Gibberellic acid embryo

More specifically, compounds like podolactone A (Fig. 10.1) inhibit proton efflux from plant cells induced by fusicoccin, without affecting ATP levels.42 The related compound, podolactone E is a strong inhibitor of 6-aminolevulinic acid and chlorophyll synthesis.34 The authors concluded that this was caused by suppression of synthesis of proteins needed in the porphyrin pathway because podolactones also inhibited gibberellic acid-induced a-amylase synthesis in barley embryos. The molecular target site(s) of this class of terpenoid phytotoxins remains to be determined. 

Our data indicate that the formation of somatic globular embryos is accompanied by the accumulation of storage protein transcripts. Figure 9.6 illustrates that transcripts for the synthesis of gibberellic acid also accompany the formation of somatic embryos. These microarray hybridizations experiments have been entered into the GEO (Gene Expression Omnibus) database of NCBI at http //www.ncbi.nlm.nih.gov/geo. For complete details on interpretation of the data, see Thibaud-Nissen et al ... 

Ammirato P (1977) Hormonal control of somatic embryo development from cultured cells of caraway. Interactions of abscisic acid, zeatin, and gibberellic acid. Plant Physiol (Bethesda) 59 579-586... 

Sussex IM (1972) Somatic embryos in long-term carrot tissue cultures Histology, cytology, and development. Phytomorphology 22 50-59 Taiz L, Jones RL (1970) Gibberellic acid, -1,3-glucanase and the cell walls of barley aleurone layers. Planta (Berl) 92 73-84... 

SO the completed vascular system is ready at an early stage for translocation of metabolites from the scutellum to the embryo, and/or (if it occurs) for the transport of gibberellins synthesized at the node to the scutellum, whence they can be released. There is evidence, coming from the use of radioactive gibberellic acid, that this hormone can indeed be transported through the vascular strand of the scutellum [112]. 

Ultrastructural studies on wheat aleurone cells over the same time period show that proliferation of long profiles of endoplasmic reticulum (ER) occurs during the first two days of incubation independently of the embryo and therefore of control by gibberellic acid (Fig. 7.9). The aleurone cells of ungerminated wheat grains (like those of barley [64]) contain numerous oil bodies around the periphery of the aleurone grains, with mitochondria packed within the... 

The distribution of a-amylase activity during the development of barley grain has been reported. Gibberellic acid induced a-amylase activity in barley Hordeum vulgare) grains with excised embryos. This increase was ascribed to de novo protein synthesis, which was suppressed by prior incubation of the grains with actinomycin D. 

The development of amylase activity in extracts of embryo-free and of GA3-treated, embryo-free maize kernels has been determined. The increase in amylase activity was accompanied by the appearance of several starch-degrading enzymes. Actinomycin D and cycloheximide prevented the amylolytic activity from developing. Other results indicated that the development of a-amylase activity in embryo-free maize kernels does not depend on gibberellic acid, but involves the de novo synthesis of protein. 

Gibberellic acid induced the de novo synthesis of limit dextrinase in barley grains with excised embryos. ... 

This supposition has been confirmed. In the mobilization of the reserve materials of barley the following events take place the embryo discharges gibberellic acid into the outermost layer of the endosperm, the aleuron. As a result genes for the synthesis of various hydrolytic enzymes are activated in the aleuron. The process culminates in the synthesis of... 

Fig. 168. The effect of gibberellic acid on the hydrolysis of starch in the embryo-free half of barley grains (modified from Plant Research 66).

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