Com coleoptiles

A further promising attempt to identify the bluelight-reducible cyt b is described by Britz et al.26) for a plasma-membrane-enriched fraction of com coleoptiles. They find that methylene blue (Scheme 2) is capable of reducing a particular cyt b which constitutes only 10—20% of the total dithionite-reducible cytochromes. Since this particular cyt b is very similar to that which is photo-reduced by endogeneous flavin in Neurospora 122,123) the two are proposed to be identical. 

Matthyssee and Phillips (20) isolated two nuclear proteins, from tobacco cells, that bound specifically to 2,4-D. Receptor proteins for auxins, kinetins, and GA have been found (21). Sub-cellular fractions from bean leaves were recently shown to bind abscisic acid (22). Preliminary experiments (22) indicated that maximum ABA binding activity coincides with the activities of membrane-bound Mg -dependent, K+-stimulated ATPase and glucan synthetase. Table I of Biswas and Roy (21) lists hormone receptor proteins reported in plant tissue. For a protein to qualify as a receptor molecule, it should have a high stereo-specific binding capacity (Kd 10 6 to 10 SM) for its particular hormone. In com coleoptiles, both IAA and NAA are equally effective in inducing cell elongations fractions of plasma membrane and endoplasmic reticular membrane contain receptor proteins with Kd values of 10 M to 10 M for auxins (5, 18). When one considers procedural... 

In 1989 Cutler et al.1 reported the isolation of 3,7-dimethyl-8-hydroxy-6-methoxyisochro-man (1) from Penicillium corylophilum and demonstrated that it inhibited etiolated wheat coleoptiles at 10-3 and 1(T4M, as did the acetoxy (2) and methoxy (3) derivatives (Figure 5.1).2 The Parent compound had originally been isolated from moldy millet hay implicated in the death of cattle,3 but the metabolite had not been tested in plants. Because of the encouraging results obtained in the wheat coleoptile bioassay, isochromans 1,2, and 3 were assayed on greenhouse-grown bean, com, and tobacco plants. The methyl ether exhibited the greatest herbicidal activity in all the plants treated, while the parent and its acetoxy derivative were active only on corn. 

Cantharidin (Figure 13), isolated from Spanish fly (Lylta vesicatoria L.), inhibits the growth of very young lupin (Lupinus albus L.) seedlings, Medico sativa L., Raphanus sativus L. and Brassica napus L. and Brassica napus L. seed germination at 20 ppm. It also inhibits the growth of wheat coleoptiles, com, tobacco and bean plants (241, 242). 

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