Three Preceding Crops Increased the Yield of and Inhibited Clubroot Disease in Continuously Monocropped Chinese Cabbage by Regulating the Soil Properties and Rhizosphere Microbial Community

Clubroot resistant in cruciferous crops: recent advances in genes and QTLs identification and utilization

Clubroot, caused by Plasmodiophora brassicae, poses a serious threat to cruciferous crop production worldwide. Breeding resistant varieties remains the most cost-effective strategy to mitigate yield losses, yet achieving durable, stable, and broad-spectrum resistance continues to be a formidable challenge. Recent advances in genetic and genomic technologies have improved the understanding of complex host-pathogen interactions, leading to the identification of key resistance loci, including dominant resistance genes such as CRa and Crr1, as well as quantitative trait loci. This review discusses the genetic mechanisms governing clubroot resistance and highlights applications in breeding, such as marker-assisted selection and CRISPR/Cas9-based genome editing, which are accelerating the development of resistant germplasm. Furthermore, integrated management strategies, encompassing resistant cultivars, crop rotation, biocontrol agents, and soil amendments, are emphasized as critical components for sustainable disease management. This review summarizes the major resistance genes against clubroot and discusses potential strategies to address the persistent threat posed by the disease.

Effects of rotation corn on potato yield, quality, and soil microbial communities

Introduction

Potato is an important crop that can be used both as grain and vegetable in northern China. However, the continuous cropping system of potato has led to a sharp decline in its yield and quality. As one of the effective strategies to alleviate the continuous cropping obstacle, crop rotation has received extensive attention in agricultural practices. On this basis, we have conducted an in-depth exploration of the effects of the potato-maize rotation system on the structure and diversity of the soil microbial community, aiming to analyze the internal correlation mechanism between the structure of the soil microbial community and the yield and quality of crops.

Methods

This study was based on fields that had been under potato monoculture for five years and established six experimental treatments: potato-potato-potato (IR-A), potato-maize-potato (IR-B), potato-maize-maize (IR-C), potato-potato-potato (RF-A), potato-maize-potato (RF-B), and potato-maize-maize (RF-C).

Results

The results showed that under the IR planting model, IR-B significantly increased potato yield and vitamin C content while reducing reducing sugar content compared to IR-A (p < 0.05). In the RF planting model, RF-B significantly increased potato yield, starch content, and vitamin C content compared to RF-A (p < 0.05). Microbial community structure results indicated that crop rotation significantly enhanced the relative abundance of microorganisms such as Bradyrhizobium, Pseudomonas, Sphingomonas, Purpureocillium, Streptomyces, and Halovivax (p < 0.05). These microorganisms are involved in the cycling of carbon, phosphorus, and other nutrients in the soil, playing an important role in promoting root growth, organic matter decomposition, and alleviating soil salinization. The LEfSe and RDA indicated significant differences in microbial communities between monoculture and crop rotation (p < 0.05), with soil slow-growing rhizobia, Burkholderia, and actinomycetes positively correlated with potato yield and quality. Additionally, KEGG functional annotation of different treatments revealed that K00239, K00626, K01681, and K01915 were involved in three key metabolic pathways related to carbon and nitrogen. A total of 20 significantly enriched pathways were identified (p < 0.05), among which K01681 is involved in the tricarboxylic acid cycle and is a differential gene in the RF-B treatment, suggesting that the efficient expression of K01681 during crop rotation contributes to the material cycling of the soil ecosystem. LEfSe analysis of the bins revealed that under the RF-C treatment, the relative abundance of Hyphomicrobiales was significantly higher than in other treatments (p < 0.05). Hyphomicrobiales are involved in the nitrogen fixation process and play an important role in soil nutrient cycling and plant nutrition. In summary, the potato-maize rotation significantly altered the composition of soil microbial communities (p < 0.05), increasing the relative abundance of beneficial microorganisms. This change helps maintain the health of the soil ecosystem, promotes nutrient cycling, reduces the incidence of diseases, and effectively improves both the yield and quality of potatoes.

Discussion

The potato-maize rotation significantly altered the composition of soil microbial communities (p < 0.05), increasing the relative abundance of beneficial microorganisms. This change helps maintain the health of the soil ecosystem, promotes nutrient cycling, reduces the incidence of diseases, and effectively improves both the yield and quality of potatoes.

The regulation of tobacco growth under preceding crop planting: insights from soil quality, microbial communities, and metabolic profiling

Introduction

Specific microorganisms and metabolites in soil play key roles in regulating organismal behavior. Currently, the effects of different preceding crops on the rhizosphere soil quality of flue-cured tobacco remain unclear.

Methods

Four treatments were compared in the study: fallow + tobacco (CK), maize + tobacco (T1), rapeseed + tobacco (T2), and wheat + tobacco (T3).

