Slow Vegetative Growth Research Articles

Aoatg11 and Aoatg33 are indispensable for mitophagy, and contribute to conidiation, the stress response, and pathogenicity in the nematode-trapping fungus Arthrobotrys oligospora

Mitophagy is one of the most important cellular processes to ensure mitochondrial quality control, which aims to transport damaged, dysfunctional, or excess mitochondria for degradation and reuse. Here, we determined the function of AoAtg11 and AoAtg33, two orthologous autophagy-related proteins involved in yeast mitophagy, in the typical nematode-trapping fungus Arthrobotrys oligospora. Deletion of Aoatg11 and Aoatg33 impairs mitophagy, mitochondrial morphology and activity, autophagy, cell apoptosis, reactive oxygen species levels, lipid droplet accumulation, and endocytosis. These combined effects resulted in slow vegetative growth; reduced conidiation, trap formation, cell nucleus, and extracellular protease activity; increased susceptibility to the stress response; and arthrobotrisin production in the ΔAoatg11 and ΔAoatg33 mutants, compared with the wild-type strain. In addition, the absence of Aoatg11 caused an endoplasmic reticulum stress response. Transcriptome analysis revealed that many differentially expressed genes in the ΔAoatg11 mutants were involved in various important cellular processes, such as lipid metabolism, the TCA cycle, mitophagy, nitrogen metabolism, endocytosis, and the MAPK signaling pathway. In conclusion, our study revealed that Aoatg11 and Aoatg33 mediate autophagy and mitophagy in A. oligospora, and provides a basis for elucidating the links between mitophagy and fungal vegetative growth, conidiation, and pathogenicity.

Plant Growth and Microbiota Structural Effects of Rhizobacteria Inoculation on Mahogany (Swietenia macrophylla King [Meliaceae]) under Nursery Conditions

Swietenia macrophylla is a tropical timber species of ecological and economic importance. However, its slow vegetative growth and root development in nurseries strongly limit its production. This study evaluated the effect of 10 rhizobacteria strains during the early stages of production of S. macrophylla. Superficially disinfected seeds were inoculated with rhizobacteria under commercial nursery conditions. Inoculation was complemented by initial fertilization without growth regulators, fungicides, or bactericides. The results indicate that the rhizobacteria strains induce different responses in plants. Significant differences in plant biomass and root architecture were found. Treatments inoculated with Bacillus sp., Bacillus polyfermenticus, and Bacillus siamensis strains; showed an increase of up to 41% (dry weight). Plants increased root biomass by 30% when inoculated with S. siamensis. All inoculated strains were identified as members of the genus Bacillus spp., and their presence three months after inoculation was assessed by 16S rRNA gene-based amplicon massive sequencing. We found that Bacillus sp. genus was only present in inoculated treatments, suggesting that inoculated bacteria could establish themselves successfully as part of the microbiota. These results support the advantages of using PGPRs in commercial tropical tree production.

Stock Plant Management of Lavandula angustifolia ‘Wee One' Using Plant Growth Regulators

Abstract Lavandula angustifolia ‘Wee One' is a drought-tolerant perennial being used in landscapes throughout the western United States. Increased demand has resulted in problems with stock plant management and propagation due to the relatively small and slow vegetative growth. The objective was to determine if gibberellic acid, benzyladenine, ethephon, or auxin [indole-3-butyric acid (IBA)] plant growth regulators (PGR) applied as a foliar spray on Wee One lavender plants could be used to increase the number of cuttings for production. Fifteen replications of Wee One Lavender were evaluated for four months for plant height, width, number of cuttings, and fresh and dry weight of the cuttings. This study was replicated twice, the first experiment was performed from March 2020 to July 2020 and the second experiment from August 2020 to December 2020. A secondary propagation study was conducted simultaneously to check if PGR residuals effected rooting. The use of different PGRs caused an increase of cuttings from stock plants throughout both experiments. Foliar applications of gibberellin (ProGibb T&O) at 100 mg·L−1 (ppm) increased stem length and branching in one experiment, resulting in a higher number of cuttings produced compared to nontreated control stock plants, although that effect was not seen in the other conducted study. In one study, ProGibb T&O application did not negatively impact the rooting of individual cuttings, while it did so in the other study. Species used in this study: Wee One lavender [Lavandula angustifolia Mill]. Chemicals used in this study: gibberellic acid (GA3), ethephon, indole-3-butyric acid(IBA), N-(phenylmethyl)-IH-purine 6-amine (BA).

