Inhibition of Ethylene Biosynthesis by Salicylic Acid

Abstract

ABSTRACISalicylic acid inhibited ethylene formation from ACC in self-buffered (pH 3.8) pear (Pyrus communis) cell suspension cultures with a K1'PP of about 10 micromolar after 1 to 3 hours incubation. Inhibition appeared noncompetitive. Among 22 related phenolic compounds tested, only acetylsalicylic acid showed similar levels of inhibition. Inhibition by salicylic acid was inversely dependent on the pH of the culture medium and did not require a continuous external supply of salicylate. When compared to known inhibitors of the ethylene forming enzyme, cobalt, n-propyl gallate, and dinitrophenol, inhibition by salicylic acid most closely resembled that by dinitrophenol but salicylic acid did not produce the same degree of respiratory stimulation. Results are discussed in terms of other known effects of salicylic acid on plants, pH-dependency, and the possible influence of salicylic acid on electron transport.Applications of SA2 and ASA to plants have been shown to influence a wide variety of biological processes including flower stimulation (12), vegetative bud formation (4), adventitious root initiation (13), disease resistance (25), stomate function (15), and heat production (24). Recently Leslie and Romani (16) further demonstrated that these compounds strongly reduce the conversion of ACC to ethylene in pear cell suspension cultures, suggesting they inhibit EFE, the putative terminal enzyme in ethylene biosynthesis. Rapid inhibition, proportional to the concentration of SA or ASA in the medium, maximized within 2 h and was followed by a slower reversal requiring a period of hours to days. This paper further characterizes this inhibition and compares SA activity to that of several previously demonstrated EFE inhibitors. under continuous light at room temperature. Experimental additions or manipulations were made following a minimum 1-h equilibration period. ACC was routinely added to increase ethylene production and amplify the effects of SA or other inhibitors. It has been shown, however, that SA inhibits both endogenous and ACC-stimulated ethylene production (16). MATERIALS AND METHODSIn experiments calling for pH adjustment all culture aliquots were supplemented with 40 mm phosphate buffer and pH was adjusted with HCI or KOH as needed. At this level the P04 did not itselfaffect ethylene production. For SA removal, the cultures were centrifuged (International model HN, swinging bucket rotor) at 1000g for 5 min, the supernatant discarded, and the cells gently resuspended in medium of appropriate pH without SA.Ethylene measurements were a modification of the procedure used by Puschman and Romani (21). The 125 mL culture flasks were flushed with a vigorous air flow and capped for 30 min with rubber septa. Six mL head space samples were collected by syringe and ethylene concentrations measured by flame ionization gas chromatography using a Carle model 211 analytical gas chromatograph fitted with an alumina column held at 80°C and employing N2 as a carrier gas.Respiration readings employed an IR CO2 analyzer (H...

Using jasmonates and salicylates to reduce losses within the fruit supply chain

“…Breaker stage maturity is the time when increase in the production of ethylene is usually observed [30,31]. The findings of Ding and Wang [29] confirmed that SA has the ability to reduce ethylene production [32] and delay ripening. A similar observation has been reported in kiwi dipped in ASA at 1000 µmol l -1 for 5 min [33,34], in strawberries, treated with SA at 1000-4000 µmol l -1 [35], in custard apples dipped in SA at 400, 800 and 1200 µmol l -1 for 15 min [25].…”

Regulation of the Wound‐Induced Myrosinase‐Associated Protein Transcript in Brassica Napus Plants

“…This notion is further strengthened by the fact that SA down-regulated both the developmentally expressed and the induced transcripts. However, SA seems capable of affecting several putative gene-regulatory pathways (Dempsey and Klessig, 1995;Doares et al, 1995;Leslie and Romani, 1988;Pena-Cortes et al, 1993;Wildon et al, 1989).…”

Effect of Salicylic Acid and Calcium Nitrate Spraying on Qualitative Properties and Storability of Fresh Jujube Fruit (Ziziphus jujube Mill.)

“…Recently, salicylic acid has been proposed as a new kind of plant hormone that led to the higher firmness of fruits and lower fruit chilling injury and decay incidences (Rao et al, 2011). Leslie and Romarini (1988) stated that salicylic acid as a simple phenolic compound maintains firmness by regulating the expression of genes involved in ACC synthase and ACC oxidase enzyme, and reducing ethylene production and cell wall degrading enzymes such as polygalacturonase, cellulase and pectinase (Shafiee et al, 2010). Zhang et al (2003) reported that salicylic acid affected cell walls and caused fruit to be stronger.…”