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Endophytic microbes are micro-organisms that live inside plant tissues. These micro-organisms live mainly inside the roots, stems and sometimes eeven the flowers, fruits and seeds of plants. Some of them can help plants to better resist disease, improve their growth and tolerate difficult environmental conditions. When they reside in seeds, they can be passed down through the genarations of the parent plants.

However, studies on the seed microbiome of metal-hyperaccumulating plants are rare - plant capable of accumulating high levels of specific metals in their tissues. This study by LSE researchers and their colleagues aimed to characterise the diversity of endophytic bacteial communities in the seeds of plant from the Brassicaceae family, to which the greatest number of hyperaccumulating species belong.

The seed collection analysed included 65 accessions grouping 53 hyperaccumulative Brassicaceae species and 12 non-accumulative species, cowering 5 genera (Bornmuellera, Odontarrhena, Noccaea, Brassica and Raphanus). These seeds were collected in various countries (Albania, Austria, France, Greece, Italy, Slovakia, Spain and Romania) between 2010 and 2021, during survey missions. Using metabarcoding approaches targeting 165 rRNA (Illumina high throughput sequencing), LSE researchers characterised the structure and diversity of endophytic bacterial communities in the seeds and studied potential correlations with the location/concentrations of nickel ini the seeds (micro-XRF approcach, i.e. X-Ray / ICP-AES analyses).

The results obtained indicate that the taxonomy of the host plant is the main determinant of the diversity of the endophytic bacterial community in Brassicaeae seeds. In addition, the seeds of non(hyperaccumulting plants harbour significantly more diverse bacterial communities than those of hyperaccumulating plants. Certain bacterial families, such as Pseudomonadaceae and Nocardiaceae, were more abundant in the seeds of non-hyperaccumulating Brassicaceae, while the genus Stenotrophomonas wes more prevalent in the nickel-rich seeds of hyperaccumulators. These differences suggest that metal accumulation in the seeds of hyperaccumulators imposes selection pressures, leading to changes in the composition of the endophytic bacterial community.

This work confirms that the taxonomy of the host plant is the main determinant of the structure and diversity of endophytic bacterial communities in seeds, correlating with the high levels of metals present in these seeds.

 

Contacts : Emile Benizri (emile.benizri@univ-lorraine.fr), Alexis Durand (alexis.durand@univ-lorraine.fr)

Référence : https://doi.org/10.1016/j.temicr.2025.100006

Partners : Luxembourg Institute of Science and Technology, Luxembourg ; Université de Lorraine, CNRS, LIEC, Nancy 54000 ; Università Degli Studi Di Firenze, Laboratorio Di Fisiologia Vegetale, Florence 50121, Italy ; University and Research, Laboratory of Genetics, Wageningen, the Netherlands.

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