, and marginal vein. Image analysis was used to study morphological variations among the silica bodies. Statistical analyses were based on 11 variables. Even within a single leaf, silica bodies were not uniform. However, the degree of morphological variation normally showed a distribution of morpholgical types around one modal shape. The most significant differences observed were between silica bodies of the midrib and those of other veins. Bodies varied with respect to both size and shape. Computer-assisted image analysis is an effective tool for categorizing basic data and for statistical analysis of variation among silica bodies. Morphological variation among silica bodies of a single leaf may be related to water-conducting systems and their influence on silica availability and phytolith formation.     

Relationships between three species ofFestuca sect.Bovinae (Poaceae)

Seed protein electrophoresis confirms the existence of polymorphism among hexaploid populations ofFestuca arundinacea. Both protein and morphological results suggest thatF. pratensis andF. arundinacea should retain independent specific status. High protein homology of these two species withF. gigantea points towards phylogenetic links between these taxa.