Introduction of xylem differentiation in lactuca by ethylene

Evidence was obtained to support the hypothesis that ethylene is involved in xylem differentiation in primary pith explants of Lactuca sativa L. cv Romaine cultured in vitro. Xylem elements differentiated when explants were supplied indole-3-acetic acid (IAA) in combination with either the ethylene biosynthetic precursor 1-aminocyclopropane-1-carboxylic acid (ACC), the ethylene-releasing agent 2-chloroethylphosphonic acid (CEPA), or kinetin. In contrast, no xylem elements differentiated in the presence of IAA, kinetin, ACC, or CEPA alone, or when kinetin was supplied together with ACC or CEPA. These results show that ethylene will substitute qualitatively for cytokinin during auxin-induced xylogenesis, and suggest that both ethylene and auxin are required for xylem differentiation in Lactuca.     

Kinos of Eucalyptus species and their acid degradation products

The kinos of Eucalyptus astringens, E. lehmannii and E. platypus contain mainly polymerized leucocyanidin, appreciable amounts of dihydrokaempferol 3-rhamnoside and trace amounts of other components, The acid degradation products of different kinos contained components not present in the products from wood and bark. These include phloroglucinol and two other components whose properties are described.     

Physiological Studies on Pea Tendrils: VII. Evaluation of a Technique for the Asymmetrical Application of Ethylene

A technique has been devised for the asymmetrical application of ethylene to specific surfaces of plant tissue. 2-Chloroethylphosphonic acid (CEPA) was dissolved in a phosphate buffer (pH 6.5) containing Tween-20 or dimethylsulfoxide as adjuvant. Ethylene evolution from tendrils of Pisum sativum cv. Alaska was greater during coiling than when they were at rest; and via topical application to the ventral surface, CEPA was able to stimulate contact coiling. Within 1 day of application of CEPA, the tendrils showed symptoms of senescence. It is concluded that ethylene participates in the control of contact coiling stimulated by touch, and it is suggested that this control may be exerted via permeability changes in the membranes of the motor cells.     

Roles of JnRAP2.6-like from the Transition Zone of Black Walnut in Hormone Signaling

An EST sequence, designated JnRAP2-like, was isolated from tissue at the heartwood/sapwood transition zone (TZ) in black walnut (Juglans nigra L). The deduced amino acid sequence of JnRAP2-like protein consists of a single AP2-containing domain with significant similarity to conserved AP2/ERF DNA-binding domains in other species. Based on multiple sequence alignment, JnRAP2-like appears to be an ortholog of RAP2.6L (At5g13330), which encodes an ethylene response element binding protein in Arabidopsis thaliana. Real-time PCR revealed that the JnRAP2-like was expressed most abundantly in TZ of trees harvested in fall when compared with other xylem tissues harvested in the fall or summer. Independent transgenic lines over-expressing JnRAP2-like in Arabidopsis developed dramatic ethylene-related phenotypes when treated with 50 µM methyl jasmonate (MeJA). Taken together, these results indicated that JnRAP2-like may participate in the integration of ethylene and jasmonate signals in the xylem and other tissues. Given the role of ethylene in heartwood formation, it is possible JnRAP2-like expression in the transition zone is part of the signal transduction pathway leading to heartwood formation in black walnut.     

Influence of chlorocholinechloride and ethrel on chlorophyll content and the “epinastic response” of the primary leaf of wheat seedlings

Wheat seedlings were cultivated in nutrient solutions containing 10^-3 M CCC, 10^-3 M CEPA or 5 × 10^-4 M CCO and CEPA, respectively. CCC applied alone or mixed with CEPA increased chlorophyll content per unit fresh matter but had no influence on the epinastio response of the primary leaf. In contrast, CEPA had no influence on chlorophyll content but greatly increased the epinastic response. The different response to the application of these substances with regard to chlorophyll content ha been claimed in a previous paper to be due to their different effect on cell extension and cell division. The epinastic response of the primary leaf suggests that ethylene participates in the reaction chain of CEPA effect on plant tissues.     

