Cloning And Functional Characterization Of CibHLH027 Involved In Leaf Senescence From Caragana Intermedia

Leaf senescence is the last phase of plant development,and it is also an essential stage to respond actively.When plants suffer from abiotic stresses,such as dark,drought,extreme temperature etc.,leaf senescence is accelerated,which may influence the plant growth and crop yield.Genetic engineering has been utilized to improve plants tolerance to stresses,enhance its ability to adapt to the environment,and postpone senescence effectively.The species Caragana has strong tolerance to cold,drought,and heat,given its ability to adapt to a variety of adverse factors in environment.It is an ideal of vegetation to improve the ecological environment,and becomes the preferred material for studying the mechanism of resistance.In this study,a bHLH encoding gene CibHLH027 was screened from the transcriptome library of Caragana intermedia under drought treatment and it function was characterized.The main results are as following:1.The ORF(open reading frame)of CibHLH027 is 738 bp,which encodes 245 amino acid,the initiation codon is ATG,the termination codon is TGA.The phylogenetic analysis including all Arabidopsis bHLH proteins and CibHLH027 showed that CibHLH027 shared 58%and 52%identities with AtbHLH027 and AtbHLH03.5 respectively.In the meantime,the multiple sequences alignment and phylogenetic analysis of bHLHs from different plants which shared highest identities with CibHLH027 revealed that all the N-termini domains of these bHLH proteins have N-E-R motif,and CibHLH027 shared 90%identities with CabHLH035 from Cicer arietinum.2.The expression of CibHLH027 was induced by ABA,NaCl,high pH,heat,darkness and drought.Subcellular localization using Arabidopsis mesophyll protoplast transient expression system indicated that CibHLH027-GFP localized in the nuclei.3.Overexpression of CibHLH027 promoted the leaf senescence in detached rosette leaves or the whole plant with darkness,with reduced chlorophyll content,increased ion leakage and cell death,and compared with wild type,the tolerance of CibHLH027 transgenetic line compromised obviously under drought stress.