Seed properties and bacterial communities are associated with feeding preferences of a seed-eating beetle
Abstract
Aims Bacterial communities inhabiting seeds may interact not only with the plant host, but also with seed predators. The study compared the bacterial communities associated with seeds of seven weeds Crepis biennis, Taraxacum officinale, Tripleurospermum inodorum, Plantago lanceolata, Thlaspi arvense, Silene latifolia and Leonurus cardiaca, after burial in soil for two years, and demonstrated how these changes relate to seed mass, viability and attractiveness for a seed predator, Pseudoophonus rufipes (DeGeer) (Coleoptera: Carabidae).
Results Bacterial diversity, assessed by Illumina MiSeq sequencing of the 16S rRNA amplicon, increased 5-10 times, while seed viability and mass decreased with burial time. Mostly, the seed species differed in their microbiomes and changes in seed properties together with their attractiveness to the beetle.
Seed microbiomes remained specific after burial and contained taxa characteristic for both plant endophytes but also insect guts. In all seeds, 5 zero radius OTUs (ZOTU) were common after one year of burial, while only one common ZOTU remained after the second year.
Seeds of T. officinale and T. inodorum lost attractiveness for the beetle approx. by 90 and 80% resp., while seeds of T. arvense improved their attractiveness by 80% after soil exposure. Changes in seed consumption were partially explained by bacterial communities and seed properties, namely the C/N ratio and seed viability.
Conclusions Seed mass, viability, C/N and beetle predation were related to the bacterial community. These relationships also changed after seed burial in soil, which may impact seed survival and consequently influence plant population dynamics and weed management.