Kinetics and implications of seedling growth responses to 2-chloroethylphosphonic acid

The effects of soaking seed in 2-chloroethylphosphonic acid (CEPA) for 24 or for 48 h on the cumulative 5-day seedling growth ofCucumis sativus L. (cucumber) andPisum sativum L. (peas) were studied. Each cucumber seed absorbed an average of 0.015 ml of CEPA solution, while pea seed absorbed 0.365 ml, over a 24 h period. In cucumber, 240 mg l^?1 CEPA concentration decreased radicle length by 23%, regardless of soaking duration. The same concentration increased radicle weight in a 24 h soaking duration, but decreased radicle weight when soaking was for 48 h. At 48 h, CEPA concentrations of 0.24 and 2.4 mg l^?1 increased plumule growth by 26%. In peas, the 240 mg l^?1 decreased the length and the weight of both the radicle and the plumule in a 48 h soaking duration, but had no significant effect at a 24 h soaking. At the low concentration of 0.24 mg l^?1, seedling growth was stimulated by over 30%. Cucumber was 3 times more efficient than peas in the utilization of CEPA for seedling growth, in terms of total fresh weight of seedling per microgram of CEPA absorbed: 1 127 and 274 mg μg^?1 CEPA in cucumber and peas respectively. Extrapolative calculation, using cucumber responses as standard, suggests from this seedling study that about 12 mg l^?1 CEPA is likely to stimulate growth and/or yield in sprayed pea plants.     

Addition of fermented and unfermented grape skin in broilers’ diets: effect on digestion,growth performance,intestinal microbiota and oxidative stability of meat

Grape skin is a source of polyphenols with antioxidant and antimicrobial properties. Little information is available regarding its application in animal feeding. The present study investigated the effect of inclusion of fermented (FS) and unfermented (UFS) grape skin at two different doses (30 g/kg, FS30 and UFS30, and 60 g/kg, FS60 and UFS60) and 200 mg/kg vitamin E (α-tocopheryl acetate) in a corn–soybean diet on growth performance, ileal protein digestibility, ileal and excreta total extractable polyphenols content and digestibility, intestinal microbiota and thigh meat oxidation in broiler chickens. Growth performance was depressed in chickens fed UFS and FS diets. A reduction in ileal protein digestibility was also observed in birds fed UFS, being this effect more pronounced in those fed 60 g/kg. The dietary inclusion of grape skin increased both ileal and excreta polyphenols contents, being higher in birds fed UFS than in those fed FS. Excreta moisture content increased in birds fed UFS and FS diets. No effect of dietary inclusion of grape skin was observed on ileal counts of lactic-acid bacteria and Clostridium, but UFS inclusion in the diet reduced ileal count of Escherichia coli as compared with FS dietary inclusion. After 7 days of refrigerated storage, values of thiobarbituric acid reactive substances (TBARS) were lower in chicken meat when grape skin was added in the diet at 60 g/kg instead of 30 g/kg, and meat from birds fed 60 g/kg of grape skin reached TBARS values similar to those of birds supplemented with vitamin E. In conclusion, high doses of grape skin polyphenols depressed growth performance and protein digestibility, and increased excreta moisture content. Unfermented grape skin contained more polyphenols than FS, and its inclusion in the diet led to higher ileal and excreta polyphenols contents and to a lower ileal count of E. coli. Furthermore, the antioxidant potential of the polyphenols present in grape skin was observed after 7 days of meat storage, with the dose of 60 g/kg of grape skin being as effective as vitamin E supplementation in maintaining oxidative stability of meat.     

Structural and Chemical Characterization of Hardwood from Tree Species with Applications as Bioenergy Feedstocks

Eucalypt species are a group of flowering trees widely used in pulp production for paper manufacture. For several decades, the wood pulp industry has focused research and development efforts on improving yields, growth rates and pulp quality through breeding and the genetic improvement of key tree species. Recently, this focus has shifted from the production of high quality pulps to the investigation of the use of eucalypts as feedstocks for biofuel production. Here the structure and chemical composition of the heartwood and sapwood of Eucalyptus dunnii, E. globulus, E. pillularis, E. urophylla, an E. urophylla-E. grandis cross, Corymbia citriodora ssp. variegata, and Acacia mangium were compared using nuclear magnetic resonance spectroscopy (NMR), X-ray diffraction (XRD) and biochemical composition analysis. Some trends relating to these compositions were also identified by Fourier transform near infrared (FT-NIR) spectroscopy. These results will serve as a foundation for a more comprehensive database of wood properties that will help develop criteria for the selection of tree species for use as biorefinery feedstocks.     

