Physiological, biochemical and symptom characteristics of Brassica napus and Orychophragmus violaceus after infection with Sclerotini

Abstract

Sclerotinia sclerotiorum is a widespread plant fungal disease with many hosts and the capacity to cause great damage. The results showed that S. sclerotiorum infestation highly significantly ( p  < 0.01) increased conductivity, the ion exocytosis percentage, the superoxide anion production rate, and proline, MDA, and oxalic acid contents, in the leaves of Brassica napus at the seedling and flowering stages and Orychophragmus violaceus at the flowering stage, and this elevation increased progressively with an increase in the amount S. sclerotiorum inoculum provided. Overall, S. sclerotiorum infestation significantly ( p  < 0.01) decreased the activity of SOD, CAT, POD, and PPO, in both seedling and flowering rape ( B. napus ) leaves, and it also significantly ( p  < 0.01) decreased the activity of SOD, POD, and PPO and increased the activity of CAT in flowering O. violaceus leaves. The inoculation with 6–12 mm S. sclerotiorum discs caused slight leaf discoloration in seedling-stage B. napus and flowering-stage O. violaceus within 3 days, while 6–9 mm inoculum discs induced similar changes in flowering-stage B. napus Necrotic lesions developed in all inoculated plants by 5 days, with symptoms worsening over time. To a certain extent, 0.10 mM oxalic acid promoted these changes in the indexes in the leaves of B. napus and O. violaceus during S. sclerotiorum infestation. This study revealed the physiological and biochemical responses of B. napus and O. violaceus under conditions of S. sclerotiorum infestation and provide a theoretical basis for the combination subjection of S. sclerotiorum and oxalic acid.