Phytopathology. 1997 May;87(5):559-64. doi: 10.1094/PHYTO.1997.87.5.559.
ABSTRACT Bacillus sp. L324-92 is suppressive to three root diseases of wheat, namely take-all caused by Gaeumannomyces graminis var. tritici, Rhizoctonia root rot caused by Rhizoctonia solani AG8, and Pythium root rot caused by several Pythium species. Populations of strain L324-92R(12), a rifampicin-resistant mutant of L324-92 applied as a seed treatment, were monitored in the rhizosphere and spermosphere of wheat and compared with populations of Pseudomonas fluorescens 2-79RN(10), a known, rhizosphere-competent, biocontrol agent. In growth chamber studies, the population sizes of L324-92R(12) on roots of wheat were approximately 1,000-fold smaller than those of 2-79RN(10) at 5 days after planting, but, thereafter, they increased while those of 2-79RN(10) decreased until the two were equal in size at 45 days after planting. In the field with winter wheat, the population sizes of L324-92R(12) on roots were at least 10-fold smaller than those of 2-79RN(10) during the fall (November 1993) and early spring (March 1994). Thereafter, the population of L324-92R(12) remained constant or increased slightly, while the population of 2-79RN(10) decreased until the two were roughly the same at 10(4) to 10(5) CFU/plant over the period of 150 days (April 1994) until 285 days (harvest) after planting. In growth chamber studies, strain L324-92R(12) remained confined to root sections within 3.5 cm below the seed, whereas 2-79RN(10) was recovered from all root sections ranging from 0.5 to 6.5 cm below the seed. In the field on winter wheat, both strains were recovered from root sections down to 5.0 to 6.5 cm below the seed at 75 days after planting (mid December), but only 2-79RN(10) was recovered at this depth at 90 days after planting. Both strains were recovered from the seed remnants 6 months after planting in the field. Both strains also were recovered from inside the roots and shoots, but population sizes of strain 279RN(10) were greater than those of L324 92R(12).
摘要 芽孢杆菌 L324-92 对小麦的三种根部病害具有抑制作用，分别是禾谷丝核菌引起的全蚀病、立枯丝核菌引起的根腐病和几种腐霉引起的腐霉根腐病。作为种子处理剂应用的 L324-92 的利福平抗性突变株 L324-92R(12)的种群在小麦根际和根区被监测，并与已知的根际竞争生物防治剂荧光假单胞菌 2-79RN(10)的种群进行了比较。在生长室研究中，L324-92R(12)在种植后 5 天在小麦根上的种群大小比 2-79RN(10)小约 1000 倍，但此后，它们增加，而 2-79RN(10)减少，直到种植后 45 天两者大小相等。在冬小麦田间，L324-92R(12)在根上的种群大小在秋季(1993 年 11 月)和早春(1994 年 3 月)期间至少比 2-79RN(10)小 10 倍。此后，L324-92R(12)的种群保持不变或略有增加，而 2-79RN(10)的种群减少，直到种植后 150 天(1994 年 4 月)至 285 天(收获)期间，两者在 10(4)到 10(5)CFU/plant 左右大致相同。在生长室研究中，L324-92R(12)仍局限于种子下方 3.5 厘米内的根段，而 2-79RN(10)则从种子下方 0.5 至 6.5 厘米的所有根段中回收。在冬小麦田间，两种菌株均在种植后 75 天(12 月中旬)从种子下方 5.0 至 6.5 厘米的根段中回收，但仅在种植后 90 天从该深度回收 2-79RN(10)。两种菌株均在种植后 6 个月从田间的种子残余物中回收。两种菌株也从根内和茎内回收，但 279RN(10)菌株的种群数量大于 L324-92R(12)。
