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A protocol for in vitro multiplication of caper (Capparis spinosa L. subsp. rupestris) from nodal segments collected from mature plants was developed. For shoot multiplication, one auxin (indol-3-butyric acid, IBA) and cytokinins of two different classes were used: the N6-substituted adenine derivatives 6-benzylamino purine (BAP), and the two synthetic phenylurea derivatives Nphenyl-N0-benzothiazol-6-ylurea (PBU) and N-phenyl-N0-(1,2,3-thidiazol-5-yl) urea (thidiazuron, TDZ). Maximum shoot production was achieved from explants cultured with the adeninic cytokinin BAP (4 lM) and the auxin IBA (0.5 lM). New shoots longer than 1 cm were used for rooting. To induce root formation, three auxins [indole-3-butyric acid (IBA), 1-naphthaleneacetic acid (NAA) and 3-Indoleacetic acid (IAA)] and two synthetic phenylurea derivatives [N,N-bis-(2,3-methylenedioxyphenyl)urea (2,3-MDPU) and N,N-bis-(3,4-methylenedioxyphenyl)urea\ud (3,4-MDPU)] were used. All rooting compounds tested stimulated the formation of roots. However, the best result in terms of a high percentage of rooted shoots having a\ud well-developed root system with many lateral roots was achieved with the synthetic phenylurea 2,3-MDPU (1 lM) with 93.7% of well rooted plantlets. About 80% of rooted\ud plantlets were successfully acclimatized and transferred to the greenhouse

No abstract

Asexual propagation in Ceratonia siliqua L.

No abstract

The foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) leads to consistent losses in tomato crops, urging to multiply investigations on the physiological bases for its infectiveness. As other P. syringae pathovars, Pst is equipped with photoreceptors for blue and red light, mimicking the photosensing ability of host plants. In this work we have investigated Pst strains lacking the genes for a blue-light sensing protein (PstLOV), for a bacteriophytochrome (PstBph1) or for heme-oxygenase-1. When grown in culturing medium, all deletion mutants presented a larger growth than wild-type (WT) Pst under all other light conditions, with the exception of blue light which, under our experimental conditions (photon fluence rate = 40 μmol m(-2) s(-1)), completely suppressed the growth of the deletion mutants. Each of the knockout mutants shows stronger virulence towards Arabidopsis thaliana than PstWT, as evidenced by macroscopic damages in the host tissues of infected leaves. Mutated bacteria were also identified in districts distant from the infection site using scanning electron microscopy. These results underscore the importance of Pst photoreceptors in responding to environmental light inputs and the partial protective role that they exert towards host plants during infection, diminishing virulence and invasiveness.

Plant phytochelatin synthases undergo evolutionarily rapid functional differentiation after duplication, allowing fast and precise adjustment of metal detoxification capacity by modulation of both transcription and enzymatic activity.

The present research investigates the possibility that three diphenylurea (DPU) derivatives, N-phenyl-N¢-benzothiazol-6-ylurea (PBU), N,N¢-bis-(2,3-methilendioxyphenyl)urea (2,3-MDPU) and N,N¢-bis-(3,4-methilendioxyphenyl)urea (3,4-MDPU), stimulate the induction of somatic embryogenesis in three Citrus species. The hypothetical embryogenic activity was assessed using stigma and styles of Citrus myrtifolia Raf., Citrus madurensis Lour. and Citrus limon (L.) Burm. The three compounds influenced the production of somatic embryos differently as regards the concentrations tested and the citrus species. PBU was able to induce somatic embryogenesis at all the concentrations tested and in all the three species with percentages that ranged from 44 (C. limon) to 85% (C. myrtifolia). 2,3-MDPU and 3,4-MDPU were completely unable to induce the production of somatic embryos in C. myrtifolia while both the compounds at the higher concentration (12 lM) acted positively in both C. madurensis and C. limon (68% of embryogenic explants). The phenylurea derivatives, used for the first time in this study to induce somatic embryogenesis in plant, showed a higher embriogenic performance when compared with 6-benzylaminopurine (BAP), a classical adenine-cytokinin, and with N-(2-chloro-4-pyridyl)-N¢-phenylurea (CPPU), a classical DPU derivative.