Involvement of long non-coding RNAs in pear fruit senescence under high-and low-temperature conditions

Pear fruit senescence under high-and low-temperature conditions has been reported to be mediated by microRNAs.Long non-coding RNAs(lncRNAs),which can function as competing endogenous RNAs that interact with microRNAs,may also be involved in temperature-affected fruit senescence.Based on the transcriptome and microRNA sequencings,in this study,3330 lncRNAs were isolated from Pyrus pyrifolia fruit.Of these lncRNAs,2060 and 537 were responsive to high-and low-temperature conditions,respectively.Of these differentially expressed lncRNAs,82 and 24 correlated to the mRNAs involved in fruit senescence under high-and low-temperature conditions,respectively.Moreover,three lncRNAs were predicted to be competing endogenous RNAs(ceRNAs)that interact with the microRNAs involved in fruit senescence,while one and two ceRNAs were involved in fruit senescence under high-and low-temperature conditions,respectively.A dual-luciferase assay showed that the interaction of an lncRNA with a microRNA disrupts the action of the microRNA on the expression of its target mRNA(s).Furthermore,four alternative splicing-derived lncRNAs interacted with miR172i homologies(Novel_88 and Novel_69)to relieve the repressed expression of their target and produce an miR172i precursor.Correlation analysis of microRNA expression suggested that Novel_69 is likely involved in the cleavage of the pre-miR172i hairpin to generate mature miR172i.Taken together,lncRNAs are involved in pear fruit senescence under high-or low-temperature conditions through ceRNAs and the production of microRNA.

PbMC1a/1b regulates lignification during stone cell development in pear(Pyrus bretschneideri)fruit

Programmed cell death(PCD)and secondary cell wall(SCW)thickening in pear fruit are accompanied by the deposition of cellulose and lignin to form stone cells.Metacaspase is an important protease for development,tissue renewal and PCD.The understanding of the molecular mechanism whereby pear(Pyrus)metacaspase promotes PCD and cell wall lignification is still limited.In this study,the Metacaspases gene family(PbMCs)from P.bretschneideri was identified.PbMC1a/1b was associated with lignin deposition and stone cell formation by physiological data,semiquantitative real-time polymerase chain reaction(RT-PCR)and quantitative RT-PCR(qRT-PCR).Relative to wildtype(WT)Arabidopsis,the overexpression of PbMC1a/1b increased lignin deposition and delayed growth,thickened the cell walls of vessels,xylary fibers and interfascicular fibers,and increased the expression of lignin biosynthetic genes.Yeast two-hybrid(Y2H),bimolecular fluorescence complementation(BiFC)and GST pull-down assays indicated that the PbMC1a/1b protein physically interacted with PbRD21.Simultaneously,the transient expression of PbMC1a/1b and PbRD21 led to significant changes in the expression of genes and lignin contents in pear fruits and flesh calli.These results indicate that PbMC1a/1b plays an important role in cell wall lignification,possibly by interacting with PbRD21 to increase the mRNA levels of some lignin synthesis-associated genes and promote the formation of stone cells in pear fruit.

Cloning and Bioinformatics Analysis of PsSFBB Gene in Xinjiang Pear

[ Objective] This study aimed to clone the PsSFBB gene from Xinjiang pear for bioinformatics analysis. [ Method ] PsSFBB gene was cloned from an- thers of Qipan pear by using RT-PCR and RACE technologies for bioinformatics analysis. [Result] A SFBBt-α gene with a full-length of 1 231 bp was cloned and named PsSFBB6-α （Genbank accession number： EU909685）. PsSFBBt-ct gene encodes a protein of 378 amino acids, with an F-box motif composed of about 50 amino acids in the N-temfinal. According to the bioinformatics analysis, the molecular formula of PsSFB6-α protein is C2000 H3034 N517 O558S223, with relative molecu- lar mass of 43 987.5 and isoelectric point of 6.02, and the secondary structure is dominated by or-helices ; theoretically, the half life period is 30 h and the instabil- ity parameter is 55.21, so PsSFBB6-α protein is an instable protein ; in addition, it is predicted that PsSFBB6-α protein is a hydrophilic and non-secreted protein with lyases activity and specifically recognized substrates, which was consistent with the function of F-box protein. [ Conclusion] This study laid the foundation for further research on SFBB proteins and the mechanism of self-incompatibility and provided theoretical basis for breeding of self-compatible cultivars of Xinjiang pear and scientific arrangement of pollination trees in production to increase the yield and quality.