Evolutionary characteristics and expression patterns of miR156 gene family in Korla fragrant pear (Pyrus sinkiangensis Yu)

Abstract

ABSTRACTThe objective of the study was to understand the evolution characteristics of miR156 gene family and its expression patterns in calyx abscission zone (AZ) tissues of Korla fragrant pear (Pyrus sinkiangensis Yu). miR156 family of Korla fragrant pear (psi-miR156) was obtained through small RNA sequencing. We analysed the mature sequences and precursor sequence, constructed phylogenetic tree, predicted the secondary structure of precursors sequence, analysed their targets, as well as expression patterns. The results showed that miR156 family of Korla fragrant pear comprises 11 precursor sequences and 6 mature sequences. These precursor sequences can form a typical and stable stem-loop structure. Their minimum folding free energy ranges from −77.20 to −7.99 kal•mol−1. Multiple sequence alignment showed that miR156 family was highly conserved. Phylogenetic tree analysis indicated that the genetic relationship of psi-miR156 family was closer to those from apple and Arabidopsis thaliana. Psi-miR156 family was predicted to target SPL (Squamosa promoter-binding protein-like), cysteine protease, trihelix transcription factor. qRT-PCR showed that different members of psi-miR156 family had similar expression tendency in calyx AZ tissue. The expression level of miR156 was significantly increased on the fifth day of the late bloom stage, suggesting that the miR156 family may play a role in calyx persistence of Korla fragrant pear.Abbreviations: AZ: abscission zone; SPL: Squamosa promoter-binding protein-like; PP333: Paclobutrazol; C_1: The collected flowers on the first day of the late bloom stage with GA3 treatment; C_5: The collected flowers on the fifth day of the late bloom stage with GA3 treatment; C_9: The collected flowers on the ninth day of the late bloom stage with GA3 treatment; T_1: The collected flowers on the first day of the late bloom stage with PP333 treatment; T_5: The collected flowers on the fifth day of the late bloom stage with PP333 treatment; T_9: The collected flowers on the ninth day of the late bloom stage with PP333 treatment.