Assessment of genetic divergence and principal component analysis in oil palm (Elaeis guineensis Jacq.)

Twenty-nine oil palm DxD crosses derived from 37 dura parents were evaluated to identify high yielding and dwarf palms. Yield performance of progenies of 29 oil palm DxD crosses varied significantly and it ranged from 102.53 to 191.37 kg/palm/year with an experimental mean of 145.95 kg/palm/year. The other yield related traits like sex ratio and bunch number also significantly varied. Palmheight increment after five years of planting ranged from 20.40 to 31.44 cmwith experimental mean of 25.93 cm. Based on cluster analysis, all 29 DxD crosses with important traits grouped into five distinct clusters. From the present study, eight genotypes (DD7, DD8, DD11, DD12, DD17, DD18, DD21, and DD22) were identified to be high yielding and with slow vertical growth habit. Among the cluster IV DxD crosses, DD7 and DD8 had a common parent 257 CD; DD17 and DD18 had a common parent 232 CD. The preferred genotypes in the present diversity studies could be utilized as desirable parent in hybridization programme which led to the improvement of dura oil palm in high yield and slow vegetative growth.

JAZ repressors of metabolic defense promote growth and reproductive fitness in Arabidopsis

Plant immune responses mediated by the hormone jasmonoyl-l-isoleucine (JA-Ile) are metabolically costly and often linked to reduced growth. Although it is known that JA-Ile activates defense responses by triggering the degradation of JASMONATE ZIM DOMAIN (JAZ) transcriptional repressor proteins, expansion of the JAZ gene family in vascular plants has hampered efforts to understand how this hormone impacts growth and other physiological tasks over the course of ontogeny. Here, we combined mutations within the 13-member Arabidopsis JAZ gene family to investigate the effects of chronic JAZ deficiency on growth, defense, and reproductive output. A higher-order mutant (jaz decuple, jazD) defective in 10 JAZ genes (JAZ1-7, -9, -10, and -13) exhibited robust resistance to insect herbivores and fungal pathogens, which was accompanied by slow vegetative growth and poor reproductive performance. Metabolic phenotypes of jazD discerned from global transcript and protein profiling were indicative of elevated carbon partitioning to amino acid-, protein-, and endoplasmic reticulum body-based defenses controlled by the JA-Ile and ethylene branches of immunity. Resource allocation to a strong defense sink in jazD leaves was associated with increased respiration and hallmarks of carbon starvation but no overt changes in photosynthetic rate. Depletion of the remaining JAZ repressors in jazD further exaggerated growth stunting, nearly abolished seed production and, under extreme conditions, caused spreading necrotic lesions and tissue death. Our results demonstrate that JAZ proteins promote growth and reproductive success at least in part by preventing catastrophic metabolic effects of an unrestrained immune response.

Killing me slowly: Harsh environment extends plant maximum life span

Life span (the age of death for individuals that survived the establishment phase) is a key trait in plant life history. Despite its importance for understanding plant–environment relationships, there are still numerous substantial knowledge gaps about variation in plant maximum life spans and the ecological processes underlying these patterns.Based on plant age data obtained by means of herbochronology, we analysed patterns of intraspecific plant maximum life span variation in three perennial species (Campanula scheuchzeri, Helianthemun nummularium and Lotus corniculatus) along environmental gradients of mean annual temperature, soil depth and soil nutrients. This variation was compared with predictions from the ‘death-by-starvation hypothesis’ proposed by Hans Molisch in 1938, an unjustly forgotten ‘extrinsic’ theory on plant life span variation.Our study suggests that plant age variation within populations responds sensitively to growing conditions. The most important finding is that mean annual temperature or environmental conditions related to it seems to be a driving factor for intraspecific variation in plant maximum life span in all species studied. Despite large within-population variation, individuals of C. scheuchzeri, L. corniculatus and H. nummularium generally had a longer life span under colder climates (uplands in our case). In addition, soil depth (as a proxy for habitat susceptibility to drought) was found to have a significant positive effect on the age values in the case of C. scheuchzeri.These findings, therefore, are in line with Molisch’s “death-by-starvation hypothesis”: extended maximum life span results from reduced production of sink tissues and slow vegetative growth. We conclude that the analysis of plant life span adjustments along gradients of environmental factors can considerably contribute to our understanding of how plants may cope with changing environmental conditions, e.g., due to global change.

