Phytopathology. 2004 Apr;94(4):351-63. doi: 10.1094/PHYTO.2004.94.4.351.
ABSTRACT Pseudomonas fluorescens B5 and Bacillus subtilis MBI 600 colonized sugar beet seedlings at matric potentials of -7 x 10(3), -140 x 10(3), and -330 x 10(3) Pa and under five temperature regimes ranging from 7 to 35 degrees C, with diurnal fluctuations of 5 to 22 degrees C. No interaction between matric potential and temperature was observed. In situ bioluminescence indicated physiological activity of Pseudomonas fluorescens B5. Colonization of the root at >/=4 cm below the seed decreased at very low matric potential (-330 x 10(3) Pa). Total population size of Pseudomonas fluorescens B5 per seedling was significantly increased at -140 x 10(3) Pa. However, matric potential had no significant effect on the population density of Pseudomonas fluorescens per gram of root fresh weight and did not affect the distribution of the population down the root. Total population size per seedling and downward colonization by Pseudomonas fluorescens B5 were significantly reduced at high temperatures (25 to 35 degrees C). Maximum colonization down the root occurred at intermediate temperature (15 degrees C) at both matric potentials (-7 x 10(3) and -140 x 10(3) Pa). Addition of B. subtilis MBI 600 to the seed had no effect on rhizosphere populations of Pseudomonas fluorescens B5. Populations of B. subtilis MBI 600, which consisted largely of spores, were slightly reduced at lower matric potentials and were not affected by temperature. Survival and dry weight of plants in soils infested with Pythium spp. decreased with increasing soil temperature and matric potential, indicating an increase in disease pressure. However, there was no significant interaction between the two factors. At -330 x 10(3) Pa, soil dryness but not Pythium infection was the limiting factor for plant emergence. At temperatures of 7 to 25 degrees C and matric potentials of -7 x 10(3) to 120 x 10(3) Pa, treatment with Pseudomonas fluorescens B5 increased plant survival and dry weight. At 7 degrees C and -120 x 10(3) Pa, there was almost complete emergence of seeds treated with Pseudomonas fluorescens B5. Antagonistic activity of Pseudomonas fluorescens B5 decreased with increasing soil temperature and decreasing matric potential. At 25 to 35 degrees C and -7 x 10(3) Pa, no effect was observed. In regimes with different day and night temperatures, the maximum (day) temperature was decisive for disease development and antagonistic activity. B. subtilis MBI 600 displayed no significant antagonistic effect against Pythium ultimum and did not influence the performance of Pseudomonas fluorescens B5 in combined inocula.
摘要 荧光假单胞菌 B5 和枯草芽孢杆菌 MBI 600 在基质势为-7×10(3)、-140×10(3)和-330×10(3)Pa 以及 7 至 35℃的五个温度范围内定殖于甜菜幼苗，昼夜波动范围为 5 至 22℃。未观察到基质势与温度之间的相互作用。原位生物发光表明荧光假单胞菌 B5 的生理活性。种子下方> = 4cm 处的根定植减少，基质势非常低(-330×10(3)Pa)。荧光假单胞菌 B5 的每株幼苗总种群数量在-140×10(3)Pa 时显著增加。然而，基质势对每克根鲜重的荧光假单胞菌种群密度没有显著影响，也不影响种群沿根向下的分布。在高温(25 至 35℃)下，每株幼苗的总种群数量和荧光假单胞菌 B5 的向下定植显著减少。在两种基质势(-7×10(3)和-140×10(3)Pa)下，荧光假单胞菌 B5 沿根向下定植的最大定植发生在中间温度(15℃)。枯草芽孢杆菌 MBI 600 加入种子中对荧光假单胞菌 B5 的根际种群没有影响。枯草芽孢杆菌 MBI 600 的种群主要由孢子组成，在较低的基质势下略有减少，不受温度影响。受腐霉属侵染的土壤中植物的存活和干重随着土壤温度和基质势的升高而降低，表明病害压力增加。然而，这两个因素之间没有显著的相互作用。在-330×10(3)Pa 时，土壤干燥而不是腐霉属感染是植物出苗的限制因素。在 7 至 25℃和基质势为-7×10(3)至 120×10(3)Pa 的条件下，用荧光假单胞菌 B5 处理可提高植物的存活率和干重。在 7℃和-120×10(3)Pa 时，用荧光假单胞菌 B5 处理的种子几乎完全出苗。荧光假单胞菌 B5 的拮抗活性随土壤温度的升高和基质势的降低而降低。在 25 至 35℃和-7×10(3)Pa 时，没有观察到效果。在不同日温和夜温的条件下，最高(白天)温度对病害发展和拮抗活性起决定性作用。枯草芽孢杆菌 MBI 600 对终极腐霉没有表现出明显的拮抗作用，也不影响荧光假单胞菌 B5 在组合接种中的性能。
