Declined soil suppressiveness to Fusarium oxysporum by rhizosphere microflora of cotton in soil sickness

Abstract

Cotton yield and quality have been severely compromised by soil sickness throughout the primary cottongrowing regions of China. The aim of this study was to gain insight into the role of rhizosphere microbial community in governing soil sickness of cotton. Plant growth, disease resistance, root exudates, and the composition of the rhizosphere microbial community of cotton were analyzed in two different (4-and 15-year) monocropped soils and in a fallow agricultural soil (control). The monocropped soils significantly influenced cotton growth and root exudates and reduced soil suppressiveness to Fusarium wilt in bioassay experiments. Additionally, pyrosequencing of the whole internal transcribed spacers (ITS1 and ITS2) and 16S rRNA gene amplicons demonstrated clear variations in the microbial composition of cotton rhizosphere between monocropped rhizosphere soils and control soil. Specifically, monocropped soils were characterized by an increase in the abundance of fungal pathogens, including Fusarium oxysporum f. sp. vasinfectum and Verticillium dahliae, relative to the rhizosphere of control soil. Some plant-beneficial and disease-suppressive bacterial taxa, including Xanthomonadaceae, Comamonadaceae, Oxalobacteraceae, and Opitutaceae, were associated with healthy cotton. A significant correlation existed between the presence of certain amino acids (e.g., glutamic acid and alanine) and the above identified taxa, indicating that some constituents in root exudates influenced the microbial compositions of the cotton rhizosphere to manage the disease status of plant in monocropped soils. Collectively, these results suggest that pathogenic fungal build-up and a reduction in the abundance of beneficial rhizobacteria in the rhizosphere contribute to changes in soil suppressiveness to soil-borne pathogens in monocropped soils, resulting in an aggravated level of soil sickness.

Prokaryotic Communities at Different Depths between Soils with and without Tomato Bacterial Wilt but Pathogen-Present in a Single Greenhouse

“…This soil, called disease-suppressive soil, has been reported for multiple soil-borne pathogens, including those causing Fusarium wilt (22), potato common scab (17), damping-off disease (15), tobacco black root rot (20), and bacterial wilt (33). However, in the present study, ND-soil with phcA was not defined as suppressive soil because we did not experimentally confirm its suppressive effects on bacterial wilt.…”

Comparison of bacterial communities in soil samples with and without tomato bacterial wilt caused by Ralstonia solanacearum species complex

“…It is widely thought that the soil microbiota contribute to the disease resistance of crop plants [5,6]. In recent years, increasing evidences have been reported for suppressing several soil-borne pathogens causing Fusarium wilt [7], potato common scab [8], damping-off disease [9], sugar beet wilt [10], and bacterial wilt [11]. In addition, further research showed that the diversity of the soil microbial community is particularly crucial for maintaining the disease suppressing capacity, which can affect the colonization success of additional species [12,13].…”

Dynamic succession of soil microbial community during continuous cropping of Astragalus membranaceus Bge. var. mongholicus (Bge.)

“…Vasinfectum, and V. dahlia were enriched and there was a lessening of pathogenic antagonistic Xanthomonadaceae, Comamonadaceae, Oxalobacteraceae, and Opitutaceae. This This would explain the negative effects of the continuous cropping of cotton (Li et al, 2015). Therefore, under continuous cropping, some pathogenic and beneficial microorganisms significantly affect the soil microbial community succession process in the rhizosphere.…”