In-gel protein kinase assays using myelin basic protein (MBP) as substrate have been used to demonstrate that abscisic acid (ABA) activates an MBP kinase (AMBP kinase) in epidermal peels prepared from leaves of the Argenteum mutant of pea, Pisum sativum L. AMBP kinase has the characteristics of a mitogen-activated protein kinase (MAPK): it utilizes MBP preferentially as an artificial substrate,...

Vein loading in unifoliate leaves of white bean seedlings exposed to excess Co(2+), Ni(2+), or Zn(2+) for 1 to 4 days was studied by incubating leaf discs in [(14)C]sucrose. The discs from plants exposed to metal exhibited an increased total uptake of radiosucrose but reduced vein loading. Differences between treatments due to infiltration of disc margins were eliminated by analyzing 7-millimet...

Acetyl-CoA carboxylase [acetyl-CoA-carbon dioxide ligase (ADP forming), EC 6.4.1.2] is a biotin-containing enzyme catalyzing the formation of malonyl-CoA. The tissue distribution of this enzyme was determined for leaves of C(3)- and C(4)-plants. The mesophyll tissues of the C(3)-plants Pisum sativum and Allium porrum contained 90% of the leaf acetyl-CoA carboxylase activity, with the epidermal ...

Experiments were carried out on four cell types: Chlorella sp., Tetraselmis sp., and mesophyll protoplasts of Dendrobium and Lilium longiflorum. The speed of cell translation in between a pair of cylindrical electrodes was measured at different solution conductivities (σs). For each field frequency, the speed was plotted against the gradient of electric field squared to obtain the real part Re[...

Spectinomycin, an inhibitor of plastid protein synthesis, can be used to mark specific cell layers in the shoot meristem of Brassica napus. Pale yellow-green (YG) plants resulting from spectinomycin-treatment can be propagated indefinitely in vitro. Microscopic examination showed that YG-plants result from inactivation of plastids in the L2 and L3 layers and are composed of a pale green epiderm...

The vacuole is the main cellular storage pool, where sucrose (Suc) accumulates to high concentrations. While a limited number of vacuolar membrane proteins, such as V-type H(+)-ATPases and H(+)-pyrophosphatases, are well characterized, the majority of vacuolar transporters are still unidentified, among them the transporter(s) responsible for vacuolar Suc uptake and release. In search of novel t...

The types of cells and tissues infected by a virus define its tissue tropism. Determinants of tissue tropism in animal-infecting viruses have been extensively investigated, but little is known about plant viruses in this regard. Some geminiviruses in the genus Begomovirus exhibit phloem limitation and are restricted to cells of the vascular system, whereas others can invade mesophyll tissue. To...

Light is one of the most important environmental factors that determine the timing of a plant's transition from the vegetative to reproductive, or flowering, phase. Not only daylength but also the spectrum of light greatly affect flowering. The shade of nearby vegetation reduces the ratio of red to far-red light and can trigger shade avoidance responses, including stem elongation and the accele...

The Zinnia elegans mesophyll cell culture is a useful system for xylogenesis studies. The system is associated with highly synchronous tracheary element (TE) differentiation, making it more suitable for molecular studies requiring larger amounts of molecular isolates, such as mRNA and proteins and for studying cellulose synthesis. There is, however, the problem of non-uniformity and significant...

Fluorescence emission spectral peaks at 685, 695 and 730 nanometers (F685, F695, and F730) were recorded 77 K from diluted leaf tissue and epidermal powders prepared from Saxifraga cernua. The time course for state 1 to state 2 transitions was monitored as changes in the ratios of the three emission peaks. During illumination with light 2 (580 nm) the F730/F695 and F730/F685 ratios increased wi...