[biological_process] arbuscular mycorrhizal association <sep> nitric oxide biosynthetic process <sep> nodulation <sep> response to abscisic acid <sep> response to cold <sep> response to cytokinin <sep> response to ethylene <sep> response to hypoxia <sep> response to nitric oxide <sep> response to sucrose <sep> response to symbiotic bacterium <sep> response to symbiotic fungus