The farmed Eucheuma species (Gigartinales,Rhodophyta) in Danajon Reef,Philippines: carrageenan properties

Six cultured strains of Eucheuma denticulatum and E. alvarezii, from which stocks can be selected for the development of a Eucheuma seedling bank, were tested for their carrageenan quality from June to November 1988. Percent yield of all the varieties taken together was apparently higher in June, becoming lower in November (regression, r –0.785, probability, p 0.001). Stepwise regression analysis was done to determine the existence of any relationship between any of the following parameters: gel strength, viscosity, sulfate content, month of sampling, and yield, whether taken individually or in combination. Results show variations of the yield with the month of sampling. ANOVA was performed to test whether there are differences in sulfate levels, gel strength, and viscosity between the Eucheuma alvarezii morphotypes. There was no significant difference between the green and the brown types.     

Disproportionate allocation of mineral nutrients and carbon between vegetative and reproductive structures in Banksia hookeriana

We compared above-ground allocation patterns in mature shrubs of Banksia hookeriana from three 13-year-old populations, growing on nutrient-impoverished sands to determine whether C (dry mass) could be a substitute for mineral nutrients (N, P, K, Ca, Mg and NA). The percentage of reproductive structures to total above-ground growth (reproductive effort; RE) was integrated over nine successive reproductive cycles. Only 0.5% of above-ground dry mass was allocated to seeds compared with 31% to total RE. Allocations of N (24%) and P (48%) to seeds, and N (44%) and P (65%) to RE were much higher. Allocations of K, Ca, Mg and Na to seeds (<1–3%), and RE (21–35%) were closer to that of dry mass. Relative allocation (RA) is defined as the proportion of a nutrient element allocated to a structure relative to its dry mass. RA of P to seeds was 91 and N was 44, but for K, Ca, Mg and Na ranged from only 6 for K to<1 for Na. Thus P, and to a lesser extent N, provide a much more sensitive measure of the relative cost of reproduction than C in this nutrient-limited system.     

Reef management in developing countries: a case study in the Philippines

Coral Reefs -  In general the most attractive and economically valuable reefs in the world are found in developing countries. Because of these attributes, they have also become the most...     

How reproductive,vegetative and defensive strategies of Mediterranean grassland species respond to a grazing intensity gradient

We analysed the morpho-functional response of grassland species to a grazing intensity gradient (1–3.5 sheep ha⁻¹) in the Mediterranean-type climate region of Chile. A total of nine morpho-functional traits (with a total of 24 attributes) were determined for 79 herbaceous plant species. Valuation of the traits enabled calculation of the reproductive, vegetative and defensive potentials for each species. A classification analysis for species x potentials identified five groups of plant functional strategies, and we analysed their responses along a grazing intensity gradient both for native and non-native species. The defensive potential of the species was negatively correlated with reproductive but was not significant in relation to vegetative potential. Grazing intensification favoured the presence of species with high defensive potential, to the detriment of those with high reproductive potential. This process affected both native and non-native species, but was more intense in the former presenting higher defensive potential. The functional group with a higher defensive strategy showed an increase in relative frequency with grazing intensity. However, self-defence alone is insufficient. This group also presents a certain reproductive potential that ensures the persistence of its annual or biennial species. The functional group combining high reproductive and vegetative potentials is the one that exhibits the biggest decrease in relative frequency due to intensified grazing. This group, however, is dominant in all the stocking treatments. All the functional groups identified include both native and non-native species, although the former dominate in those with greater defensive potential.     

The Barrier Reef sediment apron: Tobacco Reef,Belize

Sedimentological and biological surveys of the back-reef sediment apron of Tobacco Reef, a continuous segment of the Belizean Barrier Reef, reveal five distinct biogeological zones: (1) coralline-coral-Dictyota pavement, (2) Turbinaria-Sargassum rubble, (3) Laurencia-Acanthophora sand and gravel, (4) bare sand and 95 Thalassia sand. These zones parallel the entire 9-km reef. The distribution of these zones is related to the spatial patterns of fish herbivory, the size of bottom sediments, and the stability of the substrate. Sedimentological and hydrodynamic studies indicate that most of the sediments in this area are transported from the reef crest and fore reef during periods of storm or hurricane activity and that their size distribution is largely the result of differential transport by high bottom-water velocities during those periods.     

