Numbers and locations of native bacteria on field-grown wheat roots quantified by fluorescence in situ hybridization (FISH).
Numbers and locations of native bacteria on field-grown wheat roots quantified by fluorescence in situ hybridization (FISH).
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DOI：
10.1111/j.1462-2920.2005.00973.x
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发表时间：
2006-05
影响因子：
5.1
通讯作者：
M. Watt;P. Hugenholtz;R. White;Kerry Vinall
中科院分区：
文献类型：
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作者：
M. Watt;P. Hugenholtz;R. White;Kerry Vinall
利用荧光原位杂交(FISH)技术对田间生长的小麦根上的土生菌、假单胞菌和丝状菌进行了定量和定位。在保护性耕作系统中，种子根在整个季节从未耕土壤中取样。这种土壤在空间上是不同的，许多根在坚硬的土壤中生长缓慢，这些土壤中有裂缝和孔洞，其中含有以前作物残留的死根。根和根际形态以及与土壤颗粒的接触被保存下来，并通过用Cy5和Cy5.5荧光染料在远红外线观察切片来避免自发荧光。空间分析表明，细菌嵌入在根表面11微米(范围2-30微米)内的稳定基质(生物膜)中，并聚集在40%的根上。一半的簇生在表皮细胞、土壤颗粒、帽状细胞或根毛之间，并有轴向凹槽；另一半与可见特征无关。在所有小麦根中，细菌平均为15.4×10(5)个/mm(3)根际，其中假单胞菌和丝状菌分别占10%和4%，采样时间的影响较小，植物年龄的影响不大。根冠沿根部细菌定殖率最高，伸长带定殖率最低。假单胞菌在根的发育过程中变化不大，占伸长区细菌总数的17%。延伸区未发现丝状细菌。然而，对小麦根际种群最显著的影响因素是与死根残留物的接触，其中假单胞菌减少，但细丝增加到细菌的57%(P<；0.001)。这与对根残留物的分析显示它们被细菌大量定植相一致，其中细丝(P<；0.001)占48%，假单胞菌(P=0.014)占1.4%。为可持续农业系统管理根际细菌的努力应继续侧重于根冠和粘液化学，以及残根作为有益细菌的来源。
Native bacteria, Pseudomonas and filamentous bacteria were quantified and localized on wheat roots grown in the field using fluorescence in situ hybridization (FISH). Seminal roots were sampled through the season from unploughed soil in a conservation farming system. Such soils are spatially heterogeneous, and many roots grow slowly through hard soil with cracks and pores containing dead roots remnant from previous crops. Root and rhizosphere morphology, and contact with soil particles were preserved, and autofluorescence was avoided by observing sections in the far-red with Cy5 and Cy5.5 fluorochromes. Spatial analyses showed that bacteria were embedded in a stable matrix (biofilm) within 11 microm of the root surface (range 2-30 microm) and were clustered on 40% of roots. Half the clusters co-located with axial grooves between epidermal cells, soil particles, cap cells or root hairs; the other half were not associated with visible features. Across all wheat roots, although variable, bacteria averaged 15.4 x 10(5) cells per mm(3) rhizosphere, and of these, Pseudomonas and filaments comprised 10% and 4%, respectively, with minor effects of sample time, and no effect of plant age. Root caps were most heavily colonized by bacteria along roots, and elongation zones least heavily colonized. Pseudomonas varied little with root development and were 17% of bacteria on the elongation zone. Filamentous bacteria were not found on the elongation zone. The most significant factor to rhizosphere populations along a wheat root, however, was contact with dead root remnants, where Pseudomonas were reduced but filaments increased to 57% of bacteria (P < 0.001). This corresponded with analyses of root remnants showing they were heavily colonized by bacteria, with 48% filaments (P < 0.001) and 1.4%Pseudomonas (P = 0.014). Efforts to manage rhizosphere bacteria for sustainable agricultural systems should continue to focus on root cap and mucilage chemistry, and remnant roots as sources of beneficial bacteria.