Cloning And Functional Analysis Of Cryptochrome La In Maize (Zea Mays L.)

Maize is not only an important crop,but also the C4 model plant with high photosynthetic efficiency.Cryptochromes(CRYs)are the blue light receptors in plants,which relate with seeding de-etiolation,flowering time,seed dormancy,and biological yield.Cryptochrome functions in Arabidopisis have been deeply elaborated,but CRYs in maize have not been studies.Since cryptochromes important effect on plant development,it is necessary to launch function exploration on maize cryptochromes.The cDNA sequences of two ZwmCRY1a genes were isolated from leaves of inbred line B73.The transcription abundancesof two ZrymCRY1a genes in different organs,and in response to different light treatments were detected by using quantitative RT-PCR(qRT-PCR);Bioinformatics analyses(DNAMAN and NCBI Blast)were employed to predict their function domains and to build a phylogentic relationship tree among plant cry1 homologs.Similar to cryl proteins from Arabidopsis thaliana(i.e.,AtCRY1)and Oryza sativa(i.e.,OsCRY1a),both ZmCRY1a proteins contained one DNA photolyase domain,one FAD binding 7 domain and one crytochrome C domain.Phylogenetic analysis indicated that two ZmCRYla proteins belong to the same branch with OsCRY1a,while shows low similarity to other CRY1 proteins from dicotyledonous species,such as Arabidopsis thaliana and Glycine max; Further quantitative RT-PCR(qRT-PCR)assays indicated that two ZmCRY1a genes were highest expressed in leaf with 52.1 or 6.2 times higher than ZmCRY1al abundance in root,respectively;their low levels of transcription abundances were detected in stem,stamen,pulvinus,sheath,and pedical.The transcription abundances of the both genes were very high under different continuous light conditions.In blue light,the both genes reached 9.5 and 9.0 times higher than the ZmCRY1a1 transcription abundance in the dark,respectively.Underfar-red light,they both were 6.3 and 8.3 times higher than the ZmCRY1a1 transcription level in the dark,respectively.Although encoding blue light receptors,they greatly respond to the light transitions from the dark to far-red or red light,During dark-to-far-red transition,the peak values of ZmCRY1a1 and ZmCRY1a2 were 4.8 and 3.9 times higher than the ZmCRY1a1 and ZmCRY1a2 transcription level in the dark,respectively.During dark-to-red transition,the peak values of ZmCRY1a1 and ZmCRY1a2 were 22.8 and 14.5 times higher than the ZmCRY1a1 and ZmCRY1a2 transcription level in the dark,respectively.In addition,their transcription abundances could also respond to photoperiod treatment(both long-day and short-day conditions).During the long-day treatment,ZmCRY1a1 transcription abundances had five peaks,three of them occurred after the B73 seedlings were transferred into the light phase for 4 h,8 h,and 12 h with 2.4,3.0,and 4.2 times higher than that in the dark,two of them came about when the seedlings were switched into the dark phase for 18 h and 12 h with 2.5 and 1.7 times higher than that of that in the dark two in dark,respectively.During the long-day treatment,ZmCRY1a2 transcription abundances had four peaks,three of them occurred after the seedlings were transferred into the light phase for 4 h,8 h,and 12 h with 4.0,4.4,and 6.6 times higher than that in the dark,one of them came about when the seedlings were switched into the dark phase for 18 h with 14.9 times higher than that of that in the dark two in dark,respectively.Both ZmCRY1a genes had two peaks in response to the short day treatment(5 to 6 times than their own expression in dark).The pBCXUN-ZmCRY1a1,pBCXUN-ZmCRY1a2 binary construct were electroporated into the Agrobacterium tumefaciens strain GV3101 and then introduced into Arabidopsis thaliana(both of the wild type and cry1-304 mutant)via a floral dip method,and harvested T0 generation seeds.Our results suggest that both ZmCRY1a genes may be involved in seedling de-etiolation and flowering time control,thus their roles in crop improvement and quality are worthy of more exploration in the future.