| UV induced anthocyanin synthesis as a kind of photomorphogenesis is regulated by light receptor signal pathway.It is known that in turnip the anthocyanin accumulation is induced by UV-A and synergism of blue+UV-B signaling besides known light receptor pathway.Meanwhile,blue+UV-B can increase the anthocyanin accumulation significantly.In order to identify the response of UV-A and blue+UV-B in non-model crop turnip,the transcriptional level changes were analyzed by RNA-seq data after different short wave length irradiation.Meanwhile,two EMS mutants with light-independent anthocyanin biosynthesis character were identified and after genetic analysis and gene mapping the main results were obtained as below:1.Differential expression analysis of anthocyanin biosynthesis related gene by RNA-seq under different short wave-lengths in turnipTo gain insight into regulation signaling of anthocyanin accumulation and the global transcriptional regulation induced by short-wavelength light,gene expression profiles were investigated in peels of turnip swollen root exposed to UV-A and blue +UV-B using RNA-seq.Among 41991 genes identified by RNA-seq,754 genes were specifically modulated by UV-A;three of these genes were anthocyanin biosynthetic structural genes:F3H1,CHI and ANS.By contrast,PAL,CHI,TT8 and PAP1the early structural genes of the anthocyanin biosynthetic pathway were modulated by both UV-A and blue + UV-B.Gene Ontology analysis manifested that non-specific signaling pathway ROS and cysteine biosynthetic process pathway were co-regulated with anthocyanin biosynthesis pathway under UV-A.This study provides a valuable overview of the transcriptome changes and gives insight into the genetic background that responsible for UV-A and blue + UV-B-induced anthocyanin biosynthesis in turnip.This study provides a valuable overview of the transcriptome changes and gives insight into the genetic background that responsible for UV-A and blue +UV-B-induced anthocyanin biosynthesis in turnip.2.Purple EMS mutant R15 identification,genetic analysis,and gene mappingA purple mutant R15 w-as obtained by chemical mutagenesis EMS.In R15,there was pigmentation on peel of storage root under the dark.QPCR result indicated that the anthocyanin biosynthesis related structural genes PAL,CHI,F3H1,UFGT,OMT,and regulator gene MYBL2 were all up regulated in sunlight and dark condition.Comparation analysis of the content of anthocyanine and flavonoid by HPLC manifested that the pigmentation under dark was caused by anthocyanin accumulation.Genetic analysis of the BC3F2 population showed the segregation of WT:mutant was 3:1.So the mutant trait in R15 was a single recessive quality trait.Resequencing and MutMap analysis indicated that the mutant interval was located in A01 chromosome 27.508M-28.622M and two functional SNPs,which caused the deletion of light response element GAG-motif were identified on the 5'UTR of PIP5K6 gene.It shown that the light repressor of PIP5K6 was induced in R15 mutant in sunlight by qPCR.Above all,PIP5K6 gene was probably the candidate gene for R15 mutant.3.White EMS mutant W68 identification,genetic analysis,and gene mappingA white mutant W68 was obtained by chemical mutagenesis EMS.In W68,there was no pigmentation on the peel of storage root under the sunlight.QPCR result indicated that the anthocyanin biosynthesis related structural gene CHS,DFR and regulator gene TT8 were all down regulated in sunlight condition.Genetic analyses of the back cross population shown the segregation of WT:mutant was all 3:1.So the mutant trait in W68 was a single recessive quality character.Resequencing and MutMap analysis indicated that the mutant interval was located in A07 chromosome 16Mb-20Mb and the mutagenesis of 486th nucleotide on the sixth exon of AAR2 homolog gene was identified.It encoded an amino acid Pro(CCT)changed to His(CAT).The expression of AAR2 homolog gene induced by UV-A but repressed in W68 mutant,but in WT.Above all,AAR2 homolog gene was probably the candidate casual gene for W68 mutant.All in all,there were two different signal pathways,UV-A and blue + UV-B induced anthocyanin biosynthesis on the peel of turnip storage root.Two EMS mutants R15 and W68 with light independent anthocyanin biosynthesis were obtained.the mutant gene in R15 and W68 probably involved in the light dependent anthocyanin biosynthesis.It also provided a research foundation for further study the UV-A and blue + UV-B induced anthocyanin biosynthesis... |
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