Unraveling the role of contaminants reshaping the microflora in Zea mays seeds from heavy metal-contaminated and pristine environment

Abstract

Heavy metal (HM) contaminants are the emerging driving force for reshaping the microflora of plants by eradicating the non-tolerance and non-resistant microbes via their lethal effects. Seeds serve as a primary source of microbial transmission from one plant generation to the next however, being exposed to metal contamination reshapes their microflora through generations. In this study, the endophytic diversity was compared within Zea mays seeds between three distinct regions in Yunnan province China i.e., HM-contaminated sites (AK) less-contaminated (SD), and a non-contaminated Site (DL). High throughput sequencing technique were used to analyze 492,177 high-quality reads for bacteria and 1,001,229 optimized sequences for fungi. Reads of interest were grouped into operational taxonomic units (OTUs), assigned to microbial genomes and analyzed for taxonomic information, alpha and beta diversity, taxonomic composition, and differential analyses. A higher diversity was recorded in AK samples than in SD and DL. Microbial community structure analysis showed higher diversity and significant fluctuation in specific taxa abundance in the metal-polluted samples exhibiting higher response of microbial flora to HM. In AK samples Gordonia and Burkholderia-Caballeronia-Paraburkholderi, were HM-resistant while Pseudomonas and Streptomyces showed moderate tolerance to HM. Fungal taxa such as Fusarium, Saccharomycopsis, and Lecanicillium also showed metal tolerance. The results revealed the role of HM in reshaping the microflora and their response in maize seeds. While investigating the microbiome from different environments of maize seeds using sequencing technology, the study will help in studying the microbiome shifts under HM conditions aiding better management strategies for reclaiming contaminated soil and crop management.