Over-immunity mediated abnormal deposition of lignin arrests the normal enlargement of the root tubers of Rehmannia glutinosa under consecutive monoculture stress

Effect of in situ vermicomposting combined with biochar application on soil properties and crop yields in the tomato monoculture system

Vermicompost and biochar have been widely used to improve soil conditions. However, little information is available regarding the efficiency and effectiveness of in situ vermicomposting with biochar (IVB) in monoculture soils. In this study, we estimated the effects of IVB on soil physiochemical and microbial properties, crop yields, and fruit quality under the tomato monoculture system. The soil treatments considered were (i) untreated monoculture soil (MS, control), (ii) MS plus 1.5 t/ha biochar applied to soil surface (MS+1.5BCS), (iii) MS plus 3 t/ha biochar applied to soil surface (MS+3BCS), (iv) MS mixed with 1.5 t/ha biochar (MS+1.5BCM), (v) MS mixed with 3 t/ha biochar (MS+3BCM), (vi) in situ vermicomposting (VC), (vii) VC plus 1.5 t/ha biochar applied to VC surface (VC+1.5BCS), (viii) VC plus 3 t/ha biochar applied to VC surface (VC+3BCS), (ix) VC mixed with 1.5 t/ha biochar (VC+1.5BCM), and (x) VC mixed with 3 t/ha biochar (VC+3BCM). In general, soil pH varied from 7.68 to 7.96 under VC-related treatments. The microbial diversity was much higher in bacterial communities (OTU: 2284-3194, Shannon index: 8.81-9.91) than in fungal communities (OTU: 392-782, Shannon index: 4.63-5.71) in VC-related treatments. Specifically, Proteobacteria was the dominant bacterial phylum, followed by Bacteroidota, Chloroflexi, Patescibacteria, Acidobacteriota, Firmicutes, and Myxococcota. It is worth noting that IVB-related treatments could increase the relative abundance of Acidobacteria and reduced the relative abundance of Bacteroidetes. In addition, the VC+1.5BCM treatment exhibited the greatest yield (9377.6 kg/667m2) and simultaneously showed higher fruit quality (vitamin C, 28.94 mg/100g; soluble sugar, 20.15%) as compared to other treatments. Our results suggested that in situ vermicomposting with biochar can improve soil properties and enhance both crop yields and fruit quality under the tomato monoculture system.

New insights into the occurrence of continuous cropping obstacles in pea (Pisum sativum L.) from soil bacterial communities, root metabolism and gene transcription

BACKGROUND

Continuous cropping is a significant obstacle to sustainable development in the pea (Pisum sativum L.) industry, but the underlying mechanisms of this remain unclear. In this study, we used 16 S rDNA sequencing, transcriptomics, and metabolomics to analyze the response mechanism of roots and soil bacteria to continuous cropping and the relationship between soil bacteria and root phenotypes of different pea genotypes (Ding wan 10 and Yun wan 8).

RESULTS

Continuous cropping inhibited pea growth, with a greater effect on Ding wan 10 than Yun wan 8. Metabolomics showed that the number of differentially accumulated metabolites (DAMs) in pea roots increased with the number of continuous cropping, and more metabolic pathways were involved. Transcriptomics revealed that the number of differentially expressed genes (DEGs) increased with the number of continuous cropping. Continuous cropping altered the expression of genes involved in plant-pathogen interaction, MAPK signal transduction, and lignin synthesis pathways in pea roots, with more DEGs in Ding wan 10 than in Yun wan 8. The up-regulated expression of genes in the ethylene signal transduction pathway was evident in Ding wan 10. Soil bacterial diversity did not change, but the relative abundance of bacteria significantly responded to continuous cropping. Integrative analysis showed that the bacteria with significant relative abundance in the soil were strongly associated with the antioxidant synthesis and linoleic acid metabolism pathway of pea roots under continuous cropping once. Under continuous cropping twice, the bacteria with significant relative abundance changes were strongly associated with cysteine and methionine metabolism, fatty acid metabolism, phenylpropanoid biosynthesis, terpenoid backbone biosynthesis, linoleic acid, and amino sugar and nucleotide sugar metabolism.

CONCLUSION

Ding wan 10 was more sensitive to continuous cropping than Yun wan 8. Continuous cropping times and pea genotypes determined the differences in root metabolic pathways. There were common metabolic pathways in the two pea genotypes in response to continuous cropping, and the DEGs and DAMs in these metabolic pathways were strongly associated with the bacteria with significant changes in relative abundance in the soil. This study provides new insights into obstacles to continuous cropping in peas.

TMT-Based Proteomic Analysis of Continuous Cropping Response in Codonopsis tangshen Oliv

The growth and development of Codonopsis tangshen, an important herb used in Chinese traditional medicine, have been seriously affected by continuous cropping obstacles. Therefore, understanding the molecular responses of C. tangshen to continuous cropping is imperative to improve its resistance to continuous cropping obstacles. Here, physiological and biochemical results showed that the levels of chlorophyll and malonaldehyde (MDA) were higher in the continuous cropping (LZ) group compared with those of the non-continuous cropping (FLZ) group, while superoxide dismutase (SOD) content was lower in the LZ group than in the FLZ group. Tandem mass tag (TMT)-based proteomic analysis was performed to investigate the response mechanism to continuous cropping obstacles in C. tangshen. A total of 70 differentially expressed proteins (DEPs) were significantly involved in relevant pathways, including photosynthesis, oxidative phosphorylation, ribosome activity, and secondary metabolites. The results suggest that these DEPs in C. tangshen might play a critical role in response to continuous cropping. These findings could provide scientific basis for improving C. tangshen’s resistance to continuous cropping obstacles.

Effect of light quality on polyphenol biosynthesis in three varieties of mung bean sprouts with different color seed coats

We investigated the mechanism of the effect of different light qualities on the synthesis and regulation of mung bean sprouts. Light quality acts as a signal molecule, strongly enhancing polyphenol biosynthesis in sprouts. Mung bean (Vigna radiata) sprouts are a popular sprouting vegetable all over the world and are an excellent source of polyphenols with high antioxidant activity. This study investigated the effects of light qualities on the kinetic changes and metabolic regulation mechanism of light signal-mediating polyphenols in three mung bean sprout cultivars. Experimental results showed that three light qualities significantly enhanced the contents of caffeic acid, rutin, vitexin, genistin and delphinidin 3-glucoside. Interestingly, ferulic acid and vitexin responded selectively to blue light and red light, severally. Most genes involved in polyphenol biosynthesis were activated under different light quality conditions, resulting in an overaccumulation of phenylpropanoids. Pearson correlation analysis showed that PAL, F3H, F3'H and F3'5'H expression correlated highly with rutin, whereas ANS expression paralleled anthocyanin biosynthesis. Moreover, MYB111, MYB3, MYB4, MYB1 and MYC2 were critical regulators of polyphenol biosynthesis in mung bean sprouts. These changes were likely due to the changes in the expression of the photoreceptor genes CRY-D, PHOT2, PHYE and light response genes (PIF3 and HY5). Our results provide insights into polyphenol biosynthesis in sprouts and microgreens.