Identification and characterization of miRNAs during flag leaf senescence in rice by high-throughput sequencing

Abstract

Flag leaf is the last leaf to senesce and its life span plays a critical role in determining grain quality and yield in rice. Little is known about the molecular changes that occur and their regulation in time-dependent manner during flag leaf senescence in rice. Several studies have explored different aspects of miRNA functions in plant development; however, a diminutive account is available about their role in flag leaf senescence. With an aim to unravel the role of miRNAs in ageing of flag leaf in rice, four small RNA libraries were prepared from three stages of senescence and sequenced by Illumina deep sequencing technology. Thirty-eight known and 494 novel miRNAs were identified in the senescing flag leaves. Digital expression analysis revealed that 21 known and 116 novel miRNAs were differentially expressed during senescence. Family member(s) of miR156, miR159, miR160, miR164, miR169, miR171, miR393, miR396, miR535, miR827, miR1428, miR1432 and miR1861 were differentially expressed in at least one stage of flag leaf senescence. The present study has generated a repository of senescence-related miRNAs that can be utilized to contemplate molecular approaches for manipulating the timing of flag leaf senescence in rice and other related crops.