Results and discussion

Results showed that preceding crops significantly enhanced soil nutrient levels and improved tobacco growth by altering rhizosphere metabolites and microbial community structure. Previous cultivation of maize and rapeseed significantly promoted tobacco growth, rapeseed and wheat cultivation enhanced the diversity of soil bacterial communities, and notably decreased the abundance of urea-degrading bacteria. In contrast, the preceding crop of maize reduced plant pathogenic fungi and promoted positive microbial interactions. Metabolomics analysis showed that different preceding crops altered lipids, organic acids, flavonoids, alkaloids, and terpenoids, enhancing secondary metabolite synthesis pathways in soil. Preceding crops regulated rhizosphere metabolites which potentially participated in soil carbon and nitrogen cycling, balancing soil nutrients, and improving tobacco yield. Overall, the three preceding crops altered the composition and function of metabolites and microbial community structures in rhizosphere soil, thereby increased soil nutrient concentration. Both maize and rapeseed cultivation significantly boosted tobacco growth and biomass. These findings offer new insights into the potential interactions between rhizosphere metabolites and microbial communities and strategies of comprehensively regulating tobacco growth.

Effects of decomposed and undecomposed straw of three crops on clubroot disease of Chinese cabbage and soil nutrients

AIMS

Straw turnover plays an important role in reducing soil diseases, improving the ecological environment of plowland and realizing the effective ecological utilization of straw.

METHODS

Pot and field experiments were carried out to investigate the effects of maize, rice and wheat straws on the growth, clubroot disease of Chinese cabbage and soil nutrients. Undecomposed and decomposed maize, rice and wheat straws were quantitatively added to the monocultural soil of Chinese cabbage, and the crops without straw were taken as the control.

RESULTS

The results showed that the addition of maize, wheat and rice straws could promote the growth of monocultural Chinese cabbage, inhibit the occurrence of clubroot disease, increase soil pH value, the content of soil organic matter, alkaline hydrolyzable nitrogen and available potassium in pot experiment. Exogenous straw application could reduce the incidence rate by 22.54 ~ 47.85%, increase the plot yield of field 95.15 ~ 365.81%.

CONCLUSIONS

In terms of inhibiting clubroot disease and improving soil properties, undecomposed rice straw is superior to maize and wheat straw, while decomposed maize straw is superior to rice and wheat straw.

Application of Rice Straw Inhibits Clubroot Disease by Regulating the Microbial Community in Soil

Straw return is an effective agricultural management practice for alleviating soil sickness, but only a few studies have focused on the incorporation of straw with deep plowing and rotary tillage practices in vegetable production. To determine the effects of rice straw return on Chinese cabbage clubroot, a field experiment for three consecutive years in the same area was performed. Soil microbial high-throughput sequencing, quantitative real-time polymerase chain reaction (PCR) and other methods were used to detect Chinese cabbage plant growth, clubroot occurrence, soil chemical properties and soil microbial diversity and abundance. The results showed that straw addition could significantly reduce the clubroot disease incidence. Through Illumina Miseq sequencing, the diversity of the fungi decreased obviously. The relative abundance of the phyla Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. Redundancy analysis suggests that soil properties may also affect the soil microbial composition; changes in the microbial structure of bacteria and fungi were associated with the available phosphorus. In conclusion, the continuous addition of rice straw can promote the growth and control the occurrence of clubroot, which is closely related to the microbial composition, and the inhibition effect is proportional to the age of addition.

Peanut-based Rotation Stabilized Diazotrophic Communities and Increased Subsequent Wheat Yield

The introduction of legumes into rotations can improve nitrogen use efficiency and crop yield; however, its microbial mechanism involved remains unclear. This study aimed to explore the temporal impact of peanut introduction on microorganisms related to nitrogen metabolism in rotation systems. In this study, the dynamics of diazotrophic communities in two crop seasons and wheat yields of two rotation systems: winter wheat - summer maize (WM) and spring peanut → winter wheat - summer maize (PWM) in the North China Plain were investigated. Our results showed that peanut introduction increased wheat yield and biomass by 11.6% (p < 0.05) and 8.9%, respectively. Lower Chao1 and Shannon indexes of the diazotrophic communities were detected in soils that sampling in June compared with those sampling in September, although no difference was found between WM and PWM. Principal co-ordinates analysis (PCoA) showed that rotation system significantly changed the diazotrophic community structures (PERMANOVA; p < 0.05). Compared with WM, the genera of Azotobacter, Skermanella, Azohydromonas, Rhodomicrobium, Azospirillum, Unclassified_f_Opitutaceae, and Unclassified_f_Rhodospirillaceae were significantly enriched (p < 0.05) in PWM. Furthermore, rotation system and sampling time significantly influenced soil properties, which significantly correlated with the top 15 genera in relative abundance. Partial least squares path modeling (PLS-PM) analysis further showed that the diazotrophic community diversity (alpha- and beta-diversity) and soil properties (pH, SOC and TN) significantly affected wheat yield. In conclusion, legume inclusion has the potential to stabilize diazotrophic community structure at the temporal scales and increase subsequent crop yield.

