Variation of growth and transcriptome responses to arbuscular mycorrhizal symbiosis in different foxtail millet lines.

BACKGROUND: Arbuscular mycorrhizal fungi (AMF) have been applied to promote the growth of different crop species, but knowledge about the impacts of symbiosis on foxtail millet at the physiological and molecular levels have remained limited. In this study, we compared the mycorrhization phenotypes of one cultivar and three different landraces and performed a comprehensive transcriptomic analysis to assess the effects of genetic variation on the responses to symbiosis.

RESULTS: Our results showed that colonization by AMF did not enhance biomass accumulation but significantly increased grain production only in three lines. More than 2,000 genes were affected by AMF colonization in all lines. Most AM symbiosis-conserved genes were induced, but the induction levels varied between lines. Gene Ontology (GO) analysis showed that Biological Function terms related to nitrogen transport and assimilation were only enriched in TT8. Similarly, two of phosphate starvation-induced phosphate transporters were only simultaneously downregulated in TT8. In the other two lines, the enrichment of GO terms associated with cell wall reorganization and lignification was observed, though the effects were different.

CONCLUSION: This study reveals the impacts of genetic variation of millet lines on the responses to AM symbiosis and provides information regarding AMF application for millet production.