Rhizosphere Bacterial Communities Differ According to Fertilizer Regimes and Cabbage (Brassica oleracea var. capitata L.) Harvest Time, but Not Aphid Herbivory

Abstract

Rhizosphere microbial communities are known to be highly diverse and strongly dependent on various attributes of the host plant, such as species, nutritional status, and growth stage. High-throughput 16S rRNA gene amplicon sequencing has been used to characterize the rhizosphere bacterial community of many important crop species, but this is the first study to date to characterize the bacterial and archaeal community of Brassica oleracea var. capitata. The study also tested the response of the bacterial community to fertilizer type (organic or synthetic) and N dosage (high or low), in addition to plant age (9 or 12 weeks) and aphid (Myzus persicae) herbivory (present/absent). The impact of aboveground herbivory on belowground microbial communities has received little attention in the literature, and since the type (organic or mineral) and amount of fertilizer applications are known to affect M. percicae populations, these treatments were applied at agricultural rates to test for synergistic effects on the soil bacterial community. Fertilizer type and plant growth were found to result in significantly different rhizosphere bacterial communities, while there was no effect of aphid herbivory. Several operational taxonomic units were identified as varying significantly in abundance between the treatment groups and age cohorts. These included members of the S-oxidizing genus Thiobacillus, which was significantly more abundant in organically fertilized 12-week-old cabbages, and the N-fixing cyanobacteria Phormidium, which appeared to decline in synthetically fertilized soils relative to controls. These responses may be an effect of accumulating root-derived glucosinolates in the B. oleracea rhizosphere and increased N-availability, respectively.

Inoculation of Ensifer fredii strain LP2/20 immobilized in agar results in growth promotion and alteration of bacterial community structure of Chinese kale planted soil

“…Soil total P, K, and Ca and soil pH were the dominant factors influencing the soil bacterial community structure. This result agrees with the reports of Li et al 11 , O’Brien et al 58 , and Zhang et al . 59 which showed that available nutrient, P, and pH were ones of important factors affecting the soil bacterial community.…”

Soil Salinity and pH Drive Soil Bacterial Community Composition and Diversity Along a Lateritic Slope in the Avon River Critical Zone Observatory, Western Australia

“…This association has been detected across many environments (Carson et al, 2009; Jones and Bennett, 2014; Kim et al, 2015) including alpine glacier forefields in Switzerland (Meola et al, 2014) and naturally metal-rich soils in Australia (Reith et al, 2015). It is important to note that the bottom sections bordered an agricultural field, which may have affected these results since soil microbial communities are significantly affected by agricultural practices such as fertilizer inputs (Nguyen et al, 2018; O’Brien et al, 2018) and tilling (Babin et al, 2018).…”

Soil microbial diversity impacts plant microbiota more than herbivory

“…While whitefly herbivory shifted the rhizosphere microbiome composition in pepper plants [26], there was no effect of aphid herbivory on the rhizosphere microbiota of Brassica oleracea var. capitata [27]. Clearly, herbivory can alter plant and rhizosphere microbiomes, but the relative impact of herbivory versus plant species or initial soil diversity on plant-associated microbiomes has not been investigated.…”