Effects of Exogenously applied palmitic acid on systemic resistance against Fusarium oxysporum f. sp. niveum in watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai)

e studied the effects of exogenously applied palmitic acid (PA) on reactive oxygen species (ROS) production, defense-related enzyme activity and malondialdehyde (MDA) content of roots and analyzed the response of defense-related genes in Fusarium oxysporum f.sp.niveum (FON) inoculated watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai). Our results showed that as compared to control, PA reduced the morbidity of Fusarium wilt by 33.3 % and disease severity by 53.2 %, increased the level of ROS of watermelon roots at early infection stage and the activity of defense related enzymes, and decreased the MDA content of watermelon roots. Moreover, PA up-regulated the expression of disease defense-related genes. These results suggested that PA promoted the accumulation of ROS and up-regulated the transcript level of defense-related genes and eventually induced the systemic resistance in watermelon against FON.

Synthesis, Characterization, and Antifungal Activity of Schiff Bases of Inulin Bearing Pyridine ring

As a renewable, biocompatible, and biodegradable polysaccharide, inulin has a good solubility in water and some physiological functions. Chemical modification is one of the important methods to improve the bioactivity of inulin. In this paper, based on 6-amino-6-deoxy-3,4-acetyl inulin (3), three kinds of Schiff bases of inulin bearing pyridine rings were successfully designed and synthesized. Detailed structural characterization was carried out using FTIR, 13C NMR, and 1H NMR spectroscopy, and elemental analysis. Moreover, the antifungal activity of Schiff bases of inulin against three plant pathogenic fungi, including Botrytis cinerea, Fusarium oxysporum f.sp.niveum, and Phomopsis asparagi, were evaluated using in vitro hypha measurements. Inulin, as a natural polysaccharide, did not possess any antifungal activity at the tested concentration against the targeted fungi. Compared with inulin and the intermediate product 6-amino-6-deoxy-3,4-acetyl inulin (3), all the synthesized Schiff bases of inulin derivatives with >54.0% inhibitory index at 2.0 mg/mL exhibited enhanced antifungal activity. 3NS, with an inhibitory index of 77.0% exhibited good antifungal activity against Botrytis cinerea at 2.0 mg/mL. The synthesized Schiff bases of inulin bearing pyridine rings can be prepared for novel antifungal agents to expand the application of inulin.