A preliminary investigation of the role of auxin and cytokinin in sylleptic branching of three hybrid poplar clones exhibiting contrasting degrees of sylleptic branching

Sylleptic branches grow out from lateral buds during the same growing season in which the buds are formed. This type of branching is present in poplar and in many tropical species. It results in the production of more branches, more leaves and expanded photosynthetic capacity and is thought to assist in increasing the overall growth and biomass of the tree at a young age. However, very little is known about the physiology of sylleptic branching in poplar, which is an extremely important source of fibre and fuel. In the present study of three hybrid poplar clones (11-11, 47-174 and 49-177) of Populus trichocarpa x P. deltoides exhibiting contrasting degrees of sylleptic branching, an analysis was carried out on parent shoot elongation and sylleptic branching, together with a preliminary comparison of the parent shoots' sensitivity to auxin (naphthaleneacetic acid) as a repressor of lateral bud outgrowth, and cytokinin (benzyladenine) as a promoter. Suggestive evidence was found for an inverse correlation between parent shoot sensitivity to auxin and the degree of sylleptic branching, as well as a partially positive correlation with respect to sensitivity to cytokinin. The present data are consistent with the hypothesis that auxin and cytokinin may play repressive and promotive roles, respectively, in the sylleptic branching of hybrid poplar.     

Ramet Demography of a Clonal Invader, <Emphasis Type="Italic">Arundo donax</Emphasis> (Poaceae), in Southern California

Arundo donax L. is a rhizomatous perennial, asexually reproducing species that has invaded riparian habitats throughout Mediterranean climate zones. This research evaluated ramet demography of A. donax in two California riparian communities that differed in nitrogen availability. Quadrats were established along 100 m transects at each site and oriented across the advancing fronts of established populations. Morphology and phenology were assessed monthly over 1 year for calculation of demographic parameters and rhizomes were excavated and mapped at the end of the experiment. A. donax exhibited seasonal patterns of recruitment but no dormancy at the high nitrogen site, while at the low nitrogen site no recruitment occurred in the winter and maximum recruitment was delayed by a month relative to the high nitrogen site. Spread of A. donax was delayed until spring and lower overall in the low nitrogen site compared to the high nitrogen site, where lower initial density, greater production of shoots, and higher linear and areal addition indicated that this population was spreading more rapidly. Temperature and precipitation influenced seasonality and amount of recruitment of A. donax in this study. Several recently established, immature clumps were found in gaps at the low nitrogen site, likely due to flood-mediated dispersal of propagules. Recruitment in these clumps occurred from shoot buds, in contrast to the mature populations that reproduced from rhizome buds. Ecologically based management strategies for A. donax and other exotic species should account for differences such as those described here and be tailored to local conditions where the species occurs.     

"Blinding" of shoots and a leaf gall in Amsinckia intermedia induced by Anguina amsinckia (Steiner and Scott, 1934) (Nemata,Tylenchidae), with a note on the absence of a rachis in A. amsinckia

"Blinding" and a leaf gall induced on Amsinckia intermedia Fisch. and Mey. by Anguina amsinckia (Steiner and Scott) are described. A. amsinckia induced blinding by galling the terminal apical meristem of its host. The leaf gall was formed by a ventral curling of the distal edge of the leaf. The absence of a rachis in the ovary of A. amsinckia is noted.     

Relations between cytokinin level, bud development and apical control in Norway spruce, Picea abies

In conifers such as Norway spruce, the extent of shoot growth is predetermined by the size and number of embryonal organs of the buds laid down the previous year. As it is known that cytokinins have a key role in bud development a possible hypothesis is that the level of cytokinin in the buds during their formation determines their size and complexity. As a first step to test this hypothesis we compared cytokinin levels in buds of different size of annual shoots from 15- to 20-year-old trees of Picea abies (L.) Karst. Apical buds from the leaders, and from branches in lower parts of the trees, were collected in April, July and August. The difference in size of the buds and the shoots growing from them was considerable in these three positions. Extracts were purified by immunoaffinity columns, and the retained compounds were separated by high-performance liquid chromatography (HPLC). Quantification was made by enzyme-linked immunosorbent assay (ELISA), and the accuracy of this method was checked by measurements with liquid chromatography-mass spectrometry (LC-MS) and UV absorption. Zeatin riboside (ZR) was the most abundant cytokinin, but isopentenyladenosine (iPA) was also present in all samples. The large apical bud of the leader contained much higher cytokinin concentrations than the considerably smaller buds from lower positions, and during the period of secondary growth in July, similar relationships were found for annual stem tissue from different positions. The possible role of ZR as a controlling factor in bud development and apical control is discussed. Our conclusion is that the level of zeatin-type cytokinins appears to play an important role in the establishment of differences in bud size and, thereby, the architecture of the tree crown.     

