In vitro Screening of Fusarium Wilt-resistant Germplasm Resources of Red Edible Seed Watermelon( Citrullus lanatus ssp. vulgaris var. megalaspermus Lin et Chao)

[ Objective] This study aimed to establish an appropriate technology system for in vitro screening of Fuzarium wilt-resistant germplasm resources of red edible seed watermelon and obtain variants resistant to fusaric acid, thus providing resistant materials for breeding Fusarium wilt-resistant red edible seed watermel- on. [ Method] Using Zhongxin No. 1 red edible seed watermelon advemitious buds as screening materials and fusaric acid （FA） as a stress agent, in vitro screen- ing of Fusarium wilt-resistant red edible seed watermelon clonal variants and identification of Fusarium wilt-resistance of the germplasm resources of red edible seed watermelon were performed. [ Result] The results showed that the appropriate FA for in vitro screening of Fusarium wilt-resistant red edible seed watermelon vari- ants was 15 mg/L. In vitro screening system for Fusarium wilt-resistant red edible seed watermelon variants was established preliminarily and FA-resistant regenera- ted plants were obtained. Among the 36 germplasm resources of red edible seed watermelon, there were 2 highly resistant materials, 6 moderately resistant materi- als, 11 slightly resistant materials and 17 highly susceptible materials. [ Conclusion] This study confirmed preliminarily that in vitro screening method is effective for obtaining resistant materials of red edible seed watermelon.

Development of an in vitro macrophage screening system on the immunomodulating effects of feed components

Background:While feed components capable of modulating the immune system are highly sought after and marketed,often little evidence is available to support functional immune response claims.Thus,a high-throughput in vitro cell screening system was developed to test these compounds for innate immune signaling effects,using Saccharomyces cerevisiae and its cell wall components in addition to lauric acid and its esters as models in two separate experiments.This screening system utilized RAW 264.7 murine macrophages to assess live S.cerevisiae cells and S.cerevisiae-derived cell wall componentsβ-glucan,mannan,and zymosan(a crude cell wall preparation containing bothβ-glucan and mannan).D-mannose was also evaluated as the monomer of mannan.We also examined the effect of a saturated fatty acid(C12:0,lauric acid)and its esters(methyl laurate and glycerol monolaurate)on innate immune cell activation and cellular metabolism.RAW cells were transfected with a vector that drives expression of alkaline phosphatase upon promoter activation of nuclear factorκ-light-chain-enhancer of activated B cells(NFκB),a major inflammatory/immune transcription factor.RAW cells were incubated with 0.01,0.1 or 1 mg/mL of yeast compounds alone or RAW cells were challenged with LPS and then incubated with yeast compounds.In a separate experiment,RAW cells were incubated with 0,0.5,2.5,12.5,62.5,and 312.5μmol/L of lauric acid,methyl laurate,or glycerol monolaurate alone,or RAW cells were challenged with LPS and then incubated with fatty acid treatments.Results:Treatment with zymosan orβ-glucan alone induced NFκB activation in a dose-dependent manner,whereas treatment with D-mannose,mannan,or live S.cerevisiae cells did not.Post-treatment with mannan after an LPS challenge decreased NFκB activation,suggesting that this treatment may ameliorate LPS-induced inflammation.Slight increases in NFκB activation were found when fatty acid treatments were applied in the absence of LPS,yet substantial reductions in NFκB activation were seen when treatments were applied following an LPS challenge.Conclusions:Overall,this cell screening system using RAW macrophages was effective,high-throughput,and sensitive to feed components combined with LPS challenges,indicating modulation of innate immune signaling in vitro.