Blade Tissue Research Articles

Reference Levels for Leaf Nutrient Diagnosis of cv. Tempranillo Grapevine in the Rioja Appellation

Plant nutritional diagnosis requires specific reference levels for each variety to effectively reflect the nutritional status of the crop. A vine nutritional survey was undertaken in the Rioja A.O.C., northeastern Spain. The survey method was used to establish the preliminary reference levels for the nutritional diagnosis of leaf blade and petiole tissues of Vitis vinifera L., cv. Tempranillo on Richter-110 rootstock. These references were generated from data obtained during the course of 11 years (2000–10) from 166 vineyards trained on Gobelet and Vertical Shoot Position (VSP), pruned in Guyot or Double Cordon Royat, systems. The database obtained included information from different altitudes, soil types, cultural practices, and climatic conditions within the Rioja appellation. The majority of the vineyards had no irrigation and soil was tilled mechanically. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) were analyzed in leaf blade and petiole dry tissues sampled at both flowering and veraison. Vineyards with phytosanitary damages, flowering problems, and data with extreme nutrient values were discarded. Data were statistically analyzed to obtain the normal average values considering the (μ ± 0.25σ) of the central data as optimal levels and the tails values (μ ± 0.84σ) of the population as excessive or deficient levels. The statistical procedure included the Kolmogorov–Smirnov nonparametric test for normality, data transformations for normality, and the calculation of percentiles when those transformations to normal distributions become unlikely (P20, P40, P60, and P80). Finally, reference levels for leaf blade and petiole at both flowering and veraison are proposed for the nutrition diagnosis of the cv. Tempranillo grapevine in the Rioja A.O.C.

Classification of rice genotypes based on their mechanisms of adaptation to iron toxicity

AbstractIron (Fe) toxicity is a nutritional disorder that affects lowland rice (Oryza sativa L.). The occurrence of excessive amounts of reduced Fe(II) in the soil solution, its uptake by the rice roots, and its transpiration‐driven transport result in elevated Fe(II) concentrations in leaf cells that catalyze the formation of reactive oxygen species. The oxidative stress causes rusty brown spots on leaves (bronzing) and the reduction of biomass and yield. While the use of resistant genotypes is the most promising approach to address the problem, the stress appears to differentially affect rice plants as a function of plant age, climatic conditions, stress intensity and duration, and the prevailing adaptation mechanism. We comparatively assessed 21 contrasting 6‐week‐old rice genotypes regarding their response (symptom score, biomass, Fe concentrations and uptake) to a 6 d iron pulse of 1500 mg L–1 Fe(II). Eight selected genotypes were further compared at different stress intensities (0, 500, 1000, and 1500 mg L–1 Fe(II)) and at different developmental stages (4‐, 6‐, and 8‐week‐old plants). Based on Fe‐induced biomass reduction and leaf‐bronzing score, the tested spectrum was grouped in resistant and sensitive genotypes. Linking bronzing scores to leaf iron concentrations allowed further differentiation into includer and excluder types. Iron precipitation on roots and organ‐specific iron partitioning permitted to classify the adaptation strategies into root exclusion, stem and leaf sheath retention, and leaf blade tissue tolerance. The effectiveness of these strategies differed with stress intensity and developmental stage. The reported findings improve the understanding of Fe‐stress response and provide a basis for future genotype selection or breeding for enhancing Fe‐toxicity resistance in rice.