Four new species of southern African octocorals (Cnidaria: Alcyonacea), with a further diagnostic revision of the genus Alcyonium Linnaeus, 1758

Four new species of soft corals are described from the shallow sublittoral of southern Africa. Three of the species are referable to the genus Alcyonium Linnaeus, 1758 (family Alcyoniidae), although two of these possess growth forms that are atypical for most members of the genus. A revised diagnosis of the genus is therefore included. A new species in the family Nephtheidae is also described, this being referable to the genus Capnella Gray, 1869. All four species are from the region between the Cape of Good Hope Peninsula and the eastern Cape Province of South Africa. This is the region of the Agulhas Bank, an austroafrican biogeographic region that shows a high incidence of endemism with respect to the marine invertebrate fauna.     

Stem fasciated, a recessive mutation in sunflower (Helianthus annuus), alters plant morphology and auxin level

BACKGROUND AND AIMS: Plant lateral organs such as leaves arise from a group of initial cells within the flanks of the shoot apical meristem (SAM). Alterations in the initiation of lateral organs are often associated with changes in the dimension and arrangement of the SAM as well as with abnormal hormonal homeostasis. A mutation named stem fasciated (stf) that affects various aspects of plant development, including SAM shape and auxin level, was characterized in sunflower (Helianthus annuus). METHODS: F1, F2 and F3 generations were obtained through reciprocal crosses between stf and normal plants. For the genetic analysis, a chi2 test was used. Phenotypic observations were made in field-grown and potted plants. A histological analysis of SAM, hypocotyl, epicotyl, stem and root apical meristem was also conducted. To evaluate the level of endogenous indole-3-acetic acid (IAA), a capillary gas chromatography-mass spectrometry-selected ion monitoring analysis was performed. KEY RESULTS: stf is controlled by a single nuclear recessive gene. stf plants are characterized by a dramatically increased number of leaves and vascular bundles in the stem, as well as by a shortened plastochron and an altered phyllotaxis pattern. By histological analysis, it was demonstrated that the stf phenotype is related to an enlarged vegetative SAM. Microscopy analysis of the mutant's apex also revealed an abnormal enlargement of nuclei in both central and peripheral zones and a disorganized distribution of cells in the L2 layer of the central zone. The stf mutant showed a high endogenous free IAA level, whereas auxin perception appeared normal. CONCLUSIONS: The observed phenotype and the high level of auxin detected in stf plants suggest that the STF gene is necessary for the proper initiation of primordia and for the establishment of a phyllotactic pattern through control of both SAM arrangement and hormonal homeostasis.     

Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants)

Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production.     

Chromonema heliothidis n. gen., n. sp. (Steinernematidae,Nematoda), a Parasite of Heliothis zea (Noctuidae,Lepidoptera), and Other Insects

Chromonema heliothidis n. gen., n. sp. is described as an entomophilic nematode of Heliothis zea and other lepidopterous larvae; the diagnosis of the family Steinernermatidae is emended. In most morphological and host-parasite features, this nematode is similar to neoaplectanid nematodes; however, males are different in having a peloderan bursa and straight to slightly curved spicules. Although the infective-stage juveniles only give rise to hermaphrodites, the nematode is heterogonic, with both males and females being produced in the second generation. Parasitized hosts are brick-red in color and luminescent in the dark because of the association of a chromogenic, bioluminescent bacterium with the nematode. The nematode is capable of parasitizing a wide range of insects with lepidopterous larvae being most susceptible.     

A comparative study on morphology, growth rate and reproduction of Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis Valenciennes, 1840, and their reciprocal hybrids (Pisces, Clariidae)

A detailed study on reproduction indicated that female C. gariepinus mature earlier (5–7 months) than female H. longifilis (12–14 months). In the reciprocal hybrids, female first sexual maturity was attained at 20–21 months. Both reciprocal hybrids and parental species displayed an equilibrated sex ratio. Macroscopical and microscopical observations revealed numerous abnormalities in gonadal development of the hybrids. GSI and fecundity in female hybrids were considerably lower than those found in the parental species. Moreover, intra-ovarian tumors occurred in 20% of the hybrids. In hybrid males, GSIs were generally higher than those found in the parental species, but the spermatozoa concentration in the semen was about 100 times less. Despite these abnormalities, viable larvae, resulting from F2 and backcross fertilizations, were obtained.     

