Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (3): 418-433.DOI: 10.17521/cjpe.2022.0049

Special Issue: 光合作用 微生物生态学

• Research Articles • Previous Articles     Next Articles

Response mechanisms of millet and its rhizosphere soil microbial communities to chromium stress

BAI Xue, LI Yu-Jing, JING Xiu-Qing, ZHAO Xiao-Dong, CHANG Sha-Sha, JING Tao-Yu, LIU Jin-Ru, ZHAO Peng-Yu()   

  1. College of Biological Sciences and Technology, Taiyuan Normal University, Jinzhong, Shanxi 030619, China
  • Received:2022-02-02 Accepted:2022-06-22 Online:2023-03-20 Published:2022-07-15
  • Contact: ZHAO Peng-Yu
  • Supported by:
    Key Research and Development Program of Shanxi Province(20163D221008-1);Science and Technology Innovation Programs of Higher Education Institutions in Shanxi(2020L0535);Construction of Innovation Discipline Cluster Servicing Valley Ecological Governance Industry (Shanxi “1331 Project”)


Aims Heavy metal chromium (Cr) contamination has toxic effects on crops and will disrupt soil microbial community homeostasis in agricultural soils. Nevertheless, the mechanisms underlying the responses of different crops and their rhizosphere soil microbial communities to Cr stress were different. By using time series data, this study analyzed the effects of Cr stress on ‘Jingu 21’ growth, functional pathways of differentially expressed genes (DEGs) in cereals and soil microbial community structure and function. Our objective was to elucidate the response mechanism of millet (Setaria italica) and soil microbial community, and provide a theoretical basis for the growth of cereals under Cr stress and the ecological restoration of the contaminated soil.

Methods We collected millet seedlings and soil samples from the pot experiments with planted millet before (CK) and 6-hour and 6-day after Cr stress (Cr_6h, Cr_6d), and determined the physiological traits of seedlings and soil physicochemical properties. The gene expression and the functional pathways enriched in the seedlings were investigated by transcriptome analysis; the dynamics of microbial community composition, structure, diversity as well as function in time series and their correlations with soil physicochemical properties were studied by high-throughput sequencing analysis.

Important findings 1) Transcriptome analysis showed that Cr stress induced up-regulation of gene expression (54% for up-regulated DEGs); GO enrichment analysis showed that DEGs significantly down-regulated the expression of photosynthesis-related genes in CK & Cr_6h, Cr_6h & Cr_6d samples, and also significantly up-regulated the expression of defense and damage regulation-related genes, and down-regulated the expression of cell wall and cell membrane and cell division-related genes in Cr_6h & Cr_6d samples. 2) High-throughput sequencing revealed a significant change in the composition of soil bacterial and fungal communities at the phylum and genus level during the time series of Cr stress. The α diversity of bacterial communities showed a phase change from stress to stability (Shannon-Wiener diversity index for CK, Cr_6h, Cr_6d were 6.09, 5.93, 6.05, respectively. Simpson diversity index for CK, Cr_6h, Cr_6d were 0.006 8, 0.007 8, 0.006 8, respectively; Chao diversity index for CK, Cr_6h, Cr_6d were 2 818.49, 2 630.73, 2 769.38, respectively), while the α diversity of fungal community decreased significantly (Shannon-Wiener diversity index for CK, Cr_6h, Cr_6d were 4.17, 3.81, 3.23, respectively). The distribution of β diversity of bacterial community in the Cr stress time series was significantly different from that of fungal community. 3) Correlation analysis between soil physicochemical properties and microbial communities showed that soil physicochemical factors were significantly correlated with a variety of fungal flora, but weakly correlated with bacterial flora. Cr stress significantly inhibited the photosynthesis of millet seedlings by reducing chlorophyll content, photosystem activity and affecting structural components such as thylakoid, and inhibited the proliferation and differentiation of leaf cells by down-regulating the expression of cell wall and microtubule-related components. At the same time, Cr stress also activated the plant defense system to overcome toxicity. Meanwhile, soil bacterial and fungal communities adapted to Cr stress through changing community composition and diversity, and their response levels and strategies differed in the stress time series.

Key words: heavy metal stress, time series, ‘Jingu 21’, microbial community, high-throughput sequencing, transcriptome analysis