Species biodiversity of microscopic fungi of common reed (Phragmites australis (Cav.) Trin. ex Steud.) in the rush communities of Lake Glinno

The studies were carried out on common reed (<i>Phragmites australis</i>) growing on the shores of Lake Glinno and forming rush communities of the alliance <i>Phragmition</i>. 10 plants with disease symptoms were gathered from each of five sites. The isolation and marking of pathogens were performed twice from fragments of leaf and blade tissues with disease symptoms. First, directly after collecting the plants incubated in sterile humid chambers and microorganism cultures on CDA and PDA medium, and then phytopathogen and saprotroph species occurring on dried green material were identified for 2-4 months. The occurrence of 31 species of microscopic fungi overall was observed on the leaves, blades and inflorescences of <i>P. australis</i>, including 2 mycelia of <i>Mycelia sterilia</i>. The most frequently occurring species, present at all sites of <i>Phragmites australis</i> are: <i>Alternaria alternata</i>, <i>Cladosporium cladosporioides</i>, <i>C. herbarum</i>, <i>Doratomyces stemonitis</i> and <i>Puccinia phragmitis</i>, <i>P. magnussiana</i> and two mycelia of <i>Mycelia sterilia</i>. The most common species occurring on blades and inside them are: <i>Acremoniella atra</i>, <i>Acremonium alternatum</i> and <i>Fusarium sambucinum</i>. Sporadically, <i>Ustilago grandis</i> was also observed inside blades. Tiny necrotic stains on leaves and blades were caused by the presence of three species of the genus Leptoshaeria: <i>L. culmifraga</i>, <i>L. eustoma</i> and <i>L. fuckelli</i>. The occurrence of the sclerote of <i>Claviceps microcephala</i> was found in inflorescences.

Influence of deficit irrigation on nutrient indices in wine grape (<i>Vitis vinifera</i> L.)

Deficit irrigation is widely used in wine grape production (Vitis vinifera L.) to meet wine quality goals yet its influence on tissue nutrient indices has not been well studied. The objective of this research was to determine whether response to water deficit compromised the prescriptive usefulness of tissue nutrient analyses. Tissue macro and micronutrient composition at bloom and veraison were evaluated over multiple seasons in nine wine grape cultivars grown under well-watered or deficit-irrigated conditions. Deficit-irrigated vines sampled at veraison had 2 to 12-fold higher petiole nitrate-nitrogen concentration, 6% lower blade nitrogen concentration and 13% lower blade copper concentration compared to well-watered vines. Water deficit influenced blade potassium concentration at veraison differently according to cultivar and was lower (cv. Malbec, Petite syrah, Viognier, Lemberger and Sangiovese), higher (cv. Merlot, Cabernet franc and Cabernet Sauvignon) or similar (cv. Grenache) to well-watered vines. Results from this study indicate that nutrient analysis of petiole or blade tissue sampled at veraison has limited diagnostic and prescriptive usefulness when vines are grown under a water deficit.

Auxin-induced leaf blade expansion in Arabidopsis requires both wounding and detachment

Elevation of leaf auxin (indole-3-acetic acid; IAA) levels in intact plants has been consistently found to inhibit leaf expansion whereas excised leaf strips grow faster when treated with IAA. Here we test two hypothetical explanations for this difference in growth sensitivity to IAA by expanding leaf tissues in vivo versus in vitro. We asked if, in Arabidopsis, IAA-induced growth of excised leaf strips results from the wounding required to excise tissue and/or results from detachment from the plant and thus loss of some shoot or root derived growth controlling factors. We tested the effect of a range of exogenous IAA concentrations on the growth of intact attached, wounded attached, detached intact, detached wounded as well as excised leaf strips. After 24 h, the growth of intact attached, wounded attached, and detached intact leaves was inhibited by IAA concentrations as little as 1 µM in some experiments. Growth of detached wounded leaves and leaf strips was induced by IAA concentrations as low as 10 µM. Stress, in the form of high light, increased the growth response to IAA by leaf strips and reduced growth inhibition response by intact detached leaves. Endogenous free IAA content of intact attached leaves and excised leaf strips was found not to change over the course of 24 h. Together these results indicate growth induction of Arabidopsis leaf blade tissue by IAA requires both substantial wounding as well as detachment from the plant and suggests in vivo that IAA induces parallel pathways leading to growth inhibition.