Responses of forest eucalypts to moderate and high intensity fire in the Tingle Mosaic,south‐western Australia: comparisons between locally endemic and regionally distributed species

Responses of three locally endemic (Eucalyptus brevistylis, Eucalyptus jacksonii and Eucalyptus guilfoylei) and three co‐occurring regional eucalypts (Eucalyptus marginata, Eucalyptus diversicolor and Corymbia calophylla) to moderate‐ and high‐intensity fires were examined in granitic terrain of the Tingle Mosaic, south‐western Australia. Significant associations between diameter distributions and community type (CT) for each species (P < 0.001) suggest that fire response will also vary according to the habitat/fire interaction. None of the species were fire sensitive, although responses differed both within and between species, and with CT. All species examined predominately consisted of several cohorts of regeneration within a forest stand. Each species had thick bark and re‐sprouted from crown epicormics following 100% scorch of the mature tree. The quantity and type of regeneration in relation to gaps created by individual dead trees following fire differed between species; for example, E. guilfoylei regeneration was strongly associated with gaps, and C. calophylla with non‐gaps. However, regeneration of the two tall open‐forest species, E. jacksonii and E. diversicolor were not most associated with either gaps or non‐gaps. The very low levels of regeneration of E. brevistylis following fire and the high proportion of stems of E. jacksonii that were hollow butted (40% of stems > 1 m DBHOB) may be factors associated with narrow endemism of these species and may affect the vulnerability of these eucalypts to fire. The interaction of seed availability, intense fires and subsequent rainfall may be critical in the long term survival of these species. Eucalyptus guilfoylei, by contrast, appears well adapted to the increasing levels of disturbance likely in the region where these species occur. The vulnerability of a locally endemic species in a fire‐prone environment is likely to reflect differences to the prevailing adaptations of the dominant species rather than an inherent ability of the species to survive or respond. Management regimes must account for variations in species responses to fire in different CTs if the long‐term survival chances of local endemics are to be enhanced.     

Ethylene inhibitors promote male gametophyte survival in rice

Rice (Oryza sativa L. cv. Lalat) was grown in pots under open field conditions during the wet season of 1997. Attempts were made to manipulate the growth and development of the male gametophyte, located on the basal region of the panicle, by exogenous application of chemicals regulating formation/action of ethylene and compare grain setting in the spikelets bearing few grain. Application of ethylene action (AgNO₃) and synthesis inhibitor (Co(NO₃)₂; paclobutrazol and uniconazole) improved grain setting in the spikelets and the ethylene releasing substance 2-chloroethyle phosphonic acid (CEPA) depressed it compared to the control. The ethylene inhibitors promoted dry mass accumulation and concentrations of starch and reducing sugars in the anthers of the basal spikelets, while CEPA reduced the level of these carbohydrates significantly. The ethylene inhibitors helped in the survival of more numbers of pollen in these anthers, but CEPA depressed their number significantly. Promotion of growth of the basal anthers was accompanied by a concomitant reduction in the concentration of nonreducing sugars and enhanced activities of acid invertase and sucrose synthase enzymes. It is concluded that male gametophyte development of the basal spikelets of rice is susceptible to ethylene at the stage of pollen mitosis. The possibility of the hormone interfering in carbohydrate metabolism of the anther during this stage of development is discussed.     

Jarrah Forest Restoration in Western Australia: Canopy and Topographic Effects

The restoration of the northern jarrah (Eucalyptus marginata) forest after bauxite mining is a major objective of Alcoa of Australia Limited. The typically variable and sometimes low emergence of broadcast seed of jarrah-forest plant species may relate to microclimatic changes associated with mining disturbance. This study examined the effect of the presence and absence of a canopy and topographic position in the post-mining landscape on the emergence of four canopy species (E. marginata, E. calophylla, E. patens, and E. diversicolor) and related these patterns to detailed measures of surface soil temperature and moisture. The absence of a canopy in the restoration appeared to result in adverse microclimatic conditions for the successful early establishment of E. marginata and E. calophylla from seed, particularly in the low topographic regions of the restoration. Emergence beneath a canopy compared to that in the open was 17% and 6%, respectively, for E. marginata and 23% and 2%, respectively, for E. calophylla. For both species, emergence was also greater at upland than at lowland open restoration sites (9% and 3%, respectively, for E. marginata; 4% and 0.3%, respectively, for E. calophylla). In contrast, canopy removal and position on the topographic landscape did not reduce the early establishment success of E. patens and E. diversicolor. Field measurements revealed that soils were drier and that diurnal temperature fluctuations were wider in the open restoration sites than beneath a canopy. Furthermore, cold conditions were more frequent at lowland than at upland restoration sites, suggesting the occurrence of cold-air drainage to Jew-lying areas. It is therefore possible that the field emergence patterns reflected the lower tolerance of E. marginata and E. calophylla than both E. diversicolor and E. patens to cold and dry surface-soil conditions. The ecological significance and practical implications of the results are discussed.     

