枯草芽胞杆菌GB519在水稻植株中的定殖及对稻瘟病田间防效

枯草芽胞杆菌GB519是一株具有广谱抑菌活性的生防菌株。本研究利用绿色荧光蛋白标记的菌株GB519-GFP处理水稻种子、根和叶片，结合激光共聚焦显微镜观察和抗生素平板回收检测的方法，探究其在水稻根茎叶中的定殖动态。结果显示：经GB519-GFP发酵液处理水稻种子、根和叶片后，菌株均可内生定殖于植株的表皮、皮层和维管束中，表明其可在水稻植株内迁移和定殖。GB519-GFP在处理部位的定殖量通常呈现先减少后增多的趋势，非处理部位3～5 d后即可检测到标记菌株。浸种处理，3 d后在幼芽中可检测到标记菌株；20 d后在根中的菌量最多，达5.7×10⁵ cfu/g。灌根处理，1 d后根中菌量为5.4×10⁵ cfu/g; 20 d后根、茎和叶中菌量均达到最大值；处理80 d后，根中定殖数量仍达1.9×10⁵ cfu/g。叶面喷施处理，1 d后叶片菌量为4.2×10⁵ cfu/g; 20 d后叶片菌量达4.4×10⁵ cfu/g。不同处理方法在各部位的定殖量几乎均在处理20 d后达到峰值。...

Colonization dynamics of Bacillus subtilis GB519 in rice plants and its biocontrol efficacy against rice blast in the field

Bacillus subtilis GB519 displays antimicrobial activity in a broad spectrum. In this study, the GFP-labeled strain, GB519-GFP was used to explore its colonization dynamics in rice plants via both the laser confocal microscope observation and antibiotic plate recovery. The strain GB519-GFP could colonize the epidermis, cortex and vascular bundle after seed-soaking, root-irrigating or foliar-spray with the fermentation broth. These results indicated that it could migrate and colonize in rice plants. In general, the colonization quantity of GB519-GFP first decreased and then increased in the treated part, and it could be detected in the untreated part after 3-5 days. The GFP-labeled strain was detected in the bud three days after seed-soaking and the maximum amount of colonization reached 5.7×105 cfu/g in the root after 20 d. The amount of colonization in the root was 5.4×105 cfu/g one day after root-irrigating. The amount reached the maximum value in the root, stem and leaf after 20 d, and remained at 1.9×105 cfu/g in the root after 80 d. The colonization was 4.2×105 cfu/g in the leaves one day after foliar-spray, and reached 4.4×105 cfu/g after 20 d. The amounts of colonization in different tissues reached the peak 20 d after treated. The control efficacy of GB519 against rice blast was 73.9% in the field by foliar-spray. It indicated that foliar spraying with GB519 could play a role in preventing rice blast. This study provides a guidance for the control of rice blast by B. subtilis GB519.