Small RNA sequencing identifies miRNA roles in ovule and fiber development

To dissect the roles of miRNAs in fiber development, we sequenced small RNAs from ovules -1 to +1 day post anthesis (DPA) and young leaves. A series of conserved and novel miRNA were identified from cotton EST database and the genome of G.raimondii, many of which were shown to be expressed differentially between ovule and leaf, indicating their potential roles in fiber development or leaf development. Cotton (Gossypium Hirsutum L.) cultivar TM-1 were grown in the greenhouse. Cotton ovules -1 to +1 day post anthesis (DPA) and young leaves were harvested for five biological replicates and immediately frozen in liquid nitrogen. They were then stored at -80°C following RNA extraction. Totals RNAs were extracted from each tissue sample using the mirVana miRNA isolation kit (Ambion, Austin, TX) according to the manufacturer’s protocol. The small RNA samples extracted from the five biological replicates were pooled together for leaf and ovule, respectively. Finally, the construction of pooled small RNA libraries and sequenced were performed by LC Sciences (Houston, TX) using Illumina high-throughput sequencing platform.