The role of vegetative and reproductive attributes in the classification of the Orchidaceae

Ninety-three orchid taxa have been arranged into three classificatory dendrograms employing respectively 40 reproductive, 34 vegetative and 74 attributes combined, and forming the hierarchy by means of group-average clustering. According to these results the non-specificity hypothesis does not hold well for vegetative versus reproductive attributes. Both types of attributes are equally efficient predictors of the classification based upon the total data, though neither data set is a very reliable predictor. Hence both should be employed in the production of general classifications and when considering the phylogenetic relationships amongst orchids.     

Phosphoenolpyruvate carboxykinase in Arabidopsis: changes in gene expression, protein and activity during vegetative and reproductive development

The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in different tissues of Arabidopsis thaliana throughout its vegetative and reproductive growth. The A. thaliana genome contains two PEPCK genes (PCK1 and PCK2), and these are predicted to generate 73,404 and 72,891 Da protein products, respectively. Both genes were transcribed in a range of tissues; however, PCK1 mRNA appeared to be more abundant and was present in a wider range of tissues. PEPCK protein was present in flowers, fruit, developing seed, germinating seed, leaves, stems and roots. Two PEPCK polypeptides, of approximately 74 and approximately 73 kDa were detected by immunoblotting, and these may arise from PCK1 and PCK2, respectively. PEPCK was abundant in cotyledons during post-germinative growth, and this is consistent with its well established role in gluconeogenesis. PEPCK was also abundant in sink tissues, such as young leaves, in developing flowers, fruit and seed. Immunohistochemistry and in situ hybridization showed that PEPCK was present in the nectaries, stigma, endocarp of the fruit wall and in tissues involved in the transfer of assimilates to the developing ovules and seeds, such as the vasculature and seed coat. The potential functions of PEPCK in A. thaliana are discussed.     

Multiple switches between vegetative and reproductive growth in annual plants

A model of growth and reproduction in annual plants was developed by Cohen (1971, J. Theor. Biol.33, 299–307) to determine the allocation strategy which maximizes seed yield. The model divides the plant into vegetative and reproductive parts and predicts that yield is maximized by a strategy consisting of a switch from purely vegetative to strictly reproductive growth. We generalize Cohen's model to include vegetative and reproductive loss terms. Both growth and loss rates are allowed to vary with time. Using optimal control theory we find that seed yield is maximized by a strategy consisting of multiple switches between vegetative and reproductive growth, for certain ranges of the model parameters. In natural systems a predictable vegetative loss burst may be necessary to promote multiple switches.     

Role of rice PPS in late vegetative and reproductive growth

The rice peter pan syndrome-1 (pps-1) mutant shows a prolonged juvenile phase and early flowering. Although the early vegetative phase and flowering time of pps-1 have been closely examined, the phenotypes in the late vegetative and reproductive phases are not yet well understood. In the ninth leaf blade of pps-1, the relative length of the midrib was comparable to the sixth leaf blade of wild-type. Moreover, pps-1 had a small inflorescence meristem and small panicles. These phenotypes indicate that in pps-1 the juvenile phase coexists with the late vegetative phase, resulting in small panicles. Gibberellin is known to promote the juvenile-adult phase transition. d18-k is dwarf and has a prolonged juvenile phase. Double mutant (d18-k pps-1) showed the same phenotype as the pps-1, indicating that PPS is upstream of GA biosynthetic genes.     

The endogenous gibberellins of vegetative and reproductive tissue of G2 peas

The gibberellins (GAs) of both vegetative (leaves and stems) and reproductive (pods and seeds) tissue of the G2 strain of peas Pisum sativum L. were characterized in purified extracts by a combination of sequential silicic-acid partition column chromatography, and gas chromatography-mass spectrometry. Gibberellins A₁₉, A₂₀, A₂₉ and an A₂₉ catabolite were identified in both types of tissue. Gibberellins A₉, A₁₇ and A₄₄ were also found in pods and seeds.Abbreviations FID Ilame ionization detector - GA(s) gibberellin(s) - GC gas chromatograph(y) - HPLC high performance liquid chromatograph(y) - LD long day - MS mass spectrum(a) or mass spectrometer(ry) - SD short day     

The abundance of rare tree species in remnant forests across the Visayas,Philippines

