Biology subjects

Marolleau, B.

Publications and source records attributed to Marolleau, B..

4 recordsLinked to original sources

bioRxiv2025

Evaluating the legacy of drought exposure on root and rhizosphere bacterial microbiomes over two plant generations

Drought is a critical risk in developing countries for staple crops like common bean (Phaseolus vulgaris L.). We conducted an experiment to understand the legacy effects of repeated drought exposure across plant generations on the root and rhizosphere microbiome of the common bean, hypothesizing that a legacy of exposure improves overall plant microbiome resilience. We profiled the bacterial microbiome using marker gene amplicon sequencing over two plant generations in a complete factorial design for two common bean genotypes, Red Hawk and Flavert. We performed parallel experiments for Red Hawk in two different countries using soils of Pays de la Loire, France, and Michigan, USA. Despite the clear and relatively consistent drought effects on the plant phenotypes, there was neither response of the Red Hawk microbiomes to drought, nor a notable legacy of drought exposure. For Flavert, there was a minor legacy drought effect for the second generation in the rhizosphere microbiome beta diversity. This study demonstrates that rhizosphere microbiomes can be resistant to drought stress and that cross-generational legacy depends on soil origin and host genotype. Such parallel experiments across countries, while difficult to implement, are useful to inform generalities and build theory towards prediction on microbiome responses to global change.

microbiology↗

bioRxiv2024

Stable, multigenerational transmission of the bean seed microbiome despite abiotic stress

Seed microbiomes initiate plant microbiome assembly, but the consequences of environmental conditions of the parent plant for seed microbiome assembly and transmission are unknown. We tracked endophytic seed bacterial communities of common bean lines exposed to drought or excess nutrients, and discovered stable transmission of 22 bacterial members regardless of parental plant treatment. This study provides insights into the maintenance of plant microbiomes across generations, even under challenging environmental stress.

microbiology↗

bioRxiv2021

Single seed microbiota: assembly and transmission from parent plant to seedling

Gaining basic understanding of processes involved in seed microbiota assembly is a prerequisite for improving crop establishment. Investigation of microbiota structure during seed development revealed that individual seeds of bean and radish were associated with a dominant bacterial taxon representing more than 75% of all reads. The identity of this taxon was highly variable between plants and within seeds of the same plant. Succession of dominant taxa occurred during seed filling and maturation through Selection. In a second step, we evaluated seed to seedling transmission of these dominant seed-borne taxa. We showed that initial bacterial abundance on seeds was not a good predictor of seedling transmission and that the identity of seed-borne taxa can impact seedling phenotype. Altogether this work unveiled that seeds are colonized by few bacterial taxa of highly variable identity, which appears to be important for the early stages of plant development.

microbiology↗

bioRxiv2019

Insect pollination is an ecological process involved in the assembly of the seed microbiota

The assembly of the seed microbiota involves some early microbial seed colonizers that are transmitted from the maternal plant through the vascular system, while other microbes enter through the stigma. Thus, the seed microbiota consists of microbes not only recruited from the vascular tissues of the plant, but also from the flower. Flowers are known to be a hub for microbial transmission between plants and insects. This floral-insect exchange opens the possibility for insect-transmitted bacteria to colonize the ovule and subsequently the seed, and to pass then into the next plant generation. In this study, we evaluated the contribution of insect pollination to the seed microbiota through high-throughput sequencing. Oilseed rape (OSR) Brassica napus flowers were exposed to visits and pollination by honey bees (Apis mellifera) or red mason bees (Osmia bicornis), hand pollination, or autonomous self-pollination (ASP). Sequence analyses revealed that honey bee visitation reduced the bacterial richness and diversity, increased the variability in the seed microbial structure, and introduced bee-associated taxa. In contrast, mason bee pollination had minor effects on the seed microbiota. We highlight the need to consider insect pollination as an ecological process involved in the transmission of bacteria from flower to seeds.\n\nIMPORTANCEInsect pollinators and flowering plants have a very old mutualistic relationship in which animal mobility is used for the dispersal of pollen. The pollination services provided by insects are extremely important to many natural plant populations as well as agricultural crops. Here we show that while visiting flowers, insect pollinators can disperse bacteria that are able to colonize the developing seed via the flower. Hence, insect pollination participates in the assembly of the seed microbiota, the inoculum for the next plant generation. This novel insight has important implications in terms of re-assessing pollinator services by including microbe transfer.

microbiology↗