Apical control of lateral bud development and shoot growth in mulberry (Morus alba)

Measurements of changes in the degree of dominance by upper laterals over lower ones in coppice shoots (1-year-old stems) of 12-year old low- pruned stumps of mulberry ( Morus alba L. cv. Shin-ichinose) were made by removal of upper stem sections (pruning) or of lateral buds (debudding.) before spring bud burst, as part of a study of the factors involved in dominance relationships between the developing buds and elongating shoots. Besides inhibition of lower laterals by the upper, leading shoots, there was evidence for mutual inhibition (competition) of neighboring laterals along the stem. Thus in stems in which every other bud, or 4 out of every 5 buds were removed, there was a delay in growth cessation of lower laterals and their greater elongation than in controls. Such competition was seen to exist even between the uppermost and sub-terminal laterals, since the former elongated more in the absence of the latter.
In contrast to high and middle pruned stems, the delay in sprouting of the buds in low-pruned stems resulted in limited elongation of the shoots from such buds. This inhibition was removed when all the stems on a stump were pruned to the same length, suggesting that it was associated with intact stems with actively growing laterals. Patterns of regrowth of the short shoots (lower laterals) after summer pruning (middle-pruned) depended on the extent of removal of other stems with vigorously growing, upper laterals. These results demonstrate that both acropetal and basipetal influences are important in bud and shoot dominance relationships.     

On a new species of the genus Newnhamia King, 1855 (Crustacea,Ostracoda) raised from Chalakkudy River sand, (Kerala,India), with notes on the taxonomy and distribution of the Notodromadidae

Hydrobiologia - A new species of the genus Newnhamia, N. dumonti n.sp., is described from Kerala, India. Newnhamia was thus far only known from Australia and adjacent islands, as it is here argued...     

Descriptions,transferences and synonymies in American Monochamini (Coleoptera,Cerambycidae, Lamiinae), with revised keys to species of Hammatoderus and Taeniotes

Hammatoderus wappesi n. sp. and H. garciaorum n. sp. are described from Mexico, Veracruz and Oaxaca and Veracruz, respectively. Hammoderus brasiliensis Breuning, 1943 and Plagiohammus camillus Dillon & Dillon, 1949 are proposed as synonyms of Hammatoderus confusor (Dillon & Dillon, 1941); Plagiohammus rotundipennis Breuning, 1950 is proposed as a synonym of Hammatoderus pollinosus (Bates, 1880). A replacement name, Deliathis neonivea nom. nov., for Deliathis nivea (Breuning, 1943) n. comb., a secondary homonym of D. nivea Bates, 1869, is proposed. Three other new combinations are proposed: Deliathis imperatrix (Thomson, 1868) n. comb.; Monochamus sargi (Bates, 1885) n. comb.; and Monochamus blairi (Breuning, 1936) n. comb. Monochamus sargi and Hammatoderus pollinosus are redescribed. Hammatoderus sticticus (Bates, 1874) is newly recorded from Bolivia, with H. confusor newly recorded from Argentina and Colombia and its known distribution in Brazil expanded to include the state of Sao Paulo. Distribution of Deliathis imperatrix in Mexico is expanded to include the state of Morelos. A key to species of Hammatoderus and a key to species of Taeniotes “amazonum” group are also provided.     

Dispersal of rice sheath blight fungus,Rhizoctonia solani AG-1(IA), and subsequent disease development in paddy fields, from survey of vegetative compatibility groups

The rice sheath blight fungus,Rhizoctonia solani AG-1(IA), was isolated from surface soil and stubble in the pretrans-planting season (early March) and from sheath blight lesions on plants at the maturing stage (late September) in two paddy fields (TW and TM:8 a). Isolates were classified into vegetative compatibility groups (VCG) based on the formation of a barrage zone (or interaction zone) at the colony interface between isolates on paired cultures. In field TW surveyed in 1991 and 1992, 128–142 isolates obtained in the pretransplanting season and 82–85 isolates from lesions on mature plants were classified into 27–29 and 28–30 VCGs, respectively. Seven to 10 VCGs (26–35%) were common between both samples, and of 30 VCGs from mature plants 12 (40%) survived the winter 1991/1992 and recovered from stubble and/or soil. In field TM in 1992, 111 isolates in the pretransplanting season and 99 from mature plants were divided into 18 and 14 VCGs, respectively. Seven (39%) out of 18 VCGs in the pretransplanting season were recovered again from mature plants. Occurence of common VCGs throughout the year indicated that ca. one third of VCGs found in the pretransplanting season caused sheath blight on rice plants about 6 mo later in the same field. Further, it was shown that about the same rate of VCGs which had caused disease overwintered on stubble and/or surface soil until the following pretransplanting season.     