Control of dicot leaf blade expansion by a WOX gene, STF

WUSCHEL-RELATED HOMEOBOX (WOX) genes are plant specific transcription factors that serve as master switches controlling key developmental programs from embryo apical-basal asymmetric patterning to organizing stem cells and development of lateral organs. Recently, we reported the requirement of a WOX1/MAW-like gene, STENOFOLIA (STF), for blade outgrowth and leaf vascular patterning in Medicago truncatula and Nicotiana sylvestris. The stf mutant in Medicago produces narrow leaves where mediolateral outgrowth of the blade is severely curtailed while proximodistal growth and trifoliate identity remain unaffected. The lam1 mutant in N. sylvestris produces leaves devoid of blade tissue with just 1-2 layers of rudimentary strips and lacks stem elongation. stf and lam1 mutants have narrow petals and are female sterile due to defective ovule development. Morphological analysis of mutants and STF expression patterns suggest that STF regulates blade outgrowth mainly by controlling cell division in the margins of leaf primordium. Both the blade and flower phenotypes of lam1 can be complemented with WUS expressed under the STF promoter suggesting a conserved mechanism in stem cell maintenance and lateral organ development.

Distribution of Phlorotannins in the Brown Alga Ecklonia cava and Comparison of Pretreatments for Extraction

The brown seaweed Ecklonia cava is known to be a rich source of phlorotannins that have diverse biological activities. Among the phlorotannins in E. cava, concentrations of dieckol and phlorofucofuroeckol-A, which were identified as major active components, were determined in different parts of the tissue. We compared the efficacy of different pretreatments for their extraction. A high- performance liquid chromatography (HPLC) method to determine phlorotannin concentrations showed good accuracy (92.64 and 94.02%, respectively), precision (3.92 and 3.94%, respectively), and linearity (r>0.996). Mature thalli contained 1.5-fold more dieckol (1.82 mg/g-dry tissue) than young thalli. In the tissues of E. cava, blade tissue contained more phlorotannins than the stipe or holdfast. Among differently dried thalli, approximately 90% or more dieckol and phlorofucofuroeckol-A were extracted from shadow-dried tissue as compared with lyophilized tissue. In sun-dried and oven-dried thalli, approximately 60% of the phlorotan- nins were extracted. Thalli washed with fresh water, boiled thalli, and steamed thalli showed reduced extraction of the compounds.

Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 13:163-173 (2011) - DOI: https://doi.org/10.3354/ab00366 Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds Kira A. Krumhansl*, Robert E. Scheibling Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada *Email: kira.krumhansl@dal.ca ABSTRACT: Population increases of the gastropod Lacuna vincta have been associated with significant damage to kelp blades and decreases in kelp biomass in subtidal kelp beds off Nova Scotia, Canada. We measured the total level and along-blade distribution of grazing damage by Lacuna vincta on the dominant kelp species at 5 sites in Nova Scotia, Canada, over a 15 mo period. Grazing was typically low or absent in the basal regions of blades, consistent with seasonal fluctuations in growth and physical properties of blade tissues. Grazing was largely concentrated in middle and distal sections, although this distribution varied with site exposure and over time. The cover of the invasive bryozoan Membranipora membranacea on the surface of kelp blades did not have a strong effect on grazing by L. vincta. The total level of grazing damage (max. 1% of blade area for Saccharina longicruris and 1.5% for Laminaria digitata) varied seasonally, with peaks in September at some sites. Spatial variation was driven in part by a negative relationship with site exposure. In a field experiment, simulated grazing damage that exceeded a threshold value of 0.5 to 1.0% of blade area caused a significant increase in blade loss during a period of heavy wave action due to a passing hurricane. Our results show that direct reductions in kelp biomass through grazing by L. vincta are relatively small, but can indirectly lead to significant losses of kelp biomass during large wave events. KEY WORDS: Lacuna vincta · Laminaria digitata · Saccharina longicruris · Grazing · ­Mesograzers · Kelp beds · Detritus · Membranipora membranacea Full text in pdf format PreviousNextCite this article as: Krumhansl KA, Scheibling RE (2011) Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds. Aquat Biol 13:163-173. https://doi.org/10.3354/ab00366 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 13, No. 2. Online publication date: September 06, 2011 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2011 Inter-Research.

