贝莱斯芽胞杆菌LQ-3防治小麦纹枯病的效果及根际定殖能力

小麦纹枯病（wheat sharp eyespot）主要是由禾谷丝核菌（Rhizoctonia cerealis）侵染引起的一种土传真菌病害，严重威胁小麦生产安全。目前，利用生防细菌防治小麦纹枯病已成为研究热点，其中，研究最多的一类生防细菌为芽胞杆菌。为明确贝莱斯芽胞杆菌（Bacillus velezensis）LQ-3防治小麦纹枯病的效果及其在小麦根部定殖能力，本研究利用LQ-3发酵液灌根处理小麦苗，调查统计LQ-3对小麦纹枯病的防效。同时利用绿色荧光蛋白标记菌株LQ-3（pGFP78）灌根处理小麦根部，并结合抗生素平板回收检测、激光共聚焦显微镜观察方法，探明LQ-3在小麦根部的定殖动态。结果表明，LQ-3防治小麦纹枯病的效果为57.49%，与化学药剂27%苯醚·咯·噻虫悬浮种衣剂（酷拉斯）的防效（59.95%）相当。LQ-3（pGFP78）的生长趋势与野生型LQ-3相比并没有显著性差异，且仍具有游动性和生物膜形成能力。 LQ-3（pGFP78）发酵液初始浓度为2.3×10⁸ cfu·mL^-1，灌根处理5 d后，其在小麦根部的定殖量已达到9.63×10⁶cfu·g^-1，25 d后，定殖量仍有1.33×10⁶cfu·g^-1，表明LQ-3在小麦根部具有较好的定殖能力。

Biocontrol Effect of Bacillus velezensis LQ-3 against Wheat Sharp Eyespot and Its Colonization Dynamics in the Rhizosphere of Wheat

Wheat sharp eyespot, primarily caused by the soil-borne fungal pathogen Rhizoctonia cerealis, poses a severe threat to wheat production security. Currently, the utilization of biocontrol bacteria for the prevention and control of wheat sharp eyespot has emerged as a research hotspot, with Bacillus being the most extensively studied biocontrol bacteria. To determine the biocontrol effect of Bacillus velezensis LQ-3 on wheat sharp eyespot and its colonization ability in wheat root, this study utilized LQ-3 fermentation to irrigate wheat root, aiming to investigate the biocontrol effect of LQ-3 against wheat eye spot. The colonization dynamics of LQ-3 in wheat root were elucidated by using green fluorescent protein labeled strain LQ-3 (pGFP78) to irrigate wheat root, combined with antibiotic plate recovery detection and laser confocal microscopy observation. The results showed that the biocontrol effect of LQ-3 on wheat sharp eyespot is 57.49%, which is equivalent to the biocontrol effect of the Kuras at 59.95%. Moreover, the growth trend of LQ-3 (pGFP78) exhibited no significant disparity when compared to the wild-type LQ-3, while still retaining its motility and biofilm-forming abilities. The initial concentration of LQ-3 (pGFP78) fermentation broth was 2.3×10⁸ cfu·mL^-1, and after 5 d of root irrigation treatment, the colonization of LQ-3 (pGFP78) in wheat root reached 9.63×10⁶ cfu·g^-1; even after 25 d, the colonization quantity still remained at 1.33×10⁶ cfu·g^-1, indicating that LQ-3 has proficient colonization capability in wheat root.