Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011.
Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011.
Plant Dis. 2019 Mar;103(3):392-397. doi: 10.1094/PDIS-02-18-0222-RE. Epub 2019 Jan 18.
The objective of this study was to determine the effects of ILeVO (fluopyram) and VOTiVO (Bacillus firmus I-1582) seed treatments on Heterodera glycines second-stage juvenile (J2) root penetration and behavior. In a growth chamber experiment, roots of soybeans grown from treated or untreated seeds were inoculated with H. glycines J2s at soil depths of 2.5, 5, or 7.5 cm. ILeVO significantly reduced H. glycines root penetration compared with the untreated control, but only when J2s were inoculated at a soil depth of 2.5 cm, which was near the seed. Changes in nematode behavior were assessed by collecting 60-s videos of J2s after 2 h of exposure to exudates from treated seeds or radicles from treated seeds or from soil leachates in which treated seeds were planted. X- and y-coordinates of each of the 13 reference points were recorded every hour for 24 h. A custom program analyzed and transformed the coordinates into nematode motion parameters (speed and total change in curvature). ILeVO, but not VOTiVO, seed exudates significantly reduced J2 speed relative to the untreated control. Soil leachates from ILeVO or VOTiVO treatments had no consistent effect on H. glycines speed or total change in curvature compared with the untreated control. In another experiment, treated or untreated seeds were incubated in wells of 6-well tissue culture plates containing 11.5% Pluronic gel. Seeds were removed after 2 h, and approximately 50 J2s then were pipetted into each well. The plates were scanned every 60 min for 24 h, and the number of J2s in each well that moved a minimum distance of ≥300 µm was determined using another custom software program. ILeVO, but not VOTiVO, significantly reduced the movement of J2 populations relative to control wells in which no seeds were added. And wells that had seeds, treated or not, yielded significantly less J2 movement compared with the no-seed control. The results of these experiments indicate that ILeVO reduces activity on H. glycines J2s but may not affect nematodes beyond a limited area surrounding the treated seed.
本研究的目的是确定 ILeVO（氟吡菌酰胺）和 VOTiVO（苏云金芽孢杆菌 I-1582）种子处理对大豆胞囊线虫第二阶段幼虫（J2）根穿透和行为的影响。在生长室实验中，从处理或未处理种子中生长的大豆根在土壤深度为 2.5、5 或 7.5 cm 处接种大豆胞囊线虫 J2。与未处理对照相比，ILeVO 显著降低了大豆胞囊线虫的根穿透，但仅在 J2 接种在接近种子的土壤深度 2.5 cm 时才有效。通过收集处理过的种子的渗出物或处理过的种子的幼根或处理过的种子种植的土壤浸出液中暴露 2 小时后的 J2 的 60 秒视频来评估线虫行为的变化。在 24 小时内，每小时记录 13 个参考点的每个 X 和 Y 坐标。自定义程序分析并转换坐标以得到线虫运动参数（速度和总曲率变化）。与未处理对照相比，ILeVO 但不是 VOTiVO 种子渗出物显著降低了 J2 的速度。与未处理对照相比，ILeVO 或 VOTiVO 处理的土壤浸出液对大豆胞囊线虫的速度或总曲率变化没有一致的影响。在另一个实验中，将处理或未处理的种子在含有 11.5% Pluronic 凝胶的 6 孔组织培养板的孔中孵育。孵育 2 小时后，将大约 50 个 J2 小心地转移到每个孔中。然后，每隔 60 分钟扫描一次平板 24 小时，使用另一个自定义软件程序确定每个孔中移动至少 300 µm 的 J2 数量。与未添加种子的对照孔相比，ILeVO 但不是 VOTiVO 显著降低了 J2 种群的运动。并且无论是否处理种子，含有种子的孔与不含种子的对照相比，J2 的运动显著减少。这些实验的结果表明，ILeVO 降低了大豆胞囊线虫 J2 的活性，但可能不会影响处理种子以外的有限区域内的线虫。
