Effects of Intercropping with Potato Onion on the Growth of Tomato and Rhizosphere Alkaline Phosphatase Genes Diversity

Abstract

Background and Aims: In China, excessive fertilization has resulted in phosphorus (P) accumulation in most greenhouse soils. Intercropping can improve the efficiency of nutrient utilization in crop production. In this study, pot experiments were performed to investigate the effects of intercropping with potato onion (Allium cepa L. var. aggregatum G. Don) on tomato (Solanum lycopersicum L.) seedlings growth and P uptake, the diversity of rhizosphere phosphobacteria and alkaline phosphatase (ALP) genes in phosphorus-rich soil.Methods: The experiment included three treatments, namely tomato monoculture (TM), potato onion monoculture (OM), and tomato/potato onion intercropping (TI-tomato intercropping and OI-potato onion intercropping). The growth and P uptake of tomato and potato onion seedlings were evaluated. The dilution plating method was used to determine the population of phosphate-solubilizing bacteria (PSB) and phosphate-mineralizing bacteria (PMB). The genomic DNAs of PSB and PMB in the rhizosphere of tomato and potato onions were extracted and purified, and then, with the primer set of 338f /518r, the PCR amplification of partial bacterial 16S rDNA sequence was performed and sequenced to determine the diversities of PSB and PMB. After extracting the total genomic DNAs from the rhizosphere, the copy numbers and diversities of ALP genes were investigated using real-time PCR and PCR-DGGE, respectively.Results: Intercropping with potato onion promoted the growth and P uptake of tomato seedlings, but inhibited those of potato onion. After 37 days of transplanting, compared to the rhizosphere of TM, the soil pH increased, while the electrolytic conductivity and Olsen P content decreased (p < 0.05) in the rhizosphere of TI. The populations and diversities of PSB, PMB, and ALP genes increased significantly in the rhizosphere of TI, compared to the rhizosphere of TM.Conclusion: The results indicated that intercropping with potato onion promoted the growth and P uptake of tomato in phosphorus-rich soil and affected the community structure and function of phosphobacteria in tomato rhizosphere. Intercropping with potato onion also improved soil quality by lowering levels of soil acidification and salinization.

Root ethylene mediates rhizosphere microbial community reconstruction when chemically detecting cyanide produced by neighbouring plants

“…This finding differs from conventional views, because rhizosphere microbial communities are generally less diverse than those in bulk soil [51,52]. In the intercropping systems, however, root microbiota often show a higher diversity [53,54]. Depending on microbial substrate preferences, secondary metabolites of plants shape the rhizosphere microbial community [11].…”

Revealing the Variation and Stability of Bacterial Communities in Tomato Rhizosphere Microbiota

“…DNA fragments of the V3-V4 region of the bacterial 16S rRNA gene were amplified using the primer pair 341F (5 -CCTACGGGNGGCWGCAG-3 ) and 805R (5 -GACTACHVGGGTATCTAATCC-3 ) fused with Illumina MiSeq adapters and a 6-bp barcode sequence unique to each sample [15,39]. PCR amplifications were carried out in triplicate in 50-µL reactions containing 10 ng of genomic DNA.…”

“…Rarefaction and rank-abundance curves were generated at a 97% OTU similarity level. Statistical analysis was performed using analysis of variance (ANOVA) with p values to determine whether the diversity indexes were statistically significant among the rhizosphere soil samples [39]. To estimate beta diversity, the similarities of the members and structures of the microbiotas were calculated by utilizing the weighted and unweighted UniFrac distances from the normalized OTU tables for the various samples [42].…”

Transcriptomic comparison of Allium cepa var. agrogatum Don. cultivars with different facilitating potentials on tomato seedlings

“…In our previous studies, we found that potato onion is an effective partner for intercropping and relay intercropping. Intercropping with potato onion increased the growth of tomato seedlings and changed tomato root architecture (Wu et al 2016;Yu et al 2017) and the root exudates of potato onion has facilitating effects on tomato seedlings (Liu et al 2013). To date, however, the effects of potato onion leaf volatiles and leachates have remained virtually unexplored.…”

“…In recent years, the role of facilitating interactions between plant species has received increased attention (Moeller 2004;Zhang and Li 2003) and the facilitating interactions have also been used for crop growth regulation (Batish et al 2001;Narwal and Zeng 2010). For example, potato onion, as a companion plant, can increase the growth of cucumber and tomato (Yang et al 2011;Liu et al 2013;Wu et al 2016). The mechanisms whereby the effects of facilitating interactions are mediated are various and the release of chemicals is one of the reasons (Inderjit et al 2011).…”