Population genetic structure of Titanotrichum oldhamii (Gesneriaceae), a subtropical bulbiliferous plant with mixed sexual and asexual reproduction

• Background and Aims Titanotrichum oldhamii is a monotypicgenus distributed in Taiwan, adjacent regions of China and theRyukyu Isands of Japan. Its conservation status is vulnerableas most populations are small and widely scattered. Titanotrichumhas a mixed system of reproduction with vegetative bulbils andseeds. The aim of this study was to understand the populationgenetic structure of Titanotrichum in relation to its specificreproductive behaviour and to determine possible implicationsfor conservation strategies. • Methods After an extensive inventory of most wild populationsof Titanotrichum in East Asia, samples from 25 populations withinits major distribution were carried out utilizing RAPD and inter-SSRmolecular fingerprinting analysis. • Key Results The findings support the conclusion thatmany populations reproduce predominantly asexually but thatsome genetic variation still exists within populations. However,significant amounts of variation exist between populations,perhaps reflecting population differentiation by drift. Thispartitioning of genetic diversity indicates that the level ofinter-population gene exchange is extremely low. These findingsare consistent with field observations of very limited seedproduction. The Chinese populations are similar to those ofNorthern Taiwan, while the Ryukyu populations fall within therange of variation of the north-central Taiwan populations.The Taiwanese populations are relatively variable and differentiationbetween north, east and south Taiwan is evident. • Conclusions The distribution of Titanotrichum seems tobe consistent with a former land connection between China, Taiwanand the Ryukyu Islands at a glacial maximum during the Quaternary,followed by progressive fragmentation of the populations. North-centralTaiwan is the centre of genetic diversity, possibly due to theproximity of the former land bridge between the regions, togetherwith the variety of suitable habitats in north Taiwan. The significanceof these findings for conservation is discussed.     

Palynological characters of Glycyrrhiza,Glycyrrhizopsis,and Meristotropis(Leguminosae),with special reference to their taxonomic significance

Li X-Y.1992.Studies on germplasm of Glycyrrhiza by using different taxonomic methods.Advances in Plant Taxonomy in Northwest China 1:7-24.

Li X-Y.1993.A study of the system and new taxa of genus Glycyrrhiza L.Bulletin of Botanical Research 13(1):14-43.

Turrill WB.1937.Glycyrrhizopsis syriaca Turrill.Bulletin of Miscellaneous Information 2:79.

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Escalation of Aggressive Interactions During Staged Encounters in Halictus ligatus Say (Hymenoptera: Halictidae), with a Comparison of Circle Tube Behaviors with Other Halictine Species'

Circle tube experiments on the primitively eusocial bee, Halictus ligatus, were performed for a variety of combinations of caste and size. Push, Lunge, and Back without reverse behaviors enabled us to determine the dominant individual in most comparisons. Behavioral differences were readily detected within the first 15 min except for different-size forager–forager and same-size foundress–foundress pairs, for which 30 min of observations was required. In same-size forager–forager pairs, no differences in behaviors between individuals were detected even after 90 min. In extended observations, decreases in the frequency of the mild dominant behaviors were accompanied by a switch to the highly aggressive mandibular hold on the neck, particularly in different-size foundress–foundress and gyne–gyne pairs. Three workers were killed by their own queen as a result of this escalation of aggression. We discuss caste-based differences in the circle tube setting in terms of behaviors expected under more normal conditions and compare our data with published results from other species.     

Changes in root-shoot ratio and ion uptake of maize (Zea mays L.) from soil as influenced by a plant growth regulator

A pot experiment with maize cv. Limac was conducted to investigate the influence of BAS 110.. W, a plant growth regulator (PGR), on root and shoot development and nutrient uptake. The PGR was applied via the soil with 0, 5, 10, 20, and 40 mg a.i. per pot. Shoot dry matter production was reduced to a higher degree than root length, resulting in a higher root-shoot ratio (RSR) of the treated plants. Shoots of treated plants contained higher concentrations of N, P, Ca, Mg, and unchanged K concentrations. The alterations in concentration could be explained by the changes in RSR induced by the plant growth retardant. The effect was strongest with P (+40%) which was limited by soil supply. N, Ca, and Mgconcentrations were positively influenced (+20%), there was no increase for Kvs RSR.     

Morphometric analysis of growth and development in wild-collected vervet monkeys (Cercopithecus aethiops), with implications for growth patterns in Old World monkeys, apes and humans

A study was undertaken of a unique sample of 63 wild vervet monkeys Cercopithecus aethiops from a single population in Uganda collected over 35 days in 1947. Twenty-five were immature (12 females and 13 males) and 38 were adults (16 females and 22 males). Body mass, external measurements, masticatory and other masses were recorded for each individual at the time of collection, and for a few specimens, the development of the reproductive organs. Each individual was evaluated for cranial capacity, limb length and dental eruption. The comparison of immature and adult animals illustrates the mosaic nature of growth in the different body systems, as well as female–male differences. An ancestral model is proposed for catarrhine growth and development, with particular reference to sex differences. This model provides a framework for assessment of immatures and for the reconstruction of socio-ecological effects on life-history stages in populations of fossil monkeys, apes and early hominids.