The genus Colpodium (Gramineae) in Africa

Recent collections of the genus Colpodium from Ethiopia and South Africa made a renewed revision of the African material of this genus desirable. Apart from the two earlier recognized African species ( C. chionogeiton and C. hedbergii ) a third one is described (C. drakensbergense ), restricted to the Drakensberg area of eastern Lesotho and amply distinct both in morphology and chromosome number. The phytogeographical position of Colpodium is briefly discussed.     

Genome relationships in the genus Dasypyrum (Gramineae)

To elucidate the genome relationships in the genus Dasypyrum and the ancestry of tetraploid D. breviaristatum, two cytotypes of D. breviaristatum and D. villosum were reciprocally crossed with one another. Chromosome pairing at the first metaphase of meiosis and fertility were examined in the F1 hybrids and the parental plants. The mean pairing configuration and mean arm pairing frequency in D. villosum-D. breviaristatum (2x) hybrids were 11.12I + 1.44II per cell and 0.107, respectively, and they were almost completely sterile. In D. breviaristatum (4x)-D. breviaristatum (2x) hybrid, up to seven trivalents were formed, and the mean pairing configuration was 3.38I + 3.20II + 3.74III + 0.005IV per cell. The mean arm pairing frequency and relative affinity calculated in that F1 hybrid were 0.915 and 0.641, respectively. Seven bivalents and seven univalents were characteristically formed in D. villosum-D. breviaristatum (4x) hybrids. Based on the present results, we clearly concluded that the genome of diploid D. breviaristatum is distantly related to the genome V of D. villosum, and that these two species have different basic genomes. We, therefore, proposed the symbol Vb for the haploid genome of diploid cytotype of D. breviaristatum. Moreover, we concluded that tetraploid D. breviaristatum is an autotetraploid with doubled sets of the genomes homologous with that of diploid D. breviaristatum, and we proposed the genome constitution VbVb for the haploid genome set of tetraploid cytotype of D. breviaristatum. Furthermore, from the chromosome pairing in the F1 hybrids involving Moroccan and Greek accessions, it was suggested that complicated rearrangements of chromosome structure have occurred in tetraploid D. breviaristatum in its natural populations across the entire distribution area.     

The cytology of the genus Alopecurus (Gramineae)

For a study of hybridization in Alopecurus , chromosome numbers, karyotypes, meiotic chromosome behaviour and breeding systems have been investigated in six species. In addition to confirming many previous chromosome numbers, new triploid and tetraploid counts have been found in A. bulbosus , which have not previously been reported. The karyotypes of all species have a very similar morphology but there are differences in chromosome size which can be related to differences in nuclear DNA content. At meiosis the diploid species form bivalents, but one population of A. aequalis contains plants that regularly form a single quadrivalent which would appear to be interchange heterozygotes. The meiotic behaviour of the tetraploids suggests that A. pratensis is an allotetraploid and A. geniculatus an autotetraploid. All species appear to be allogamous, although some, such as A. myosuroides are obligate outbreeders resulting from the presence of a self-incompatibility system, outbreeding is promoted in others by differences in the time of maturity of stigmas and anthers.     

The cytology of the genus Briza L. (Gramineae)

Chromosome numbers have been determined and karyotypes studied in several species of the genus Briza L. Nuclear DNA amounts have also been determined for some of the species and show a considerable variation between the species. The evolution of the karyotypes, particularly that of B. minor, is discussed and an attempt made to relate nuclear DNA content to karyotypes, breeding systems and habit in the different species.     

Quantitative nuclear DNA changes inEleusine (Gramineae)

2C nuclear DNA amounts were determined in 30 collections belonging to 10 species ofEleusine. About a 2.5-fold variation in genome size is evident in the genus. The 2C DNA amount in the diploid species ranged from 2.50 pg inE. verticillata to 3.35 pg inE. intermedia. In contrast, the tetraploid species showed a range from 4.95 pg inE. africana to 6.13 pg inE. floccifolia. At intraspecific level 10 collections ofE. coracana, 6 ofE. indica, 4 ofE. africana, 2 ofE. tristachya, and 2 ofE. kigeziensis did not show any significant variation. However, 2 collections ofE. floccifolia, connected with polyploidy, displayed about 90% variation. Polyploid species showed approximately double the genome size of that of their corresponding diploids. An evolutionary increase in DNA amount is evident inE. coracana during the course of its origin and domestication fromE. africana.     