Functional analysis of a regulator of G-protein signaling CgRGS1 in the rubber tree anthracnose fungus Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides is the causal agent of rubber anthracnose, which is also one of the important biological factors threatening the development of natural rubber industry in the world. Regulators of G-protein signaling (RGS) are key negative regulators of G-proteins, which play important roles in growth, development and pathogenic processes of plant pathogens. In this study, a RGS gene CgRGS1 was functionally characterized in C. gloeosporioides. Compared to the wild type, the CgRGS1 deletion mutant had slow vegetative growth, reduced conidia with multi-end germination, low appressorium formation rate, high resistance to oxidative stress and SDS. Moreover, the mutant was sensitive to osmotic pressure and showed decreased virulence. In conclusion, CgRGS1 is involved in regulation of vegetative growth, conidiation, germination, appressorium formation, oxidative stress, osmotic pressure response and pathogenicity in C. gloeosporioides.

Suitable indicators using stem diameter variation-derived indices to monitor the water status of greenhouse tomato plants.

It is very important to seek a simple nondestructive method to continuously measure plant water status for irrigation scheduling. Changes in stem diameter in response to plant water status and soil water content (SWC) were experimentally investigated during the growing seasons of 2011/2012 and 2012/2013 in pot-cultivated tomato (Lycopersicon esculentum L.) plants in a plastic greenhouse. This study was conducted to determine suitable SDV (stem diameter variation)-derived indices as indicators of tomato plant water status for irrigation scheduling. The experiment was designed as a two-factor randomized block using the SWC and growth stages as variables. The SWC was controlled at 70–80% (well-watered), 60–70% (slightly deficit watered), 50–60% (moderately deficit watered) of the field capacity (FC), and the prescribed growing stages were vegetative, flowering and fruit-forming, and harvesting stages. Regression analysis showed that the SD6 (the difference between the stem diameter value at 06:00 am and the initial sensor reading) was closely related to the SWC (p<0.01) during rapid vegetative growth, whereas the MDS (the maximum daily shrinkage) was closely related to the SWC (p<0.01) during slow vegetative growth. Our results suggest that SDV-derived indicators can be used for determining plant water status and for scheduling irrigation at different growth/developmental stages.

PROPAGASI IN VITRO ANGGREK (Dendrobium phalaenopsis Fitzg) TERHADAP PEMBERIAN HORMON IBA DAN KINETIN

Orchids are a very popular ornamental plants, but orchids have a very slow vegetative growth, thus requiring special treatment in the grown.To spur grow than development can be used through tissue culture techniques of multiplication. But the success of the technique of tissue culture is inseparable with give a substance on the plant growth regulator. This study aims to determine the growth an influence D.phalaenopsis Fitzg orchids of giving a gaint swith IBA administration and Kinetin according to in vitro and as well as to obtain a concentration combination of IBA and Kinetin on the best orchid D.Phalaenops is Fitzg explants. Base don’t he results of the study indicate that the combination of IBA and Kinetin concentration giving a influence percentage of live explants, number of shoots and number of roots orchid D. phalaenopsis Fitzg explants.Combination treatment of IBA 1.0 ppm and 0.1ppm Kinetin is a combination of the best treatment to produce a number of shoots orchids.The giving of IBA 0.5ppm in the medium without the addition of kinetin concentration can increase the number of roots of the orchid D.phalaenopsis Fitzg.

