Soil seed bank of the invasive Robinia pseudoacacia in planted Pinus nigra stands

Pinus nigra and Robinia pseudoacacia are exotic trees used for afforestation in Hungary. Pinus nigra was non-invasive, however R. pseudoacacia escaped from cultivation and invaded several vegetation types including pine plantations. It has recently been planned to cut P. nigra plantations and replace them by native tree stands, especially in nature reserves. The scattered presence of R. pseudoacacia specimens in pine stands might place constraints on planned tree replacement because of their vegetative resprouting and recolonization from an established seed bank. The aim of this study was to investigate the soil seed bank under the canopy of solitary R. pseudoacacia specimens found in P. nigra plantations. Altogether 250 soil samples were collected from the 0–6 and 6–12 cm soil layers under solitary Robinia trees of varying ages (with basal areas between 62.4 and 1089.3 cm2). Seeds were separated by sieving then scarified and germinated. Seed bank density ranged between 640 and 2285 seedsm–2 with an average distribution of 82.7% and 17.3% in the upper and lower soil layer, respectively. Total density of the seed bank and also the seed bank ratio of the lower soil layer increased with tree age. The accumulated seed bank of R. pseudoacacia should be considered in the careful planning of tree replacement operations in Pinus nigra stands

Effects of brassinosteroid on cotton regeneration via somatic embryogenesis

Brassinolide (BR), which is the most biologically active brassinosteroid, was used to examine the potential effect of hormone on cotton somatic embryogenesis. Ten-day-old cotton (Gossypium hirsutum L, cv. Cooker) seedlings were used for explant source and hypocotyls were removed and cultured on MS basal medium with 135 vitamins supplemented with 1 mg/L 6-benzylaminopurine + 0.5 mg/L kinetin for callus induction. After one month proliferating calli pieces were collected and cultured on MS basal medium containing various concentrations of BR (0.1, 0.5, 1.0 AM) with their controls. BR treatments were negatively effective on the fresh weight of calli when compared to control. Differential somatic embryogenesis maturation rates due to BR treatment were observed. Somatic embryogenesis was stimulated especially for transition to cotyledonary phase at 0.5 mg/L BR. Histological preparations from embryogenic calli and somatic embryos at different stages of development revealed the spontaneous polyploidisation during early somatic embryogenesis on BR-treated calli. Present results suggest that BR negatively effected calli growth, however, had a stimulating role in maturation of somatic embryos

Antibacterial activity of seed proteins of Robinia pseudoacacia

A low molecular weight cationic peptide was isolated from Robinia pseudoacacia seed and tested in vitro against seven bacteria (Corynebacterium michiganense, Staphylococcus aureus, Bacillus subtilis, Erwinia carotovora subsp. carotovora, Pseudomonas syringae pv syringae, Xanthomonas campestris pv campestris, and Escherichia coli). The peptide inhibited the growth of the tested strains. The effective concentrations required for 50% inhibition of bacterial growth ranged between 20 and 120 mug ml(-1) protein. S. aureus was found to be the most sensitive strain, however, E. coli was not affected much when compared with others. Reduction of antibacterial activity of the peptide with CaCl2 addition into the growth medium was also observed. (C) 2004 Elsevier B.V. All rights reserved

Direct plant regeneration from node and apex explants of cotton in Turkey

The objective of this project is to obtain resistance cotton plants to Verticillum dahliae, which is one of the important diseases of cotton in Turkey. One of the method to improve the resistance against such disease is to genetically engineer plants for the expression of antifungal genes (encoding proteins) that are directly toxic to pathogen of interest. Since regeneration protocols for cotton clones from Turkey has not been reported, a shoot regeneration for two important cotton clones (Nazilli M-503 and Sel-5) was developed and presented here. Shoot regeneration from different explants (leaves, petioles, internodes, nodes, hypocotyl and apex) of cotton was investigated on Murashige and Skoog (MS) medium with appropriate supplements of growth regulators. The highest shoot regeneration efficiency was obtained from the nodes and apex explants on MS11 (MS with 2 mg/l zeatin and 2mg/l kinetin) and MS12 (MS with 2 mg/l BAP and 2mg/l zeatin) respectively. Root formation was obtained on MS supplemented with 0.5 mg/l indolebutyric acid (IBA). This regeneration system can be used for further studies on transformation of cotton with antifungal genes

Yr10 gene polymorphism in bread wheat varieties

Yellow rust resistance locus Yr10 located on chromosome 1B in Moro and originated from the Turkish line PI178383 was investigated in terms of polymorphism in seven winter type bread wheat cvs.(Triticum aestivum ssp. Aestivum) Altay2000, zgi2001, Sönmez2001 (yellow rust resistant), Aytýn98, ES14, Harmankaya99 (yellow rust susceptible) and PI178383 as control. Exon 1 (1 - 833 bp) and Exon 2 (1989 - 3630 bp) parts of Yr10 were amplified with three primers. Amplification was not observed with E2A primers in Harmankaya99, zgi2001 and Sönmez2001 cvs, while amplification products were observable at all tested varieties with the other primers. PCR results showed that E2A reverse primer is not able to anneal to the three varieties mentioned above. Sequence analysis and bioinformaticsanalysis proved that there has been single nucleotide changes especially in the second exon. The most similar sequences to the first exon of Harmankaya99, zgi01 and Sönmez2001 are AF509535 (Aegilops tauschii NBS-LRR-like gene), AF509534 (A. tauschii NBS-LRR-like gene sequence) and AF509534, respectively. These results could be helpful in revealing divergence between resistant and susceptible varieties