Integration of Transcriptomics and Metabolomics Reveals the Responses of Sugar Beet to Continuous Cropping Obstacle

Abstract

Sugar beet is vulnerable to years of continuous cropping, and allelopathy is one of the important factors leading to continuous cropping disorder. To explore the physiological and molecular mechanisms behind continuous cropping obstacles on sugar beet, this study combined transcriptomics and metabolomics to analyze the effects of different years of continuous cropping on metabolite changes, differential gene expression, and root exudate regulation in sugar beet. We collected sugar beet’s root samples from 1–, 3–, and 5-year continuous cropping systems for metabolome and transcriptome analyses. Our data revealed that T3 and T5 had 50 and 33 metabolites significantly different from T1, respectively. The autotoxic substance salicylaldehyde was found to continuously accumulate in root exudates with increasing years of continuous cropping. Sucrose was highly reduced in T3 (4.05-fold decrease) and T5 (2.01-fold decrease) compared to T1. Respectively, 2,660 and 3,515 differentially expressed genes (DEGs) were significantly regulated in T3 and T5 compared to T1. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that metabolic pathways and biosynthesis of secondary metabolites were perturbed in T3 and T5 vs. T1. Integrated metabolomics analyses identified 73 DEGs involved in enriched metabolic pathways, all of which were the oxidation-reduction process pathways. In conclusion, this study provides evidence that continuous cropping obstacles can change the metabolome and transcriptome of sugar beet, affecting its growth and quality.

Natural Salicylaldehyde for Fungal and Pre- and Post-Emergent Weed Control

“…The aqueous extracts of cattail plants, which also contain two phenolic agents (namely, 2-chlorophenol, SA), inhibited the growth of the watermoss Salvinia, suggesting SA could function as one of the allelopathic substances released from T. domingensis [42]. Recently, the sugar crop "sugar beet" has been determined to be vulnerable to continuous cropping, where allelopathy was one of the crucial factors triggering cropping disorder [43]. The transcriptomics and metabolomics study identified that SA was one of the allelochemicals continuously accumulated in sugar beet root exudates with continuous cropping; it functioned as an autotoxic substance [43].…”

“…Recently, the sugar crop "sugar beet" has been determined to be vulnerable to continuous cropping, where allelopathy was one of the crucial factors triggering cropping disorder [43]. The transcriptomics and metabolomics study identified that SA was one of the allelochemicals continuously accumulated in sugar beet root exudates with continuous cropping; it functioned as an autotoxic substance [43]. It was hypothesized in the study that continuous cropping changes the metabolome of sugar beet, which interferes further with the diversity of the rhizosphere microbial community, thus negatively affecting sugar beet growth and quality [43].…”

“…The transcriptomics and metabolomics study identified that SA was one of the allelochemicals continuously accumulated in sugar beet root exudates with continuous cropping; it functioned as an autotoxic substance [43]. It was hypothesized in the study that continuous cropping changes the metabolome of sugar beet, which interferes further with the diversity of the rhizosphere microbial community, thus negatively affecting sugar beet growth and quality [43]. However, none of these studies explored the mechanisms of the phytotoxic action of SA or its structural derivatives.…”

The response of sugar beet rhizosphere micro-ecological environment to continuous cropping

“…The cultivation area and yield of sugar beet are second only to sugar cane ( Mall et al, 2021 ). A good soil environment is a prerequisite for high sugar yields in sugar beet, which is a taproot crop that should not be grown continuously ( Geng et al, 2020 ; Huang et al, 2021 ). However, due to poor land use and cultivation practices, sugar beet is often grown in succession, resulting in poor plant growth, frequent pests and diseases, reduced sugar content, and lower yields ( Huang et al, 2020 ).…”

“…The effects of continuous cropping obstacles on soil microorganisms and plant growth have been studied (Huang et al, 2020(Huang et al, , 2021. However, a comprehensive study of the diversity of soil and root microbial communities during the growth of sugar beet seedlings in continuous cropping soil has not yet been reported.…”