Effects of Two Burn Scales on Northern Bobwhite Demographic Parameters and Home Range Size

Properties managed for bobwhite hunting in the Red Hills region use prescribed fire to burn 40-60% of their upland areas annually. Burning large areas could negatively affect bobwhite survival by increasing predation risk. Burning small areas could influence daily habitat use patterns and may influence nesting or brooding processes. Research on how the scale of management influences home range size and demographics of bobwhites is lacking. Therefore, on Tall Timbers Research Station (TTRS) we established 4-140 ha experimental treatment areas and randomly assigned 2 areas to be burned at a small scale (~2.25 ha burn patch size) and 2 areas to be burned at a large scale (~8 ha burn patch size). Upland habitat areas were divided into similar size patches, depending on treatment, with half of the units in the treatment areas burned annually in an alternating pattern. We annually radio-tagged bobwhites (2003-2005) and monitored their survival, productivity, and home range size during the breeding season. In 2003-2004, the risk of mortality was higher on large scale versus small scale treatments during March-May, but there were no differences in 2005. Per capita nest production was higher on small scale areas (0.68 nests/bird) than large scale areas (0.43 nests/bird). Autumn density was higher on small scale treatment areas (3.5 bobwhite/ha, SE = 0.62) compared to large scale treatment areas (2.7 bobwhite/ha SE = 0.67; F1,2 = 12.9, P = 0.07). On TTRS, there were marginal benefits of small scale management for early breeding season survival and productivity, especially during years with high late winter mortality or slow vegetative growth after burning due to drought, but the gains we observed may not be enough to supersede other management priorities.

A new paradigm for producing astaxanthin from the unicellular green alga Haematococcus pluvialis.

ABSTRACTThe unicellular green alga Haematococcus pluvialis has been exploited as a cell factory to produce the high‐value antioxidant astaxanthin for over two decades, due to its superior ability to synthesize astaxanthin under adverse culture conditions. However, slow vegetative growth under favorable culture conditions and cell deterioration or death under stress conditions (e.g., high light, nitrogen starvation) has limited the astaxanthin production. In this study, a new paradigm that integrated heterotrophic cultivation, acclimation of heterotrophically grown cells to specific light/nutrient regimes, followed by induction of astaxanthin accumulation under photoautotrophic conditions was developed. First, the environmental conditions such as pH, carbon source, nitrogen regime, and light intensity, were optimized to induce astaxanthin accumulation in the dark‐grown cells. Although moderate astaxanthin content (e.g., 1% of dry weight) and astaxanthin productivity (2.5 mg L−1 day−1) were obtained under the optimized conditions, a considerable number of cells died off when subjected to stress for astaxanthin induction. To minimize the susceptibility of dark‐grown cells to light stress, the algal cells were acclimated, prior to light induction of astaxanthin biosynthesis, under moderate illumination in the presence of nitrogen. Introduction of this strategy significantly reduced the cell mortality rate under high‐light and resulted in increased cellular astaxanthin content and astaxanthin productivity. The productivity of astaxanthin was further improved to 10.5 mg L−1 day−1 by implementation of such a strategy in a bubbling column photobioreactor. Biochemical and physiological analyses suggested that rebuilding of photosynthetic apparatus including D1 protein and PsbO, and recovery of PSII activities, are essential for acclimation of dark‐grown cells under photo‐induction conditions. Biotechnol. Bioeng. 2016;113: 2088–2099. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Identification of degenerate nuclei and development of a SCAR marker for Flammulina velutipes.

Flammulina velutipes is one of the major edible mushrooms in the world. Recently, abnormalities that have a negative impact on crop production have been reported in this mushroom. These symptoms include slow vegetative growth, a compact mycelial mat, and few or even no fruiting bodies. The morphologies and fruiting capabilities of monokaryons of wild-type and degenerate strains that arose through arthrospore formation were investigated through test crossing. Only one monokaryotic group of the degenerate strains and its hybrid strains showed abnormal phenotypes. Because the monokaryotic arthrospore has the same nucleus as the parent strain, these results indicated that only one aberrant nucleus of the two nuclei in the degenerate strain was responsible for the degeneracy. A sequence-characterized amplified region marker that is linked to the degenerate monokaryon was identified based on a polymorphic sequence that was generated using random primers. Comparative analyses revealed the presence of a degenerate-specific genomic region in a telomere, which arose via the transfer of a genomic fragment harboring a putative helicase gene. Our findings have narrowed down the potential molecular targets responsible for this phenotype for future studies and have provided a marker for the detection of degenerate strains.