Effect of 2,4-D on Seedling Physiology and Cytogenetical Studies in Triticum aestivum and Phalaris minor ( Gramineae )

Effects of 2, 4 -D on seedling growth and chromosomal abnormalities were studied in Triticum aestivum and Phalaris minor. Seeds were soaked at different concentrations of 2,4 -D （0.01%, 0.1%, 1.0% ） for 4, 8, 12 and 16 hours. 2,4-D suppressed the germination more severely in P. minor than in T. aestivum. Shoot and root length was retarded with the increase of concentration and time of treatment in both species. Generally radical was more negatively affected than coleoptile and emergence of radical was not observed at 1.0% concentration at 8, 12, and 16 hours of treatment in T. aestivum while in P. minor there was a total lack of radical emergence at 1.0% concentration for all durations of treatment. Stiff and curled roots and undifferentiated callus like scutellar tissues were observed in T. aestivum, while in P. minor the coleoptile obtained was lean, pale green in colour and was lying flat on filter paper. Mitotic index decreased, while chromosomal abnormalities, bridges and laggards were increased with the increase of concentration and soaking time however, laggards were not observed in T. aestivum. Clumping and chain formation of chromosomes at metaphase was also noticed in P. minor.     

A new species of arthropogon (Gramineae: Arthropogoneae) and a revised key for the genus

Arthropogon bolivianus is described as a new species. A revised key for the seven species of the genus is provided.     

Nuclear DNA content in the genus Hepatica (Ranunculaceae)

Using flow cytometry, we measured the nuclear DNA contents of all known taxa in Hepatica. Nuclear DNA content of Hepatica falconeri (diploid, crenate leaf lobes) was significantly lower than that of diploid entire species. Among the tetraploid species, crenate species had lower DNA contents than the entire taxon H. nobilis var. pubescens. The DNA content of the tetraploid species was more than double that of the diploid species among the same leaf-type groups.     

Apomixis in Eremopogon foveolatus (Gramineae)

The investigation deals with the reproductive behaviour in Eremopogon foveolatus (Del.) Stapf, a member of the tribe Andropogoneae. The magaspore mother cell or the products of its meiotic division degenerate in a majority of ovules and four–nucleate unreduced embryo sacs are formed from the surrounding cells of the nucellus. Eight–nucleate reduced embryo sacs are also formed in some ovules but the percentage of such ovules is very low. The unreduced egg develops parthenogenetically but fertilization of the polar nucleus appears to be essential for the formation of endosperm.     

Chromosome studies on the Bambusoideae (Gramineae)

Meiotic chromosome numbers and observations were made in eleven species belonging to nine different genera of Bambusoideae. The numbers include counts in eight species that have never been investigated cytologically:Arundinaria aff.amabilis (n=24), Chusquea bambusoides (n=ca. 20),Cryptochloa dressleri (n=11), Olyra ciliatifolia (n=11), Sucrea monophylla (n=11), Raddia brasiliensis (n=11), Strephium distichophyllum (n=11), andPariana aurita (n=22). The generaStrephium andSucrea have not been studied previously with respect to their chromosomes. The significance of these results are discussed in relation to the over 140 published counts in the subfamily, which indicates a preponderance of polyploidy in the woody members, or bamboos, but not in their herbaceous allies. Aneuploidy is rare in the former but frequent in the latter. It is postulated that the herbaceous bambusoids, which flower every year and produce recombinants regularly and in short-time cycles, could have tolerated successive reductions of the linkage groups and their genetic flexibility. These changes would not have been favored in the bamboos, which have more genetic constancy due to the long lapse (often 20–120 years) between flowering generations.     

Nucellar degeneration inCortaderia (Gramineae)

Summary Vigorous degradation of nucellar tissue in the apomictic grassCortaderia jubata is associated with early degeneration of the megaspore mother cell and the subsequent enlargement of several cells to form somatic embryo sacs. Nucellar degeneration is recognised by the separation of the nuclear membranes, at first along only small sectors of the nucleus, and the appearance within the enlarging perinuclear space of vesicles formed by blebbing of both the inner and outer membranes of the nuclear envelope. Invaginations of the bounding membrane of the dilating RER are responsible for many single-membrane-bound vesicles lying in cisternae throughout the cytoplasm. Eventually the nucleus, enclosed mainly in the inner nuclear membrane, and the cytoplasm, are subject to extensive vesicularization. An electron opaque substance is present in the perinuclear space, in the ER, in vacuoles, and outside the plasmalemma adjacent to the degenerating cell wall, and is similar to a substance which appears on the inner and outer membrane surfaces of mitochondria during later stages of cell degeneration. It is suggested that the genesis and growth of embryo sacs inC. jubata are linked with a programmed nucellar cell autolysis.     

