 This study aimed to identify new microRNAs, myrna's, in soybean that are regulated by water deficit and rust stress. Eight small RNA libraries were constructed from drought-sensitive and tolerant seedlings, rust-susceptible and resistant soybeans with or without stresses. Solexa sequencing was used to detect 256 myrna's, including 24 families of novel myrna's, six families of conserved myrna's, and 22 families previously reported in soybean. RTQPCR was performed to validate the expression profiles of 11 myrna's across all libraries. The results showed that most myrna's were up-regulated during water deficit stress in sensitive plants, while most were down-regulated in tolerant genotypes. In contrast, most myrna's were down-regulated during rust attack in the susceptible genotype, but not in the resistant one. The study provides molecular evidence for the involvement of myrna's in water deficit and rust stress responses in soybean. This article was authored by Nacimento Leandro Si, Abdelno Riccardo Vi, Mocellino Guimores Francis Marci, and others. We are article.tv, links in the description below.