Biological Flora of the British Isles:Campanula rotundifolia

1. This account presents information on all aspects of the biology of Campanula rotundifolia L. that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivory and disease, history, and conservation. 2. Campanula rotundifolia is a slender, rhizomatous, prostrate to erect herb with long-stalked roundish basal leaves, linear stem leaves, and a blue, bell-shaped corolla. It is widespread in the British Isles though absent from parts of Ireland. Globally, C. rotundifolia has a circumpolar distribution extending from the Arctic Circle to northern Mexico and North Africa. It forms a polyploid complex with some characters linked to ploidy level. Populations in the British Isles are predominantly tetraploid and hexaploid, with occasional pentaploids. The distribution of these cytotypes in the British Isles has a strong spatial structure. 3. Campanula rotundifolia has a wide ecological amplitude, tolerating very dry conditions but also occasionally occurring in permanently saturated habitats, and it grows on a very wide range of soil types, from coarse sands through loams to heavy clays and pure peats. However, C. rotundifolia is rarely found on fertile lowland clays where competition from more vigorous species may limit growth. Campanula rotundifolia is found in a range of grassland, heath, mire, scrub and sand dune communities spanning a wide range of soil pH. 4. Campanula rotundifolia is perennial and spreads by seed and by rhizome. Plants generally overwinter as frost-resistant green rosettes. As the spring season progresses, plants make slow vegetative growth. Erect flowering stems develop from June onwards. Campanula rotundifolia is largely self-incompatible, and is insect pollinated, regularly producing large quantities of viable seed. 5. Although C. rotundifolia is a widespread and locally very common species there is some evidence from Britain and across Europe that it is in decline. These losses are likely to be due to a number of factors including agricultural intensification, reversion of grassland to scrub and woodland, disturbance, and atmospheric pollution.

The trafficking protein SYP121 of Arabidopsis connects programmed stomatal closure and K+ channel activity with vegetative growth

The vesicle-trafficking protein SYP121 (SYR1/PEN1) was originally identified in association with ion channel control at the plasma membrane of stomatal guard cells, although stomata of the Arabidopsis syp121 loss-of-function mutant close normally in ABA and high Ca²⁺. We have now uncovered a set of stomatal phenotypes in the syp121 mutant that reduce CO₂ assimilation, slow vegetative growth and increase water use efficiency in the whole plant, conditional upon high light intensities and low relative humidity. Stomatal opening and the rise in stomatal transpiration of the mutant was delayed in the light and following Ca²⁺-evoked closure, consistent with a constitutive form of so-called programmed stomatal closure. Delayed reopening was observed in the syp121, but not in the syp122 mutant lacking the homologous gene product; the delay was rescued by complementation with wild-type SYP121 and was phenocopied in wild-type plants in the presence of the vesicle-trafficking inhibitor Brefeldin A. K⁺ channel current that normally mediates K⁺ uptake for stomatal opening was suppressed in the syp121 mutant and, following closure, its recovery was slowed compared to guard cells of wild-type plants. Evoked stomatal closure was accompanied by internalisation of GFP-tagged KAT1 K⁺ channels in both wild-type and syp121 mutant guard cells, but their subsequently recycling was slowed in the mutant. Our findings indicate that SYP121 facilitates stomatal reopening and they suggest that K⁺ channel traffic and recycling to the plasma membrane underpins the stress memory phenomenon of programmed closure in stomata. Additionally, they underline the significance of vesicle traffic for whole-plant water use and biomass production, tying SYP121 function to guard cell membrane transport and stomatal control.