Grazing damage and encrustation by an invasive bryozoan reduce the ability of kelps to withstand breakage by waves

Increased breakage of macroalgal fronds during large wave events can significantly reduce canopy cover and biomass. We examined the effects of encrustation by the invasive bryozoan Membranipora membranacea and damage by the snail Lacuna vincta on the ability of kelp blades (Saccharina longicruris, Laminaria digitata, and Laminaria complanata) to withstand wave forces. Using standard materials testing procedures, we documented significant reductions in the maximum stress before breakage, toughness, and extensibility of blade material following bryozoan encrustation. Histological sections of blade tissue indicated a significant degradation of the outer layers of cells following prolonged encrustation by M. membranacea as a likely cause of weakening. Full-thickness perforations and partial-thickness grazing scars also reduced blade strength, suggesting that grazing damage can initiate cracks that lead to blade breakage. Our findings provide a mechanistic link between the damaging effects of mesograzers and encrusting bryozoa on their algal hosts and the export of detrital material from subtidal kelp beds.

The effects of short term salinity exposure on the sublethal stress response of Vallisneria americana Michx. (Hydrocharitaceae)

Short term exposure of Vallisneria americana to elevated salinity was found to induce a stress response that could be quantified by a series of metabolic assays measuring oxidative stress, photosynthetic efficiency, and dark adapted respiration. Plant specimens exposed to elevated salinity for 24 h displayed signs of oxidative damage represented by the accumulation of reactive oxygen species (ROS) and lipid hydroperoxides in blade tissue (noted at salinities of 10 and 15, respectively). Respiratory demand nearly doubled (140 nanomoles O 2 consumed min −1 g −1) when plants were placed in a salinity of 15 for 24 h versus control specimens maintained at 0. After 1 week of exposure a significant increase in respiration and lipid hydroperoxide content was detected in plants incubated at or above a salinity of 13. In addition, effective quantum yield ( Δ F / F ′ m ) dropped significantly compared to plants maintained at a salinity below 13. These results highlight the use of cellular stress assays to monitor salt-induced sublethal responses in V. americana.

Comparison of the role of the foliar sheath in nutrient (ammonium and phosphate) acquisition by the seagrass Thalassia hemprichii (Ehrenb.) Aschers. at two different sites on tropical Hainan Island, China

Generally, the foliar sheaths of seagrass contribute a large biomass to the dry weight of plants, and are found to be above-sediment biomass or, sometimes, below-sediment biomass. However, the role of foliar sheaths of seagrass in nutrient uptake has not yet been established. Thus, this study was performed to test whether the growth form of foliar sheaths affects the nutrient uptake properties of the seagrass. Two separate sets of morphotypes of the seagrass Thalassia hemprichii were collected from two different tropical meadows in coastal Hainan Island, China in the South China Sea. Ammonium (NH4+) and phosphate (Pi) uptake by solely blades and roots (experiment I), and above and below-sediment tissues (experiment II) of the two sets of specimens were examined in partitioned chambers using laboratory incubations. Curve profiles of the blade and root saturation uptake kinetics were shown to be similar for the two morphotypes of T. hemprichii. However, the above and below-sediment tissues uptake kinetics had different characteristics between the two morphotypes. For plants with above-sediment foliar sheaths, uptake by the above-sediment tissues contributed an important part of the whole plants’ nutrient acquisition. In contrast, for plants with below-sediment foliar sheaths, the contribution of nutrient uptake by above-sediment foliar blade tissues seemed almost negligible. Therefore, the results demonstrated that foliar sheaths of the tropical seagrass T. hemprichii were able to absorb NH4+ and Pi. Especially interesting is that the capacity for uptake by robust foliar sheaths growing beneath the sediment was remarkable (we termed this the Zhang–Huang–Thorhaug effect). The role of sheaths in nutrient acquisition found in this study is critical in elucidating seagrass nutrient uptake strategies.

