Abstract:
In this study, the difference of the secretion of exopolysaccharides and lipopolysaccharide of
R.
solanacearum and their effects on the number of
R.
solanacearum adsorbed in tobacco roots were studied at different pH values. The results showed that the maximum single and total yield of EPS were 3.27×10
-12 and 50.12×10
-2 g at pH 6.5, respectively. While the minimum single and total yield of EPS were at pH 8.0. The maximum total yield of LPS was 9.41×10
-3 g at pH 7.0, and the maximum single yield was 17.51×10
-15 g at pH 7.5; In addition, the single yield of EPS was much higher than LPS at the same pH value. EPS had a promotive effect on the adsorption and invasion of
R.
solanacearum in tobacco roots, while LPS had a suppressive effect, and the promotive effect of EPS played a major role at the same concentration. When added EPS under the pH6.6, the number of
R.
solanacearum adsorbed and invaded in the root surface were the maximum, reaching 15.43×10
8 and 10.73×10
9 cfu/g
mf (fresh matter) respectively, and the bacterial number of
R.
solanacearum deposited on the root surface and clogged in the cross section with its secretion were the most, and root tip deformitied seriously. Therefore, EPS secretion was increased under acidic conditions, which promoted the identification and adsorption of
R.
solanacearum on tobacco roots, and the degree of disease occurrence was further improved. LPS secretion was increased under neutral and alkaline conditions, which reduced disease occurrence.
下载: