Construction of pSM103, a plasmid for amiRNA-mediate gene silencing in legume roots. pSM101 is an intron-GFP7 Agrobacterium-compatible binary plasmid for plant transformation, derived from pCAMBIA1300 by addition between T-DNA borders of a 35S promoter-erGFP7INT-NOS terminator (Mankin et al. 2001). pSM102 is pSM101 with a promoterless Arabidopsis miRNA miR319a gene. pSM103 is pSM102 with the miR319a driven by a promoter from the soybean ubiquitin-3 gene for strong expression in legume roots. After opening with PstI and BamHI to remove the miR319a, pSM103 can receive user-designed amiRNA gene silencing constructs from the widely used plasmid pRS300 (http://wmd3.weigelworld.org/; Schwab et al 2006), or other constructs.