Phytogeographical studies ofCalamagrostis sachalinensis (Gramineae)

Chromosome numbers were determined on 223 collections ofCalamagrostis sachalinensis from 18 localities in Japan. The plants were found to be tetraploid (2n=28), hexaploid (2n=42) or octoploid (2n=56). A few collections were found to include one or two B-chromosomes. The tetraploid collections were made from central Honshu and Mt. Apoi in Hokkaido, while the hexaploids and the octoploids were detected in many localities. Pollen examination of these collections showed that the tetraploids with but one exception have good pollen and the hexaploids and the octoploids have no pollen or have bad pollen with stainability less than 10%. With the help of pollen examination of a number of herbarium specimens, the distribution of the tetraploids and that of the assemblage of the hexaploids and octoploids were delineated. Morphological studies indicated that the tetraploid, hexaploid and octoploid plants can not be separated in gross and spikelet morphology and that the tetraploids in central Honshu and those in Mt. Apoi are significantly different in leaf features. It was concluded thatC. sachalinensis represents an apo-amphimictic complex, which includes the following four races: 1) tetraploid, amphimictic, having thin leaf blades 5–10 mm broad and growing on the subalpine conifer forest belt and the conifer forest-alpine ecotone in the mountains of central Honshu; 2) tetraploid, amphimictic, having hard leaf blades 2–6 mm broad and growing on the stony, arid and exposed alpine belt on Mt. Apoi in Hokkaido; 3) hexaploid, mainly apomictic, the most variable ecologically, widely distributed; 4) octoploid, mainly apomictic, frequent in the upper montane to alpine belts, probably widely distributed.     

Exine Sculpture in Pariana Pollen (Gramineae)

Pollen grains of eieven species of Pariana, a small genus of herbaceous bamboos, were studied using LM, SEM and TEM. Ten of them have the Pariana stenolemma-type of pollen characterized by areolate exine due to relatively high and well separated denticulate processes on a slightly undulated tectum, vestigial columellae and no distinct annulus. At the pore edge the foot layer is thickened and folded.

P. campetris (P. campestris-type) shows this exine feature only at magnifications higher than x 2000, whereas the denticulate processes are clearly visible at x 400 magnification in the other ten species. The pores are bordered by a distinct annulus.

The high relief of the Pariana pollen forming a relatively rough surface would offer more friction in wind transport than the smooth surface of other grass pollen grains. Insects visiting the flowers have been observed which support the idea of possible insect pollination. If this would be the case, the parianas would be an example of correlation between pollen form and function in the evolution of the Gramineae.     

Chromosome size and DNA values in sundews (Droseraceae)

Relative DNA content has been determined Feulgen cytophotometrically and autoradiographically for roottip nuclei of Drosophyllum lusitanicum L., (2n=12), Drosera rotundifolia L. (2x=20), D. intermedia Hayne (2x=20), D. linearis Goldie (2x= 20), D. binata Labill. (3x=32), D. capensis L. (4x= 40), D. spathulata Labill. (8x=80), all Droseraceae. Relative DNA values per diploid genome for Drosophyllum and diploid, triploid, and higher polyploid Drosera were approximately as 16421. These values are terms of a geometric series and are compatible with a multistranded (polyneme) interpretation of chromosome structure.     

甘蔗亚族的地理分布

对甘蔗亚族植物在世界的分布状况和在中国的分布特点进行了讨论,通过分析甘蔗亚族各属种的分布区类型,认为亚洲东南部为甘蔗亚族的分布中心和多样性中心,同时对甘蔗亚族起源作了推测。     

Anthocyanin composition of and distribution in the Poaceae (Gramineae)

Delphinidin 3, 5-diglueoside was identified in Nardus stricta and peonidin 3-arabinoside in Plialaris arundinaeea. Cyanidin 3-glucoside was found in all of 21 other grasses examined; it was accompanied by the 3-arabinoside in seven species. It is concluded that anthocyanin pigmentation has no general taxonomic importance in the family but that this is the result to be expected in a wind-pollinated plant group.     

Transfer aleurone cells inSetaria lutescens (Gramineae)

Summary Typical aleurone cells occur around the periphery of the caryopsis. These cells are tabular with moderately thick walls and lack cell wall ingrowths. Transfer aleurone cells only occur adjacent to the placental vascular bundle, which supplies the developing embryo and endosperm. These specialized aleurone cells are approximately columnar, with thick walls bearing ingrowths on the outer radial and outer tangential walls. The wall ingrowths of transfer aleurone cells appear similar to those of transfer cells previously described and quite likely also function in short-distance transport of substances.Journal paper No. J-6737 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1685.     

Nuclear DNA content in species ofEleusine (Gramineae): A critical re-evaluation using laser flow cytometry

Interest in dinitroaniline herbicide resistant biotypes ofEleusine indica, and an as yet undetermined taxon ofEleusine, necessitated a revaluation of reported nuclear genome size estimates for available species in the genus. Laser flow cytometry showed that the nuclear DNA content of six of the seven species examined had 15 to 50% less DNA than reported previously. It was also determined that roots, as contrasted to leaves, possessed a large fraction of nuclei at the 4C or 8C DNA content level, in diploid or tetraploid species, respectively (i.e. the G2/M peak). Two major reasons for the previously reported overestimation may include sampling only of root tissues where endopolyploid and normal diploid nuclei both occur and the inappropriate choice of onion nuclei as an internal standard.