Inhibition of the growth of cariogenic bacteria in vitro by plant falvanones

Phytoalexins, defensive compounds produced by plants against microbial infections, were purified fromSophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2,4-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 g/ml.     

甘薯薯瘟病原细菌对甘薯植保素的诱导初探

甘薯（Ｉｐｏｍｏｅａ ｂａｔａｔａｓ）抗病品种“湘薯６号”和感病品种“新种花１８３”经薯瘟病原细菌（Ｐｓｅｕｄｏｍｏｎａｓ ｓｏｌａｎａｃｏａｒｕｍ Ｅ．Ｆ．Ｓｍｉｔｈ）的诱导，９０％甲醇提取后，用乙酸乙酯萃取和ＳｅｐｈａｄｅｘＬＨ－２０柱层析分离纯化得到４个吸收峰，经抑菌试验检测出“湘薯６号”的抑菌活性区在第２峰，而新种花１８３的抑菌活性区在第３峰，硅胶Ｃ２５４薄板层析法鉴定该提取物可能是植保素     

Host-plant oligosaccharins in the honeydew ofSchizaphis graminum (Rondani) (Insecta,Aphididae)

Summary The honeydew of the aphidSchizaphis graminum (Rondani) contains hetero-oligosaccharides (mol. wt>2200 D) having neutral sugar and uronic acid compositions similar to the pectic substances of the host plant,Sorghum biocolor (L.) Moench. These oligosaccharides are pectic fragments which result from the depolymerization of pectic substances in the phloem by aphid salivary polysaccharases.     

A transgenic wheat with a stilbene synthase gene resistant to powdery mildew obtained by biolistic method

Stilbene, a kind of phytoalexin, plays an important role in resistance to fungal and bacterial infection in plants. It strongly inhibits the growth of fungi and sprout of spore. Stilbene synthase gene (Vst1) obtained from grapevine has been transferred into common spring wheat Jinghong 5 by using the biolistic transformation method. Five transgenic plants (T₀) were obtained from the bombarded 2014 immature embryos. One immune plantlet and 3 plantlets with mid-resistance to powdery mildew were identified from the transgenic plants of T₃ generation which came from 2 T₀ transgenic plants.