In several tropical regions of the world, formerly widespread forests have been reduced to scattered remnants, and many tree species are becoming increasingly endangered. Knowledge on the population status of rare species is essential to inform conservation efforts and, in particular, the use of native species for reforestation projects stemming from emerging land-use strategies. We studied 20 mostly red-listed native species in remnant forests on five limestone-, four volcanic- and one ultramafic site(s) across the Visayas in the Philippines, with 40 plots being assessed at each site. Seventeen of the species showed a median density of less than two trees per hectare, with ten species showing median densities of zero due to low species frequency, although some had higher local densities. One species (Dracontomelon edule) was not encountered at all, while two other species (Dipterocarpus validus and Dracontomelon dao) were only encountered as singletons. Six species were confined to limestone sites and showed associations with other better-known limestone specialists. The other study species occurred at both site types. Four of the species showed significant relationships between stem density, soil pH and stand basal area. The particular rarity of the majority of the species calls for immediate conservation measures to be adopted to protect species and associated remnant forests. In addition to legal measures such as the designation of remnant forests as protected areas, we recommend the establishment of mixed native forest stands giving due regard to the species associations and site characteristics identified in this study.     

'Node counting': an internal control of balanced vegetative and reproductive development

Plants can complete an entire life cycle in uniform environments. This is evidence that while shoot apices reiterate leaf formation they also change as a function of their own development. These changes occur in individual apices rather than the plant as a whole, and they are most closely correlated with the number of nodes an apex has formed. Evidence about the mechanism of 'node counting' suggests a working hypothesis: apical transitions depend on cumulative information about the distances of an apex from the roots, rather than on any single, critical state. Studies of the ecological roles of plant size and age have neglected the physiological information about 'node counting'. Yet it is evident in field conditions, especially in the morphological location of flowers on branches situated at different heights along the main axis. 'Node counting' affects flower formation, but as a component rather than sole determinant of apical differentiation it displays pronounced phenotypic plasticity. The ecological advantages of 'node counting' could include its being a basis for concurrent vegetative and reproductive development on the same plant. It also allows for environmental responses that are a function of the state of plant sectors without constraining the sizes of leaves and other organs.     

Adaptation to metal-contaminated soils in populations of the moss,Ceratodon purpureus: vegetative growth and reproductive expression

Many observations suggest that morphological evolution occurs slowly in bryophytes, and this has been suggested to reflect low genetic diversity within species. Isozyme studies, however, stand in apparent contrast and have shown that bryophytes can contain high levels of genetic variability within and among populations. In light of this conflict, we tested the potential of the moss, Ceratodon purpureus, to undergo adaptive change (i.e., ecotypic differentiation) in response to soils that have been contaminated with high levels of metals for 90 years by measuring gametophytic growth and reproductive expression under experimental conditions. Variation in protonemal growth in sterile culture indicates that plants from one population growing on contaminated soil near a smelter are significantly more tolerant of zinc, cadmium, and lead than plants from uncontaminated sites. Results from a common garden experiment, in which plants were grown on soil from the smelter site, indicate that plants from near the smelter are significantly more tolerant of contaminated soils than plants from uncontaminated sites for vegetative growth. The same experiment suggests that plants from the smelter site are also more tolerant in terms of gametangial production (although we could not test this statistically). Our results demonstrate that C. purpureus has been able to undergo relatively rapid evolution in response to strong selective pressures.     

Distribution of endogenous gibberellins in vegetative and reproductive organs of Brassica

Recognizing the physiological diversity of different plant organs, studies were conducted to investigate the distribution of endogenous gibberellins (GAs) in Brassica (canola or oilseed rape). GA₁ and its biosynthetic precursors, GA₂₀ and GA₁₉, were extracted, chromatographically purified, and quantified by gas-chromatography-selected ion monitoring (GC-SIM), using [²H₂]GAs as internal standards. In young (vegetative) B. napus cv. Westar plants, GA concentrations were lowest in the roots, increased acropetally along the shoot axis, and were highest in the shoot tips. GA concentrations were high but variable in leaves. GA₁ concentrations also increased acropetally along the plant axis in reproductive plants. During early silique filling, GA₁ concentrations were highest in siliques and progressively lower in flowers, inflorescence stalks (peduncles plus pedicels), stem, leaves, and roots. Concentrations of GA₁₉ and GA₂₀ showed similar patterns of distribution except in leaves, in which concentrations were higher, but variable. Immature siliques were qualitatively rich in endogenous GAs and GA₁, GA₃, GA₄, GA₈, GA₉, GA₁₇, GA₁₉, GA₂₀, GA₂₄, GA₂₉, GA₃₄, GA₅₁, and GA₅₃ were identified by GC-SIM. In whole siliques, GA₁₉, GA₂₀, GA₁, and GA₈ concentrations declined during maturation due to declining levels in the maturing seeds; their concentrations in the silique coats remained relatively constant and low. These studies demonstrate that GAs are differentially distributed in _Brassica with a general pattern of acropetally increasing concentration in shoots and high concentration in actively growing and developing organs.     