Control of Arabidopsis Leaf Morphogenesis Through Regulation of the YABBY and KNOX Families of Transcription Factors

The patterning of initiating organs along specific axes of polarity is critical for the proper development of all higher organisms. Plant lateral organs, such as leaves, are derived from the shoot apical meristems located at the growing tips. After initiation, the leaf primordia of species such as Arabidopsis thaliana differentiate into a polarized structure consisting of a proximal petiole and a distal blade, but the molecular mechanisms that control proximal-distal pattern formation are poorly understood. The transcriptional activators BLADE-ON-PETIOLE1 (BOP1) and BOP2 are known to control Arabidopsis lateral organ differentiation by regulating gene expression along the adaxial-abaxial (dorsal-ventral) and proximal-distal polarity axes. Here, we demonstrate that the development of ectopic blade tissue along bop1 bop2 leaf petioles is strongly suppressed in a dosage-dependant manner by mutations in either of two closely related YABBY (YAB) genes, FILAMENTOUS FLOWER (FIL) and YAB3. Three KNOTTED-LIKE HOMEOBOX (KNOX1) genes also make lesser, and partially redundant, contributions to ectopic blade development in bop1 bop2 leaves. Mutation of these YAB and KNOX1 genes together causes nearly complete suppression of bop1 bop2 ectopic organ outgrowth at the morphological and cellular levels. Our data demonstrate that BOP1 and BOP2 regulate leaf patterning by controlling YAB and KNOX1 gene activity in the developing petiole.

About the Cover.

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCover“Who is nibbling at my little house?” The old witch in the fairy tale “Hänsel und Gretel” had reason to be concerned because if the nibbling had continued, over time the house would have experienced serious damage. The lesson could be to not build your house out of food. However, this is exactly what many marine invertebrates do. How do they manage to maintain the integrity of the house while at the same time satisfying their food requirements? This is the question that Osvaldo Cerda and co-authors investigated in their study (pp. 248–258) on the nest-building habits of the marine amphipod Peramphithoe femorata.Amphipods from the family Ampithoidae make nests on algae by gluing together algal pieces or curling up kelp blades. The kelp curler Peramphithoe femorata, a common inhabitant of kelp forests in the SE Pacific, curls up blades of the giant kelp Macrocystis pyrifera. Spinning self-produced silk threads between the two sides of the kelp blades, these amphipods double over the blade and construct a closed, tube-like nest within a few hours (*for short videos of nest-building, see BEDIM, 2010). The amphipods feed on the blade tissues inside their nests, and females, as seen on the cover, share nests with their small offspring.How do these amphipods avoid eating themselves out of house and home? Carefully observing the amphipods in their nests, Cerda et al. noticed that nests are continuously renovated in fine-tuned synchrony with the growth dynamics of the kelp blades. A blade grows from its basis outward—that is, toward the tip. An amphipod, in turn, starts its nest near the tip of the blade and expands it toward the blade basis while feeding on the nest walls. Thus, the nest is not static, but a dynamic structure that steadily moves against the growing blade like a running conveyor belt. The authors suggest that this continuous nest renovation allows amphipods to remain for prolonged periods in a safe (and tasty) home. Nevertheless, aging kelp blades stop growing, forcing the amphipods to move on and start a new nest, most likely on young and growing blades.Credits: Cover photo and layout, Iván A. Hinojosa (Universidad Católica del Norte, Coquimbo, Chile).* BEDIM (Biology, Ecology & Diversity of Invertebrates from Marine Environment). 2010. Nest-building behavior by the amphipod Peramphithoe femorata on the kelp Macrocystis pyrifera. [Online] Available: http://www.bedim.cl/videos.htm [2010, 20 May]. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 218, Number 3June 2010 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv218n3cover Views: 204Total views on this site © 2010 by Marine Biological Laboratory. All rights reserved.PDF download Crossref reports no articles citing this article.

