| Photoperiod sensitivity response is one of the important factors,which can affect whether flowering time of maize under different light lengths.Tropical maize germplasm is richer in genetic diversity than temperate germplasm,and has high combining ability and resistance,but it has the deficiency of strong photoperiod sensitivity.Maize nine leaf stage is the most sensitive period to light.It is important to analysis genome expression differences between tropical maize photoperiod sensitive and photoperiod insensitive inbred under different light conditions,which can provide more scientific proofs for understanding the molecular mechanism of photoperiod sensitive variation.In this study,light insensitive inbred line QR273 and light sensitive inbred line T32 were treated with long sunshine(LD: 16 h light / 8 h dark)and short sunshine(SD:8 h light / 16 h dark)respectively by manually controlling the light length,and the genomic expression differences of maize nine leaf stage were analyzed by transcriptome technology.The main research results are listed as:1.The evaluation of photoperiod sensitivity showed that under two different light conditions in Zhangye,Gansu Province and Sanya,Hainan Province,Tropical Maize Backbone lines T32 and QR273 showed strong photoperiod sensitivity and insensitive sensitivity respectively.Compared with the photosensitivity index of warm Maize Backbone Inbred lines,T32 and QR273 showed strong photoperiod sensitivity and insensitive sensitivity in tasseling stage,powdering stage,silking stage,plant height The photosensitive index of the six light sensitive related traits,panicle height and leaf number of the whole plant,showed a very significant difference.In this study,QR273 was used as control material and T32 was used as experimental material to study the genes related to photoperiod sensitivity.2.Through the analysis of transcriptome technology and bioinformatics methods,it can be seen that a total of 4735 genes are differentially expressed in the two materials under LD conditions,including 2079 genes that are significantly up-regulated and 2656 genes that are significantly down-regulated in T32.Under SD conditions,a total of 3024 genes were differentially expressed in the two materials,of which 1431 genes were significantly up-regulated and 1593 genes were significantly down regulated in T32.The differentially expressed genes of T32 under SD condition were lower than those under LD condition.3.Under different light conditions,the differentially expressed genes of circadian clock,response to light stimulation and response to radiation related biological functions were the most and reached a very significant level.4.In the circadian rhythm pathway,the main way to control maize flowering is GI-CO-FT.18 differentially expressed genes were screened under the LD condition.Proteins or enzymes that encode four major families: blue light receptor,photosensitive pigment,MYB transcription factor and ubiquitination ligase.10 of them were downregulated in T32 significantly: Zm00001e028469,Zm00001e023970,Zm00001e023799,Zm00001e012030,Zm00001e019815,Zm00001e032156,Zm00001e027418,Zm00001e015041,and so on.Zm00001e016975 and Zm00001e016746;Eight genes were significantly up-regulated in T32:Zm00001e026057,Zm00001e012154,Zm00001e030377,Zm00001e023792,Zm00001e021724,Zm00001e026443,Zm00001e008817 and Zm00001e001055.Among the 15 genes differentially expressed under SD conditions,encoding major blue light receptor,photosensitive pigment,nuclear proteins GI and ubiquitination ligase four family proteins or enzymes.4 genes were significantly down regulated in T32:Zm00001e002655,Zm00001e032156,Zm00001e016746,Zm00001e025454;11 genes were significantly up-regulated in T32: Zm00001e001055,Zm00001e011193,Zm00001e025891,Zm00001e041007,Zm00001e0009095,Zm00001e01671,Zm00001e010231,Zm00001e024573,Zm00001e012154,Zm00001e030377,Zm00001e034804.These genes play a key role in the growth,development and flowering of maize.Under the condition of LD,Zm00001e030377,Zm00001e023792 and Zm00001e021724 up-regulated in T32 encode E3 ubiquitination ligase and MYB transcription factor CCA1,which are flowering suppression genes.Zm00001e012030,Zm00001e019815,Zm00001e032156,Zm00001e027418,Zm00001e015041 and Zm00001e016746 up-regulated in QR273 encode FT protein,photosensitive pigment and light morphogenetic factor HY5,which are flowering promoting gene,which promotes flowering under LD condition.The 10 genes are important candidate genes to control the photoperiodic response of maize.5.Through the expression analysis of 10 light sensitivity related genes with known functions,it was found that under different light conditions,different light response related genes showed circadian oscillation expression patterns among different inbred lines.It may be one of the key genes of photoperiod sensitivity variation in tropical germplasm,and its function needs to be further verified. |
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