Microsporogenesis,reproductive behavior,and fertility in five Pennisetum species

Summary Microsporogenesis, reproductive behavior, pollen fertility and seed set were studied in Pennisetumbasedowii Summerhayes and C. E. Hubbard, 2n = 54; P. macrostachyum (Brough.) Trin., 2n = 54; P. macrourum Trin., 2n = 36; P. polystachion (L.) Schult, 2n = 54; and P. squamulatum Fresen 2n = 54. Meiosis was regular in P. basedowii with primarily bivalent pairing. As many as 54 univalents were observed at metaphase I in P. macrostachyum. A high frequency of univalents at metaphase I in P. macrourum resulted in lagging chromosomes and micronuclei at anaphase I and telophase I, respectively. Pennisetum polystachion and P. squamulatum showed frequent multivalent chromosome associations. Studies of megasporogenesis and embryo sac development in P. basedowii showed sexual reproduction. Pennisetummacrostachyum was highly male sterile with predominantly aposporous apomictic embryo sac development. Pennisetum macrourum, P. polystachion, and P.squamulatum had only aposporous embryo sac development. Seed propagated progenies of these latter three species were uniform and matromorphic, confirming the obligate apomixis nature.     

Plant profilin isovariants are distinctly regulated in vegetative and reproductive tissues

Profilin is a low-molecular weight, actin monomer-binding protein that regulates the organization of actin cytoskeleton in eukaryotes, including higher plants. Unlike the simple human or yeast systems, the model plant Arabidopsis has an ancient and highly divergent multi-gene family encoding five distinct profilin isovariants. Here we compare and characterize the regulation of these profilins in different organs and during microspore development using isovariant-specific monoclonal antibodies. We show that PRF1, PRF2, and PRF3 are constitutive, being strongly expressed in all vegetative tissues at various stages of development. These profilin isovariants are also predominant in ovules and microspores at the early stages of microsporogenesis. In contrast, PRF4 and PRF5 are late pollen-specific and are not detectable in other cell types of the plant body including microspores and root hairs. Immunocytochemical studies at the subcellular level reveal that both the constitutive and pollen-specific profilins are abundant in the cytoplasm. In vegetative cell types, such as root apical cells, profilins showed localization to nuclei in addition to the cytoplasmic staining. The functional diversity of profilin isovariants is discussed in light of their spatio-temporal regulation during vegetative development, pollen maturation, and pollen tube growth.     

Gibberellins promote vegetative phase change and reproductive maturity in maize.

Postembryonic shoot development in maize (Zea mays L.) is divided into a juvenile vegetative phase, an adult vegetative phase, and a reproductive phase that differ in the expression of many morphological traits. A reduction in the endogenous levels of bioactive gibberellins (GAs) conditioned by any one of the dwarf1, dwarf3, dwarf5, or another ear1 mutations in maize delays the transition from juvenile vegetative to adult vegetative development and from adult vegetative to reproductive development. Mutant plants cease producing juvenile traits (e.g. epicuticular wax) and begin producing adult traits (e.g. epidermal hairs) later than wild-type plants. They also cease producing leaves and begin producing reproductive structures later than wild-type plants. These mutations greatly enhance most aspects of the phenotype of Teopod1 and Teopod2, suggesting that GAs suppress part but not all of the Teopod phenotype. Application of GA3 to Teopod2 mutants and Teopod1, dwarf3 double mutants confirms this result. We conclude that GAs act in conjunction with several other factors to promote both vegetative and reproductive maturation but affect different developmental phases unequally. Furthermore, the GAs that regulate vegetative and reproductive maturation, like those responsible for stem elongation, are downstream of GA20 in the GA biosynthetic pathway.     

The development and structure of vegetative and reproductive organs ofBinghamia californica (Rhodophyta)

Although the species has been known for more than 70 years, no published accounts have been made of the details of development of the reproductive structures ofBinghamia californica J. Ag., a member of the Rhodymeniales of limit d distribution in the eastern and western Pacific. The present studies indicate that there is a close relationship in vegetative structure and in the ontogeny of the reproductive structure toLomentaria, especially toL. hakodatensis Yendo. This study is dedicated to Professor Yositeru Nakamura on the occasion of his academic retirement.