Productivity estimation of Zostera marina on the southern coast of Korea: Effects of leaf marking height and duration

The effects of marking height and duration were examined to determine optimal marking height and duration for accurate productivity estimation of eelgrass, Zostera marina, on the southern coast of Korea. Shoots were pierced through the sheath at 2, 5, and 8 cm above the meristem and through the leaf blade at 1 cm above the blade/sheath junction (+ 1 cm blade). The marked shoots were collected weekly during periods of 4-week duration; the experiments were conducted seasonally. Leaf productivities were estimated using three measurement methods, the conventional leaf marking method (CLM), Short '87 method (Short, 1987; Gaeckle and Short, 2002), and plastochrone method. The optimal marking height and duration for leaf productivity estimation varied with the measurement method. CLM and the Short '87 method, but not the plastochrone method, were affected by marking height. The productivity estimates were lowest with a 2-cm marking height treatment due to injury of immature leaf blade tissues. The highest marking height on the sheath gives a more reliable productivity estimate with CLM, whereas any location on the sheath other than the base was appropriate as a marking point for the Short '87 method. CLM and the plastochrone method, but not the Short '87 method, were significantly affected by marking duration. CLM underestimated leaf productivity with less than a 1- or 2-week marking duration because more immature leaf tissues were counted with shorter marking durations. The marking duration should be longer than the plastochrone interval (about 2 weeks in this study) to prevent under- or overestimation of leaf productivity, but the duration should not be longer than the triple-plastochrone interval (about 6 weeks in this study) to prevent underestimation due to the sloughing off of the marked leaves.

Differences in growth, morphology and tissue carbon and nitrogen of Macrocystis pyrifera within and at the outer edge of a giant kelp forest in California, USA

To investigate the extent to which alteration of physical factors by giant kelp beds affects the growth of kelp within the bed, we conducted analyses of frond morphometrics at 2 mo intervals, elongation rates and tissue chemistry of individuals of Macrocystis pyrifera on the interior and edge of a kelp bed off the coast of Santa Barbara, California, USA. The density of the kelp canopy varied greatly during the 13 mo study, ranging from 0.03 to 8.03 m 2 blade tissue m -2 sea surface. Time series analysis of flow velocity, light, temperature and seawater nitrate concentrations inside and out- side of the bed indicated that when canopy density was high (May to September) current speeds in the bed were 25% of incident flow, and light below the canopy (at 1 m depth) was reduced to 10% surface irradiance. Nitrate concentrations were highly variable and similar between inside and out- side moorings. When the canopy was well developed, kelp fronds on the seaward edge of the bed had faster elongation rates and larger blades, resulting in higher overall growth rates (mass added per day) than interior fronds. Carbon and nitrogen accumulation by edge fronds was also higher dur- ing this period, which fueled growth rates of edge fronds that were nearly twice as high as interior fronds when the canopy was densest. Thus, the growth and tissue chemistry of M. pyrifera within the kelp bed depended on the extent to which the bed modified ambient physical conditions.

Differences in resource storage pattern between Laminaria longissima and Laminaria diabolica (Laminariaceae; Phaeophyta) reflecting their morphological characteristics

