The Mode of Action of Maleic Hydrazide: Inhibition of Growth

Maleic hydrazide (MH) inhibits corn root elongation through an effect on cell division apparently without inhibiting cell enlargement. The decrease in the rate of elongation was apparent only after a considerable lag, over 14 hours, even with a concentration as high as 5 mM. MH (1 mM) did not inhibit His growth of roots from corn seeds given very large doses of Γ-irradiation or excised corn root segments including the elongation Zone or the cell enlargement induced by IAA in corn coleoptile sections. Many compounds including purines, pyrimidines, nucleosides. cysteine, pyridoxal, pyruvate. kinetin and CoCl 2 , many of which had previously been reported to alleviate MH inhibition in other tissues, were tested for their ability to prevent the inhibition of corn root elongation by MH, but none were effective. These data do not support the theory that MH acts by inhibiting the synthesis of or competing with some simple metabolite or hormone. Whatever its mechanism of action the failure of MH to inhibit cell enlargement in most systems indicates that it is fairly selective.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74891/1/j.1399-3054.1969.tb07375.x.pd

Qualitative Study on the Production of the Allelochemicals Benzoxazinones by Inducing Polyploidy in Gramineae with Colchicine

The possibility of inducing polyploidy in grasses by treatment with colchicine and its effect 2 on the production and root exudate content of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-3 one (DIMBOA) and 2,4-dihydroxy-2H-benzoxazin-3-one (DIBOA) was studied in wheat, corn 4 and rye. Caryopses treated with colchicine at concentrations in the range 0.1–10 mg/mL for 8 and 5 48 hours, and with inoculation of the growth medium, are markedly affected both in terms of the 6 distribution and concentration levels of allelochemicals in plants. A greater accumulation was 7 observed in the root with respect to the stem and this increased with increasing concentration of 8 colchicine and with treatment time. Analysis of the compounds released by root exudates showed 9 that treatment with colchicine at a concentration higher than 1 mg/mL caused a significant 10 increase in the concentrations of allelochemicals measured in the growth medium. It is proposed 11 that treatment with colchicine of seedling caryopses mixoploids plant populations, and that the 12 overall effect is an increase in the levels of allelochemicals released. The ecological implications 13 of this behavior are discussed along with the impact of plant-plant interactions (allelopathy)