Efficacy of Streptomyces melanosporofaciens strain X216 at controlling clubroot disease on oilseed rape

Oilseed rape (Brassica napus L.) is highly susceptible to infection from the soilborne pathogen Plasmodiophora brassicae Woronin that causes clubroot disease and deleteriously affects production throughout the world. In this study, biological control resources were explored by isolating 237 strains of bacteria from fields of oilseed rape using the gradient dilution coating method. A strain with strong antagonistic ability was screened using a plate confrontation test and designated X216. It was identified as Streptomyces melanosporofaciens owing to its morphological characteristics and 16S rRNA gene sequence. This study also examined the lethality of strain X216 to the resting spores of P. brassicae, its influence on infection in root hairs, and its ability to control clubroot on oilseed rape. The corrected lethality rate on resting spores after strain X216 had been used for 14 days was 56.59% ± 1.97%, which was significantly higher than the use of 75% of the fungicides chlorothalonil WP and 20% Fluazinam SC. Significantly fewer root hairs were infected after this treatment. A pot test showed that X216 was 62.14% effective at controlling the disease, which was not significantly different from that of the fungicide 100 g L-1 cyazofamid SC diluted 1,000-fold but significantly higher than those of 75% chlorothalonil and 50% carbendazim WP. Strain X216 controlled 43.16% of the incidence of clubroot in the field, which could significantly reduce the disease index of oilseed rape clubroot. Therefore, strain X216 is promising to study for the biological control of oilseed rape clubroot.

Distinct prokaryotic and eukaryotic communities and networks in two agricultural fields of central Japan with different histories of maize-cabbage rotation

Crop rotation is an important agricultural practice for homeostatic crop cultivation. Here, we applied high-throughput sequencing of ribosomal RNA gene amplicons to investigate soil biota in two fields of central Japan with different histories of maize-cabbage rotation. We identified 3086 eukaryotic and 17,069 prokaryotic sequence variants (SVs) from soil samples from two fields rotating two crops at three different growth stages. The eukaryotic and prokaryotic communities in the four sample groups of two crops and two fields were clearly distinguished using β-diversity analysis. Redundancy analysis showed the relationships of the communities in the fields to pH and nutrient, humus, and/or water content. The complexity of eukaryotic and prokaryotic networks was apparently higher in the cabbage-cultivated soils than those in the maize-cultivated soils. The node SVs (nSVs) of the networks were mainly derived from two eukaryotic phyla: Ascomycota and Cercozoa, and four prokaryotic phyla: Pseudomonadota, Acidobacteriota, Actinomycetota, and Gemmatimonadota. The networks were complexed by cropping from maize to cabbage, suggesting the formation of a flexible network under crop rotation. Ten out of the 16 eukaryotic nSVs were specifically found in the cabbage-cultivated soils were derived from protists, indicating the potential contribution of protists to the formation of complex eukaryotic networks.

Characteristics of rhizosphere and bulk soil microbial community of Chinese cabbage (Brassica campestris) grown in Karst area

Understanding the rhizosphere soil microbial community and its relationship with the bulk soil microbial community is critical for maintaining soil health and fertility and improving crop yields in Karst regions. The microbial communities in the rhizosphere and bulk soils of a Chinese cabbage (Brassica campestris) plantation in a Karst region, as well as their relationships with soil nutrients, were examined in this study using high-throughput sequencing technologies of 16S and ITS amplicons. The aim was to provide theoretical insights into the healthy cultivation of Chinese cabbage in a Karst area. The findings revealed that the rhizosphere soil showed higher contents of organic matter (OM), alkaline hydrolyzable nitrogen (AN), available phosphorus (AP), total phosphorus (TP), available potassium (AK), total potassium (TK), total nitrogen (TN), catalase (CA), urease (UR), sucrase (SU), and phosphatase (PHO), in comparison with bulk soil, while the pH value showed the opposite trend. The diversity of bacterial and fungal communities in the bulk soil was higher than that in the rhizosphere soil, and their compositions differed between the two types of soil. In the rhizosphere soil, Proteobacteria, Acidobacteriota, Actinobacteriota, and Bacteroidota were the dominant bacterial phyla, while Olpidiomycota, Ascomycota, Mortierellomycota, and Basidiomycota were the predominant fungal phyla. In contrast, the bulk soil was characterized by bacterial dominance of Proteobacteria, Acidobacteriota, Chloroflexi, and Actinobacteriota and fungal dominance of Ascomycota, Olpidiomycota, Mortierellomycota, and Basidiomycota. The fungal network was simpler than the bacterial network, and both networks exhibited less complexity in the rhizosphere soil compared with the bulk soil. Moreover, the rhizosphere soil harbored a higher proportion of beneficial Rhizobiales. The rhizosphere soil network was less complicated than the network in bulk soil by building a bacterial-fungal co-occurrence network. Furthermore, a network of relationships between soil properties and network keystone taxa revealed that the rhizosphere soil keystone taxa were more strongly correlated with soil properties than those in the bulk soil; despite its lower complexity, the rhizosphere soil contains a higher abundance of bacteria which are beneficial for cabbage growth compared with the bulk soil.