0.5mM NO3-+0.5mM NH4+ 3
For maize, 5 days old maize seedlings were grown in modified Hoagland nutrient solution with different Al concentrations ([AlCl3] 0 and 25 M) combined with different N forms for 12 h and then cut 9 1cm maize root apex for RNA extraction. For Arabidopsis, approximately 200 seedlings were grown in 2% modified MGRL agar solid-medium for 6 d, and then the plants were treated with different Al concentrations ([AlCl3] 0 and 20 M) combined with different N forms for 6 h.