Project description:The microbiota associated to xerophyte is a "black box" that might include microbes involved in plant adaptation to the extreme conditions that characterize their habitat, like water shortage. In this work, we studied the bacterial communities inhabiting the root system of Argania spinosa L. Skeels, a tree of high economic value and ecological relevance in Northern Africa. Illumina 16S rRNA gene sequencing and cultivation techniques were applied to unravel the bacterial microbiota's structure in environmental niches associated to argan plants (i.e., root endosphere, rhizosphere, root-surrounding soil), not associated to the plant (i.e., bulk soil), and indirectly influenced by the plant being partially composed by its leafy residue and the associated microbes (i.e., residuesphere). Illumina dataset indicated that the root system portions of A. spinosa hosted different bacterial communities according to their degree of association with the plant, enriching for taxa typical of the plant microbiome. Similar alpha- and beta-diversity trends were observed for the total microbiota and its cultivable fraction, which included 371 isolates. In particular, the residuesphere was the niche with the highest bacterial diversity. The Plant Growth Promotion (PGP) potential of 219 isolates was investigated in vitro, assessing several traits related to biofertilization and biocontrol, besides the production of exopolysaccharides. Most of the multivalent isolates showing the higher PGP score were identified in the residuesphere, suggesting it as a habitat that favor their proliferation. We hypothesized that these bacteria can contribute, in partnership with the argan root system, to the litter effect played by this tree in its native arid lands.
Project description:Background: The Argane tree ( Argania spinosa L. Skeels) is an endemic tree of southwestern Morocco that plays an important socioeconomic and ecologic role for a dense human population in an arid zone. Several studies confirmed the importance of this species as a food and feed source and as a resource for both pharmaceutical and cosmetic compounds. Unfortunately, the argane tree ecosystem is facing significant threats from environmental changes (global warming, over-population) and over-exploitation. Limited research has been conducted, however, on argane tree genetics and genomics, which hinders its conservation and genetic improvement. Methods: Here, we present a draft genome assembly of A. spinosa. A reliable reference genome of A. spinosa was created using a hybrid de novo assembly approach combining short and long sequencing reads. Results: In total, 144 Gb Illumina HiSeq reads and 7.2 Gb PacBio reads were produced and assembled. The final draft genome comprises 75 327 scaffolds totaling 671 Mb with an N50 of 49 916 kb. The draft assembly is close to the genome size estimated by k-mers distribution and covers 89% of complete and 4.3 % of partial Arabidopsis orthologous groups in BUSCO. Conclusion: The A. spinosa genome will be useful for assessing biodiversity leading to efficient conservation of this endangered endemic tree. Furthermore, the genome may enable genome-assisted cultivar breeding, and provide a better understanding of important metabolic pathways and their underlying genes for both cosmetic and pharmacological purposes.