[Research on chemotaxis response of Alternaria panax to amino acid of ginseng root exudates].

Plate assay and spore germination method were used to study the chemotaxis response of Alternaria panax to arginine, glutamic acid, aspartic acid and threonine. The result showed that the optimum temperature of A. panax chemotaxis response to four amino acids were all 25 ℃. And chemotaxis responses of A. panax were different under conditions of different concentration and pH value. The chemotaxin reached to the highest under the condition of 2 mg•L⁻¹ and pH value was 7 for arginine, glutamic acid and threonine while 20 mg•L⁻¹ and pH value was 6 for aspartic acid . The data of chemotactic migration index (CMI) were 1.24, 1.38, 1.27, 1.31 and chemotactic growth rates(CGR) were 0.451 0, 0.353 0, 0.381 3, 0.228 8 and spores germination rates(SGR) were 57.33%，63%，56.67%，58% and the dry weight of mycelial (DWM) were 372.9, 348.5, 314.4, 390.2 mg•L⁻¹ respectively. It indicated that the low and middle concentration of amino acid had significant promoting effect on chemotaxis response of A. panax. As important substances generated in ginseng root, amino acids exhibited an efficient chemotactic effect on A. panax, and some even show inhibition effect under high concentration.

[Chemotaxis response of Erwinia carotovora on sugars and amino acids of root exudates of Panax ginseng].

The chemotaxis response of Erwinia carotovora to different sugars and amino acids in four kinds of chemotactic parameters (concentration, time, temperature and pH ) was determined by capillary method. The results showed that when pH was 8, concentration was 0.025 mg•L ⁻¹, culture temperature was 25 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of lysine was 2.509,when pH was 6, concentration was 0.25 mg•L ⁻¹, culture temperature was 25 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of arginine was 2.218 8,when pH was 7, concentration was 0.25 mg•L ⁻¹, culture temperature was 30 ℃ and the duration was 60 minutes, the optimal chemotaxis rate of L-rhamnose was 3.091 2, when pH was 6, concentration was 0.25 mg•L ⁻¹, culture temperature was 30 ℃ and the duration was 45 minutes, the optimal chemotaxis rate of D-arabinose was 3.026 3. Sugars and amino acids had obvious chemotaxis with E. carotovora,the high concentration of carbohydrate and amino acid exited an inhibitory effect on chemotaxis response of E. carotovora, and the chemotaxis response decreased with the increase of concentration of carbohydrates and amino acids.