Intergeneric Somatic Hybridization Between Brassica napus L. and Sinapis alba L.

Electrically induced protoplast fusion was used to produce somatic hybrids between Brassica napus L. and Sinapis alba L. Seven hybrids were obtained and verified by the simple sequence repeat and cleaved amplified polymorphic sequence analysis of the genefael, indicating that the characteristic bands from S. alba were present in the hybrids. The hybridity was also confirmed by chromosome number counting because the hybrids possessed 62 chromosomes, corresponding to the sum of fusion-parent chromosomes. Chromosome pairing at meiosis was predominantly normal, which led to high pollen fertility,ranging from 66% to 77%. All hybrids were grown to full maturity and could be fertilized and set seed after self-pollination or back-crosses with B. napus. The morphology of the hybrids resembled characteristics from both parental species. An analysis of the fatty acid composition in the seeds of F1 plants was conducted and the seeds were found to contain different amounts of erucic acid, ranging from 11.0% to 52.1%.     

Climate–growth relationship of tree species from a mixed stand of Apuseni Mts., Romania

We present the first results of a dendroecological investigation on three prevailing species growing in the Apuseni Mountains. In this study we succeeded in building up about 200-year long local master chronologies for spruce, fir and beech. These chronologies will serve as a reference for crossdating of (sub-fossil) logs that were preserved in ice caves at the Apuseni Mts.

The analysis of climate–growth relationship provided interesting and different results for the three studied species: we found significant correlations between the beech chronology and the mean temperature of the prior July, autumn and January of the actual year as well as the weather conditions at the beginning of the vegetation period. Conifers yielded coherent results for the mean temperature of prior July and sum of precipitation in April. In addition, fir seems to be favouring above-average temperatures in January and February. The coherent and significant correlations with the April precipitation suggest a common coniferous phenomenon. Finally, beech index showed negative correlation with April temperature.     

Biochar and alternate partial root-zone irrigation greatly enhance the effectiveness of mulberry in remediating lead-contaminated soils

土壤铅污染日益严重,植物修复是一种环保的污染土壤修复技术。本文旨在研究四种土壤铅污染水平下,添加生物碳和分根区交替 灌溉(Alternative Partial Root-zone Irrigation,APRI)对桑树幼苗的生长、铅适应性和铅积累的影响。我们以生物碳(添加与不添加生物碳)、灌溉方式(APRI 与常规灌溉)和土壤铅水平(0、50、200 和800 mg kg⁻¹ Pb)为三因素实施了温室试验。通过测定桑树幼苗的生长性状、渗透物质代谢、抗氧化酶活性、铅的积累和转运等参数,探讨了不同处理对桑树生长发育的影响。结果表明,桑树对土壤铅污染有较强的适应能力;生物碳和APRI 在不同土壤铅水平上协同提高了生物量和吸收根表面积。桑树通过调节谷胱甘肽 (GSH)、脯氨酸代谢和过氧化物酶(POD)活性,增加了渗透和抗氧化调节能力,进而提高了对重度铅污染土壤(800 mg kg⁻¹)的抗性。桑苗中的铅离子主要集中在根中,与土壤铅浓度具有剂量效应。土壤铅、生物碳和ARPI的交互作用影响了叶片和根系中铅的浓度、转运和生物富集系数。综上所述,在桑树栽培中结合外源生物碳和APRI可有效地用于修复土壤铅污染。     

Transformation of elite white poplar (Populus alba L.) cv. ' Villafranca' and evaluation of herbicide resistance

 Transgenic white poplar plants (Populus alba L.) expressing the nptII gene and the bar gene from Streptomyces hygroscopicus have been produced using Agrobacterium tumefaciens-mediated gene transfer. Eleven kanamycin-resistant plant lines were obtained with a transformation frequency of 7%. Successful genetic transformation was confirmed by Southern and northern analyses. The level of resistance to the commercial preparation of phosphinothricin (Basta; Roussel-Hoechst Agrovet) was evaluated by in vitro and in vivo assays. Using in vitro selective conditions for phosphinothricin, only plantlets from four kanamycin-resistant independent lines remained green and continued to grow and root. After transfer to the growth chamber, all selected transgenic lines were shown to be completely resistant to the herbicide Basta with doses equivalent to 6 l ha^–1 (normal field dosage) and were tolerant at concentration of 12 l ha^–1. This is the first report describing the genetic transformation of a P. alba clonal cultivar of commercial interest with a gene of agronomic value. Received: 12 June 1999 / Revision received: 6 March 2000 / Accepted: 7 March 2000     

Four New Flavonoids with α‐Glucosidase Inhibitory Activities from Morus alba var. tatarica

Four new flavonoids, mortatarins A–D ( 1 – 4 , resp.), along with eight known flavonoids ( 5 – 12 ) were isolated from the root bark of Morus alba var. tatarica. Their structures were established on the basis of spectroscopic data analysis, and the absolute configuration of 4 was determined by analysis of its CD spectrum. All isolates were tested for inhibitory activities against α‐glucosidase. Compounds 4, 7 , and 8 exhibited a significant degree of inhibition with IC₅₀ values of 5.0±0.3, 7.5±0.5, and 5.9±0.2 μM , respectively.     

Obtention d'épinastie des cotylédons de Sinapis alba en éclairement rouge Iointain continu.

Obtention of epinasty in the cotyledons of Sinapis alba under continuous far-red illumination. Relation to the development of hypocotyl and cotyledons. Treatment by far red light induces epinasty of the cotyledonary leaf. The effects of light treatments of different intensities were recorded for hypocotyl length, percentage of epinasty and the cotyledon leaf area. The percentage of epinasty increases as a function of treatment duration and light intensity. As from the second day of treatment a correlation is obtained between the percentage of epinasty and hypocotyl length when the seedlings are given far-red light treatment of different durations.     

Sulphate and micronutrients can modulate the expression levels of myrosinases in Sinapis alba plants

The myrosinase‐glucosinolate system is considered to be a major component of the preformed defence system of Brassicaceae species. This hypothesis has influenced the belief that the components of the myrosinase‐glucosinolate system are present at fixed levels which are independent of environmental factors. In the present study we show that external availability of nutrients can modulate the expression levels of myrosinase enzymes (EC 3.2.3.1). Nutrients such as sulphate, iron, copper, zinc and manganese were tested for their modulation effect on myrosinase expression levels and activity in roots, stems, cotyledons and buds of Sinapis alba seedlings at four different developmental stages. The most sensitive organ was the bud where iron deficiency approximately doubled the myrosinase activity. Removal of sulphate and all four micronutrients reduced the myrosinase activity to approximately half of the activity in plants supplemented with all these nutrients. The myrosinase polypeptides can be divided into classes based on molecular mass after reduction. The nutritional status influenced mainly the 68‐kDa class of myrosinases as revealed by western blot and laser scan densitometry of the immunolabelled blots.     

Measurements of redox activity at the plasmalemma

Salt (NaCl) tolerance of 3 eucalypt species ( Eucalyptus alba Reinw. ex Bl., E. camaldulensis Dehnh and E. microtheca f.v. Muell.) was studied: three-month-old seedlings grown in a greenhouse were watered by a saline solution (up to 700 m M ) for 1 month. Mineral, water and sugar contents were highly affected by the saline stress. Sodium, K and Ca were accumulated in the leaves. No significant differences were found between E. camaldulensis and E. microtheca , the tolerant species, in water and mineral contents. Sugar contents were greater in E. microtheca . In E. microtheca Na was highly accumulated in roots [up to 910 μmol (g fresh weight)⁻¹], less in stems [up to 580 μmol (g fresh weight)-1] and leaves [up to 410 μmol (g fresh weight)^−r]. Chloride was also accumulated, its content was greater than the total content of Na and K, especially in the salt-tolerant provenance. Potassium and Ca contents were variously affected by the saline stress whereas soluble protein, amino acid and sugar contents were increased. Just after the saline stress, plants showed a large increase in the Na content of the leaf while the decrease in the K content of the stem and leaf continued. Plants were killed by the stress, probably because of too high accumulation of Na in leaves or roots according to the provenance. Osmoregulation and especially the participation of Na are discussed.     

The mid-Holocene extinction of silver fir (Abies alba) in the Southern Alps: a consequence of forest fires? Palaeobotanical records and forest simulations

Pollen records suggest that Abies alba played a dominating role in both the montane and lowland forests at the border of the Southern Alps between ca. 8500 and 5700 years ago. Two major declines in fir, at about 7300–7000 cal b.p. and at ca. 6000 cal b.p., followed by the local extinction of the species are characteristic of the area below ca. 1000 m a.s.l. In order to test the impact of fire on the population dynamics of silver fir, a dynamic model (DisCForm) with a fire module was applied to simulate the early- and mid-Holocene forest development. Simulation outputs based on different fire scenarios were compared with the pollen record from Lago di Annone (226 m a.s.l.). The marked Abies decreases shown in the pollen record can be simulated with very intensive fire scenarios, but they do not result in an extinction of silver fir in the model. Low charcoal influx values related to the Abies declines in the palaeobotanical record suggest that fire was not the only reason for the extinction of silver fir. Human impact, as well as Holocene climatic changes leading to temporary moisture deficits and reduced adaptability due to low genetic variation may have had a significant impact on the Abies forests.     

Transferability and characterization of nine microsatellite markers for the tropical tree species Tabebuia roseo-alba

Microsatellite loci that were previously developed in the tropical tree Tabebuia aurea were used for the genetic analysis of Tabebuia roseo-alba populations. Nine of 10 simple sequence repeat markers were amplified, and the polymorphism was assessed in 58 individuals sampled from two stands in southeastern Brazil. All loci were polymorphic with Mendelian inheritance. The allele numbers were high, ranging from 5 to 13 in population I and 3 to 7 in population II, with means of 8.9 and 5.5, respectively. We conclude that these markers can be efficiently used for parentage and gene-flow studies.