Genome-wide transcriptome profiling provides insights into the responses of maize (Zea mays L.) to diazotrophic bacteria

Abstract

We applied for the first time a high-throughput transcriptome approach to elucidate biochemical and physiological mechanisms controlling early events in the interaction between maize seedlings and different beneficial diazotrophic bacteria. mRNA transcriptomes from maize (Zea mays L.) seedlings were characterized seven days after inoculation with Azospirillum brasilense sp245 and Herbaspirillum seropedicae HRC54. The expression profiles of selected genes were validated by quantitative reverse transcription–polymerase chain reaction analysis. Transcriptome profiling revealed a total of 764 and 3595 differentially expressed genes (DEGs) in maize when exclusively associated with A. brasilense and H. seropedicae, respectively, whereas 455 DEGs were shared by both treatments. Our results support the modulation of the host nitrogen metabolism and phytohormone responses by both diazotrophic bacteria as well as distinct activation of host immune responses. Diazotrophic bacteria modulate maize metabolism, with some common responses to both beneficial bacteria, while others are specific to each bacterial species. This study provides a valuable contribution on how these beneficial bacteria might amend host metabolism to improve growth and fitness.