Auxin (2,4‐dichlorophenoxyacetic acid) starvation and treatment with glucan elicitor isolated from Phytophthora megasperma induces similar responses in soybean‐cultured cell suspensions

Abstract

Auxin (2,4-dichlorophenoxyacetic acid) starvation of soybean cell suspension leads to the arrest of cell division after about 4 days. Readdition of 4 pM of auxin enables cells to divide again after a lag phase of 1 day. Accumulation of a well-known isoflavonoid-derived phytoalexin (glyceollin) and a highly elevated catalytic activity of two of the enzymes associated with glyceollin biosynthesis, phenylalanine ammonia-lyase and chalcone isomerase, is described. Moreover, stimulation of catalytic activity of the enzymes chitinase and 0 1,3-glucanase, which are involved in plant defense against pathogens, is observed at the same time. By comparing the patterns of in vitro protein synthesis, we have identified groups of polypeptides whose synthesis is either positively or negatively regulated by auxin. Some of these polypeptides are also induced by fungal elicitor treatment. Our results provide evidence of a dual control by auxin and fungal elicitor working in an opposite manner on the inducibility of enzymes and proteins that play a role in the induced defense response of soybean.

Iron Induction of Ferritin Synthesis in Soybean Cell Suspensions

“…In this case, iron appears to influence either the transcription or the stability of ferritin Soybean cell cultures (Glycine max cv Mandarin, line Sbe4) were a gift of Dr. J. P. Jouanneau (CNRS, Gif sur Yvette, France). Cultures were grown at 30°C in the dark in B5 medium with 5 ,AM 2,4-D and 0.2% casein hydrolysate as described by Leguay and Jouanneau (9). This medium contains 100 ,M FeNa2 EDTA.…”

Oligogalacturonide-Auxin Antagonism Does Not Require Posttranscriptional Gene Silencing or Stabilization of Auxin Response Repressors in Arabidopsis

“…The observations that defense responses induced by a Phytophthora glucan preparation are inhibited by auxin in protoplasts (Leguay and Jouanneau, 1987) and that auxin-induced growth is competitively inhibited by elicitor-active oligogalacturonides (OGs) in pea (Pisum sativum) stem segments (Branca et al, 1988) provided, to our knowledge, the first evidence of an antagonistic action between this hormone and elicitors. More recently, the microbe-associated molecular pattern (MAMP) flagellin and its derived active peptide flg22, as well as the defense-associated hormone salicylic acid (SA) were shown to possess auxinantagonistic activity (Navarro et al, 2006;Wang et al, 2007).…”

In Plant Protoplasts, the Spontaneous Expression of Defense Reactions and the Responsiveness to Exogenous Elicitors Are under Auxin Control

“…Of interest were the observations that the expression of these proteins was under a negative control by auxin ( 15,25,26) in tobacco protoplasts and under both auxin and cytokinin controls (13,28,33) in tobacco tissue cultures. In soybean cell cultures, we also provided evidence that auxin could interfere negatively with the expression of defense reactions (22,24).…”

“…These protoplasts were chosen because they had been previously reported (27) to lose the ability to react to Pmg elicitors that was initially observed in cells from which they were prepared. Soybean cells which respond positively to Pmg elicitor by the induction of a series of PR proteins (22,24) were used as starting material for protoplast preparation. The auxin 2,4-D was omitted from or added at 4 AM concentration (as used for cell growth induction) to digestion and protoplast culture media.…”

“…In soybean, we had previously shown (22,24) that the infection of seedlings by Pmg or the elicitation of cultured cells by Pmg wall extracts stimulated the synthesis of a 17 kD polypeptide family (P17). Although the role of P17 polypeptides in the defense strategy of soybean was not determined, these polypeptides exhibited obvious properties of PR proteins.…”