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

Senescence is the ultimate stage of plant development. Among the different levels of senescence processes, flag leaf senescence plays a crucial role in determining grain quality in rice. In the present study, efforts are made to identify the possible involvement of miRNAs in flag leaf senescence. Four small RNA libraries were generated from different stages of flag leaf senescence and sequenced by Illumina deep sequencing. A total of 29 known miRNA families and 494 novel miRNAs were identified in the senescing flag leaves. 21 known and 116 novel miRNAs exhibited differential expression pattern. Computational prediction and analysis of putative targets of detected miRNAs revealed that miRNAs regulate the flag leaf senescence mainly by regulating transcription factors and hormone metabolism genes. The present study gives a clue about the senescence-associated miRNAs which can be used as a tool for manipulating flag leaf senescence in rice and other crops. Total four small RNA libraries of flag leaf senescence (US, ES, MS and LS) were constructed and high-throughput sequencing was performed using Illumina GA Iix system .