Small RNAs from male strobili of Cryptomeria japonica.

Deep sequencing of small RNAs (sRNAs) expressed in developing male strobili of Cryptomeria japonica was performed in order to address the role of sRNAs in the male strobili development. The material trees were second-generation offspring originating from a naturally occurring nuclear genic male sterile tree. The material tree carries a recessive male sterile gene, which has not been isolated. The male sterile tree has a deficiency in the development of lamellar structure of microspores at the tetrad stage. sRNA samples of male strobili were isolated from two male sterile and two fertile offspring on five different sampling dates corresponding to the early pollen developmental stage.