Root production by soybean cotyledons transformed using A. rhizogenes carrying amiRNA silencing constructs. A, Fayette cotyledons three weeks after treatment with A. rhizogenes pSM103 (control, plasmid carries A. thailiana miRNA319a lacking any known soybean target), or with A. rhizogenes pSM103 derivative carrying amiRNA GmLRR-K I. Representative explants are shown. B, Transformation efficiency reduction when A. rhizogenes deliver amiRNAs targeting the Rhg1-locus LRR-kinase gene. Efficiency is the % of treated cotyledons that produced at least one GFP7-positive root segment; * indicates significant difference from Fayette control (χ2-test, see text). Cotyledons transformed with pSM103 derivates carrying amiRNA GmLRR-K I developed roots approximately two weeks later than those transformed with the control pSM103 vector, and developed fewer roots per cotyledon. This effect was also present, but less dramatic in the cotyledons that received the amiRNA GmLRR-K II.