Effect of inhibitors of gibberellin biosynthesis on the induction of ?-amylase in embryoless caryopses of Hordeum vulgare cv. Himalaya

Planta ◽  
1984 ◽  
Vol 162 (1) ◽  
pp. 89-90 ◽  
Author(s):  
Sarah J. Gilmour ◽  
Jake MacMillan
Planta ◽  
1992 ◽  
Vol 188 (2) ◽  
pp. 252-257 ◽  
Author(s):  
Elke Gro�elindemann ◽  
MervynJ. Lewis ◽  
Peter Hedden ◽  
JanE. Graebe

Author(s):  
O. E. Bradfute ◽  
R. E. Whitmoyer ◽  
L. R. Nault

A pathogen transmitted by the eriophyid mite, Aceria tulipae, infects a number of Gramineae producing symptoms similar to wheat spot mosaic virus (1). An electron microscope study of leaf ultrastructure from systemically infected Zea mays, Hordeum vulgare, and Triticum aestivum showed the presence of ovoid, double membrane bodies (0.1 - 0.2 microns) in the cytoplasm of parenchyma, phloem and epidermis cells (Fig. 1 ).


Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.


1992 ◽  
Vol 86 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Steffen Reinbothe ◽  
Christiane Reinbothe ◽  
Jorg Lehmann ◽  
Benno Parthier

1995 ◽  
Vol 93 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Salla Marttila ◽  
Berne L. Jones ◽  
Anita Mikkonen

1973 ◽  
Vol 29 (03) ◽  
pp. 633-643
Author(s):  
H Gjønnæss

SummaryThe cold promoted activation of factor VII occurs in parallel with an activation of a plasma arginine esterase, and, on inhibition of the cold activation of factor VII, the esterase activation also decreased. The inhibitor pattern supported our theory that the arginine esterase that is activated in the cold activation of factor VII is plasma kallikrein.The cold activation of factor VII was completely inhibited with soya bean trypsin inhibitor in doses that did not interfere with the contact activation. On the other hand, inhibition of the contact activation with hexadimethrine bromide did not interfere with the cold activation of factor VII except when this was kaolin induced. Contact and cold activation therefore appear to represent two different pathways for the activation of factor VII. The cold activation reaction is probably mediated by the activation of plasma prekallikrein, and inhibition of the plasma kallikrein activity correlates with the inhibition of the cold promoted activation of factor VII.


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