Fungal Communities in Decaying Sapwood and Heartwood of a Conifer <Emphasis Type="Italic">Keteleeria evelyniana</Emphasis>

Fungal communities in decaying sapwood and heartwood of K. evelyniana were demonstrated through construction of four 18 S rRNA gene libraries. The 210 sequenced clones were clustered into 11 subgroups, belonging to Basidiomycota (71.9%) and to Ascomycota (22.4%) and unclassified (1 subgroup; 5.7%). The heartwood displayed higher species richness than the sapwood. Basidiomycota were dominant in either the heartwood or the sapwood. Phylogenetically diverse Homobasidiomycetes were detected in the heartwood, contrary to the sapwood, where Heterobasidiomycetes were detected. Clones close to Spongipellis unicolor dominated in the heartwood (21 of 99 clones), while those close to Hydnochaete olivacea dominated in the sapwood (41 of 111 clones). The common species between the two parts were those related to S. unicolor, Calocera cornea, Debaryomyces hansenii, Davidiella tassiana, and Nomuraea rileyi and those from Chaetothyriomycetes.     

Species distribution and crown decline are associated with contrasting water relations in four common sympatric eucalypt species in southwestern Australia

Background and aims

Drought-associated vegetation declines are increasingly observed worldwide. We investigated whether differences in water relations can potentially explain the distribution and vulnerability to drought-induced decline of four common tree species in Mediterranean southwestern Australia.

Methods

We compared seasonal and daily water relations of four eucalypt species (i.e. C. calophylla, E. accedens, E. marginata, E. wandoo) when co-occurring as well as on nearby typical sites for each species.

Results

When co-occurring, species generally inhabiting drier regions (i.e. E. accedens, E. wandoo) had lower summer leaf water potentials, osmotic potential, and vulnerability to cavitation and higher stomatal conductance and relative sapflow velocity. Both wetter zone species (e.g. C. calophylla and E. marginata) had remarkably high vulnerabilities to cavitation for Mediterranean woody species but showed greatly improved leaf water status on nearby sites where they dominate. Using local soil moisture retention curves of saprolitic clay layers underlying southwestern Australia we show the large disadvantage that the wetter zone species have in terms of accessing tightly bound water in these layers.

Conclusions

Our work shows that species distribution and local dominance of four dominant overstorey species in southwestern Australia is largely a function of plant water relations interacting with local soil profiles. The observed differences in water relations amongst species are consistent with some of the declines that have been observed in recent decades.     

Convergence of tree water use within an arid-zone woodland

We examined spatial and temporal patterns of tree water use and aspects of hydraulic architecture in four common tree species of central Australia—Corymbia opaca, Eucalyptus victrix, E. camaldulensis and Acacia aneura—to better understand processes that constrain water use in these environments. These four widely distributed species occupy contrasting niches within arid environments including woodlands, floodplains and riparian environments. Measurements of tree water use and leaf water potential were made at two sites with contrasting water table depths during a period of high soil water availability following summer rainfall and during a period of low soil water availability following 7 months of very little rainfall during 2007. There were significant differences in specific leaf area (SLA), sapwood area to leaf area ratios and sapwood density between species. Sapwood to leaf area ratio increased in all species from April to November indicating a decline in leaf area per unit sapwood area. Despite very little rainfall in the intervening period three species, C. opaca, E. victrix and E. camaldulensis maintained high leaf water potentials and tree water use during both periods. In contrast, leaf water potential and water use in the A. aneura were significantly reduced in November compared to April. Despite contrasting morphology and water use strategies, we observed considerable convergence in water use among the four species. Wood density in particular was strongly related to SLA, sapwood area to leaf area ratios and soil to leaf conductance, with all four species converging on a common relationship. Identifying convergence in hydraulic traits can potentially provide powerful tools for scaling physiological processes in natural ecosystems.     

Sapwood characteristics of Quercus robur species from the south-western part of the Pannonian Basin

We analysed sapwood characteristics in 344 pedunculate oak (Quercus robur L.) samples from the south-western part of the Pannonian Basin. The samples came from 13 sites, located in Slovenia, Croatia and Serbia. The trees had an average of 13.3 sapwood rings, with a minimum of 5 and maximum of 32. Fifteen log-log linear regression models were employed to assess the statistical relationship between sapwood and heartwood variables. The number of sapwood rings (N_SW), which is usually needed in dendroarchaeological dating, is significantly related to the number of heartwood rings (N_HW), heartwood width (W_HW) and heartwood growth rate (G_HW). Older and more slowly growing trees had a higher average number of sapwood rings. Using N_HW and W_HW, we employed an additional multiple regression model and calculated coefficients for N_SW predictions for real-world dendroarchaeological dating from the south-western part of the Pannonian Basin.     

