Establishment and optimization of a high-efficient hairy-root system in foxtail millet（Setaria italica L.）

To establish a system for rapid identification of millet gene functions, in this study, we compared the effects of explants from different foxtail millet cultivars, the concentrations of acetyleugenone, bacterial solution, and co-culture time on the hairy root induction mediated by Agrobacteria rhizogenes strain K599. When the shoot tips were infected with bacterial solution 0.5 optical density（OD）and containing 100 μmol L–1 acetyleugenone, and co-cultured for three days, the induction efficiency of hairy roots reached to 80.24%. Using this system, we analyzed the transformation efficiency of the hairy roots, the subcellular localization of SiDVL1 and SiDVL3, and gene functions of SiNHX2, SiCBL4, and Si CBL7. The PCR results of GFP gene and GFP fluorescence microscopic observation indicated that the transformation efficiency of the hairy roots was over 70%. The subcellular localization of SiDVL1 and SiDVL3 was similar in millet hairy-root and tobacco epidermal cells. Simultaneously, the survival rates of SiNH