Atmospheric dielectric barrier discharge (DBD) was attempted to improve the resistance of wheat seed to drought stress. Effects of DBD plasma on wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation, reactive oxygen species (ROS), antioxidant enzyme activity, abscisic acid, and drought resistant related genes expression under drought stress were investigated. The changes of the wheat seed coat before and after the DBD plasma treatment were explored. Experimental results showed that the DBD plasma treatment could alleviate the adverse effects of drought stress on wheat seed germination and seedling growth; the germination potential and germination rate increased by 27.2% and 27.6%, and the root length and shoot length of the wheat seedlings also increased. Proline and soluble sugar levels under drought stress were improved after the DBD plasma treatment, whereas the malondialdehyde content decreased. ROS contents under drought stress were reduced after the DBD plasma treatment, whereas the activities of superoxide dismutase, catalase, and peroxidase were promoted. DBD plasma treatment promoted abscisic acid generation in wheat seedlings, and it also regulated functional gene LEA1 and stimulated regulation genes SnRK2 and P5CS to resist drought stress. Etching effect and surface modification occurred on the seed coat after the DBD plasma treatment.
Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors including swarming motility and biofilm formation. Swarming motility plays an important role in the bacterium's spread to new environments, attachment to surfaces, and biofilm formation. Bacterial biofilm is associated with many persistent infections and increased resistance to antibiotics. In this study, we tested the effect of a 2-alkyl-4(1H)-quinolone (AHQ) signal, the Pseudomonas quinolone signal (PQS) on P. aeruginosa swarming and biofilm formation. Our results show that PQS repressed the swarming motility of P. aeruginosa PAO1. Such repression was independent of its cognate receptor PqsR and was not related to changes in the flagellae, type IV pili or the production of the surface-wetting agent rhamnolipid surfactant. While PQS did not affect twitching motility in PAO1, a pqsR deletion abolished twitching motility, indicating that pqsR is required for twitching motility. Our results also indicate that the enhancement of biofilm formation by PQS is at least partially dependent on the GacAS-Rsm regulatory pathway but does not involve the las or rhl QS systems.
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