Phenylalanine ammonia-lyase activity in soybean hypocotyls and leaves following infection with Phytophthora megasperma f.sp. glycinea (original) (raw)
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Scientific reports, 2017
Phytophthora root and stem rot of soybean [Glycine max (L.) Merr.] caused by Phytophthora sojae is a destructive disease worldwide. Phenylalanine ammonia-lyase (PAL) is one of the most extensively studied enzymes related to plant responses to biotic and abiotic stresses. However, the molecular mechanism of PAL in soybean in response to P. sojae is largely unclear. Here, we characterize a novel member of the soybean PAL gene family, GmPAL2.1, which is significantly induced by P. sojae. Overexpression and RNA interference analysis demonstrates that GmPAL2.1 enhances resistance to P. sojae in transgenic soybean plants. In addition, the PAL activity in GmPAL2.1-OX transgenic soybean is significantly higher than that of non-transgenic plants after infection with P. sojae, while that in GmPAL2.1-RNAi soybean plants is lower. Further analyses show that the daidzein, genistein and salicylic acid (SA) levels and the relative content of glyceollins are markedly increased in GmPAL2.1-OX transg...
Physiological Plant Pathology, 1982
Etiolated 6-day-old soybean hypocotyls were inoculated with Ph>tophthora megas@ma f. sp. glycinca by placing drops of zoospore suspensions onto the hypocotyl surface. Polyphenoloxidase (PPO) activity at the inoculated sites was determined after various periods of incubation by replacing the inoculum drops with L+3,4dihydroxyphenylalanine (L-Dopa) and measuring the formation of dopaquinone spectrophotometrically (Its,, .,). Activity was detected at incompatibly-reacting sites within 2 to 3 h following inoculation. No activity was detected at compatibly-reacting sites, although these sites developed activity if subsequently re-inoculated with an incompatible race. Activity was also demonstrated in hypocotyl tissues injured by abrasion or localized freezing. The results indicate that the development of PPO activity is one of the earliest recognixable events in incompatible interactions and suggest that it is a consequence of cell damage that is induced by incompatible but not by compatible races.
gazi university journal of science, 2012
In this study, PAL activity in stems of pepper ( Capsicum annuum L.) plants infected by the root rot pathogen Phytophthora capsici - 22 in a resistant ( PM-702 ) and two susceptible (Kahramanmaras-Hot ( KM-Hot) and Demre-8 ) cultivar were studied. The response of the PAL activity in the resistant cultivar was faster and higher than in the susceptible cultivars (p < 0.01) . The increase in production of PAL upon Phytophthora capsici -22 were higher in the infected plants compared to the non-infected (control) plants ( p < 0.01) . An early induction of PAL was observed in the stems of three peppers infected with P.capsici within two days. Keywords: Capsicum annuum , defence, pepper, phenylalanine ammonia lyase , Phytophthora capsici
European Journal of Plant Pathology, 2008
We tested the hypothesis that PAL activity in chilli plants CM-334 inoculated with Nacobbus aberrans (Na) alone or in combination with Phytophthora capsici (Pc), is lower than in those inoculated only with Pc. At 21 days after nematode inoculation, inoculated plants showed a significant (P < 0.01) reduction of 48% in PAL activity compared to those non-inoculated in two separate experiments. In two other tests, where plants were inoculated with the oomycete 21 days after inoculation with the nematode, PAL activity at 2, 4, 6, 8 and 24 h after inoculation with Pc was significantly higher (Tukey, P < 0.01) in plants inoculated only with Pc than in plants inoculated only with Na or both pathogens (Na+Pc).
