Effect of Peroxyacetyl Nitrate on Growth & Cell Wall Metabolism of Avena Coleoptile Sections

Abstract

In-doleacetic acid (IAA) induced growth of sections which had been pre-treated with 2.4 ppm peroxyacetyl nitrate (PAN) for 6 hours at pH 4, was inhibited 84% during the 4-hour period following fumigation. Production of c14O2 in IAA-free, carrier-free glucose solution (ca. 10-5 [image]) was inhibited about 75% by this pretreatment while oxygen uptake was unaffected. Incorporation of C14 into cellulose and into the acid soluble wall fraction was inhibited 90%. Incorporation into other wall fractions was less inhibited. Pretreatment with 2 ppm PAN at pH 6 followed by incubation in glucose-free solutions with IAA resulted in only 20% inhibition of growth. At a glucose C14 concentration of 0005 M, C14O2 production was inhibited only 16% following pretreatment by 2.7 ppm PAN at pH 4.8 to 5.5. Under these conditions growth was inhibited 54%. Incorporation of C14 into the acid soluble wall fraction was inhibited 55% and incorporation into cellulose was inhibited 77%. Under conditions of severe growth inhibition, a marked decline relative to other sugars was found of C14 incorporation into galacturonic acid of the aqueous soluble wall fraction. Similar declines were also observed in the xylose of the hot water soluble and 1 [image] NaOH soluble fractions. Inhibition of growth by PAN may be associated with inhibition of cellulose metabolism. Inhibition of metabolism of aqueous soluble pectin and of acid soluble polysaccharides may also account for restraint of growth.