The Date Palm Tree Rhizosphere Is a Niche for Plant Growth Promoting Bacteria in the Oasis Ecosystem

Figure 1

Station location and analysis of bacterial community structure associated with soil fraction of date root system. (a) The location of the studied oases is indicated on the map of Tunisia. (b) A principal coordinate analysis (PCO), deduced from the 16S rRNA gene-based PCR-DGGE profiles, resumes the diversity of the bacterial communities associated with the date palm root soil fractions. 84.8% of total variation is explained in the presented PCO. The soil fractions analysed are R: rhizosphere; S: root surrounding soil; and B: bulk soil. (c) Dist LM analysis to evaluate which are the main geoclimatic variables influencing the structure of the bacterial communities associated with date palm root soil fractions. Lat. N: latitude north; Long. E: longitude east; Alt.: altitude; : minimum temperature; : maximum temperature; Rainfall min: minimum rainfall; Rainfall max: maximum rainfall. (d) Box-plot graph represents the quantification of 16S rRNA gene by qPCR. The number of copies is expressed in Log₁₀. Statistical analysis (pairwise test) of bacterial assemblage across locations was indicated by the letter.

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