In the developing xylem bundles of young stems, the presence of immature living vessel elements can strongly restrict or even block axial hydraulic conductance, especially in newly matured vessels. Lateral connections between vessels may provide an alternative pathway for water movement to bypass these closed, living elements. Using the grapevine as a model system, the present study aimed to demonstrate the effects of living vessel elements on water movement patterns, and the importance of lateral flow for effective water conductivity in the developing bundles. Living vessel elements were detected using dye staining and the pattern of vessel development and maturation was then monitored. The importance of lateral flow was confirmed using several approaches: (1) capacity for lateral flow, (2) effect of increasing the distance of water transport, and (3) effect of ion concentrations. Living vessel elements were found along the developing bundles, they occupied a significant proportion of the distal and peripheral parts of the flow path, forming a substantial barrier to apoplastic water flow. Water in the developing xylem bundles could move easily from vessel to vessel and between secondary and primary xylem. Furthermore, data from increasing the transport length and altering the ion concentrations supported the critical contribution of the lateral flow to the total hydraulic conductance within the developing bundles. The hydraulic architecture of the developing xylem bundles is described. The results are discussed in terms of reliability and efficiency of water transport during shoot growth and development.

The aim of the present study is to investigate the effect of three entomopathogenic fungi (EPF) (Beauveria bassiana, Cladosporium cladosporioides, and Verticillium alfalfae) on the aphid species, Metopolophium dirhodum (Walker) (Hemiptera: Aphididae). The selected EPF were isolated from the agricultural soil of the National Institute of Plant Protection (INPV) in Constantine, Algeria, and were tested against the aphid insects that were collected from the same area. The aphid species M. dirhodum were exposed to each fungal spore suspensions 10 7 conidia/ml for 10 s. Percent mortality was recorded at 1, 3, 5, and 7 days post treatment. Percentage mortalities, 7 days post treatment, were 95.83, 63.98, and 51.83% by B. bassiana, C. cladosporioides, and V. alfalfae, respectively. The higher protease activities were observed for isolate V. alfalfae with 95 U/ml, followed by B. bassiana with 38.26 U/ml, and finally C. cladosporioides with 35, 65 U/ml. The results presented in this study revealed that there was no relation between high alkaline protease activities and high virulence isolates.

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Despite the long history of research on xylem structure and function, there are no reports in the literature explaining how xylem vessel elements began conducting water just after their maturation. This study was conducted to demonstrate the anatomical arrangement of newly matured vessels, looking specifically for the first pathways connecting newly matured vessels to the transpiration stream. Using the developing stems of Paraserianthes lophantha ation and maturation along the developing bundles was followed by using the dye-pressure method. Water pathways from newly matured vessels to other functioning vessels were directly visualized by the technique of single-vessel dye injection. Some isolated newly matured vessels from the transpiration stream were detected using two apoplastic tracers. The results of this study converge to support the hypothesis that the movement of water in the newly matured vessels depends completely on lateral contacts with other functioning vessels via vessel-to-vessel paths or vessel relays. In cases where the lateral pathways were absent, the flow within the newly matured vessels was substantially blocked resulting in a significant hydraulic isolation of the newly matured vessels. These results might contribute to a better understanding of the pattern of water movement within the developing xylem systems, and underscore that xylem vessels start conducting water through lateral transport, although their primary function is the axial transport.

Leaf essential oils of Juniperus oxycedrus (Cupressaceae) wild grown in the region of Oum El Bouaghi (semi- arid area) in Algeria have been analysed by gas chromatography/mass spectrometry (GC/MS). Fifty seven compounds were identified in the leave oils. The leaf oils were mainly composed of 5-Tetradecen-1-ol, acetate, (Z)-(12.9%) ç-Muurolene (9.1%), α-Cadinol (5.1%) (ñ)-Cadinene (3.9 %) and some other compounds which were only present in minor amounts. Aims: This study aimed to extracted, identification of essential oils of Leaves of J. oxycedrus L. ssp. macrocarpa (S. et Sm.) BalI. growing in Oum El Bouaghi (semi- arid area), Algeria and evaluation of their antibacterial capacity. Results: The GC/MS analysis of the Leaves of J. oxycedrus L. (yielded 0, 36 %) permitted the identification of fifty seven components. The composition and percentage of the compounds are listed by their order of retention times. The main constituents of the essential oil were composed of 5-Tetradecen-1-ol, acetate, (Z) - (12.9%) ç-Murolene (9.1%), α-Cadinol (5.1%) (ñ)-Cadinene (3.9 %) and some other compounds were only present in minor amounts. The antimicrobial activity of the essential oils were evaluated by the disc diffusion method and tested against Gram-negative Escherichia coli, Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. Results showed that Staphylococcus aureus was the highly resistant to the essential oil. Conclusion: The results of analysis of the components Leaves of Juniperus oxycedrus ssp. macrocarpa (S. et Sm.) BalI. growing in Oum El Bouaghi (semi- arid area), Algeria, permitted the identification of fifty seven components. The essential oil showed that the essential oil of juniperus oxycedrus has the potential to act as an antibacterial agent.