Carrot genotypes differentially alter soil bacterial communities and decomposition of plant residue in soil

Abstract

Purpose Farmers need alternative approaches to manage nitrogen (N) that meet crop needs while reducing loss to the environment. Identifying crop genotypes that promote decomposition of organic materials and understanding the potential mechanisms responsible could help address this challenge. Consequently, we aimed to 1) determine whether carrot genotypes differ in their potential to facilitate organic matter decomposition in soil, and 2) identify bacterial taxa that are stimulated by carrot roots, and thus could play a role in these processes. Methods We grew five genotypes expected to differ in N use efficiency in a nutrient-poor soil amended with 15 N-enriched corn residue, tracked changes in carbon (C) and N pools, quantified microbial activity and bacterial community composition, and predicted the potential expression of microbial genes involved in soil C and N cycles. Results Experimental genotype 8503 had the greatest capacity to promote decomposition of corn residues. This genotype had the highest % of N from the corn residue in its taproots and on average, promoted higher b-glucosidase activity in soils. Distinct bacterial communities from the families Micromonosporaceae, Chromatiaceae, and Rhodospirillaceae were also enriched in the soils of genotypes like 8503 that were most effective in obtaining N from the corn residue, and this was correlated with greater potential expression of genes responsible for β-glucosidase and nitrification activity. Conclusions Carrot genotypes do differ in their potential to alter soil bacterial communities and stimulate microbially-mediated decomposition of organic materials indicating that it may be possible to begin selecting for this important trait.

Root exudation and rhizosphere microbial recruitment are influenced by novel plant trait diversity in carrot genotypes

“…The results of this study suggest that plant-soil microbe interactions are influenced by trait breeding in organic carrot. This aligns with previous findings that carrot genotypes host distinct root-associated microbiomes that potentially differ in their functionality (Triviño et al 2023, Abdelrazek et al 2020). Moreover, we show that root exudation patterns were distinct across genotypes.…”

“…Nitrsosphaeraceae was positively associated with genotypes NR and H; Nitrsosphaeraceae is an ammonia oxidizing bacteria, which are considered indicators of soil health (Mundepi et al 2019). These results align with observations that genotype NR hosts distinct N-associated functions (e.g., ammonia oxidation; Triviño et al 2023). Genotype H was additionally enriched with members of the Chitinophagaceae , a family identified as containing N fixing taxa, at midseason (Martin et al 2022).…”

“…To determine the effect of plant trait diversity on soil microbial community assembly, four genotypes of carrot were selected for a field trial based on previous research and current breeding efforts (Simon et al 2016, Keller-Pearson et al 2020, Simon et al 2021, Triviño et al 2023. The selected genotypes are phenotypically diverse in terms of root shape, flavor, and color, and include one heirloom variety (Red Core Chantenay, hereafter "H"), one hybrid variety (Bolero, hereafter "Hy"), an experimental nematode resistant line (Nb8503, hereafter "NR"), and an experimental purple/orange-cored carrot (P0114, hereafter "PO") (Table 1).…”

“…Pathogenic nematode resistance and enriched anthocyanin content associated with purple coloration are presently being explored in experimental carrot lines. These ongoing carrot breeding efforts have demonstrated potential impacts to rhizosphere functioning in climate-controlled field and greenhouse settings, making carrot a suitable candidate for exploring plant-microbe interactions across trait diversity in organic vegetable systems in a field setting (Keller-Pearson et al 2020, Triviño et al 2023). The mechanisms driving these observed shifts in plant-microbe interactions across carrot cultivar development are currently unknown.…”

Annual Weeds Suppression and Oat Forage Yield Responses to Crop Density Management in an Oat-Cultivated Grassland: A Case Study in Eastern China

“…It indicated that both plant species and interspecific competition can change the abundance of dominant bacteria, which is due to their adaptability to a new microenvironment [57,58]. Moreover, the beneficial species (i.e., Bacillaceae, Xanthobacteraceae, Streptomycetaceae, Paenibacillaceae, Planococcaceae, Micromonosporaceae) can favor plant growth and improve nutrient availability by stimulating plants to secrete auxin while simultaneously fixing nitrogen, solubilizing phosphate, and decomposing organic matter [59][60][61][62][63][64]. Apart from their ability to stimulate plant growth, Bacillaceae, Streptomycetaceae, and Geodermatophilaceae can prevent plants from soil-borne disease and abiotic stresses (e.g., drought) through the synthesis of substances akin to lipopeptides that make plants more resistant to external stresses [65,66].…”