Journal of Plant Physiology, 2001
The inoculation of the roots of resistant (BSTN) and susceptible (JHL) cultivars of date palm seedlings by Fusarium oxysporum f. sp. albedinis (Foa) induces an increase in activity of phenylalanine ammonia-lyase (E.C. 4. 3. 1. 5., PAL). The post-infectional response in the PAL activity in the resistant cultivar roots was faster and higher than that in the susceptible cultivar. However, the elicitation of the seedlings by the hyphal wall preparation (HWP) of Foa induces an identical PAL response in the resistant and the susceptible cultivars. The elicitor activity of HWP was dose-dependent, the optimal concentration which induces a maximum PAL activity was 10 mg of mycelium per mL. The elicitor present in the HWP was thermostable since its elicitor activity was maintained after heat treatment (121˚C for 45 min). The treatment of the HWP with protease (Pronase E) does not have an effect on the HWP elicitor activity. However, the treatment of the HWP with sodium periodate inhibits its elicitor activity. This data suggests that the HWP elicitor is a carbohydrate compound. In addition, the HWP elicitor is non-specific since it induces identical responses of the PAL activity in two cultivars showing different behaviors to the pathogen. The absence of specificity of HWP elicitors and the differential response of the PAL activity to the infection by Foa and to the elicitation by the HWP are discussed. An explanation of the general interactions between plant and parasite is proposed.
Biologia plantarum, 2006
The inoculation of the seedling roots of the resistant (Bousthami Noir) and susceptible (Jihel) date palm (Phoenix dactylifera) cultivars by Fusarium oxysporum f. sp. albedinis induced an increase in phenylalanine ammonia-lyase (PAL) activity. The response of the PAL activity in the resistant cultivar was faster and higher than in the susceptible one. However, the elicitation of the seedlings with the hyphal wall elicitor (HWE) of the pathogen induced identical PAL activity in both cultivars. In the resistant cultivar, the the PAL activity elicited with the HWE was not influenced by the addition of the fungal culture filtrate (FCF) whereas it was suppressed in the susceptible cultivar. This FCF suppressor effect was dose-dependent, not influenced by sodium periodate, whereas it was strongly reduced by the heat (121 °C for 45 min) and pronase E. These results show that differential induction of the defence mechanisms in both cultivars was not related to differences in the induction of the PAL activity, but to the suppression of its elicitation in the susceptible cultivar.
Physiological and Molecular Plant Pathology, 2004
Differential expression of pal1 and hmgr2 was investigated using northern blot analysis in two potato cultivars (Russet Burbank (RB), susceptible and Kennebec (KB), moderately tolerant) after inoculation with two Phytophthora infestans isolates from the formerly (US-1) and currently predominant genotypes (US-8). The accumulation of pal1 transcripts was weaker in response to US-8 as compared to US-1 and occurred earlier in KB than in RB. The stronger expression of pal1 in response to US-1, as compared to US-8, is suggested to be due to defense gene suppression by the latter. No apparent strong accumulation of hmgr2 transcripts was recorded in RB as compared to KB inoculated with either US-1 or US-8. The induction of pal1 and hmgr2 was first observed in un-inoculated (proximal) close to the inoculated leaflets, then in un-inoculated (distal) leaflets of leaves adjacent to the inoculated leaf, and finally in local inoculated leaflets. The stronger expression of the two genes in proximal and distal leaflets, as compared to the local site of inoculation suggests the translocation of signal(s) from this site to healthy parts of the plant. q
Physiological and Molecular Plant Pathology
The expression of resistance and susceptibility to inoculation with zoospores of Phytophthora megasperma f. sp.g{ycinea race I was determined ill roots, hypocotyls, and cotyledons of etiolated and green seedlings and in leaves of soybean cvs Harosoy (rpsl) and Harosoy 6~(Rpsl)' Gene-specific resistance was demonstrated in all organs tested, except for cotyledons of etiolated seedlings. In each case higher concentrations of the glyceollins accumulated in resistant than in susceptible reactions; the differential being greatest in hypocotyls and smallest in roots. The relative proportions of glyceollins I, II and III varied with the organ, exposure of'the seedlings to light, the interaction type and the incubation period. Glyceollin I was relatively the most abundant isomer in roots and to a lesser extent in hypocotyls. Glyceollin III was relatively the most abundant isomerin leaves. Major differences in accumulation rates were observed in time-course experiments and, after reaching a maximum, all three isomers decreased in leaves and glyceollin I decreased in hypocotyls, suggesting that concentrations and hence isomeric proportions were finely controlled by rates of biosynthesis and metabolism.