Maize - continued

Fig. 1. SDS gel analysis of proteins synthesised by excised maize roots incubated at continuous 40 °C. Roots of 3-day-old maize seedlings were excised and incubated at 40 °C for increasing times as indicated. Labelling with [ Sjmethionine was carried out in the final 20 min of the incubation. Proteins were visualised by fluorography. Mol wt distribution in kDa indicated at left. From Cooper Ho (1983).

Diffusion-mediated release of root exudates is likely to be affected by root zone temperature due to temperature-dependent changes in the speed of diffusion processes and modifications of membrane permeability (259,260). This might explain the stimulation of root exudation in tomato and clover at high temperatures, reported by Rovira (261), and also the increase in exudation of. sugars and amino acids in maize, cucumber, and strawberry exposed to low-temperature treatments (5-10°C), which was mainly attributed to a disturbance in membrane permeability (259,262). A decrease of exudation rates at low temperatures may be predicted for exudation processes that depend on metabolic energy. This assumption is supported by the continuous decrease of phytosiderophore release in Fe-deficient barley by decreasing the temperature from 30 to 5°C (67). 

Using a maize HDAC system, aroyl-pyrrolyl-hydroxamides (APHA) had been shown to exhibit 7-78-fold class Ha selectivity when appropriately modified. Continued fine-tuning of the APHA inhibitors, such as meta-fluorine-substituted 20, enabled the generation of an even more selective HDAC inhibitor, with HD1-A IC50 of 0.22 (iM, 176-fold selectivity and which inhibited human HDAC4 but not HDAC1 [53]. 

A plant accumulates nutrients from the soil as it grows. Such accumulation depletes the amount of nutrient remaining in the soil so, harvesting an arable crop, such as maize, barley or com, removes nutrients from the field. A farmer needs to replenish the nutrients continually if the land is not to become exhausted after a few seasons. 

Steinke, J.D., Johnson, L.A., and Wang, C. 1991. Steeping maize in the presence of multiple enzymes. IE Continuous countercurrent steeping. Cereal Chem. 68, 12-17. 

Abscisic acid is a negative regulator in that it primarily antagonizes the action of cytokinins, auxins, and in particular, gibberellins. Abscisic acid decreased the activity of polymerase in radishes (52), peas (53), maize coleoptiles (54), and pear embryos (55). More detailed studies are needed before the question of ABA-induced "modification" of RNA polymerase (54) or "alterations" in the number of sites for template activity (56) can be answered. In barley aleurone cells, ABA-induced suppression of GA-induced <-amylase formation was presumed to involve the continuous synthesis of a short-lived RNA (57). 

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