Biology subjects

Macia Vicente, J.

Publications and source records attributed to Macia Vicente, J..

2 recordsLinked to original sources

bioRxiv2024

On the diversity of nematode antagonists in an agricultural soil, and their steerability by root-knot nematode density and cover crops

Plant-parasitic nematodes are harmful pathogens for many agricultural crops. Within this category, root-knot nematodes (RKN, Meloidogyne spp.) are worldwide regarded as the most impactful because of their wide geographical distribution and their polyphagous nature. Host plant resistances against RKN have been successfully introduced in a few crops only. As the use of nematicides is becoming increasingly restricted because of environmental and human health concerns, there is a need for alternative strategies to control RKN. One such approach is the stimulation of local nematode antagonists. We investigated this in an experimental field setting with two main variables: density of the Columbia root-knot nematode Meloidogyne chitwoodi, and the type of cover of crop. For each of the three M. chitwoodi densities, the effects of ten cover crop treatments were tested on both the resident (DNA) and the active (RNA) fractions of the bacterial and fungal communities. In our analyses, we focussed on changes in the abundance of plant-parasitic nematode antagonists. From the eight bacterial and 26 fungal genera known from global literature to harbour potential antagonists of plant-parasitic nematodes, we detected respectively five and 14 genera in our agricultural field. Among the bacterial genera, four included bacterial species for which nematode antagonism has been documented. The fungal genera included facultative nematode parasites (e.g., Arthrobotrys spp.), endophytes strengthening host defences (e.g., Acremonium spp.), as well as multiple obligatory nematophagous species. This study revealed that conventionally managed arable fields may harbour an unexpectedly high diversity of nematode antagonists. Multiple antagonists were stimulated by cover crops in a cover crop-specific manner, and, to a lesser extent, by increased RKN densities. The richness in putative nematode antagonists did not translate into M. chitwoodi suppression probably because most antagonists have a facultative nematophagous lifestyle and will only predate nematodes under poorer nutritional conditions.

ecology↗

bioRxiv2022

Pinpointing the distinctive impacts of ten cover crop species on the resident and active fractions of the soil microbiome

Cover crops are used in agriculture to minimise soil erosion, prevent nutrient leaching and increase soil organic matter content. Cover crops can also be grown to stimulate the soil microbial community to improve soil biological conditions. Despite their widespread use, little is known about the impact of different cover crop species on the composition and activity of the soil microbiome. Here we investigate the effect of distinct cover crop species on the rhizosphere microbiome and to characterise both the resident (DNA-based) and the active (RNA-based) fractions of the bacterial, fungal, protist and metazoan communities in the cover crops rhizosphere. We conducted a field experiment using 70-litre bottomless containers in which we grew ten monocultures of commonly used cover crop species belonging to five plant families, and an unplanted control treatment (fallow). The total DNA and RNA were extracted from soil and the bacterial, fungal, protistan and metazoan communities were characterized using Illumina MiSeq sequencing. We found that all cover crop species significantly impacted the resident and active microbial community composition. Moreover, cover crops showed distinct selection strengths on their rhizospheres. Together with borage (Boraginaceae), oilseed radish (Brassicaceae) was shown to provoke the strongest microbial shifts, in part attributable to a promotion of the bacterial family Pseudomonadaceae and a repression of Microascaceae in the rhizosphere. Lentil (Fabaceae) showed enrichment in fungal taxa, including Trichocomaceae and fungal members of the Glomerales order, whereas black oat, hybrid ryegrass (both Poaceae) and marigold (Asteraceae) induced relatively mild changes in the soil microbial communities. Predominantly, differences in selection strengths were consistent among the four organismal groups under investigation and were observed in both the active and resident communities. Our work provides a broad baseline for the effects of cover crops on four organismal groups, which may facilitate future cover crop selection to advance soil health.

ecology↗