Screening Of Mutation Related Genes In Sunflower Mutant Cb1

As an important oil and food crop,the development of sunflower is directly related to the reproduction of its offspring,and it also directly affects the benefits of agricultural production.In this paper,a preliminary study was performed on the sunflower male sterile mutant cb1 induced by space flight.In this mutant line,the floral organs could not be differentiated normally and a cauliflower-like inflorescence was formed.Based on comparing wild type(WT)sunflower and cb1 flower development,the mutation occurrence period was defined and mutation-related genes were screened during flower development by real-time fluorescence quantitative analysis of tissue expression patterns of related genes,and by comparing WT and cb1 expression levels in the four stages of flower development.The role of related genes for mutation formation was analyzed,and the conjecture of the molecular mechanism of mutation formation was proposed.Below are key research findings:(1)Through morphological dissection,6 bract-like structures were separated from the cb1 mutant,corresponding to 8 periods of WT sunflower flower development to fruit development,namely the shoot apical meristem period,floral primordium period,floral organ primordium period,middle stage of flower organ development,semi-maturity of flower organ,flowering stage,withering stage and ovary enlargement stage.(2)The morphological and histological analysis jointly found that the key period of cb1 phenotype and WT phenotype change is st3.(3)37 genes were screened out from the sunflower flower development transcriptome in our laboratory.They belong to LFY,AP2 family,SUP family and MADS-box family.Among these gene,1 belongs to LFY,10 to AP2,3 to SUP,and 23 to MADS-box gene,respectively.(4)A conjecture of the formation mechanism was put forward that after the SVP gene was up-regulated,the normal differentiation of inflorescence meristems into flower meristems was inhibited,and then the overexpression of LFY gene was activated,subsequently inflorescence meristems were continuously produced.At this time,AP2 is down-regulated by upstream genes,preventing the transformation of these inflorescence meristems.Afterwards,the SUP gene and the E-type MADS-box gene were down-regulated as genes regulating floral organogenesis,inhibiting the formation of floral organs.Finally,the down-regulation of genes controlling the development of major floral organs in AG and PI subfamilies led to the failure of floral organ development.In summary,the phenotypic analysis and quantitative analysis of related genes in the flower development of sunflower cb1 mutant were performed in this paper.It was found that the differentiation process of floral meristems into floral organs failed,correspondingly flower organs could not be produced normally,and bract-like structures and secondary meristems reappeared,resulting in cauliflower-like inflorescences.In addition,through the quantitative analysis of 37 related genes,a preliminary conjecture of the molecular mechanism of cb1 formation is proposed.It laid an important preliminary foundation for the subsequent research on the key mutant genes of cb1,and provided an important reference for studying the regulation mechanism of sunflower flower development and improving agricultural production efficiency.