In the latter case the length of the cells in the different rows may be equal, or they may become shorter towards the centre of the mesophyll. The cells of the palisade parenchyma may be arranged in one or more layers. They have an elongated shape, and in cross-section of the leaf they are rod-shaped and appear to be arranged in rows, while in a section parallel to the leaf surface these cells are seen to be rounded and separated or only slightly attached to one another. The palisade cells are always found on the adaxial surface of the leaf. In roses, as in many plants, particularly in dicotyledons, the mesophyll is differentiated into palisade parenchyma and spongy parenchyma ( Figure 4). Mesophyll is usually specialized as a photosynthetic tissue. Torre, in Encyclopedia of Rose Science, 2003 Mesophyll Parenchyma This study indicates that major changes in Asparagus mesophyll cells, occur in chloroplast RNA and proteins before cells are committed to division. Chloroplasts showed little change in size or morphology for the first 8-9 days of culture, after which they divided to form small proplastid-like structures. The chloroplast rRNA levels also declined to basal levels by day 6. Because of a lack of new synthesis, the corresponding proteins gradually declined in abundance, falling to basal levels by days 6 to 7, which coincided with the onset of rapid cell division. It was found that the mRNA for the small subunit of RUBISCO (encoded by a nuclear gene) was undetectable within 1 day and that of the large subunit (encoded by plastidic DNA) decreased to low levels within 2 days postisolation. In one study, changes in mRNA and protein levels of small and large subunits of RUBISCO were followed in asparagus (Asparagus officinalis) mesophyll cells that had been isolated and kept in culture. Mesophyll cells are highly differentiated cells where certain proteins associated with photosynthesis, such as the small and large subunits of RUBISCO and CHLa,b proteins, are highly expressed, whereas many other genes, such as those associated with the cytoskeleton or lignin biosynthesis, e.g., tubulin genes and PAL genes, respectively, are expressed little or not at all. Srivastava, in Plant Growth and Development: Hormones and Environment, 2002 8.1.2. Moreover, the possibilities that mesophyll conductance offers for yield and leaf water use efficiency improvement will be discussed. This chapter will focus on the response of mesophyll conductance to water stress and recovery, including drought acclimation, and will show its importance in constraining photosynthesis under water-limited conditions. In the last decade, mesophyll conductance has received increased attention as one of the key players in determining photosynthesis under water stress conditions, and also as a target for improving plant productivity and water use efficiency. Among them, aquaporins, chloroplast distribution, and cell wall thickness are its principal determinants. Carbon dioxide diffusion across the leaf mesophyll is a complex process implying both biochemical and anatomical factors. Mesophyll conductance is a vital component of photosynthesis, whose importance for accurate characterization of photosynthetic limitations has increased during the last two decades. It was a good kind of antibacterial textile material with strong bacteriostatic and bactericidal action against Staphylococcus aureus, Escherichia coli and Candida albicans.Miquel Nadal, Jaume Flexas, in Water Scarcity and Sustainable Agriculture in Semiarid Environment, 2018 Abstract The mechanical properties reached top standard. The basic properties met the requirements of the first grade of viscose fiber. Pineapple leaf viscose fiber belonged to cotton-type viscose staple fiber. The pyrogenation mechanism of pineapple leaf viscose fiber was similar to that of pineapple leaf fiber, but thermal stability of pineapple leaf viscose fiber was slightly lower than that of pineapple leaf fiber. The fiber had characteristic groups of cellulose and absorption peaks at 1737.74, 1506.82 cm-1 almost disappeared, and it showed high purity. Irregular zigzaging and the skin-core structure were observed in cross section.
Its arrangement was verticall y parallel with some obvious grooves. The results showed that the prepared pineapple leaf viscose fiber was white, shiny, fine, smooth, soft, and somewhat curly with even fineness. To develop a new kind of functional textile material, viscose fiber was prepared from natural and antibacterial pineapple leaf fiber and its structures and properties were explored with analyzing methods of sensory evaluation, SEM, FT-IR, TG, DTG and DSC.
0 kommentar(er)
