title: A cost-effective method for Illumina small RNA-Seq library preparation using T4 RNA ligase 1 adenylated adapters.
abstract: BACKGROUND
  Deep sequencing is a powerful tool for novel small RNA discovery. Illumina small RNA sequencing library preparation requires a pre-adenylated 3' end adapter containing a 5',5'-adenyl pyrophosphoryl moiety. In the absence of ATP, this adapter can be ligated to the 3' hydroxyl group of small RNA, while RNA self-ligation and concatenation are repressed. Pre-adenylated adapters are one of the most essential and costly components required for library preparation, and few are commercially available.
  
  
  RESULTS
  We demonstrate that DNA oligo with 5' phosphate and 3' amine groups can be enzymatically adenylated by T4 RNA ligase 1 to generate customized pre-adenylated adapters. We have constructed and sequenced a small RNA library for tomato (Solanum lycopersicum) using the T4 RNA ligase 1 adenylated adapter.
  
  
  CONCLUSIONS
  We provide an efficient and low-cost method for small RNA sequencing library preparation, which takes two days to complete and costs around $20 per library. This protocol has been tested in several plant species for small RNA sequencing including sweet potato, pepper, watermelon, and cowpea, and could be readily applied to any RNA samples.
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, 14853, USA. sz284@cornell.edu.
authors.forename: Yun-Ru
authors.initials: YR
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Bao
authors.initials: B
authors.lastname: Liu
authors.forename: Silin
authors.initials: S
authors.lastname: Zhong
authors.forename: Jim
authors.initials: J
authors.lastname: Giovannoni
authors.forename: Zhangjun
authors.initials: Z
authors.lastname: Fei