RELATIONSHIP BETWEEN SOME PLANT GROWTH PARAMETERS AND GRAIN YIELD OF CHICKPEA (Cicer arietinum L.) DURING DIFFERENT GROWTH STAGES

Relation between some plant growth parameters (Leaf Area Index (LAI), Net Assimilation Rate (NAR), Relative Growth Rate (RGR), Leaf Area Ratio (LAR), Leaf Area Duration (LAD) and Crop Growth Rate (CGR)) with biomass and grain yield of chickpea (Cicer arietinum L.) during four growth stages (slow vegetative growth stage, linear vegetative growth stage, flowering stage and grain filling stage) were studied in the field experiments conducted at Bornova, Izmir. There was a wide variation among genotypes for all the growth parameters during the growth stages. Highest values of LAI and LAD were recorded for the period of linear vegetative growth stage; RGR and LAR through slow vegetative growth stage; NAR and CGR during flowering stage. Significant correlations among most of the growth parameters were found during all the growth stages. Most of the growth parameters except NAR also showed significant correlation with biomass. Mean grain yield was 1.86 t ha -1 that varied between 1.41 and 2.27 t ha -1 for different varieties.

Intraspecific variation in Capsella bursa‐pastoris in plant quality traits for insect herbivores

SummaryThe arable plant Capsella bursa‐pastoris is phenotypically variable in many life history traits, particularly time from germination to flowering. The hypothesis was investigated that, associated with this variation, there are differences in traits that influence plant quality for insect herbivores. Significant within‐species variation was found in plant growth, leaf surface characteristics and tissue nutrient composition among 21 accessions of Capsella. Short flowering time plants exhibited slow vegetative growth, relatively large shoot nitrogen content, high leaf hair densities and differences in phloem composition, compared with long flowering time plants. Insect herbivore response to distinctive trait combinations was assessed on a subset of seven accessions using the phloem‐feeding aphids Aphis fabae and Myzus persicae. Variation in aphid performance was small but significant, with 15–25% fewer nymphs produced on plant variants that exhibited greater tissue water content and low tissue C:N ratio (A. fabae) or on variants with less phloem nitrogen (M. persicae). The differential responses exhibited by the two aphid species to the test accessions confirmed that quantifying intraspecific plant variation is a necessary first step in understanding plant functional diversity and its impact on consumers in arable systems.

Structural Study of Graphite Materials Prepared by HTT of Unburned Carbon Concentrates from Coal Combustion Fly Ashes

Unburned carbon concentrates with different mineral matter contents were obtained from coal combustion fly ashes by an oil agglomeration procedure. The concentrates were then heated in the temperature interval 1800–2700 °C for the purpose of exploring their ability to graphitize. The influence of the treatment temperature and mineral matter of the unburned carbon on the structural characteristics of the materials prepared was studied. The interlayer spacing, d002, and crystallite sizes along the c-axis, Lc, and the a-axis, La, calculated from X-ray diffractometry (XRD) as well as the relative intensity of the Raman D-band, ID/It, were used to assess the degree of structural order of the materials. Graphite materials with structural characteristics comparable to those of other oil-derived synthetic graphites were prepared from the unburned carbon concentrates at temperatures ≥2400 °C. It was also observed that more-ordered materials were obtained from the unburned carbon concentrates with higher mineral matter content. The influence of the mineral matter on the graphitization of the unburned carbon concentrates is the result of two countereffects, thus limiting its extent. On the one hand, the lateral coalescence of the crystallites is preferentially promoted. Reasonably good linear correlations were attained between the mineral matter of the unburned carbon concentrate and the XRD parameter La of the materials. However, on the other, this coalescence also facilitates the flattening of the pores, thus decreasing the temperature at which their breakage occurs. As a consequence, from this point on, the structural evolution of the materials with increasing mineral matter is only noticeable by the slow vegetative growth of the crystallites along the a-axis.

Sexual versus asexual colonization by Phragmites australis: 25-year reed dynamics in a mediterranean marsh, Southern France

Colonization by common reed (Phragmites australis) is often assumed to be driven mainly by vegetative growth of rhizomes. Seedlings are rarely observed in the field despite the annual flowering, the large seed production, and germination potential. We considered that this was mainly a consequence of the rare occurrence of the regeneration window of reed but, provided the suitable conditions were created, reed could efficiently colonize empty space by seedling establishment. We analyzed the relative importance of sexual and asexual propagation in a reed-dominated marsh in Southern France using past aerial photographs to reconstruct the reedbed dynamics over the last 25 years and a full-scale experiment simulating a rarely occurring low water level in spring. We observed phases of slow colonization corresponding to vegetative growth and periods of rapid closure of mudflats by reed. Reedbed dynamics were a combination of slow vegetative growth and a few phases of seedling establishment. The preservation of stable water levels favored colonization by vegetative growth. The experimental spring drawdown led to a 25% increase in reed area with up to 40 m progressions. Such rare events with low water levels in spring favor sexual colonization. Sexual reproduction plays an important role in the pioneer stage of reedbeds, allowing both fast progression and establishment of genetically diverse stands.

Patch dynamics and response to disturbance of the seagrass Zostera novazelandica on intertidal platforms in southern New Zealand

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 189:275-288 (1999) - doi:10.3354/meps189275 Patch dynamics and response to disturbance of the seagrass Zostera novazelandica on intertidal platforms in southern New Zealand Deborah L. Ramage*, David R. Schiel** Marine Ecology Research Group, Zoology Department, University of Canterbury, Private Bag 4800, Christchurch 1, New Zealand *Present address. Zoology Department, University of Queensland, Queensland 4072, Australia **Addressee for correspondence. E-mail: d.schiel@zool.canterbury.ac.nz ABSTRACT: We examined the patch dynamics of the intertidal seagrass Zostera novazelandica on 2 reef platforms in order to understand the processes governing the establishment, maintenance and mortality of patches. The size distribution of patches at 3 tidal heights (low, mid and high shore) was assessed. Eighty patches, ranging in initial size from 0.1 to 2.4 m2 surface area, were tagged and video image analysis was used bi-monthly for 14 mo to calculate rates of expansion and contraction of these patches. Permanently marked 150 m2 areas of reef were monitored monthly to record patch recruitment and mortality. Initially, 75% of patches were <0.5 m2. All patches decreased in size during winter, probably due to increased wave action, and expanded during spring and summer. The proportional expansion and contraction of patches was independent of initial patch size. At the end of the study the size distribution of patches was similar to the initial distribution. Patch mortality was restricted to those <0.4 m2, of which 60% disappeared during the study. Larger patches suffered partial mortality through fragmentation. No large patches were formed through the amalgamation of smaller patches. Seedlings recruited into small sediment pockets in tidepools during spring, but few survived through summer because of removal by wave action. Experimental perturbation of patches resulted in increased erosion followed by decreased growth rates and, in many small patches, mortality. Removing only seagrass blades, however, resulted in increased production of new shoots relative to controls. Overall, seagrass patches are susceptible to disturbance, successful recruitment by seedlings may be rare or at least episodic, and populations are probably long-lived and depend on slow vegetative growth for maintenance and expansion. KEY WORDS: Seagrass · Patch dynamics · Disturbance · Zostera novazelandica · Intertidal · New Zealand Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 189. Publication date: November 26, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Genomic disruption of six budding yeast genes gives one drastic example of phenotype strain-dependence.

Using PCR to construct disruption cassettes, null alleles of six genes have been created in Saccharomyces cerevisiae. In a FY1679 background, no defects were detected in any of the haploid deletion mutants with respect to growth, gross morphology, or mating. A diploid FY1679-derived delta ygl194c/delta ygl194c homozygous disruptant displayed reduced sporulation. In contrast to the lack of phenotypic consequences of delta yol100w disruptions in the FY1679 background, in the CEN.PK2 strain even a heterozygous disruption of the same gene caused striking effects, very slow vegetative growth and highly impaired sporulation. Tetrad analysis showed YOL100w to be an essential gene in this strain. A copy of the YGL194c or the YOL100w wild-type gene borne on a centromeric episomal plasmid was introduced into a corresponding disruption mutant strain, and in both cases was found to partially complement the defects.