The apoplastic antioxidant system in Prunus: Response to long-term Plum pox virus infection

This work describes, for the first time, the changes taking place in the antioxidative system of the leaf apoplast in response to Plum pox virus (PPV) in different Prunus species showing different susceptibilities to PPV. The presence of p-hydroxy mercury benzoic acid (pHMB)-sensitive ascorbate peroxidase (APX) (Class I APX) and pHMB-insensitive APX (Class III APX), superoxide dismutase (SOD), peroxidases (POX), NADH-POX and polyphenoloxidase (PPO) was described in the apoplast from both peach and apricot leaves. PPV infection produced different changes in the antioxidant system of the leaf apoplast from the Prunus species, depending on their susceptibility to the virus. In leaves of the very susceptible peach cultivar GF305, PPV brought about an increase in Class I APX, POX, NADH-POX and PPO activities. In the susceptible apricot cultivar Real Fino, PPV infection produced a decrease in apoplastic POX and SOD activities, whereas a strong increase in PPO was observed. However, in the resistant apricot cultivar Stark Early Orange, a rise in Class I APX as well as a strong increase in POX and SOD activities was noticed in the apoplastic compartment. Long-term PPV infection produced an oxidative stress in the apoplastic space from apricot and peach plants, as observed by the increase in H2O2 contents in this compartment. However, this increase was much higher in the PPV-susceptible plants than in the resistant apricot cultivar. Only in the PPV-susceptible apricot and peach plants was the increase in apoplastic H2O2 levels accompanied by an increase in electrolyte leakage. No changes in the electrolyte leakage were observed in the PPV-inoculated resistant apricot leaves, although a 42% increase in the apoplastic H2O2 levels was produced. Two-dimensional electrophoresis analyses revealed that the majority of the polypeptides in the apoplastic fluid had isoelectric points in the range of pI 4-6. The identification of proteins using MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) and peptide mass fingerprinting analyses showed the induction of a thaumatin-like protein as well as the decrease of mandelonitrile lyase in peach apoplast due to PPV infection. However, most of the selected polypeptides showed no homology with known proteins. This fact emphasizes that, at least in Prunus, most of the functions of the apoplastic space remain unknown. We conclude that long-term PPV infection produced an oxidative stress in the leaf apoplast, contributing to the deleterious effects produced by PPV infection in leaves of inoculated, susceptible Prunus plantsThis work has been supported by grant AGL-2002-02115 from the CICYT (Comisión Interministerial de Ciencia y Tecnología) of Spain and grant 23BIO2005-04-6444 from the Comunidad de Murcia (Spain). P.M. Periago thanks the Ministerio de Ciencia y Tecnología for her contract in the Programme “Ramón y Cajal”.Peer reviewe

Effect of Plum Pox virus infection on the antioxidant capacity of leaf apoplast from apricot plants

En: XIII International Symposium on Apricot Breeding and Culture, Murcia (España). Editors: F. Romojaro, F. Dicenta, P. Martínez-Gómez.In the apoplastic space from apricot plants, the presence of both p-hydroxy mercury benzoic acid (pHMB)-sensitive and pHMB-insensitive APX, SOD, peroxidase, NADH-POX and PPO was observed. In the susceptible apricot cultivar (‘Real Fino’), a decrease in POX and SOD took place, whereas in the resistant cultivar (‘SEO’) an increase in APX, POX and SOD occurred. These results suggest that, in the apoplastic space, the resistant plants had a higher capability to eliminate AOS than the susceptible cultivar. In both cases, PPO was induced in infected plants, although the increase was much higher in the susceptible plants than in the resistant ones. In susceptible plants, the apoplastic H2O2 levels increased nearly 2-fold in infected leaves. This effect was accompanied by an increase in leaf electrolyte leakage. However, in the PPV-resistant cultivar, H2O2 levels only increased by 42% and no changes were observed in electrolyte leakage. The results suggest that long-term PPV infection produced an oxidative stress in the apoplastic space only in susceptible apricot plants.Peer reviewe

Early treatment with anti-tumor necrosis factor agents improves long-term effectiveness in symptomatic stricturing Crohn's disease.

There is limited evidence on the effectiveness of biological therapy in stricturing complications in patients with Crohn's disease. The study aims to determine the effectiveness of anti-tumor necrosis factor (TNF) agents in Crohn's disease complicated with symptomatic strictures. In this multicentric and retrospective study, we included adult patients with symptomatic stricturing Crohn's disease receiving their first anti-TNF therapy, with no previous history of biological, endoscopic or surgical therapy. The effectiveness of the anti-TNF agent was defined as a composite outcome combining steroid-free drug persistence with no use of new biologics or immunomodulators, hospital admission, surgery or endoscopic therapy during follow-up. Overall, 262 patients with Crohn's disease were included (53% male; median disease duration, 35 months, 15% active smokers), who received either infliximab (N = 141, 54%) or adalimumab (N = 121, 46%). The treatment was effective in 87% and 73% of patients after 6 and 12 months, respectively, and continued to be effective in 26% after a median follow-up of 40 months (IQR, 19-85). Nonetheless, 15% and 21% of individuals required surgery after 1 and 2 years, respectively, with an overall surgery rate of 32%. Postoperative complications were identified in 15% of patients, with surgical site infection as the most common. Starting anti-TNF therapy in the first 18 months after the diagnosis of Crohn's disease or the identification of stricturing complications was associated with a higher effectiveness (HR 1.62, 95% CI 1.18-2.22; and HR 1.55, 95% CI 1.1-2.23; respectively). Younger age, lower albumin levels, strictures located in the descending colon, concomitant aminosalicylates use or presence of lymphadenopathy were associated with lower effectiveness. Anti-TNF agents are effective in approximately a quarter of patients with Crohn's disease and symptomatic intestinal strictures, and 68% of patients are free of surgery after a median of 40 months of follow-up. Early treatment and some potential predictors of response were associated with treatment success in this setting