The kelps Laminaria longissima and L. diabolica, belonging to the groups of L. angustata and L. japonica, respectively, differ greatly in their morphological characteristics although their geographical distributions overlap widely along the eastern coast of Hokkaido. To clarify the interaction between the morphological and physiological characteristics of the two species, and their link with environmental variables, hatchery-raised young sporophytes of L. longissima and L. diabolica collected from Hokkaido were cultivated simultaneously under similar conditions in Matsushima Bay, Miyagi, from January to July 2004. Seasonal morphological characteristics, gross photosynthetic rate, nutrient uptake rates, and resource contents were examined. The blade lengths of L. longissima and L. diabolica reached a maximum of 329.9 cm and 256.7 cm, respectively, in April to May, and decreased to 284.4 cm and 68.6 cm, respectively, in July. The total elongation length of L. longissima (412.5 cm) was similar to that of L. diabolica (373.8 cm). However, the total erosion length of L. longissima (145.9 cm) was approximately half that of L. diabolica (302.9 cm). The gross photosynthetic rate and uptake rates of NH4-N, NO3-N, and PO4-P of the two species were similar. However, the carbon, nitrogen, and phosphorus contents were transferred and stored in the whole blade tissues in the case of L. longissima, but in the meristem of L. diabolica from May to June. These results suggest that morphological differences are a response to different resource storage patterns. The storage patterns of L. longissima and L. diabolica are likely to be genetically fixed characteristics, which have evolved in adaptation to the specific habitat environments of the groups of L. angustata and L. japonica. The low water temperature and rich nutrients provided by the Oyashio Current are conducive to storage of resources in the whole blade tissues and a large surface area retained for photosynthesis and nutrient uptake in the L. angustata group. Conversely, high temperature and poor nutrients, or large fluctuations in these parameters, provided by the Tsushima Warm Current are more conducive to intensive storage of resources in the meristem for maturation and further growth in the L. japonica group. L. diabolica retains the storage pattern of the L. japonica group but grows in regions affected by the Oyashio Current, allowing it to become the widest distributed Laminaria species.

Species-specific defense strategies of vegetative versus reproductive blades of the Pacific kelps Lessonia nigrescens and Macrocystis integrifolia

Chemical defense is assumed to be costly and therefore algae should allocate defense investments in a way to reduce costs and optimize their overall fitness. Thus, lifetime expectation of particular tissues and their contribution to the fitness of the alga may affect defense allocation. Two brown algae common to the SE Pacific coasts, Lessonia nigrescens Bory and Macrocystis integrifolia Bory, feature important ontogenetic differences in the development of reproductive structures; in L. nigrescens blade tissues pass from a vegetative stage to a reproductive stage, while in M. integrifolia reproductive and vegetative functions are spatially separated on different blades. We hypothesized that vegetative blades of L. nigrescens with important future functions are more (or equally) defended than reproductive blades, whereas in M. integrifolia defense should be mainly allocated to reproductive blades (sporophylls), which are considered to make a higher contribution to fitness. Herein, within-plant variation in susceptibility of reproductive and vegetative tissues to herbivory and in allocation of phlorotannins (phenolics) and N-compounds was compared. The results show that phlorotannin and N-concentrations were higher in reproductive blade tissues for both investigated algae. However, preferences by amphipod grazers (Parhyalella penai) for either tissue type differed between the two algal species. Fresh reproductive tissue of L. nigrescens was more consumed than vegetative tissue, while the reverse was found in M. integrifolia, thus confirming the original hypothesis. This suggests that future fitness function might indeed be a useful predictor of anti-herbivore defense in large, perennial kelps. Results from feeding assays with artificial pellets that were made with air-dried material and extract-treated Ulva powder indicated that defenses in live algae are probably not based on chemicals that can be extracted or remain intact after air-drying and grinding up algal tissues. Instead, anti-herbivore defense against amphipod mesograzers seems to depend on structural traits of living algae.

