棉花根系分泌物对枯草芽胞杆菌NCD-2菌株趋化性的影响

 枯草芽胞杆菌NCD-2菌株在不同棉花品种根际定殖能力表现不同,在感黄萎病品种冀棉11根际的定殖能力最强,而在耐病品种中棉所41根际的定殖能力最弱。本研究收集了5个不同棉花品种的根系分泌物,测定了NCD-2菌株对根系分泌物的趋化作用,结果表明NCD-2菌株对冀棉11根系分泌物的趋化作用最强,而对中棉所41根系分泌物的趋化作用最差。通过柱前衍生高效液相色谱法(AccQ-Tag-HPLC)测定了根系分泌物中氨基酸的成分及含量,结果表明不同氨基酸在不同棉花品种中含量不同。冀棉11的根系分泌物中氨基酸种类最多,可达17种。在中棉所41的根系分泌物中氨基酸种类最少且大多数氨基酸含量均为最低。测定了NCD-2菌株对14种氨基酸标准品的趋化性,结果表明NCD-2菌株对精氨酸(Arg)、丙氨酸(Ala)和赖氨酸(Lys)趋化性最强,但对甘氨酸(Gly)呈现负趋化性。RT-qPCR试验表明冀棉11的根系分泌物可提高cheA和cheD基因在NCD-2菌株中的表达量。室内防治试验表明,NCD-2菌株对冀棉11黄萎病的防效最好,防治效果可达到66.68%。本研究明确了棉花根系分泌物中氨基酸对NCD-2菌株趋化性的影响,该菌株在棉花根际定殖能力与棉花根系分泌物中氨基酸对本菌株的趋化性相一致。

Effect of cotton root exudates on the chemotaxis of Bacillus subtilis strain NCD-2

Bacillus subtilis strain NCD-2 had different colonization abilities on the rhizosphere of different cotton cultivars, and the strongest colonization ability was achieved on cotton cultivar Jimian 11, but the weakest colonization was observed on cultivar Zhongmiansuo 41. In this study, the chemotaxis assays were performed to determine the chemotactic response of strain NCD-2 towards root exudates of the five cotton cultivars. Results showed that strain NCD-2 exhibited the strongest chemotactic response toward the root exudates of Jimian 11 and the weakest chemotactic response toward the root exudates of Zhongmiansuo 41. The amino acids from the five cotton cultivars root exudates were analyzed by high performance liquid chromatography method with AccQ-Tag precolumn derivatization (AccQ-Tag-HPLC). Results showed that the concentrations of certain amino acids varied significantly among the cotton cultivars. The root exudates of Jimian 11 have the most species of amino acids up to 17. However, the root exudates of Zhongmiansuo 41 have the least species of amino acids and the lowest concentration of amino acids. Chemotaxis assays were performed to determine the chemotactic responses of strain NCD-2 towards the standard samples of 14 amino acids. Results showed that strain NCD-2 exhibited the strongest chemotactic responses toward Arg, Ala and Lys and negative chemotactic responses toward Gly. RT-qPCR assay showed that the expression of the cheA and cheD gene increased significantly in response to root exudates of Jimian 11. Control effect of cotton verticillium wilt by strain NCD-2 in greenhouse indicated that the highest biocontrol efficacy of 66.68% was achieved on susceptible cultivar Jimian 11,while only 20.69%-25.58% biocontrol efficacy was achieved on resistant cultivar Pima 90. The results of this study showed that the amino acids in cotton root exudates affected the chemotaxis of strain NCD-2, and the colonization ability of strain NCD-2 was consistent with the chemotaxis towards to the amino acids.