Heterologous Transformation Of Arabidopsis HFR1 In Maize And Transcriptional Responses Of Its Two Maize Homologous Genes In Response To Different Light Treatments

Light signals such as light intensity,light quality and duration in the environment regulate plant growth and development and crop yield traits.In the Arabidopsis thaliana,HFR1 is a b HLH transcription factor that plays an important role downstream of either far-red light receptor PHYA,blue light receptor CRY1 and UV-B receptor UVR8.It can participate in plant growth and development processes such as seed germination,photomorphogenesis,flowering induction,shade avoidance response and leaf senescence.We heterologous expression of the Arabidopsis HFR1 in maize with the aim of improving maize by altering its light signaling pathway.Compared with non-transgenic plants,the plant height and ear position of the HFR1 maize transgenic lines decreased by 26.8% and 22.5%,respectively.And the number of internodes decreased by 2.5.The results showed that it could effectively change the plant type by heterologous expressing of HFR1 in maize.In addition,we used the amino acid sequence of Arabidopsis HFR1 to align on the Maize GDB website.We found two b HLH transcription factors which are most closely related to HFR1 in maize,named Zm PIF-La and Zm PIF-Lb,respectively.To explore their functions,we cloned the two Zm PIF-L genes from the maize inbred line B73 by RT-PCR.The domain prediction and phylogenetic tree of Zm PIF-L were analyzed by the bioinformatics website.We further analyzed the transcriptional abundances of two Zm PIF-L genes in different tissues and their response to different light qualities and photoperiods by real-time quantitative PCR.We found that Zm PIF-La and Zm PIF-Lb encode DNA fragments of 1689 bp and 558 bp,respectively.Either the maize Zm PIF-L proteins or other common plant HFR1 proteins have only one b HLH domain,and those sequences shared high amino acid sequence identity.But their consistency of full-length sequence was extremely low,indicating that they might have serious functional differentiation.Zm PIF-La and Zm PIF-Lb genes were mainly expressed in maize stems,bracts and leaves.Both Zm PIF-La and Zm PIF-Lb could respond to different light qualities and photoperiod treatments,while the expression patterns of two genes differed among different treatments.These results indicate that Zm PIF-L had got functional differentiation in maize.Taken together,the two Zm PIF-L genes have distinct expression patterns in response to different light treatments.Zm PIF-La could rapidly respond to various light treatments,while Zm PIF-Lb has a sustained response to various light treatments.These results indicate that PIF-L had got functional differentiation in maize.This study provides a foundation for exploring the functions of Zm PIF-La and Zm PIF-Lb genes and their application in maize variety improvement.