Investigation Of Agronomic Characters And Physiological And Biochemical Analysis Of Tobacco Leaf Color Mutant Yl2

Tobacco is one of the important economic crops,Photosynthesis significantly affects its material accumulation and quality.Chlorophyll is the most important pigment in photosynthesis,the localization and cloning of chlorophyll accumulation genes will be provide theoretical and material support to the pigment-related genetic mechanisms and high-efficiency breeding.In this study,by studying the phenotype,physiological and biochemical studies,senescence Marker gene expression analysis、population genetic analysis and initial localization of yl2,a leaf early yellowing mutant produced by EMS ZY100 mutation,conducted to analyze the Physiological and biochemical,molecular regulation mechanisms and localization information of leaf color abnormal phenotype,the results are as follows:The agronomic traits of leaf color mutant yl2 in multiple periods after transplanting showed that the leaves of yl2 whole leaves were lighter than the leaves of the same part of the control,the middle and lower leaves of 58 days after transplanting began to show obvious yellowing phenotype,the plant appeared yellow in about 17 days in advance than control;the early yellowing of the leaves affected its growth and development,and the yl2 was significantly lower than Control in the agronomic indicators such as plant height,stem circumference,pitch,number of leaves,maximum leaf length and maximum leaf width.The chlorophyll content,chlorophyll fluorescence parameters,protein content and ion leakage rate of tobacco leaves from multiple periods and locations after transplanting were tested,the results showed that the chlorophyll content,chlorophyll fluorescence parameters and protein content of yl2 were lower than the same period in the whole field in control ZY100,yl2 and control chlorophyll content,chlorophyll fluorescence parameters and protein content increased first and then decreased with the transplanting time,but the highest value of chlorophyll content and chlorophyll fluorescence parameters of yl2 appeared in 50 days,the control was advanced for 15days,while the yl2 protein content and the control showed the highest value at the same time;the ion leakage rate of yl2 was higher than that of the control ZY100 at each period,and the difference between the control was the highest at 65 days after transplanting.The results of transcriptional level detection of SAG12 and RBCS related to aging in yl2 showed that the expression level of SAG12 in yl2 during each field period was higher than that of ZY100 during the same period;The expression of RBCS was lower than ZY100 during the same period.yl2 mutants showed significantly higher senescence than controls,YL2 genes may be involved in the same process as SAG12and RBCS,which jointly regulate leaf senescence.The genetic analysis of two F₂ generation isolates constructed by yl2hybridization with CB-1、yl2 hybridization with GX-3 showed that both F₁ plants generation plants presented normal phenotype,and the normal phenotype and early yellowing phenotype of F₂ generation plants separation ratio were 3:1,it is indicated that the phenotype of early yellow flower was controlled by a pair of recessive nuclear genes.The YL2 gene was preliminarily located by mapping cloning technology,the results showed that YL2 gene was located in the 24th linkage group,and was separated from SNP markers c19-10 and c19-7 by 12c M and 15c M.The localization results provided a basis for further fine mapping and cloning of the YL2 gene.