The effect of ethylene inhibitors （AgNO3, AVG）, an ethyleneliberating compound （CEPA） and aeration on the formation of protocorm-like bodies of hybrid Cymbidium （Orchidaceae）

Protocorm-like bodies （PLBs） or thin cell layers （TCLs） derived from PLBs of hybrid Cymbidium Twilight Moon ＇Day Light＇ can induce new or neo-PLBs on Teixeira Cymbidium （TC） medium, which contains 0.1 mg/L a- naphthaleneacetic acid, 0.1 mg/L kinetin, 2 g/L tryptone and 20 g/L sucrose, and is solidified with 8 g/L Bacto agar. This study aimed to assess the response ofneo-PLB formation to an ethylene-liberating compound （2-chloroethylphosphonic acid （CEPA））, to two ethylene inhibitors （silver nitrate （AgNO3） and aminoethoxyvinylglycine （AVG））, and to aeration （made possible by using Milliseal~ or autoclaved filter paper）. AgNO3 at 1 or 2 mg/L in TC medium significantly increased the fresh weight of PLBs while 1 mg/L of AgNO3 also showed a significant increase in the number ofneo-PLB from both half-PLBs and from tTCLs. In contrast, AVG and CEPA inhibited neo-PLB formation. Neo-PLB formation from half-PLB or TCL explants in the presence of aeration resulted in significantly lower neo-PLB weight. The use of AgNO3 and aeration are alternative means to mass produce neo-PLBs for micropropagation purposes.     

Promotion ofin vitro shoot formation from excised roots of silktree (Albizzia julibrissin) by an oxime ether derivative and other ethylene inhibitors

Summary This report describes the regeneration response of excised seedling roots of silktree (Albizzia julibrissin) to added ethylene precursors/generators (1-amino-cyclopropane-1-carboxylic acid [ACC], 2-chloroethylphosphonic acid [CEPA]), biosynthesis inhibitors (aminoethoxyvinylglycine [AVG], an oxime ether derivative [OED={[(ispropylidene)-amino]oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester], CoCl² [Co⁺⁺]), and an ethylene action inhibitor (AgNO₃ [Ag⁺]). When placed on B5 medium, about 50% of the control explants formed shoot buds within 15 days. Addition of ACC or CEPA (1–10 µM) to the culture medium decreased both the percentage of cultures forming shoots and the number of shoots formed per culture. In contrast, AVG and OED (1–10 µM) increased shoot formation to almost 100% and increased the number of shoots formed per culture. Likewise, both Co⁺⁺ and Ag⁺ (1–10 µM) increased shoot regeneration, but the number of shoots produced after 30 days was less than with AVG or OED. The inhibitors of ethylene biosynthesis were partially effective in counteracting the inhibitory effect of ACC on shoot formation. These results suggest that modulation of ethylene biosynthesis and/or action can strongly influence the formation of adventitious shoots from excised roots of silktree.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AVG aminoethoxyvinylglycine - CEPA 2-chloroethylphosphonic acid - OED oxime ether derivative     

Within-thallus variation in polyphenolic content and antifouling activity in Sargassum vulgare

The brown seaweed Sargassum vulgare C. Agardh abounds along the southeast coast of Rio de Janeiro State, Brazil, creating unique habitats, and its polyphenols play an important ecological role as antifouling agents. In order to understand more precisely this defensive strategy of S. vulgare, we collected this macroalga at Ilha de Itacuruçá in May and October 2009. Thalli were separated according to tissue type: pneumatocysts, receptacles, leaflets, and axis. Phenolic extracts from each specific part of the plant were obtained and the associated antifouling activity was tested in order to assess whether a tissue specialisation/antifouling activity pattern exists. Preliminary separation process was carried out on a phenolic extract to separate the polyphenols from the remaining compounds. Such fractionation allowed us to study the involvement of strictly phenolic compounds in antifouling activity. Within-thallus variation in both phenolic content and antifouling activity were highlighted, and seasonal variation in both those characters was also observed. For both experiments, pneumatocyst and leaflet phenolic extracts were the most active against the attachment of Perna perna, but no correlation was observed between phenolic concentration and antifouling activity. On the contrary, the extract containing only phenolic compounds was twice less active than the extract from which 80 % of the polyphenols were removed. These results led us to hypothesise that polar compounds other than polyphenols are involved in the antifouling activity.