Leaf tissues degradation of signalgrass hay pretreated with urea and submitted to in vitro digestion

An experiment using signalgrass hay treated with increasing urea levels (0, 20, 40, and 80 g/kg of dry matter), and submitted to in vitro digestion times (0, 6, 12, 24 or 72 hours) was conducted to evaluate the effects of ammoniation rates and digestion times on leaf blade tissue degradation. A completely randomized design with a 4 × 5 factorial treatment arrangement, with three replicates was used. Data were submitted to multivariate analysis. Urea-treated hay presented smaller proportion of remaining tissues measured in leaf blades cross-sections after in vitro digestion. Tissues more affected by urea treatment degradation were parenchyma bundle sheath and sclerenchyma. The hay treated with 80 g urea/kg DM and in vitro digested for 24 or 72 hours showed smallest proportion of tissues with thick and lignified cell walls such as parenchyma bundle sheath and sclerenchyma. The treatment with urea also reduced the time necessary to tissue degradation. The urea-treated hay in vitro digested for 12 hours, showed the same tissue proportion found in untreated hay submitted to 24 or 72 hours of in vitro digestion. The epidermis and lignified vascular tissue showed the smallest degradation following in vitro digestion. Results indicated that treatment of signalgrass hay with urea contributed to cell wall structure disruption, enhancement of tissues microbial degradation and reduction of the time necessary to digestion.

Production of Alien Addition Lines in Polyploid Bunching Onion (Allium fistulosum) Carrying 1A Chromosome(s) of Shallot (Allium cepa) and Their Application to Breeding for a New Vitamin C-Rich Vegetable

Eight Allium fistulosum L.–Allium cepa L. Aggregatum group (shallot) monosomic addition lines (2n = 17, FF+1A–FF+8A) have been useful in revealing the effects of single alien chromosomes from A. cepa on the production of l-ascorbic acid in the leaf tissue of A. fistulosum. In this study, the determination of ascorbic acid content revealed that the incorporation of alien chromosome 1A into a diploid background of A. fistulosum increased the internal ascorbic acid content of the leaf blade tissue. We produced a 1A disomic addition in the tetraploid of A. fistulosum (2n = 34) and demonstrated high-frequency transfer of the alien chromosome in crosses with A. fistulosum. Five plants of the 1A disomic additions were regenerated via apical meristem culture of the FF+1A on a Murashige and Skoog medium containing colchicine. These 1A disomic additions showed partial fertility for female and male gametes. Most of the progenies from selfing of the 1A disomic additions and reciprocal crossing with A. fistulosum possessed chromosome 1A. Interestingly, 64% (18 of 28) of the plants obtained from the reciprocal crosses were 1A monosomic additions in a triploid background of A. fistulosum. These monosomic additions were more vigorous and vitamin C-rich than euploid plants of A. fistulosum.

Genetic Variation for Shelf-life of Salad-cut Lettuce in Modified-atmosphere Environments

Packaged salad-cut lettuce (Lactuca sativa L.) for food service and salad mixes is an increasingly important component of the lettuce industry. The product is highly perishable; cold storage and modified-atmosphere (MA) packaging are used to extend its shelf life. Given the importance of this market, lettuce cultivars, breeding lines, and populations should be selected for increased shelf life in MA environments. The objectives of this research were to determine the genetic variation in lettuce for shelf life in low-O2 MA environments and to develop rapid evaluation methods suitable for a lettuce breeding program. Lettuce was processed from field-grown plants of 33 romaine and three crisphead cultivars over 2 years. Shelf life was evaluated after storage in MA bags and in CO2-free controlled-atmosphere (CA) chambers with gas ratios of 0.2% O2:99.8% N2, 1.0% O2:99.0% N2, or 5.0% O2:95.0% N2. Deteriorated leaf blade tissue was water soaked and wilted with a dull to dark or black color, and midrib tissue and heart leaves were water soaked with a translucent to dark brown color. Genetic variation for shelf life was detected using MA bags or CA chambers, and the results from both years and testing methods were significantly correlated. Oxygen concentration did not affect shelf life in the CA chamber experiment, which indicated that the observed symptoms in the majority of cultivars were probably not from low O2 damage or CO2 injury, although multiple mechanisms of deterioration may be involved. Selection for lettuce cultivars, breeding lines, and populations with extended shelf life is possible using MA bags or CA chamber testing methods and could facilitate a consistent release of germplasm with stable shelf life in MA environments.